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gaetanomarano
2006-Sep-14, 12:25 AM
.

I think that the NASA/ESAS/LockMart Orion's Service Module design has a GIANT mistake built-in!

I explain my opinion in my latest article here: www.gaetanomarano.it/articles/013orionSM.html

The new Orion's SM design is different from Apollo since (now) it can't perform (both) the Lunar Orbit Insertion and Trans Earth Injection with MANY safety and operational problems for the astronauts and moon missions.

The most dangerous issue of this (bad!) choice is that, if the LSAM engines will fail in LOI, the Orion will have not sufficient propellant to enter the lunar orbit or ONLY the propellant for that operation (without the LSAM docked) but NOT for TEI to come back to earth!

.

Bob B.
2006-Sep-14, 12:48 AM
The most dangerous issue of this (bad!) choice is that, if the LSAM engines will fail in LOI, the Orion will have not sufficient propellant to enter the lunar orbit
If the LSAM engines fail then what's the point of entering lunar orbit?

captain swoop
2006-Sep-14, 01:05 AM
Has NASA done anything good? or are they just a bunch of know nothings who should just give up and go ohome?? Why do u disagree with everything they seem to do?? why should we give your ideas mor ecredancew than the professionals who have the experience, training and education in the subject?

gaetanomarano
2006-Sep-14, 01:11 AM
If the LSAM engines fail then what's the point of entering lunar orbit?

to save the astronauts' life (with a bigger SM they will have a second chance for LOI and the fuel for TEI)

.

gaetanomarano
2006-Sep-14, 01:17 AM
Has NASA done anything good?
MANY THINGS, great part of them!
and the best is the Apollo project that was perfect and successful despite many "too young" technologies was used
why do they change so much to accomplish the same missions?

Why do u disagree with everything they seem to do?
on all space forums and blogs there are peoples that agree with NASA (or ESA) choices and people that disagree... where is the problem?

professionals who have the experience, training and education in the subject?
in fact, they have already changed many (previuously bad) choices

Bob B.
2006-Sep-14, 01:30 AM
to save the astronauts' life (with a bigger SM they will have a second chance for LOI and the fuel for TEI)
Why go into orbit if there is a non-functioning LSAM? It seems you want to go into orbit just to leave orbit. What's the point in that? Just swing around the Moon and come straight home.

gaetanomarano
2006-Sep-14, 01:43 AM
Why go into orbit if there is a non-functioning LSAM? It seems you want to go into orbit just to leave orbit. What's the point in that? Just swing around the Moon and come straight home.

the Orion missions are not like the Soyuz tourists' fly-around missions or the SMART-like crash (or land-direct) missions
they will have a lunar insertion trajectory and will discover only in the last minuts if the LSAM engines will work or not
also, you must look at the full list of problems of a small SM:
- no rescue missions (after the surface missions end) with a remote-controlled Orion
- no small cargo sent around the moon
- no emergency life support (or fuel, istruments, etc.) sent to an orbital LSAM, Orion or Lunar Space Station
- no (manned or unmanned) Apollo-8-like flights for tests, LSS crew rotation, orbital science, etc.
- no big (experiments, instruments, moon samples, etc.) 3+ mT cargo-return from lunar orbit/surface but only a (30 times small) 220 lbs. Orion cargo
- less lunar life support and/or exploration hardware sent on the moon (to have TWICE the exploration time and quality with the SAME price!)
- a bigger AresV that must use the 5-segments SRB
- etc.
the Apollo-like SM has so many safety and operational advantages that I (really!) wonder why it was not adopted from the first ESAS plan!!!

and don't forget that a bigger SM needs a 40 mT paylaod Ares-I able to launch one ISS-Orion + one SM-light + 15 mT of cargo with a SINGLE rocket (like FOUR-FIVE cargo+crew launches for the price of ONE!!!) or... a small cargo lander on the moon (without spend 5+ times to launch an AresV+cargoLSAM) or... 40 mT interplanetary probes, or... two new ISS modules with ONE launch... etc.

Bob B.
2006-Sep-14, 03:34 AM
the Orion missions are not like the Soyuz tourists' fly-around missions or the SMART-like crash (or land-direct) missions
they will have a lunar insertion trajectory and will discover only in the last minuts if the LSAM engines will work or not
If the LSAM engines don't work the vehicle will swing around the Moon and start heading back in the general direction of Earth. At that point we just jettison the LSAM and perform a course correction to put Orion on the right trajectory for a safe return.


the Apollo-like SM has so many safety and operational advantages that I (really!) wonder why it was not adopted from the first ESAS plan!!!
I suspect one of the main reasons is because Orion is using hypergolic propellants and the LSAM is using LOX/liquid hydrogen. This means the LSAM has a more efficient propulsion system and can perform LOI with less propellant. This reduces the overall mass of the lunar payload, which is a very important benefit.

gaetanomarano
2006-Sep-14, 04:11 AM
I suspect one of the main reasons is because Orion is using hypergolic propellants and the LSAM is using LOX/liquid hydrogen. This means the LSAM has a more efficient propulsion system and can perform LOI with less propellant. This reduces the overall mass of the lunar payload, which is a very important benefit.

I don't suggest to change the LSAM propellant, only to resize its tanks and weight to have a small (but useful) increase of the payload (and THIS is a real benefit!)

the Orion propellant may weight more, but it will be launched with another (bigger) rocket (that can be used in many different, all very useful, ways)

Nicolas
2006-Sep-14, 07:54 AM
and the best is the Apollo project that was perfect and successful despite many "too young" technologies was used
why do they change so much to accomplish the same missions?

Says the man who attacks NASA on chosing a conical capsule like they did successfully for Apollo.

gaetanomarano
2006-Sep-14, 08:08 AM
Says the man who attacks NASA on chosing a conical capsule like they did successfully for Apollo.

if you take a look at the ESAS plan (from the links Bob B. posted in the EggCEV thread) you discover that NASA (not me!) has tested different shapes for the new Orion (but not a full "egg") that means a cone is not the only possible shape

I'm not against changes, the use of the low cost and powerful SRB (in the 4-seg. version) is a good change ...and the small SM is a BAD change (in my opinion, of course)

also, I DON'T "attack" NASA but I only write critics and suggestions (that is a different thing)

Grand_Lunar
2006-Sep-14, 01:19 PM
I don't believe you give the NASA engineers and contractors enough credit.

They're certain to have solutions to the so-called mistakes you see in the design.

Besides, it's best to wait for it to fly before making snap judgements.

Bob B.
2006-Sep-14, 02:18 PM
I don't suggest to change the LSAM propellant, only to resize its tanks and weight to have a small (but useful) increase of the payload (and THIS is a real benefit!)

the Orion propellant may weight more, but it will be launched with another (bigger) rocket (that can be used in many different, all very useful, ways)
Switching the LOI burn to Orion will decrease payload. How much total mass can be sent to the Moon is limited by the Earth Departure Stage (EDS), thus there is a finite maximum. Orion will require more propellant mass to perform the LOI burn than if it were performed by the LSAM. Since the total mass of the CEV+LSAM cannot increase, increasing propellant mass requires that the spacecraft itself must decrease in size. Here's an example:

The numbers I've heard places the CEV (Orion) mass at around 23 mT and the LSAM at around 33 mT for a total of 56 mT, which is the maximum the EDS can send to the Moon. I don't know the specific impulses of the propulsions systems, but let's assume 315 s for the CEV and 425 s for the LSAM, which are reasonable numbers for the proposed propellants. NASA has budgeted 1,100 m/s for the LOI burn. If the LSAM performs the LOI burn, the amount of payload remaining after the burn is,

Mf = Mo*e^-(dV/(Isp*g))

Mf = 56,000*e^-(1,100/(425*9.807))
Mf = 43,010 kg

And if the CEV performs the burn,

Mf = 56,000*e^-(1,100/(315*9.807))
Mf = 39,223 kg

We therefore have a 9% decrease in useful payload by using the CEV to perform the LOI burn.

Doodler
2006-Sep-14, 02:54 PM
Good God, what a strawman. Whether the LSAM is on the Service Module or an independent module means precisely SQUAT as to whether the mission is screwed if it fails. The mission is hosed on an LSAM failure either way, so what, pray tell, is the point of this conversation?

gaetanomarano
2006-Sep-14, 04:53 PM
I don't believe you give the NASA engineers and contractors enough credit.
they have made a "plan" one year ago, then, they have changed it in many (little and big) points... that means they have made some "mistakes" and corrected them

...it's best to wait for it to fly before making snap judgements.
too late to discover mistakes (if there are...)

gaetanomarano
2006-Sep-14, 05:02 PM
Switching the LOI burn to Orion will decrease payload. How much total mass can be sent to the Moon is limited by the Earth Departure Stage (EDS), thus there is a finite maximum. Orion will require more propellant mass to perform the LOI burn than if it were performed by the LSAM. Since the total mass of the CEV+LSAM cannot increase, increasing propellant mass requires that the spacecraft itself must decrease in size.
I've evaluated that thinking to the lower hypergolic efficiency
probably the change I suggest needs a different EDS (maybe, with two J-2x and a larger tank) but the (safety and operational) advantages are so many that worth the change
about the LSAM, I've read that its weighit is 45 mT

gaetanomarano
2006-Sep-14, 05:08 PM
...mission is hosed on an LSAM failure either way, so what...
not true, the LSAM fail to LOI may be not a definitive LSAM failure
if the space-convoy enter the lunar orbit (with an SM burn) the astronauts can verify if the LSAM can be used or not without a full and immediate mission abort

Bob B.
2006-Sep-14, 05:23 PM
they have made a "plan" one year ago, then, they have changed it in many (little and big) points... that means they have made some "mistakes" and corrected them
Designing a mission is all about making trades, thus to get one thing often means sacrificing something else. There is often a fine line between option A and option B. As the mission parameters develop sometimes different trades are selected. That doesn't mean the first decision was a mistake; it just seemed like the better option at the time for one reason or another. Flip-flopping between trades is a normal part of mission development and shows that all options are being considered.

gaetanomarano
2006-Sep-14, 05:29 PM
...That doesn't mean the first decision was a mistake; it just seemed like the better option at the time for one reason or another...
I think that every time a choice is better for safety and operational work the previous choice was (clearly) "a mistake" while, if two design have the same performances and advantages, they are (simply) two "alternative choices"

Bob B.
2006-Sep-14, 05:33 PM
I've evaluated that thinking to the lower hypergolic efficiency
probably the change I suggest needs a different EDS (maybe, with two J-2x and a larger tank)
Increasing the EDS size means you need a bigger rocket to get it into orbit. And no matter what the size of the EDS, you will always get more payload into lunar orbit using the higher efficiency LSAM engines for LOI than you will using the CEV engines. Furthermore, there is probably no greater a chance of a LSAM engine failure than there is of a CEV engine failure, so I see no advantage to making such a change. A failure is a failure no matter what engine is used.

gaetanomarano
2006-Sep-14, 05:40 PM
...Furthermore, there is probably no greater a chance of a LSAM engine failure than there is of a CEV engine failure, so I see no advantage to making such a change.
no, with a bigger SM we have two chances for LOI (Orion or emergency-LSAM) and great part of the advantages are in the (manned or unmanned, crew or cargo) missions that an bigOrion can accomplish alone, without launch (everytime) a big AresV and an expensive LSAM for LOI

JMV
2006-Sep-14, 05:58 PM
no, with a bigger SM we have two chances for LOI (Orion or emergency-LSAM)
If this bigger Orion SM fails and is not able to perform LOI, it surely wouldn't be able to perfom TEI either. In that case why would they go into lunar orbit with LSAM in the first place? They wouldn't be able to both land on the moon and get back.

R.A.F.
2006-Sep-14, 06:01 PM
they have made a "plan" one year ago, then, they have changed it in many (little and big) points... that means they have made some "mistakes" and corrected them.


I think that every time a choice is better for safety and operational work the previous choice was (clearly) "a mistake"...

Why do you insist on using the word "mistake"? I don't see where you have justified it's usage in this particular discussion.

Doodler
2006-Sep-14, 06:07 PM
I don't think he gets the difference between design refinement and error correction. There's nothing to say that any previous iteration of the system wouldn't work, only that a newly considered alternative works better.

I also wonder if he's honestly aware that the design process is more than heading for the men's room with a newspaper and sitting there until a fully scoped design pops into your head in a moment of relieved inspiration.

The odds of a first draft design being the same one that actually does the job are slightly higher than waking up one morning and discovering you changed gender overnight. Even during the Apollo missions, the first versions of the LEM that went up were absolutely incapable of performing their ultimate task because the designs for them were still evolving through revision and adjustment.

gaetanomarano
2006-Sep-14, 06:30 PM
If this bigger Orion SM fails and is not able to perform LOI, it surely wouldn't be able to perfom TEI either.
with two similar vehicles (both) with sufficient propellant for LOI and TEI (and a good sofware...) they will have two chances
however, if the bigOrion will fail the LOI, the LSAM must be used only for TEI and the mission will be aborted
in future we can hope to have a small docking/repair/refuel station to avoid any loss of mission

gaetanomarano
2006-Sep-14, 06:34 PM
Why do you insist on using the word "mistake"? I don't see where you have justified it's usage in this particular discussion.
I've not posted the full article (http://www.gaetanomarano.it/articles/013orionSM.html)
I think that the lack (with a small SM) of a (possible) rescue-mission with a remote-controlled 2nd Orion already is (by itself) a very good reason to define the small SM "a mistake"

gaetanomarano
2006-Sep-14, 06:42 PM
I don't think he gets the difference between design refinement and error correction.
I know that some changes are only "refinements" but I can't avoid to define other choices "mistakes" if (I think) they are less safe or have less options or need too much time or too much money of a better design
why have not the best?

Doodler
2006-Sep-14, 06:52 PM
I know that some changes are only "refinements" but I can't avoid to define other choices "mistakes" if (I think) they are less safe or have less options or need too much time or too much money of a better design
why have not the best?

Ok, so how, without revision and design change, do you start with a concept and end up with the best design?

My earlier comment about the first draft being the final draft stands. Revisions will be made, ideas will be examined, found to be inadequate, and changed again.

These are not mistakes, these decisions which are a legitimate part of the design process.

JMV
2006-Sep-14, 07:02 PM
with two similar vehicles (both) with sufficient propellant for LOI and TEI (and a good sofware...) they will have two chances
however, if the bigOrion will fail the LOI, the LSAM must be used only for TEI and the mission will be aborted
in future we can hope to have a small docking/repair/refuel station to avoid any loss of mission
Why should the Orion be able to do LOI?

If LSAM fails they won't go to lunar orbit and there is no need for LOI and TEI. Free-return trajectory would just swing them around the moon and bring the astronauts back home. If they're not on free-return-trajectory at the time, Orion can perfrom a simple correction burn to put the spacecraft on one.

Bob B.
2006-Sep-14, 07:03 PM
with two similar vehicles (both) with sufficient propellant for LOI and TEI (and a good sofware...) they will have two chances however, if the bigOrion will fail the LOI, the LSAM must be used only for TEI and the mission will be aborted in future we can hope to have a small docking/repair/refuel station to avoid any loss of mission
LOI is basically one shot that occurs near pericynthion on the first pass around the Moon's far side. If the engine fails there is not time to turn 180-degrees around and use the alternative engine. And besides, doing so is totally pointless.

In your scenario the CEV performs LOI. If the CEV engine fails and you use the LSAM for LOI (which I don't think is even possible considering the timing), then you can't land on the Moon because the LSAM no longer has enough propellant. So why did you bother going into lunar orbit? You now have to make one more burn to leave lunar orbit, thus increasing your odds of a further failure. Going into orbit following an engine failure makes zero sense. The odds of a safe return are best if you just swing around the Moon and get on a course for Earth.

Nicolas
2006-Sep-14, 07:06 PM
I think that every time a choice is better for safety and operational work the previous choice was (clearly) "a mistake" while, if two design have the same performances and advantages, they are (simply) two "alternative choices"

IMO there is a difference betzeen a less optimal option and a mistake.

stutefish
2006-Sep-14, 07:27 PM
IMO there is a difference betzeen a less optimal option and a mistake.

IMO there is a difference between a less optimal option and Gaetano's claims of a less optimal option.

That difference being the proof of his claims that Gaetano says he lacks the budget and expertise to provide.

Bob B.
2006-Sep-14, 07:30 PM
IMO there is a difference betzeen a less optimal option and a mistake.
Gaetanomarano is also not considering the ripple effect. A single change in one trade may necessitate further changes elsewhere. Those additional changes do not mean mistakes were made; in fact, the original decisions may have been exactly right for the original parameters. However, when a parameter changes then the right choice for some related item may be different than originally decided.

Nicolas
2006-Sep-14, 07:35 PM
Against all expectations, it boils down to the design process, featuring things such things as a design option tree, trade-off review, resource allocation, and other things unseen here.

Doodler
2006-Sep-14, 07:40 PM
Against all expectations, it boils down to the design process, featuring things such things as a design option tree, trade-off review, resource allocation, and other things unseen here.

Yup, as I've pointed out previously. I see that kind of thing happen on a daily basis. Some of the buildings my office has done the design work for change shape on paper on a dozen times or more before a working design is chosen. Even then, requirements of the permit approval process, realities in the field which were unforseen, and even the client's budget, can have ripples even as the building is going up.

Nicolas
2006-Sep-14, 07:46 PM
I've seen an aircraft transforming from regular to extreme canard, before concluding the original shape was the winner, in a few weeks time :)

That doesn't mean the Canard was a mistake. It was a promising option, that did not live up to expectations compared to other alternatives. It was shown to be a less optimal option, but given the info at hand earlier in the design process, pursuing that idea a bit further was no mistake.

Had it already been proven it was inferior in a general sense with no sign of improvements, then it would have been a mistake to put lots of extra effort in that option.

On top of that, the canard design proved to be extremely ripple sensitive. Changing the canard wings alters the vertical tailplanes alters the wings alters the fuselage alters the stability alters the canard wings alters the vertical tailplanes.....you get it.

gaetanomarano
2006-Sep-14, 09:40 PM
These are not mistakes, these decisions which are a legitimate part of the design process.
that's true only if the revisions and design changes end with the best choice but the final choice for the SM is not the best, then, it's a mistake (in my opinion, of course)

gaetanomarano
2006-Sep-14, 09:49 PM
...If the engine fails there is not time to turn 180-degrees around and use the alternative engine...
that's true with the '60s (manual-driven) Apollo technology
with the fast and 100% automatic Orion technology, rotate the convoy and burn the LSAM will be a matter of seconds

...Going into orbit following an engine failure makes zero sense. The odds of a safe return are best if you just swing around the Moon and get on a course for Earth.
only with an Apollo-like vision, but, in future, we can imagine that a failed SM and a burned LSAM can wait weeks docked to a lunar station waiting for a spare Orion and an LSAM refuel (without abort the mission nor risk the astronauts' life)
similar scenarios can't never happen without BETTER designed vehicles

Doodler
2006-Sep-14, 09:51 PM
that's true only if the revisions and design changes end with the best choice but the final choice for the SM is not the best, then, it's a mistake (in my opinion, of course)

Its a mistake if it doesn't work. If it works less efficiently, its a compromise.

gaetanomarano
2006-Sep-14, 09:53 PM
IMO there is a difference betzeen a less optimal option and a mistake.
a "less optimal option" become "a mistake" when it's used in the final version (like sell the latest computer operating system version with all bugs found in the beta versions)

gaetanomarano
2006-Sep-14, 09:57 PM
...is also not considering the ripple effect. A single change in one trade may necessitate further changes elsewhere...
but we are in early days of the "plan" ...if changes are not made now, when they can?

gaetanomarano
2006-Sep-14, 10:03 PM
Its a mistake if it doesn't work. If it works less efficiently, its a compromise.
but I don't see any reason for that compromise since the change doesn't modify so much the time, costs, weight, etc.
it's only BETTER

gaetanomarano
2006-Sep-14, 10:08 PM
I've seen an aircraft transforming from regular to extreme canard, before concluding the original shape was the winner, in a few weeks time.
in the Orion's case, the ESAS design IS the canard (and I suggest to change it to the, better, apollo-like design... in a few weeks time...)

Bob B.
2006-Sep-14, 10:29 PM
only with an Apollo-like vision, but, in future, we can imagine that a failed SM and a burned LSAM can wait weeks docked to a lunar station waiting for a spare Orion and an LSAM refuel (without abort the mission nor risk the astronauts' life)
similar scenarios can't never happen without BETTER designed vehicles
The billions of dollars spent to design for a 1 in 1000 contingency is probably far more than the cost of simply aborting 1 in 1000 missions. Designing for an extremely costly and difficult refueling operation in the remote possibility it may be needed doesn't make economic sense to me.

gaetanomarano
2006-Sep-14, 10:35 PM
The billions of dollars spent to design for a 1 in 1000 contingency is probably far more than the cost of simply aborting 1 in 1000 missions.
safer missions is not the only reason to have better vehicles
in future, the best scenario is to have some reusable-LSAMs docked to a lunar orbit station so only some cargo and crew Orion will be sent form earth
that (very efficient and cost saving) scenario needs an autonomous Orion with a bigger SM and the better Orion must be made NOW since it will fly unmodified in the next 30+ years!

Bob B.
2006-Sep-14, 11:29 PM
only with an Apollo-like vision, but, in future, we can imagine that a failed SM and a burned LSAM can wait weeks docked to a lunar station waiting for a spare Orion and an LSAM refuel (without abort the mission nor risk the astronauts' life)
I just thought of another flaw in this logic. In your scenario the LSAM is used for LOI only if the CEV engine fails. In that case, refueling the LSAM does you no good. After the LSAM lands and returns to orbit its tanks are now empty and you have a non-functioning CEV engine to get back home. Furthermore, the more powerful descent stage engine has been left behind on the surface. If you could somehow refuel the LSAM again, you only have the small ascent stage, which is likely not adequate for TEI. Your scenario seems unworkable and filled with unacceptable risk.

R.A.F.
2006-Sep-14, 11:51 PM
Your scenario seems unworkable and filled with unacceptable risk.

In other words...


...wait for it...


...gaetanomarano's scenario is a mistake. :)

JMV
2006-Sep-15, 12:06 AM
I just thought of another flaw in this logic. In your scenario the LSAM is used for LOI only if the CEV engine fails. In that case, refueling the LSAM does you no good. After the LSAM lands and returns to orbit its tanks are now empty and you have a non-functioning CEV engine to get back home.
That's what I was after with my first post. If the CEV fails and they spend the LSAM propellant for lunar landing and ascent they won't be able to get back to Earth.

captain swoop
2006-Sep-15, 01:06 AM
hhm! I suppose NASA gets its Rocket Scientists and Engineers at a Yard sale from this thread!

Boxes
2006-Sep-15, 01:12 AM
only with an Apollo-like vision, but, in future, we can imagine that a failed SM and a burned LSAM can wait weeks docked to a lunar station waiting for a spare Orion and an LSAM refuel (without abort the mission nor risk the astronauts' life)
similar scenarios can't never happen without BETTER designed vehicles

I'm no rocket surgeon, and I think this has been alluded to by other posters. If the Orion engines fail on LOI, you are already on a close course to Earth, only minor corrections are required. In the future you may be able to do LOI with the LSAM and dock with a Lunar station, but you still wouldn't unless life support is compromised. This is because you now have no backup. If you get halfway through an LOI burn and now lose the LSAM thrust you are in it deep. Better to head for Earth and hope the LSAM will handle the minor changes needed for return.

Would you need the main LSAM engines for course correction, or are there secondary thrusters planned which would handle this?

PhantomWolf
2006-Sep-15, 01:27 AM
I have a very couple of simple questions for you gaetanomarano.

- What is your formal education in Engineering and what Qualifications in this field do you hold?
- What is your professional experience in the area of Areospace?
- What working space vehicles have you either designed and developed yourself, or been part of a team in designing and developing? This is to only include ones that have actually been designed, built and are currently in service or have been previously in service by any space agency, public or private.

Nicolas
2006-Sep-15, 08:03 AM
in the Orion's case, the ESAS design IS the canard (and I suggest to change it to the, better, apollo-like design... in a few weeks time...)


The difference here is that we worked full shifts with a team for weeks to determine that it was a less optimal design, through hard engineering. I have seen no such effort from you, so even if your conclusion is correct, there's a LOT less certainty to it. I assumethe NASA engineers did do their job and took more effort in comparing solutions than you did. You can't possibly know all aspects in the design option tree. And small aspects can be very important.

captain swoop
2006-Sep-15, 10:04 AM
It seems to me to be an example of starting with the result you want then trying to work back from it.

Nicolas
2006-Sep-15, 11:04 AM
Picking in to that, it was hard to decide to let go of the Canard design we all loved (and had some very elegant, unseen features) and choosing yet another Beluga design instead. But the science was against the Canard.

gaetanomarano
2006-Sep-15, 01:56 PM
I just thought of another flaw in this logic. In your scenario the LSAM is used for LOI only if the CEV engine fails. In that case, refueling the LSAM does you no good. After the LSAM lands and returns to orbit its tanks are now empty and you have a non-functioning CEV engine to get back home. Furthermore, the more powerful descent stage engine has been left behind on the surface. If you could somehow refuel the LSAM again, you only have the small ascent stage, which is likely not adequate for TEI. Your scenario seems unworkable and filled with unacceptable risk.
the first reason to have bigger SM is to double the astronauts' safety
if the Orion engine will fail and the LSAM will perform the LOI, the surface mission is LOST since the remains LSAM fuel must be used for TEI
however, if we will send (first) a small Lunar Space Station with many months of life support (the Orion can survive six months alone, but only 15 days with the astronauts aboard) may be possible to send from earth another (uncrewed) remote-controlled Orion with a refuel module for the LSAM (that, of course, must be designed to be refuelable) and save (both) the astronauts' life and the lunar mission, without any need to send again a remote-controlled big (and very expensive) AresV/EDS/LSAM convoy

gaetanomarano
2006-Sep-15, 02:14 PM
...gaetanomarano's scenario is a mistake
as you can read in my reply to Bob B. post, "my" scenario is not "a mistake" and doesn't "add risks" but doubles the missions' safety
also, it is not "my" scenario but (simply) the APOLLO SCENARIO that have already accomplished the moon missions (while, so far, the Orion's missions are only a paper-plan)

R.A.F.
2006-Sep-15, 02:18 PM
The difference here is that we worked full shifts with a team for weeks to determine that it was a less optimal design, through hard engineering. I have seen no such effort from you...

Perhaps if gaetanomarano would simply label his opinions as such, instead of saying "NASA is making mistakes/my ideas are better"...

gaetanomarano
2006-Sep-15, 02:19 PM
If the CEV fails and they spend the LSAM propellant for lunar landing and ascent they won't be able to get back to Earth.
as explained in my reply to the Bob B. post, the LSAM used for LOI is an abort-mission scenario and the LSAM can't land on the moon but only burn again its engines for TEI (if something goes wrong we can't want "too much" but we must already be happy if we will save the astronauts)

gaetanomarano
2006-Sep-15, 02:22 PM
Perhaps if gaetanomarano would simply label his opinions as such, instead of saying "NASA is making mistakes/my ideas are better"...
also the "bigger SM" (for LOI and TEI) is a NASA's idea (used in a SUCCESSFUL project called "Apollo"...)

gaetanomarano
2006-Sep-15, 02:28 PM
hhm! I suppose NASA gets its Rocket Scientists and Engineers at a Yard sale from this thread!
great part of to-day's engineers have no direct experience of moon missions and vehicles, since all Apollo's engineers are retired or dead (including a guy who had the name of "Wernher von Braun"...)

R.A.F.
2006-Sep-15, 02:29 PM
also the "bigger SM" (for LOI and TEI) is a NASA's idea (used in a SUCCESSFUL project called "Apollo"...)

I don't understand...are you under the impression that Orion's SM will be smaller than the Apollo SM??

That doesn't make sense...

gaetanomarano
2006-Sep-15, 02:37 PM
I don't understand...are you under the impression that Orion's SM will be smaller than the Apollo SM?? That doesn't make sense...
I suggest you to read the Apollo and Orion specs

the Apollo SM mass was 24.5 mT with 18.4 mT of propellant

the Orion SM mass will be less than 10 mT with less than 7 mT of propellant

JMV
2006-Sep-15, 02:42 PM
as explained in my reply to the Bob B. post, the LSAM used for LOI is an abort-mission scenario and the LSAM can't land on the moon but only burn again its engines for TEI (if something goes wrong we can't want "too much" but we must already be happy if we will save the astronauts)
But in an abort situation they don't need to go into lunar orbit at all. Free-return trajectory will just swing them around the moon for safe return like they did on Apollo 13. No need for LOI or TEI. Smaller correction burns are probably needed, but the small CEV can handle those.

Doodler
2006-Sep-15, 02:46 PM
But in an abort situation they don't need to go into lunar orbit at all. Free-return trajectory will just swing them around the moon for safe return like they did on Apollo 13. No need for LOI or TEI. Smaller correction burns are probably needed, but the small CEV handle those.


BUT! You can't revise an old design based on what you learned in the field!!!!!! The old design WORKED!!!! The NEW design MUST work the EXACT SAME WAY or it will cost billions of dollars, take five years longer to develop, AND STILL WON'T WORK!!

/channelmode OFF

captain swoop
2006-Sep-15, 03:10 PM
And none of the Nasa engineers designing it worked on Apollo! so they can't do it that way!

gaetanomarano
2006-Sep-15, 03:12 PM
But in an abort situation they don't need to go into lunar orbit at all. Free-return trajectory will just swing them around the moon for safe return like they did on Apollo 13. No need for LOI or TEI. Smaller correction burns are probably needed, but the small CEV can handle those.
that's may be true but we don't know the plans for Orion about this point
however, a bigger SM is the BEST choice for MANY other (safety and operational) reasons explained in my article and in my previous posts here
so, why don't have it?

Doodler
2006-Sep-15, 03:13 PM
And none of the Nasa engineers designing it worked on Apollo! so they can't do it that way!

I was under the impression they brought a few of the old boys in to consult.

gaetanomarano
2006-Sep-15, 03:20 PM
I was under the impression they brought a few of the old boys in to consult.
latest months' news say NASA has already done that...

gaetanomarano
2006-Sep-15, 03:34 PM
I'm no rocket surgeon, and I think this has been alluded to by other posters. If the Orion engines fail on LOI, you are already on a close course to Earth, only minor corrections are required. In the future you may be able to do LOI with the LSAM and dock with a Lunar station, but you still wouldn't unless life support is compromised. This is because you now have no backup. If you get halfway through an LOI burn and now lose the LSAM thrust you are in it deep. Better to head for Earth and hope the LSAM will handle the minor changes needed for return. Would you need the main LSAM engines for course correction, or are there secondary thrusters planned which would handle this?
I've already posted an answer about this point
the advantage of a bigger SM is to have TWO CHANCES for (both) LOI and TEI (or to "fly-around") and (I think) in the (very risky) space flights TWO chances are BETTER than ONE
also, we must add all the operational advantages of bigger SM... ApolloVIII-like missions, cargo send/return (to lunar orbit and/or surface) without a big and very expensive AresV/EDS/LSAM, Lunar Space Station reboost, etc.

gaetanomarano
2006-Sep-15, 03:40 PM
What is your professional experience in the area of Areospace?
I'm not an engineer, but... do you think that only astronauts can talk of space, only senators can talk of politics, only olympics gold medals' athletes can talk of sport (etc.) ?
if that will happen, 99.99% of world's peoples can't talk of nothing!

gaetanomarano
2006-Sep-15, 03:47 PM
The difference here is that we worked full shifts with a team for weeks to determine that it was a less optimal design, through hard engineering.
that very "hard engineering" work was made 40 years ago by Apollo's engineers... and the (successful) "optimal design" was a bigger SM able to perform (both) LOI and TEI
also, it's very easy to "compare solutions": the small SM has only ONE operational profile, while, a bigger SM may have MANY different (and useful) flight's options, then, the latter is BETTER

Grand_Lunar
2006-Sep-15, 03:58 PM
I'm not an engineer, but... do you think that only astronauts can talk of space, only senators can talk of politics, only olympics gold medals' athletes can talk of sport (etc.) ?
if that will happen, 99.99% of world's peoples can't talk of nothing!

I believe the point is you're passing judgement on something that you're probably not qualified in. If you offered conjectures, questions, or beliefs, you might not be criticized.

Also, keep in mind what we see so far are design studies. The final product will undoutably be something different.

captain swoop
2006-Sep-15, 03:58 PM
I was under the impression they brought a few of the old boys in to consult.

Was refereing to Mr G constantly implying that Nasa engineers don't know what they are doing because they have no experience working on Apollo.

Bob B.
2006-Sep-15, 03:59 PM
that very "hard engineering" work was made 40 years ago by Apollo's engineers... and the (successful) "optimal design" was a bigger SM able to perform (both) LOI and TEI
Apollo didn't have the advantage of a high specific impulse LOX/LH2 engine. The Apollo SM and LM used the same propellant, thus there was no advantage of one over the other. The new plan is taking advantage of a high efficiency engine to squeeze payload into the mission.

Doodler
2006-Sep-15, 04:02 PM
Was refereing to Mr G constantly implying that Nasa engineers don't know what they are doing because they have no experience working on Apollo.

Ack, sorry. Misunderstood.

Grand_Lunar
2006-Sep-15, 04:03 PM
The new plan is taking advantage of a high efficiency engine to squeeze payload into the mission.

Ah, there you go then.
Better engine, smaller SM needed.
Bada bing bada boom!

gaetanomarano
2006-Sep-15, 04:06 PM
I believe the point is you're passing judgement on something that you're probably not qualified in. If you offered conjectures, questions, or beliefs, you might not be criticized.
in my articles and forums/blogs' posts I only give my opinions and everyone can judge if I'm right posting their opinions and replies

Also, keep in mind what we see so far are design studies. The final product will undoutably be something different.
and I feel that the "final product" will have a bigger SM... :)

gaetanomarano
2006-Sep-15, 04:12 PM
...they have no experience working on Apollo.
HOW they can have such experience if many of them was born AFTER the Apollo17 ?

Doodler
2006-Sep-15, 04:17 PM
HOW they can have such experience if many of them was born AFTER the Apollo17 ?

Oh, I dunno, maybe because they've been designing and lofting large things on columns of fire in the intervening years, and the ladies and gents who designed the old birds kept copious notes.

These are fairly bright people, I'm sure they can read a design spec or a blueprint.

gaetanomarano
2006-Sep-15, 04:18 PM
Apollo didn't have the advantage of a high specific impulse LOX/LH2 engine. The Apollo SM and LM used the same propellant, thus there was no advantage of one over the other. The new plan is taking advantage of a high efficiency engine to squeeze payload into the mission.
the problem is not the propellant or the engines' specific impulse but (only) if it's better to have the LOI fuel in the LSAM or in the Orion's SM
I think that the (small) advantage to have a few extra-tons payload in a cargo-LSAM (of the first solution) doesn't worth the (safety and operational) advantages of an autonomous Orion/SM (of the latter solution) and the safety of a DOUBLE option for (both) LOI and TEI (no matter if and which option the missions will use)

gaetanomarano
2006-Sep-15, 04:22 PM
These are fairly bright people, I'm sure they can read a design spec or a blueprint.
I'm sure of that, but I talk of PRACTICAL EXPERIENCE of moon missions' hardware (probably they will do a work better than Apollo, in future, but, now, they have NO direct experience of that)

stutefish
2006-Sep-15, 05:02 PM
I'm sure of that, but I talk of PRACTICAL EXPERIENCE of moon missions' hardware (probably they will do a work better than Apollo, in future, but, now, they have NO direct experience of that)
They still have plenty more experience than you do, yet you presume to lecture them and us on their failures to design rockets and spacecraft that meet your standards of excellence.

If we're going to judge aerospace professionals based on the amount of experience they have in that field, then we have to judge in favor of NASA.

JMV
2006-Sep-15, 05:04 PM
I've already posted an answer about this point
the advantage of a bigger SM is to have TWO CHANCES for (both) LOI and TEI (or to "fly-around") and (I think) in the (very risky) space flights TWO chances are BETTER than ONE
But they don't need to go into lunar orbit if one chance fails. If either one of the engines fails before or at LOI, trying another LOI with the other engine would put the crew to unnecessary risk, because now the would have to perform TEI to get off lunar orbit. What if the TEI failed? The safest solution is to follow free-return trajectory. They might also go for hybrid trajectory, but if needed transferring back to FRT shouldn't be be a big problem as it wasn't for Apollo 13.

It would be great if they had two engine options for TEI after succesful lunar landing and ascent, but that's just not possible with either NASA's plan or your proposition.

[EDIT: Just to clarify my point.
You might say that going for another LOI is not unnecessary risk, because they would have only one chance for TEI anyway. But that's a risk weighted with succesful lunar surface operations. If the landing is scrubbed as would be be most likely done with an engine failure, going into lunar orbit would be pretty much pointless.]

gaetanomarano
2006-Sep-15, 05:25 PM
...more experience than you do...
more than me but less than Apollo's guys that have (clearly) done the right design choices
I don't give any "lecture" but only mu opinions (like many peoples do every day)

gaetanomarano
2006-Sep-15, 05:40 PM
But they don't need to go into lunar orbit if one chance fails.

1. we don't know (now) which kind of flight and contingency may occur

2. you yet ignore the long list of advantages of an autonomous Orion as explained in my article and in my posts here

3. in a future (more complex) scenario all vehicles may be repaired and/or refueled in earth and lunar orbit (or in lunar surface) but that (safer and useful) options (good also to gain experience for Mars missions) will never happen if the new vehicles aren't designed to do more than a simple "moon mission's show" with the extra-suspance of less reliable vehicles and rescue options to have some new (and "very exciting" for TV audience) ApolloXIII missions!

Doodler
2006-Sep-15, 05:48 PM
We didn't know then, either. Guess what? We flew anyway, knowing a serious enough situation would result in dead astronauts.

Bob B.
2006-Sep-15, 05:55 PM
If the landing is scrubbed as would be be most likely done with an engine failure, going into lunar orbit would be pretty much pointless.]
I absolutely agree. Losing a main engine is such a critical failure that I cannot possibly imagine the mission rules allowing for anything other than an abort. If such a major failure occurred, I'm almost certain an immediate return to Earth would be ordered. Apollo rules wouldn't even allow a landing if one of three fuel cells failed, which is far less significant than the loss of a primary propulsion system.

The safest thing for the astronauts would be to not go into lunar orbit, swing around the Moon, and head immediately back to Earth. Going into lunar orbit only puts the astronauts lives needlessly at risk.

gaetanomarano
2006-Sep-15, 06:38 PM
...knowing a serious enough situation would result in dead astronauts.
high redundancy and multiple flight options help to reduce the (very high) risks of space exploration

Doodler
2006-Sep-15, 06:49 PM
high redundancy and multiple flight options help to reduce the (very high) risks of space exploration

Or you overdesign the one option with sufficient capacity to operate in a lesser mode for abort operations and accept the reality that a massive failure is likely unsurvivable.

gaetanomarano
2006-Sep-15, 06:54 PM
The safest thing for the astronauts would be to not go into lunar orbit, swing around the Moon, and head immediately back to Earth. Going into lunar orbit only puts the astronauts lives needlessly at risk.
the new moon missions are designed like a TV show: giant business (thanks to the 99% expendable hardware) high suspance (with a lower redundancy, no emergency life support and no rescue if something goes wrong) and smaller results per mission (to have more business)
but, if the claim that "moon missions will be made to gain experience for Mars and beyond" is true, that experiences include the WORST cases!
if I ask myself about the kind of skills the future astronauts MUST have, the answer is "they must be able to REPAIR and REFUEL their hardware"
HOW they can survive (in the worst cases) in space or on the moon and mars if the hardware used MUST BE 100% PERFECT for 100% of the time? ...a very long time for a mars mission!
it's simply impossible!
then, I suggest that they will be trained for all possible scenarios and that ALL future space hardware must be OPEN (not "embedded") to be modified, repaired, upgraded, refueled, etc. IN SPACE
if humans wants to travel in space like in sci-fi movies we MUST be able to do in space the SAME complex things the sci-fi movies' astronauts do!

gaetanomarano
2006-Sep-15, 06:57 PM
...accept the reality that a massive failure is likely unsurvivable.
no spacecraft nor spaceflight will ever be 100% safe, but they must be designed to be as safe as possible

Doodler
2006-Sep-15, 07:12 PM
no spacecraft nor spaceflight will ever be 100% safe, but they must be designed to be as safe as possible

Hence man-ratings requiring overdesigned, redundancy inundated equipment to ensure the first system doesn't fail, rather than carrying a second system just as likely to fail as the first.

gaetanomarano
2006-Sep-15, 07:15 PM
...a second system just as likely to fail as the first.
if you refer to the bigger SM, it is not a "second system" but only a shift of propellant from LSAM to Orion SM to double the LOI/TEI chances and have MANY other useful (manned and unmanned) flights' options

Boxes
2006-Sep-15, 07:19 PM
if you refer to the bigger SM, it is not a "second system" but only a shift of propellant from LSAM to Orion SM to double the LOI/TEI chances and have MANY other useful (manned and unmanned) flights' options

Perhaps you could restate these many other useful flight options, since the second chance at LOI/TEI is obviously too dangerous and would not ever be used.

Doodler
2006-Sep-15, 07:31 PM
if you refer to the bigger SM, it is not a "second system" but only a shift of propellant from LSAM to Orion SM to double the LOI/TEI chances and have MANY other useful (manned and unmanned) flights' options

It doesn't have to be bigger, just more efficient. Keep in mind, the smaller size may have absolutely nothing to do with the workings of the machine inside. If the mechanics of the beast are sufficiently miniaturized, they could very well need less space to get the job done. Also remember that being wider, you're losing the need to be quite as long, again, this may result in a more efficient distribution of the SM components.

As for inflight fuel transfers, not even Apollo messed with that. You build each stage with the fuel needed to do its job plus a margin, and you leave well enough alone. The pumps needed to accomodate inflight fuel shifting is a bulk of junk that robs the vehicle of mass for operational gear, and creates another complex system that has a chance to trip you up.

gaetanomarano
2006-Sep-15, 07:39 PM
Perhaps you could restate these many other useful flight options
I've explained them in my article and in my posts in this thread
I will write soon a small update and a post here, but (clearly) an autonomous Orion is better than a reduced version

...since the second chance at LOI/TEI is obviously too dangerous and would not ever be used.
it's the better and more efficient way if (as I suggest) all vehicles will be designed and built "modular" to be refueled and repaired in lunar orbit
just look at this option/advantage (that needs a small Lunar Space Station) if the SM will fail:
the astronauts will wait in lunar orbit while from earth will be sent another (uncrewed) Orion and the LSAM's refuel (or a full LSAM)
it costs money (especially if NASA will launch another AresV+LSAM) but it may avoid that a crew will fly (and risk) for nothing (only an aborted flight!) and that a new crew (that must be trained for the SAME mission) will take the (completely useless) risk of a further earth-moon travel!
the first crew can (simply) wait in lunar orbit and accomplish the planned missions with only a few weeks of delay!
THIS is the most efficient and rational choice!

gaetanomarano
2006-Sep-15, 07:45 PM
It doesn't have to be bigger...
it absolutely MUST be bigger since the small SM will have less than 7 mT of propellant, while, for LOI of the Orion/bigSM/LSAM and TEI, the SM needs (probably) 25 mT of propellant

...for inflight fuel transfers...
the choice is simple:
a) easy vehicles for a new TV show on the moon, or...
b) complex vehicles (including refuel and repair in space) for REAL space flights (especially on "Mars and beyond")

Boxes
2006-Sep-15, 07:56 PM
I've explained them in my article and in my posts in this thread
it's the better and more efficient way if (as I suggest) all vehicles will be designed and built "modular" to be refueled and repaired in lunar orbit
just look at this option/advantage (that needs a small Lunar Space Station) if the SM will fail:
the astronauts will wait in lunar orbit while from earth will be sent another (uncrewed) Orion and the LSAM's refuel (or a full LSAM)
it costs money (especially if NASA will launch another AresV+LSAM) but it may avoid that a crew will fly (and risk) for nothing (only an aborted flight!) and that a new crew (that must be trained for the SAME mission) will take the (completely useless) risk of a further earth-moon travel!
the first crew can (simply) wait in lunar orbit and accomplish the planned missions with only a few weeks of delay!
THIS is the most efficient and rational choice!

Wrong! The safest approach would be the return to Earth orbit. Burning into Lunar orbit after a major system failure, when you are already on course for Earth would be risky. At this point the money would not be an issue and you would rather launch a new vessel than risk using a compromised one.

Bob B.
2006-Sep-15, 08:14 PM
the new moon missions are designed like a TV show: giant business (thanks to the 99% expendable hardware) high suspance (with a lower redundancy, no emergency life support and no rescue if something goes wrong) and smaller results per mission (to have more business)
but, if the claim that "moon missions will be made to gain experience for Mars and beyond" is true, that experiences include the WORST cases!
if I ask myself about the kind of skills the future astronauts MUST have, the answer is "they must be able to REPAIR and REFUEL their hardware"
I don't see how refueling will ever be an option on a Mars flight, however I do agree the ability to make repairs will be important. Therefore we should design for it and we should test it, but we do not knowingly allow our astronauts to fly into a dangerous situation just because we've designed into the system the capability for them to repair a potentially life-threatening malfunction. If a major malfunction occurs and the option for an abort exists, then we exercise that option and get the crew safely home.

Inserting the spacecraft into lunar orbit with a backup system following a main engine failure is putting the crew into an unknown and potentially dangerous situation. There is simply not enough time to diagnose the problem, so we get the heck out of there and not put ourselves at risk. Just because we should be able to make a repair doesn't mean we bet your lives on our ability to do so. That's like jumping out of an airplane with a knowingly flawed parachute and relying on your skill to repair it while plummeting toward the ground. If you discover on the way down the parachute is flawed then knowing how to repair it may save your life, but if you know it is flawed beforehand then you donít make the jump.

gaetanomarano
2006-Sep-15, 08:53 PM
Burning into Lunar orbit after a major system failure, when you are already on course for Earth would be risky.
it's not a problem of money
I don't think that both SM and LSAM can fail in the same mission
if the SM will fail the LSAM can do a safe LOI
with a small lunar station the crew (trained for the mission) van wait the new hardware
that avoid to lose the planned mission, train a new crew for the same mission and launch the new crew (an useless risk if there is a trained crew in lunar orbit that wait only a new hardware)
this is the most efficient scenario for a mission (and launch a small module around the moon doesn't cost so much)

Bob B.
2006-Sep-15, 09:17 PM
train a new crew for the same mission
Why train a new crew? If LOI fails the crew does a circumlunar fly around and are back home six days after they left. By the time we're ready to try the mission again we can send up the same crew without losing any of their experience and training.

EDIT: Before you criticize, let me point out this has happened before. In 1997 the STS-83 mission was aborted after only four days due to a fuel cell problem. The mission was then re-flown as STS-94 just three months latter with the same crew.

Boxes
2006-Sep-15, 11:15 PM
I don't think that both SM and LSAM can fail in the same mission


I suggest that you consult with an engineer on this.:D :D :D :D :D

gaetanomarano
2006-Sep-15, 11:30 PM
I suggest that you consult with an engineer on this.
I don't say it is impossible, only that its probability is very little and, if that will happen, nothing can be done
the chances can doble, the way I suggest, but not multiplied ten times!

gaetanomarano
2006-Sep-15, 11:40 PM
If LOI fails the crew does a circumlunar fly around and are back home six days after they left. By the time we're ready to try the mission again we can send up the same crew without losing any of their experience and training.
that's true, but we don't know if the full crew will like to fly again after a serious risk to die (lose the only engine around the moon is not "exactly" like lose a fuel-cell)
but the problem is not the duplication of crew or training, but the duplication of risks
a flight in space is full of risk, but (I think you can agree) the main risks are the launch and reentry in the atmosphere
well, with a launch abort, two crew (or the same crew) must risk twice, while, with a small orbital station, the crew can wait and accomplish the mission without any duplication of manned launch and reentry
less risk for the astronauts (that is the most important point) but, also, less time and money since we don't need to launch another (very expensive) LSAM/AresV/EDS but only refuel the first LSAM

gaetanomarano
2006-Sep-16, 12:01 AM
I don't see how refueling will ever be an option on a Mars flight
not only refuel is important, but it is MOST important than repair since it must become a standard operation in all moon and mars missions!
I can't imagine a large space exploration made (everytime!) with 100% expendable vehicles!
that choice, already ridiculous for moon missions (since all earth vehicles are refuelable, not used once!) become incredibly crazy for a mars mission with all, new, single-use, vehicle sent from earth!!!!
all moon and mars vehicles must be designed (now!) to be refuelable!

...we should design for it and we should test it, but we do not knowingly allow our astronauts to fly into a dangerous situation just because we've designed into the system the capability for them to repair a potentially life-threatening malfunction...
of course, I don't suggest to break the hardware in space for training!
but all vehicle must be designed for easy repair (like the Hubble) and all astronauts must be trained (on earth and in space) to repair them (only if necessary, of course) sending the spare parts in lunar orbit and surface

...the spacecraft into lunar orbit with a backup system following a main engine failure is putting the crew into an unknown and potentially dangerous situation...
again, that's true (and the only choice) without any lunar station, spare parts, rapair/refuel training and autonomous rescue-Orions sent form earth, etc.
this is the reason I suggest to launch a small station, design refuelable vehicles, build a bigger SM, etc.

Just because we should be able to make a repair doesn't mean we bet your lives on our ability to do so.
it's absurd
I suggest to train all astronauts about hardware repair in space to USE their skills (when necessary), not as space-hobby!
if they don't use that opportunity (if and when it is necessary) why spend money for that

If you discover on the way down the parachute is flawed then knowing how to repair it may save your life, but if you know it is flawed beforehand then you don’t make the jump.
all possible problems of a mission can be predicted and a solution planned (with procedures, training and spare parts)
of course, if something new and unexpected will happen, the best choice is to come back to earth as soon as possible!
however, also "repair the unexpected" is an ESSENTIAL part of the training for Mars!

Bob B.
2006-Sep-16, 12:51 AM
it's not a problem of money
I don't think that both SM and LSAM can fail in the same mission
if the SM will fail the LSAM can do a safe LOI
with a small lunar station the crew (trained for the mission) van wait the new hardware
that avoid to lose the planned mission, train a new crew for the same mission and launch the new crew (an useless risk if there is a trained crew in lunar orbit that wait only a new hardware)
this is the most efficient scenario for a mission (and launch a small module around the moon doesn't cost so much)
Okay, letís look at this more closely. We have two LOI options: (1) using the LSAM, or (2) using the CEV. In case of a primary engine failure we have two abort options: (A) circumlunar fly-around, or (B) abort to lunar orbit using backup engine. Gaetanomarano advocates options 2 and B. I definitely advocate option A on the abort and Iím leaning toward option 1 on LOI because it is more efficient and gives us more usable payload.

Assuming we have a primary engine failure, letís look at some of the pros and cons:

LSAM LOI / Circumlunar Abort

On LSAM engine failure, the CEV/LSAM does a circumlunar fly-around. The CEV engine then performs a course correction to get on the proper trajectory for a return to Earth. The course correction delta-v is probably small enough that it can be performed with the LSAM still attached. This gives the added safety precaution of having the LSAM available for the return home in the case of an Apollo 13-type disaster. We also still have the LSAM ascent stage engine as a backup. This scenario results in a very high probability of safe crew return.

After the astronauts return home they can crew a re-flight mission within a few months, thus not losing their training and experience. By the time of the next launch window they will be well rested.

This scenario is expensive in that completing the mission requires two complete sets of hardware: two Ares I, two Ares V, two LSAM, and two CEV SM. The CEV CM is reusable so we lose only the refurbishment cost. We also require two crew launches.

CEV LOI / Abort to Orbit

On CEV engine failure the LSAM engine is fired as a backup, placing the CEV/LSAM in lunar orbit. We now have a vehicle in orbit with the primary TEI engine non-functional and the LSAM lacking the propellant required to perform a lunar landing. If necessary TEI can be performed with the LSAM descent engine, but there is no backup.

According to gaetanomarano, the purpose of this abort scenario it to leave the crew in lunar orbit until replacement hardware and propellant can be sent to them. The hardware consists of, at a minimum, a replacement CEV SM. And probably about 13 mT of LOX/LH2 is required for refueling the LSAM (not counting loses due to boil-off).

The propellant required to refuel the LSAM exceeds the capacity of the cargo CEV, therefore a separate propellant carrier will have to be developed along with the accessories required to allow in orbit refueling.

If only a replacement CEV SM is sent, then an in orbit removal of the old SM must be performed and the new SM attached. If an entirely new CEV is sent, then we simply replace the old with the new. However in this case there is no way to get the old CEV CM back to Earth. Since the CM is meant to be reusable, we lose its entire cost.

Since the delay will change the lighting conditions at the landing site, a full lunar cycle of 29.5 days will have to transpire before a landing attempt can be made. This means one monthís worth of additional consumables must be provided. Furthermore, the month wait in lunar orbit will add to crew fatigue, which could degrade performance once the primary mission resumes.

The unit cost of this scenario is high but probably a little less than the former. It requires: one Ares I, two Ares V, one LSAM, two CEV SM, possibly one CEV CM, and a refueling module. Only one crew launch is required but the crew must endure an extended stay in space.

Any unit cost savings is probably more than offset by the expense of developing new contingency hardware and procedures, particularly if the hardware and procedures are never used, which is likely since an engine failure is a remote possibility.

Bob B.
2006-Sep-16, 01:33 AM
...we should design for it and we should test it, but we do not knowingly allow our astronauts to fly into a dangerous situation just because we've designed into the system the capability for them to repair a potentially life-threatening malfunction...
of course, I don't suggest to break the hardware in space for training!
Purposely breaking the hardware is not what I meant. If the CEV engine fails to ignite for LOI then the spacecraft has unintentionally broken. If you then proceed with LOI using the LSAM, then you are knowingly placing a broken spacecraft and its crew into lunar orbit and into a potentially perilous situation. I think that is an extremely reckless policy. The cost of saving the mission is not worth the risk to the astronauts.

Take the Space Shuttle for example. We have now developed procedures for repairing damage to the thermal protection system in orbit. However, let's say that during a launch severe damage to the Shuttle's wing is observed while there is still time to order an abort and return safely to a contingency landing site. Do you order an immediate abort or do you decide to proceed and fix the damage after getting into orbit? The conscientious thing to do is get the crew on the ground right now rather than bet their lives on repair procedures that run the risk of being unsuccessful. The repair procedures are only a last option and the crew should never be knowingly put into a situation that relies on them if it can be avoided.

Your scenario knowingly places the astronauts in a situation that relies on emergency contigency procedures.

gaetanomarano
2006-Sep-16, 02:09 AM
We have two LOI options: (1) using the LSAM, or (2) using the CEV. In case of a primary engine failure we have two abort options: (A) circumlunar fly-around, or (B) abort to lunar orbit using backup engine. Gaetanomarano advocates options 2 and B.
despite the long article and all my posts my true opinion is not clear yet
I don't "want" the (B) option as standard
I only suggest to put the propellant for LOI and TEI in BOTH vehicles (with a bigger SM and a smaller LSAM) to have TWICE the options of to-day's TEI-only SM
then, the aborted mission can work with the option A (without a lunar station) or with the option B (with a linar station)
note that BOTH design can accomplish the option A while ONLY the bigger-SM design can accoplish the option B and ALL other useful (manned and unmanned) options that need an autonomous Orion: rescue Orion, cargo Orion, cargo-return Orion, etc.
we have not two LOI options but THREE: LOI with LSAM (ESAS) and LOI with Orion-SM or LSAM (with a bigger SM)
a bigger SM is the ONLY design that offers BOTH options, no matter which option will be used in real flights
if you drive a car in your city you need only one spare wheel (since it's easy to buy a wheel in a city) but, if you got a trip in a desert or a forest, you bring two, three, four spare wheels, no matter if you never use them!
well, my suggestion is to have an Orion/LSAM "car" with TWO "spare wheels" at (about) the same price and weight

On LSAM engine failure, the CEV/LSAM does a circumlunar fly-around.
this is the only option without a lunar station and can be performed with both small or big SM

This gives the added safety precaution of having the LSAM available for the return home in the case of an Apollo 13-type disaster.
the LSAM can remain docked also with a bigger SM

...not losing their training and experience...
they don't lose the training but must perform TWICE the launch and reentry with a risk MANY times higher than remain docked to a lunar station!

On CEV engine failure the LSAM engine is fired as a backup, placing the CEV/LSAM in lunar orbit.
not as standard but only if there is a lunar station (that, I think, MUST be ready from first manned missions!)

...therefore a separate propellant carrier will have to be developed along with the accessories required to allow in orbit refueling...
I suggest that all LSAMs will be refuelable to perform 10+ missions, then, build a refuel vehicle and send it around the moon must be a standard job
a reusable-LSAM is a giant saving of hardware (and money) that absolutely needs an autonomous Orion for crew rotation
only with a big SM the Orion can perform this kind of missions
with a small SM the Orion missions must be the same in the next 30+ years!

...then an in orbit removal of the old SM must be performed and the new SM attached...
there is no change of SM (that we can't send from earth alone without the Orion's navigation system) but the entire Orion can be sent back to earth with a 30 minutes RCS burn (as planned with Apollo and Orion as backup) and can fly remote controlled, land on earth and refurbished
this (risky) option is the only possible (after the lunar surface missions) if the main engine don't work, but, if we have a lunar station, it's better and SAFER to send back the damaged Orion uncrewed and launch a fresh vehicle
another (costly) option is to burn the Orion's RCS to crash it in a crater (on the far side of the moon) used as hardware cemetary (good for all unused space hardware to avoid the problem of dangerous debris in lunar orbit)

...we lose its entire cost...
TWO FULL MISSIONS costs more than ONE mission + one Orion (that may come back uncrewed with an RCS burn) + one LSAM refuel

This means one monthís worth of additional consumables must be provided. Furthermore, the month wait in lunar orbit will add to crew fatigue, which could degrade performance once the primary mission resumes.
1. a lunar station must have months of consumables since this is exactly its purpose
2. the astronauts can wait many months in orbit and (for an astronauts) it may be a relaxing situation, not a stress
3. landing on the moon (at 1/6 the gravity) after one month at zero gravity is not the same than land on earth (at full gravity) after one month on the ISS
4. the best choice is to have a small refuel tank near the lunar station to refuel the LSAM within a few hours, land on the moon and perform the mission in the planned days while the spare-Orion come form earth (and the damaged Orion come back) so the astronauts must wait only a few days in lunar orbit AFTER they have accomplished the lunar surface mission!

however, I don't suggest to plan any standard or abort scenarios, now, but only to build the Orion with a bigger SM to have the choice of use it in ALL possible missions' profile and not only ONE "standard profile" for ALL flights of the next 30+ years!

Grand_Lunar
2006-Sep-16, 02:38 AM
and I feel that the "final product" will have a bigger SM...




So why complain?

Grand_Lunar
2006-Sep-16, 02:46 AM
it absolutely MUST be bigger

That doesn't sound like an opinion. More like you're trying to tell the qualified engineers how to do their job.
I'm sure they can manage without your "advice".

gaetanomarano
2006-Sep-16, 02:51 AM
...the risk to the astronauts...
again... I don't suggest ANY "standard abort procedure"
I only want a bigger SM to have BOTH (orbital insertion and fly-around) options to use the first now (without a lunar station) and the latter in future (when we will have a lunar station)
also, don't forget that, while a bigger SM doesn't change nothing in a fly-around abort mission, an autonomous Orion can be used for many other, different (manned or unmanned) missions (simply) impossible with the small SM

...Do you order an immediate abort...
wrong example
an immediate abort is safer only at low-mid altitude and speed
if the immediate abort (with a seriously damaged TPS) will happen at high altitude and speed, the Shuttle may have a Columbia-like reentry...

gaetanomarano
2006-Sep-16, 02:53 AM
So why complain?
because it's not 100% sure (look at the crazy Ares-I design that STILL is the #1 choice!)

gaetanomarano
2006-Sep-16, 03:01 AM
That doesn't sound like an opinion. More like you're trying to tell the qualified engineers how to do their job. I'm sure they can manage without your "advice".

this is the full text of my post:

"it absolutely MUST be bigger since the small SM will have less than 7 mT of propellant, while, for LOI of the Orion/bigSM/LSAM and TEI, the SM needs (probably) 25 mT of propellant"

it's not an "order" or an "advice" since, to perform (both) LOI and TEI, the SM must have more propellant, then, it MUST be bigger, no matter which are the engineer that design it!

engineers can't do miracles!

.

Bob B.
2006-Sep-16, 03:34 AM
wrong example
an immediate abort is safer only at low-mid altitude and speed
if the immediate abort (with a seriously damaged TPS) will happen at high altitude and speed, the Shuttle may have a Columbia-like reentry...
It was only a hypothetical example to illustrate a point; you are taking it too literally. And besides, you're wrong. The critical time for foam strikes occurs at relatively low altitude when the air it still thick enough to cause high velocity impacts. When a piece of foam breaks lose it is rapidly decelerated by the air producing a high velocity difference between the foam and the oncoming Shuttle. At high altitude the air is too thin to produce a dangerous impact velocity. The time of concern for foam strikes ends at 135 seconds after launch. A return to launch site abort can occur up to 260 seconds after launch.

Bob B.
2006-Sep-16, 04:18 AM
despite the long article and all my posts my true opinion is not clear yet
Ö
I only suggest to put the propellant for LOI and TEI in BOTH vehicles (with a bigger SM and a smaller LSAM) to have TWICE the options of to-day's TEI-only SM
Here is what Iíve understood your argument to be: The primary responsibility for LOI will be transferred from the LSAM to the SM. The SM will be enlarged and enough propellant added to give it the capability to perform LOI. The LSAM will be decreased in size and the propellant previously allotted to LOI deleted. Despite the reduction in size, the LSAM decent module still houses enough propellant to perform LOI should the SM fail. However, in performing LOI the LSAM uses its descent propellant, thus rendering it incapable of landing on the Moon without refueling.

Is this correct? If yes, I've understood you perfectly well. If not, please clarify.


I don't "want" the (B) option as standard
Iím not sure what you mean by ďstandardĒ. To me the ďstandardĒ is everything working as planned.

Every post you have made up until now has strongly suggested option B is your preferred method of abort should the primary engine fail. Not until post #108 can I recall you suggesting anything otherwise.

gaetanomarano
2006-Sep-16, 01:14 PM
And besides, you're wrong.
not true
your post was about Shuttle launch abort, not about foam damage
an high altitude abort may be lethal, no matter when the Shuttle is damaged
it's better and safer to reach the orbit and verify the wings without rush

R.A.F.
2006-Sep-16, 01:33 PM
So why complain?


because it's not 100% sure.

Can you explain to us just how posting "it must be bigger" here (or on your blog) will change how Orion is built? Seems like you're getting yourself all upset about something that you can do absolutely nothing about.

gaetanomarano
2006-Sep-16, 01:35 PM
The SM will be enlarged and enough propellant added to give it the capability to perform LOI. The LSAM will be decreased in size and the propellant previously allotted to LOI deleted. Despite the reduction in size, the LSAM decent module still houses enough propellant to perform LOI should the SM fail. However, in performing LOI the LSAM uses its descent propellant, thus rendering it incapable of landing on the Moon without refueling. Is this correct?
yes, it's correct
the only (possible) misunderstanding may be around the flight's choices
I suggest to build a bigger SM to have both (SM and LSAM) options to LOI
if the lunar convoy has the right trajectory and there are no lunar station, the best choice is to "fly-around" the moon
however, also without a lunar station, the option "B" is not impossible nor dangerous

Iím not sure what you mean by ďstandardĒ.
for me, a "standard" choice is (also) when there are no different options

...strongly suggested option B is your preferred method...
although not "strongly", I must admit that this is my preferred choice since (sometimes) I think and talk under a "ghostNASA" logic instead of the (unfortunately real) ESAS plan
in other words, since I've suggested months ago to send (first) a Lunar Space Station (that, I think, is absolutely necessary!) I write the following articles WITH a station in lunar orbit
clearly, with an LSS, the best choice is to enter the lunar orbit, dock to the station, refuel the LSAM (best with a small tank ready available) perform the lunar surface missions, come back to the LSS and wait a few days while the new Orion (or the spare parts to repair the old Orion) come from earth

gaetanomarano
2006-Sep-16, 01:42 PM
..."it must be bigger" here (or on your blog) will change how Orion is built...
an Orion SM able to perform (both) LOI and TEI must be "bigger" (simply) to have tanks with sufficient volume for extra propellant
with a TEI-only SM, the tanks don't need to be "bigger"

R.A.F.
2006-Sep-16, 01:53 PM
an Orion SM able to perform (both) LOI and TEI must be "bigger" (simply) to have tanks with sufficient volume for extra propellant
with a TEI-only SM, the tanks don't need to be "bigger"

That's nice, but you didn't answer my question...so I will repeat...


Can you explain to us just how posting "it must be bigger" here (or on your blog) will change how Orion is built?

gaetanomarano
2006-Sep-16, 02:01 PM
Can you explain to us just how posting "it must be bigger" here (or on your blog) will change how Orion is built?
I don't know
but talk of it is not useless (or "not more than talk of other alternative choices" like all space forums do everyday)

R.A.F.
2006-Sep-16, 02:12 PM
I don't know.

"I don't know" is a reasonable answer...thank you...

Grand_Lunar
2006-Sep-16, 02:24 PM
In fact, the answer "I don't know" is the best answer I've seen in this entire thread by Gaetanomarano.

Bob B.
2006-Sep-16, 03:02 PM
not true
your post was about Shuttle launch abort, not about foam damage
My post was about a hypothethical choice between two options -- it was about neither a Shuttle abort nor foam damage per se. And besides, what do you think my reference to the TPS repair procedures and a damaged wing on ascent were about if it wasn't presuming a foam strike? I can't see how you could interpret it any other way unless you are just being obstinate.


an high altitude abort may be lethal, no matter when the Shuttle is damaged
it's better and safer to reach the orbit and verify the wings without rush
My example was only hypothetical. Rather than answering the question in the spirit in which it was asked, you are trying to confuse the issue with a bunch of minutia. You have change the conditions of the hypothetical scenario so that you can answer the question in the way you want to. That is unfair and dishonest.

The hypothetical question is this:

You have a spacecraft that is known to have sustained possible life-threatening damage. You can exercise one of two options: (1) an immediate abort that carries a very high probability of safe crew recovery, or (2) proceed and force the crew to perform a repair that has a less certain outcome for survival. Which option do you choose? (This is a very simple question, please don't try to change it by pasting your own conditions to it.)

gaetanomarano
2006-Sep-16, 05:12 PM
My example was only hypothetical.
it's "too hypothetical" since, a Shuttle's low altitude abort, an high altitude abort, a premature re-entry due to a fuel-cell failure and an automated (uncrewed) reentry from ISS orbit after a serious TPS damage, are too different scenarios, between them, and, all them, very much different from lunar orbit abort (fly-around or LOI/TEI) scenarios (so different they can't be compared nor used as an example)

about the lunar orbit trajectory, I've read these post/reply of another forum's user:

Post: "The Apollo missions chose their trajectory carefully: that if no LOI burn was performed, the vehicle would slingshot around the Moon and return to Earth with no other action required. No action required."

Reply: "I would like to add to this to mention that this is the case ONLY if they are using a free-return trajectory. After Apollos 8, 10, 11 and 12, NASA has decided that use of the FRT was not necessary. Apollo 13 actually did not use a FRT, which is why the correction burns were required. All flights following Apollo 13 required FRT again."

if that's true, all Apollo flights (before ApolloXIII) used a trajectory who NEEDS a LOI and, only after the ApolloXIII accident, the fly-around trajectory was used (to come back to earth without any engines' burning if something goes wrong)

.

R.A.F.
2006-Sep-16, 05:31 PM
...please don't try to change it by pasting your own conditions to it.

...and "change it" is exactly what gaetanomarano did....

Bob B.
2006-Sep-16, 06:25 PM
it's "too hypothetical" since, a Shuttle's …
The question is no longer about the Shuttle. I would appreciate you kindly answering the question that was asked.

”You have a spacecraft that is known to have sustained possible life-threatening damage. You can exercise one of two options: (1) an immediate abort that carries a very high probability of safe crew recovery, or (2) proceed and force the crew to perform a repair that has a less certain outcome for survival. Which option do you choose?


Post: "The Apollo missions chose their trajectory carefully: that if no LOI burn was performed, the vehicle would slingshot around the Moon and return to Earth with no other action required. No action required."

Reply: "I would like to add to this to mention that this is the case ONLY if they are using a free-return trajectory. After Apollos 8, 10, 11 and 12, NASA has decided that use of the FRT was not necessary. Apollo 13 actually did not use a FRT, which is why the correction burns were required. All flights following Apollo 13 required FRT again."

if that's true
I agree that flights prior to Apollo 13 were on free-return trajectories, but I disagree with the last sentence, “All flights following Apollo 13 required FRT again.” The following is a quote from Henry Spencer, who is a highly regarded space enthusiast and historian:

“Actually, it's impossible to fly anything but an equatorial orbit using a free-return trajectory. In fact, Apollo 11 was the last lunar mission to use a pure free-return trajectory. The "H" missions (12-14) started out in free-return trajectories but shifted to non-return ones after S-IVB separation and CSM-LM docking, with the shift done progressively earlier in the later flights. The "J" missions injected directly into non-return trajectories, again getting increasingly aggressive about it as time went by -- in the event of an SM engine failure, Apollo 15 could have moved back to a free-return trajectory using its RCS thrusters, while Apollo 17 would have had trouble doing it even with the LM descent engine.”


all Apollo flights (before ApolloXIII) used a trajectory who NEEDS a LOI and, only after the ApolloXIII accident, the fly-around trajectory was used (to come back to earth without any engines' burning if something goes wrong)
You have it backwards, all the early flights (Apollo 8, 10-14) were on initial free-return trajectories that would have brought the spacecraft back to Earth on a survivable trajectory without any further intervention. Apollo 12-14* deviated from the FRT while on the way to the Moon. This was considered a safe procedure because shifting from the FRT demonstrated the SM engine was working properly. Had the engine failed, the spacecraft would have remained on its FRT.

In the unlikely event the SM engine failed at LOI, the spacecraft would have still done a circumlunar fly-around and headed back toward Earth. Not being on a FRT meant only that the trajectory would not intersected Earth at the correct angle for a survivable reetry. After swinging around the Moon a course correction burn would have been performed using the LM’s descent engine or the SM RCS thrusters to get the spacecraft back on a survivable trajectory.

Under no circumstances was a LOI burn necessary to get the spacecraft home. A LOI burn would only be performed if all the systems were working properly. The default in case of failure was a circumlunar fly-around and an immediate return to Earth.


* I thought deviation from FRT started with Apollo 13, however Henry Spencer says it started with Apollo 12. I'll concede that Henry is probably correct, and I agree with what he said regarding the other missions.

Bob B.
2006-Sep-16, 06:57 PM
yes, it's correct
the only (possible) misunderstanding may be around the flight's choices
I suggest to build a bigger SM to have both (SM and LSAM) options to LOI
if the lunar convoy has the right trajectory and there are no lunar station, the best choice is to "fly-around" the moon
however, also without a lunar station, the option "B" is not impossible nor dangerous
Obviously there is no lunar space station and, as far as I know, there are no near-term plans for a lunar space station. It appears likely that when the CEV/LSAM lunar missions occur circa 2020, they will be perform without the benefit of a lunar space station. Conceding this fact, do you still advocate transferring primary LOI responsibility from the LSAM to the CEV? If so, why?

gaetanomarano
2006-Sep-16, 09:03 PM
”You have a spacecraft that is known to have sustained possible life-threatening damage. You can exercise one of two options: (1) an immediate abort that carries a very high probability of safe crew recovery, or (2) proceed and force the crew to perform a repair that has a less certain outcome for survival. Which option do you choose?

substantially, my latest posts include an answer to your question that is:

whithout a lunar space station, an immediate abort is the BETTER and SAFER choice, however, a LOI+TEI abort is unnecessary but possible and absolutely not dangerous since the probability that two very high reliability vehicles like Orion and LSAM will fail in the same mission is extremely little

WITH a lunar space station (and repair/refuel/exchange techniques) a LOI abort is the ONLY choice and the most (technical and econiomical) efficient, rational and safe since it doesn't delay the mission and avoid to the same (or another) crew to perform an useless and VERY RISKY second launch and second reentry from/to earth

.

gaetanomarano
2006-Sep-16, 09:15 PM
Obviously there is no lunar space station and, as far as I know, there are no near-term plans for a lunar space station. It appears likely that when the CEV/LSAM lunar missions occur circa 2020, they will be perform without the benefit of a lunar space station. Conceding this fact, do you still advocate transferring primary LOI responsibility from the LSAM to the CEV? If so, why?

"obviously" there is NOTHING now!

yes, I still advocate that choice
a bigger SM doesn't change nothing in a standard ESAS mission (as planned to-day) but is absolutely necessary when a small space station will be launched around the moon
the change MUST be made and MUST be made NOW becasuse the LSS and Orion have two different timelines and operational life
an LSS is not planned now but can be launched a few years after the first moon mission
it may be part of a NASA/ESA/Russia cooperation (as Griffin claimed in a recent interview) and may be very fast, easy and cheap (about the price of a single moon mission) to build and launch from (modified) ISS modules or ATV design
Orion is planned to fly UNMODIFIED (or only with small changes) in the next 30-40 years!
then, it must designed NOW to be ready for all changes in moon missions' profile (that may include an LSS, reusable-LSAM, etc. and needs crew rotations, repair, spare-Orions, etc.)

Grand_Lunar
2006-Sep-17, 02:06 AM
If the Apollo missions managed without a space station in lunar orbit, why can't we with the new missions?
And if you say "because of the smaller SM", then that's a moot point, as demostrated earlier.

Also, why do you insist on acting like the design we see is the final one? Why not wait until the thing is built to make cricticisms? Wether you make such claims now or then matters little; I doubt what you say will influence the engineer's plans.

gaetanomarano
2006-Sep-17, 12:57 PM
If the Apollo missions managed without a space station in lunar orbit, why can't we with the new missions?
because there was not sufficient money and technology to build it in '60s
a small lunar station offers many safety and operational options

And if you say "because of the smaller SM", then that's a moot point, as demostrated earlier.
as explained many times here, a bigger SM is ready for the planned missions AND for all new (complex) scenarios while a small SM must be used for the same (small) missions FOREVER

Also, why do you insist on acting like the design we see is the final one?
because it can't be bigger in the final design
the Ares-I payload is 25 mT max and the planned SM can't be more than 10 mT with 7 mT of propellant

I doubt what you say will influence the engineer's plans.
I give only my opinions, I don't want to "influence" anyone

Bob B.
2006-Sep-17, 04:03 PM
because it can't be bigger in the final design
the Ares-I payload is 25 mT max and the planned SM can't be more than 10 mT with 7 mT of propellant
The SM as currently planned must be bigger than your estimates.

The launch mass of the CM is currently published at around 8.5 mT, which should also be a good estimate of its on orbit mass. We don't know the mass of the SM but let's estimate it's dry mass at 3 mT, which is the same figure gaetanomarano is using (the Apollo SM was about 6 mT). This gives us a total dry mass of 11.5 mT. The SM's delta-v is published at 1,855 m/s. The specific impulse of the SM propulsion system should be typical of other hypergolic systems. The Shuttle's OMS has an Isp of 313 s and the Apollo SPS had an Isp of 314 s. Using a comparable Isp, the mass ratio of the CEV must be 1.83 to get the required delta-v. We therefore need at least 9.55 mT of propellant.

Bob B.
2006-Sep-17, 05:00 PM
the probability that two very high reliability vehicles like Orion and LSAM will fail in the same mission is extremely little.
I think the probability that one will fail is extremely low, which is why I think you are making a mistake by building inefficiency into each mission to safeguard against one unlikely scenario. You are not looking at the big picture and taking into consideration the accumulative effect of the inefficiency you are advocating.


a bigger SM doesn't change nothing in a standard ESAS mission
Yes it does. You are switching LOI from a more efficient to a less efficient engine, which means more propellant will be required to perform the maneuver. Since you have to carry more propellant, you canít carry as much payload (since the total mass is limited by the launch system). I calculated some approximate numbers to demonstrate this way back in post #13 (http://www.bautforum.com/showpost.php?p=825560&postcount=13).

I donít know the odds of an engine failure but I canít imagine it being more than 1 in 100. Letís be pessimistic and say 1 in 50. Therefore, according to the ESAS plan, 49 of every 50 launches are successfully inserted into lunar orbit. According to gaetanomaranoís plan, all 50 are inserted because of the backup contingency. Using my numbers from post #13, the total mass placed in lunar orbit is,

ESAS: 49 x 43.0 = 2,107 mT

Gaetanomarano: 50 x 39.2 = 1,960 mT

Even with the one failure, the ESAS plan has put significantly more payload in lunar orbit. To match the ESAS payload, gaetanomarano must perform four additional missions for a total of 54. With fewer missions, the ESAS plan is cheaper and safer.

gaetanomarano
2006-Sep-17, 05:28 PM
We therefore need at least 9.55 mT of propellant.
the GLOW of the Orion+LAS+adapter to 2nd stage is 15 mT
LM give no data about the SM and propellant wheight, but, since the max payload of the Ares-I is 25 mT, the difference is 10 mT with 7 mT of propellant, according with your evaluation of SM dry mass (that I agree)
however, both (7 mT or 9.55 mT) figures are sufficient ONLY for a TEI burn of the Orion, not (also) for a LOI of a the 65+ mT mass of an Orion+LSAM since the (20 mT smaller) Apollo+LEM used 18.4 mT of propellant for LOI and TEI

gaetanomarano
2006-Sep-17, 05:48 PM
...the probability that one will fail is extremely low...the big picture...
the accidents and problems in real spaceflights clearly demontrates that it is not so low (and spacecrafts can't be perfect)
also if we may have only ONE possible LOC, designers must build all vehicle to save THAT single crew!
about the "big picture"... you still ignore all the advantages of an autonomous Orion, all the (rescue and normal) missions' profiles it can accomplish and how much "bigger" the "picture" is with it (compared with your/NASA/ESAS TEI-only Orion picture)

Yes it does. You are switching LOI from a more efficient to a less efficient engine, which means more propellant will be required to perform the maneuver.
that's true (as I've already said in my answer to one of your previous posts) but it must be compared with the advantages (explained many times here and in my articles) of an autonomous Orion
also, you are right ONLY about the payload-per-launched point of view but you're COMPLETELY WRONG under the PAYLOAD-PER-DOLLAR point of view
ypu must calculate the max payload launched with the given ESAS funds, not the max payload launched with the given rockets' propellant
with an autonomous Orion, MANY (small) cargo and crew rotation missions (for single or multiple lunar landings) can be accomplished without the giant AresV and the very expensive LSAM (the only vehicle able to do a LOI in the ESAS plan!) with a money saving (probably) sufficient to launch TWICE the total payloads with the SAME funds!
last... if NASA will use an "LSS+resuableLSAM" architecure (that need to launch only the LSAM refuel and resupply) the total number of missions may be FIVE TIMES than ESAS with the same funds!

Bob B.
2006-Sep-17, 07:06 PM
the GLOW of the Orion+LAS+adapter to 2nd stage is 15 mT
LM give no data about the SM and propellant wheight, but, since the max payload of the Ares-I is 25 mT, the difference is 10 mT with 7 mT of propellant, according with your evaluation of SM dry mass (that I agree)
The 25 mT performance of the Ares I is the payload delivered to orbit. The launch abort system (LAS) is not delivered to orbit and is therefore not included in the 25 mT. Deducting the spacecraft adapter, the total mass of the CM+SM can therefore approach 24 mT.

By the way, Mark Wade of astronautix.com agrees with me because his estimate is very close to mine:

Orion SM Mass: 13,000 kg
Orion SM main engine propellants: 9,750 kg
Source: astronautix.com, Orion SM (http://www.astronautix.com/craft/orionsm.htm)

There cannot be only 7 mT of propellant or Orion cannot produce the 1,855 m/s delta-v.

Bob B.
2006-Sep-17, 08:36 PM
the accidents and problems in real spaceflights clearly demontrates that it is not so low (and spacecrafts can't be perfect)
We are not talking about all the various problems that can be encountered in space flight, we're talking about one specific problem -- the failure of an engine at LOI. Earlier you said it was not at all dangerous to place a crew in lunar orbit with only one functioning backup engine because the odds that engine would fail are exceedingly low. Well, the odds of the primary engine failing are also exceedingly low. It makes no sense to decrease the payload of every mission flown by 9% to guard against that one remote possibility. The economics of the situation tells us it is better to just accept the fact we may on rare occasion lose a payload.


about the "big picture"... you still ignore all the advantages of an autonomous Orion, all the (rescue and normal) missions' profiles it can accomplish and how much "bigger" the "picture" is with it (compared with your/NASA/ESAS TEI-only Orion picture)
No, I don't ignore the other options. An autonomous Orion with LOI/TEI capability can easily fit within a 24-mT package. The current delta-v requirement of 1,855* m/s is already enough, in some cases, for LOI/TEI assuming the vehicle flies alone without having to insert the mass of the LSAM. We have also seen preliminary specs for the manned version only; we don't know what the specs will be for an autonomous version. If NASA builds an autonomous version then clearly they will build something that works. Please give NASA engineers credit for knowing their business and stop worrying about it.

* The median LOI/TEI delta-v for the Apollo missions was 1,885 m/s.

Bob B.
2006-Sep-17, 09:08 PM
you are right ONLY about the payload-per-launched point of view but you're COMPLETELY WRONG under the PAYLOAD-PER-DOLLAR point of view
Please prove your point with numbers and not opinion (and please cite sources for your numbers).


with an autonomous Orion, MANY (small) cargo and crew rotation missions (for single or multiple lunar landings) can be accomplished without the giant AresV
No, there is nothing in the current or planned launch vehicle inventory that can send an Orion-sized vehicle to the Moon other than the Ares V. The Ares I can deliver Orion to LEO only. The next biggest vehicle in the inventory with lunar delivery capability appears to be the Delta IV-Heavy, which can inject only 10 mT on a translunar trajectory.

The better option, in my opinion, is an autonomous LSAM. The Ares V can launch a very large 55 mT unmanned LSAM that can deliver large payloads of about 20-25 mT to the surface of the Moon. I believe delivering a few large payloads is more efficient than delivering many small payloads. A Delta IV-H can probably deliver not more than 3 mT to the lunar surface, thus one Ares V can do what it would take 7 or 8 Delta IV-H to do.

gaetanomarano
2006-Sep-17, 09:21 PM
The 25 mT performance of the Ares I is the payload delivered to orbit. The launch abort system (LAS) is not delivered to orbit and is therefore not included in the 25 mT. Deducting the spacecraft adapter, the total mass of the CM+SM can therefore approach 24 mT.
By the way, Mark Wade of astronautix.com agrees with me because his estimate is very close to mine:
Orion SM Mass: 13,000 kg
Orion SM main engine propellants: 9,750 kg
There cannot be only 7 mT of propellant or Orion cannot produce the 1,855 m/s delta-v.
now we don't know the right LM figures, but (probably) both, you and Wade, are wrong in your evaluations since the figures you give are very close to the early 5.5 m. CEV (with a 13.4 mT SM) design, before the 0.5 m. diameter and -6500 lbs. reduction (and the change from SSME to J-2x for the 2nd stage engine)
but, also with 2.75 mT more propellant, it sill remains sufficient only for TEI while I suggest to have a bigger SM with propellant for LOI of Orion+LSAM and TEI of the Orion alone

gaetanomarano
2006-Sep-17, 09:35 PM
...the failure of an engine at LOI...
nonsense, since the piece of hardware that has a failure may be the engine
but (I repeat for the "nth" time) I suggest to shift the LOI fuel from LSAM to Orion for this reason AND half dozen of other good reasons

...autonomous Orion with LOI/TEI capability can easily fit within a 24-mT package. The current delta-v requirement of 1,855* m/s is already enough, in some cases, for LOI/TEI assuming the vehicle flies alone without having to insert the mass of the LSAM...
I don't use the word "autonomous" for "remote-controlled" but to say that it can do (manned or unmanned) the earth-moon-earth flight (with LOI and TEI) without the LSAM
that feature CAN'T FIT the "24 mT package" for three reasons:
1. the full "package" will be less than 24 mT
2. Orion is bigger than Apollo and needs more propellant for (both) LOI and TEI
3. according to the ESAS plan, the LOI fuel (simply) doesn't exist (and will never exist) in the SM tanks since NASA have moved it in the LSAM tanks, then, also if the "vehicle flies alone" it has NO fuel for LOI and has no importance if it flies "without having to insert the mass of the LSAM" since is the LSAM that must "insert the mass" of Orion+LSAM in lunar orbit!

Grand_Lunar
2006-Sep-17, 09:54 PM
You say these are all opinions, Gaetanomarano, yet I get the impression you are touting them about as if they are facts.

Well, my opinion is that you're making too many strawman claims.

When we see the Orion in operation, we shall see if your opinions are valid or not.
I think you will see that the final product will have features you haven't considered or have read of.

gaetanomarano
2006-Sep-17, 09:57 PM
Please prove your point with numbers and not opinion (and please cite sources for your numbers).
I don't need to cite (unexisting) "sources" to prove my point since the saving (that comes form LESS AresV and LSAM launched) clearly talks by itself!
EVERY launch of lander's refuel-only, Orion crew rotation, send/return Orion-cargo, rescue-Orion, etc. WITHOUT an AresV/bigEDS/LSAM will be a multi-billion$$$$ saving!
you're right about the launchers max payload, but, if we want all the advantages of an autonomous Orion, reusable-LSAM, Lunar Space Station, etc. we must exit form the logic and vehicles of the ESAS plan and enter in a ghostNASA logic, with different vehicles and (also) different rockets
the fly-alone Orion can't be launched with an Ares-I but don't need a big and very expensive AresV
two possible solutions: a 60 mT Ares-I able to launch the bigOrion and smallEDS or a 30 mT Ares-I with two launches for the Orion and its EDS
both solutions costs (about) like an 1.5 Orion launch (since the bigger Ares or the second Orionless Ares may cost half the price of a full Ares/Orion)
the launch of a (e.g.) rescue-Orion needs only 1.5 Aeres instead of one Ares-I + one Orion + one AresV + one bigEDS + one LSAM (for LOI)
don't ask me about prices but think about the cost (+$3 billion?) of the extra hardware we need to accomplish the SAME rescue (or small cargo, or cargo return) mission!
an autonomous (cargo or crew) LSAM is useful (and will be used) but it is not the BEST choice in all flights since the LSAM will be the most expensive vehicle of the entire ESAS plan (also due to the very low units built)
however, I only suggest to shift the LOI fuel from LSAM to SM to have (also) these options if and when we want them

gaetanomarano
2006-Sep-17, 10:05 PM
You say these are all opinions, Gaetanomarano, yet I get the impression you are touting them about as if they are facts. Well, my opinion is that you're making too many strawman claims. When we see the Orion in operation, we shall see if your opinions are valid or not. I think you will see that the final product will have features you haven't considered or have read of.
no
SOME are "opinions", other are FACTS
my poposal to shift the LOI fuel from LSAM to SM is an OPINION
the current design of the LSAM and SM (with the LSAM used for LOI and a TEI-only SM fuel) is a FACT because this is what decided in the ESAS plan (and not changed so far)
the "final product" may have many changes (the shape, the color, the solar panels, etc.) but NOT this change because, to have the LOI fuel in the "final" SM, it must be 10+ mT BIGGER than planned and also the Ares-I must be changed to lift the extra weight!

Bob B.
2006-Sep-17, 10:13 PM
3. according to the ESAS plan, the LOI fuel (simply) doesn't exist (and will never exist) in the SM tanks since NASA have moved it in the LSAM tanks, then, also if the "vehicle flies alone" it has NO fuel for LOI and has no importance if it flies "without having to insert the mass of the LSAM" since is the LSAM that must "insert the mass" of Orion+LSAM in lunar orbit!
The CEV can't perform LOI while lugging the LSAM along with it because it lacks enough propellant to slow down both itself and the larger LSAM. Eliminate the LSAM however, as would be the case if the Orion was sent to the Moon autonomously on a rescue mission, and it does have (or is at least very close to having) enough propellant for both LOI and TEI. All that matters is how much delta-v it can produce. Just because there is no CEV propellant allocated for LOI on a normal CEV/LSAM mission, doesn't mean you can't re-budget the propellant for different purposes on a different mission.

Bob B.
2006-Sep-17, 10:21 PM
but (I repeat for the "nth" time) I suggest to shift the LOI fuel from LSAM to Orion for this reason AND half dozen of other good reasons
The problem is that you have yet to convince me, and probably many other people, that your reasons are good ones.

gaetanomarano
2006-Sep-17, 11:09 PM
The CEV can't perform LOI while lugging the LSAM along with it because it lacks enough propellant to slow down both itself and the larger LSAM. Eliminate the LSAM however, as would be the case if the Orion was sent to the Moon autonomously on a rescue mission, and it does have (or is at least very close to having) enough propellant for both LOI and TEI. All that matters is how much delta-v it can produce. Just because there is no CEV propellant allocated for LOI on a normal CEV/LSAM mission, doesn't mean you can't re-budget the propellant for different purposes on a different mission.
I wonder you say that!
with or without tha LSAM, the SM doesn't have sufficient fuel nor sufficient tanks (and a bigger SM structure) since (both) are NOT PLANNED in the ESAS' flight profile, then, LM never adds these dead-weights!
the 7-9 mT of propellant (about 40% of the, smaller, Apollo CSM propellant!) will be sufficient ONLY for TEI of the Orion ALONE (as planned in ESAS)
without the LSAM the Orion needs 7-9 mT of propellant for TEI and MORE for LOI (since the engine must brake the Orion weight + the TEI fuel weight) for a total fuel weight (probably) around 20 mT
but, since the SM must be built to work with and without the LSAM, we must include also the propellant to brake the LSAM to LOI (maybe +5 mT)
THE CURRENT Orion DESIGN CAN'T BE USED FOR ANY LSAMLESS MOON FLIGHT WITHOUT A (two times) BIGGER SM

gaetanomarano
2006-Sep-17, 11:12 PM
...many other people, that your reasons are good ones.
I'll try to do soon

Bob B.
2006-Sep-17, 11:28 PM
now we don't know the right LM figures, but (probably) both, you and Wade, are wrong in your evaluations since the figures you give are very close to the early 5.5 m. CEV (with a 13.4 mT SM) design, before the 0.5 m. diameter and -6500 lbs. reduction (and the change from SSME to J-2x for the 2nd stage engine)
No, we are basing our calculations on the latest information available. The specs in the original ESAS report were:

CM total mass: 9,506 kg
SM inert mass: 4,576 kg
SM propellant mass: 9,071 kg
SM propellant: LOX/methane
SM specific impulse: 363.6 s
SM delta-v: 1,724 m/s

Since the award of the Lockheed-Martin contract, we now know the following:

CM total mass: 8,485 kg
SM inert mass: ?
SM propellant mass: ?
SM propellant: N2O4/MMH
SM specific impulse: ?
SM delta-v: 1,855 m/s

We can make a reasonable estimate of the specific impulse from other comparable systems and be very close (the normal variation between systems is very small). The Space Shuttle OMS uses the same propellant and produces an Isp of 313 s, so let's use that. Your own estimate of the SM insert mass was 3,000 kg, while Mark Wade used 3,250 kg. Both of these numbers are considerably less than the original 4,576 kg from the ESAS report. Let's use Mark's figure. We now have,

CM total mass: 8,485 kg
SM inert mass: 3,250 kg
SM propellant mass: ?
SM propellant: N2O4/MMH
SM specific impulse: 313 s
SM delta-v: 1,855 m/s

Based on the known information and our own educated estimates, we can calculate the amount of propellant using Tsiolkovsky's rocket equation,

Mf = 8,485 + 3,250 = 11,735 kg

Mo = Mf*e^(dV/C)
Mo = 11,735*e^(1,855/(313*9.807)) = 21,473 kg

Mp = Mo - Mf
Mp = 21,473 - 11,735 = 9,738 kg

I'm sure Mark performed a calculation very similar to what I just did and then simply rounded off his estimates.

Even though the SM has been downsized in both dimension and inert mass since the original ESAS report, there is actually more propellant because (1) the delta-v budget has been increased, and (2) the propulsion system has been changed to less efficient hypergolic propellant. Despite the greater mass, N2O4/MMH occupies a smaller volume because it is considerable denser than LOX/methane.

Bob B.
2006-Sep-17, 11:39 PM
with or without tha LSAM, the SM doesn't have sufficient fuel nor sufficient tanks (and a bigger SM structure) since (both) are NOT PLANNED in the ESAS' flight profile
Nonsense, look at the delta-v! The delta-v is all that matters.

Orion delta-v = 1,855 m/s

Here is the LOI+TEI delta-v for all the Apollo lunar-orbit missions:

Apollo 8 = 1,986 m/s
Apollo 10 = 2,031 m/s
Apollo 11 = 1,889 m/s
Apollo 12 = 1,808 m/s
Apollo 14 = 1,976 m/s
Apollo 15 = 1,843 m/s
Apollo 16 = 1,882 m/s
Apollo 17 = 1,839 m/s

Orion’s delta-v exceeds the LOI+TEI of three of the Apollo missions (12, 15 and 17).


THE CURRENT Orion DESIGN CAN'T BE USED FOR ANY LSAMLESS MOON FLIGHT WITHOUT A (two times) BIGGER SM
Hogwash! You don’t know what you are talking about.

Grand_Lunar
2006-Sep-17, 11:59 PM
Hogwash! You don’t know what you are talking about.

That has been obvious for some time now.

All I've seen are strawman arguements about a spacecraft that hasn't even preformed in real life.
How can anyone guess what faults exist?

gaetanomarano
2006-Sep-18, 02:49 AM
Nonsense, look at the delta-v! The delta-v is all that matters.

in all your previous (and latest) posts you (still) IGNORE a simple FACT (that also the fishes in the deep ocean know!)

the 5.5 m., 5 m., NASA, ESAS, old, new, Wade, Your, Boeing and Lockheed Martin Orions ALL have propellant ONLY for TEI to bring back to earth the Orion (alone) at end of the mission

the propellant for LOI (of the entire Orion+LSAM convoy) is planned to be ONLY in the LSAM

not to say the obvious, but the Orion+LSAM convoy doesn't need TWICE the LOI propellant (in both vehicles) since it must perform only ONE lunar orbit insertion per mission!

put the LOI propellant in both vehicles is (clearly) a GIANT waste of weight and money, then, ONLY one vehicle will have the LOI fuel!

an autonomous (manned or unmanned) Orion able to perform (both) LOI and TEI without the LSAM, must have the extra-propellent (and larger tanks) for LOI (propellant now in the LSAM)

if (in your calculations) you refer to the propellant/mass/size of the SM for the CURRENT (ESAS/NASA/LM) missions' plan, you're probably correct (despite LM has not released, so far, the real data of the SM)

but the NASA/ESAS/LM/Wade Orion has NO propellant for LOI that (clearly) must be added if we want that the Orion can fly alone, without the LSAM

if the propellant for TEI-only is (e.g.) 9 mT, the extra propellant for an (autonomous) LOI must be MORE than 9 mT (since, at LOI, the engine must brake the Orion + the TEI-fuel mass)

you can calculate the TEI+LOI propellant weight, but I think may be over 20 mT in total

also, since the Orion must be a "standard vehicle", we must add the LOI propellant also for the missions that Orion will perform WITH the LSAM

probably, to brake the full Orion+LSAM convoy with the SM engine and have sufficient propellant for TEI, we need over 25 mT of propellant and, since 20 mT (or 25 mT) are MORE than 9 mT, the SM must be bigger than current design!

or... do you are saying that the current (ESAS/NASA/LM) Orion's SM has the propellant for (both) LOI and TEI ?

I can't believe you're REALLY saying that!

.

Bob B.
2006-Sep-18, 05:00 AM
in all your previous (and latest) posts you (still) IGNORE a simple FACT (that also the fishes in the deep ocean know!)

the 5.5 m., 5 m., NASA, ESAS, old, new, Wade, Your, Boeing and Lockheed Martin Orions ALL have propellant ONLY for TEI to bring back to earth the Orion (alone) at end of the mission

the propellant for LOI (of the entire Orion+LSAM convoy) is planned to be ONLY in the LSAM.
I know that, I have not ignored it.


not to say the obvious, but the Orion+LSAM convoy doesn't need TWICE the LOI propellant (in both vehicles) since it must perform only ONE lunar orbit insertion per mission!

put the LOI propellant in both vehicles is (clearly) a GIANT waste of weight and money, then, ONLY one vehicle will have the LOI fuel!
I agree.


an autonomous (manned or unmanned) Orion able to perform (both) LOI and TEI without the LSAM, must have the extra-propellent (and larger tanks) for LOI (propellant now in the LSAM)
Not exactly, it must have enough propellant for LOI, TEI, and whatever other maneuvers it will perform. It needs extra propellant only if the sum of the maneuvers exceeds the spacecraft's delta-v of 1,855 m/s.


but the NASA/ESAS/LM/Wade Orion has NO propellant for LOI that (clearly) must be added if we want that the Orion can fly alone, without the LSAM
Not necessarily, see above and below.


if the propellant for TEI-only is (e.g.) 9 mT, the extra propellant for an (autonomous) LOI must be MORE than 9 mT (since, at LOI, the engine must brake the Orion + the TEI-fuel mass)
Herein lies the crux of the problem. The 9-10 mT of CEV propellant is for more than just TEI. The CEV is probably going to have to perform several maneuvers, similar to what Apollo did. Apollo had to perform altitude changes, plane changes, course corrections, etc. TEI itself required only about 1,000 m/s delta-v. The CEV has a delta-v of 1,855 m/s. If you are sending a CEV to the Moon just to enter orbit, dock with a station, and leave again, then it wonít have to perform many of the other maneuvers for which propellant has been budgeted. This extra propellant can then be used for LOI. There may not be enough excess to completely account for LOI, but we probably donít need to add nearly as much as you think.


you can calculate the TEI+LOI propellant weight, but I think may be over 20 mT in total
The Apollo CSM had a delta-v of 2,800 m/s, which we can probably consider a worst-case scenario. If we assume the inert CEV mass is 12 mT, then we will need about 18 mT of propellant to achieve this. However, if we just need enough for LOI+TEI plus a few course corrections, then maybe we can get by with 2,200 m/s or so. In this case we would need about 12 mT of propellant. The total vehicle mass would then be 24 mT, which is what I told you in an earlier post.


also, since the Orion must be a "standard vehicle", we must add the LOI propellant also for the missions that Orion will perform WITH the LSAM
Not necessarily. Orion can have the capacity to carry enough propellant for independent operations while still having the LSAM perform LOI for joint CEV/LSAM operations. Make Orionís tanks large enough to carry 12 mT when operating alone but fill them to only 9-10 mT (as mission requirements dictate) when operating with the LSAM. Using the LSAMís higher efficiency engines for LOI will allow about 4 mT more payload each mission.


probably, to brake the full Orion+LSAM convoy with the SM engine and have sufficient propellant for TEI, we need over 25 mT of propellant and, since 20 mT (or 25 mT) are MORE than 9 mT, the SM must be bigger than current design!
I think youíre pretty close on this one. I previously calculated that about 17 mT of propellant is needed for LOI if performed by the CEV. Adding this to its already existing propellant quantity and weíre at about 26-27 mT. Adding some weight for bigger tanks and the total vehicle mass will probably be about 40 mT. Of course you could reduce the propellant load considerable for independent CEV operations.


or... do you are saying that the current (ESAS/NASA/LM) Orion's SM has the propellant for (both) LOI and TEI ?

I can't believe you're REALLY saying that!
No, Iím not saying that. The CEV has enough propellant for TEI plus other maneuvers performed during normal landing missions. For missions in which these other maneuvers need not be performed, the excess propellant budgeted to them can be used for LOI, or at least part of LOI.

gaetanomarano
2006-Sep-18, 01:49 PM
Make Orion’s tanks large enough to carry 12 mT when operating alone but fill them to only 9-10 mT (as mission requirements dictate) when operating with the LSAM. Using the LSAM’s higher efficiency engines for LOI will allow about 4 mT more payload each mission.
this is a rational option, but a LOI+TEI Orion needs more propellant

I think you’re pretty close on this one. I previously calculated that about 17 mT of propellant is needed for LOI if performed by the CEV. Adding this to its already existing propellant quantity and we’re at about 26-27 mT. Adding some weight for bigger tanks and the total vehicle mass will probably be about 40 mT. Of course you could reduce the propellant load considerable for independent CEV operations. The CEV has enough propellant for TEI plus other maneuvers performed during normal landing missions. For missions in which these other maneuvers need not be performed, the excess propellant budgeted to them can be used for LOI, or at least part of LOI.
this is (exactly) the point
an autonomous Orion needs more propellant than only for TEI, some maneuvers and "HALF" LOI

Grand_Lunar
2006-Sep-18, 05:07 PM
This arguement (or whatever we want to call it) seems to be getting out of hand and going around in circles.

Its going nowhere.

gaetanomarano
2006-Sep-18, 07:46 PM
This arguement...going nowhere.
my opinion is simple: I suggest to design an Orion with sufficient propellant for LOI (with or without the LSAM) TEI and orbital maneuvering