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Mespo_Man
2003-Feb-06, 03:33 PM
In all the discussions I've read so far about the "what ifs" of the Columbia disaster, most of the posts were spent trying to figure out how long it would take to launch a Cadillac (Atlantis) to rescue a Cadillac (Columbia) or for Columbia to claw it's way up to the ISS without the required fuel or docking hardware.

WAIT A MINUTE

It's time to plan for the next disaster. Instead of assuming that "every precaution has been taken" and hope for the best, how about assuming "sh*t happens" and plan for the worst. Design engineers can't possibly cover all likely scenarios and build every conceivable safety feature into the next generation shuttle. But they CAN design the next generation life boat.

RIGHT NOW:
The Soyuz TM space craft weighs in at about 7 tons. It can hold 3 people right now. For some several hundreds of millions of dollars, several of these craft can be launched and placed in low earth orbit. Pre-positioned, pre-stocked life boats.

SHORT TERM:
What other rockets can lift on or near 7 tons?
European Arianne 5 - 10 tons
Chinese Long March IV - 5 tons
American Delta IV - 7 tons

Could the Soyuz descent pod be modified to fit these rockets?

LONG TERM:
How about an international consortium to design and build the next life boat? Pre-positioning them in low earth orbit also has the advantage that they can be brought down on a rotational basis to refresh the consumables AND test the heat shield to boot.

More shuttle launches increases the mathematical probability of failure. Let's assume more failures will occur and plan for them. I'm not an engineer by trade, but it just seems that the hardware to give future shuttle crews a fighting chance is right at our fingertips. Abandoning a shuttle craft in orbit because of damage sustained during launch or while in orbit should be an option.

"Give me a vector to the nearest lifeboat" should be a part of the shuttle commander's operations handbook.

(:raig

Laser Jock
2003-Feb-06, 03:40 PM
I don't know about that. It seems to me that randomly putting "lifeboats" in LOE would be about as logical as putting several real lifeboats in the Atlantic in case any ships sink. Yes, spacecraft have some manuverability, but space is very big and you have three dimensions to move in not just two (on the surface of the ocean).

Mainframes
2003-Feb-06, 03:46 PM
Probably better to have a shuttle on permanent standby. Say a slightly dulled down version with no special equipment, just the ability to get up quickly and carry a larger crew compliment and get them down safely.

logicboy
2003-Feb-06, 03:46 PM
You would have to replace all the lifeboats every six months to keep them reliable just like they do with the space stations lifeboat.

This would be very costly

Doodler
2003-Feb-06, 03:48 PM
Putting Soyuz's 'on station' is an expensive undertaking. They are barely going to meet ther commitments for the space station, how on Earth are they going to put them on station, or even on stand by, just in case? Putting them in orbit means replacing them every six months, to say nothing of whether their parking orbit will be such as to make them immediately usable in the event of an emergency. Keeping them on the ground makes them last longer, maybe, but the orbit compatability remains an issue. Can you do a quadruple launch and put them all within reach of the shuttle? (I say quadruple, cause you're looking at a three man craft with one seat taken by the pilot with seven folks you need to rescue) Can launching them from other sites/facilities get them aligned in orbit fast enough? Last I checked, Canaveral and the Baikonur (Yeah, I mangled that one) can launch two each at best, but CERTAINLY not simultaneously. Think orbital alignment on the fly is bad with two different tragectories from one facility is bad (two tragectories, cause like i said, you aren't launching two at once) Try doing four tragectories where the two launch facilities aren't even putting them in the same orbital plane. Its just not feasable.

There was supposed to be a 7 man lifeboat built. The US was supposed to build it, but we got infatuated with the idea of Core Complete (or Corpse Complete, since three people amount a dead science program there) and shelved it.

Jim
2003-Feb-06, 04:19 PM
There was supposed to be a 7 man lifeboat built. The US was supposed to build it, but we got infatuated with the idea of Core Complete ... and shelved it.

Are you talking about the X-38? It was intended as a lifeboat for the ISS. However, when the (economic) decision was made to scale down the ISS complement from 7 to 3, the X-38 became "unnecessary" and funding was ended.

Doodler
2003-Feb-06, 04:25 PM
On 2003-02-06 11:19, Jim wrote:
There was supposed to be a 7 man lifeboat built. The US was supposed to build it, but we got infatuated with the idea of Core Complete ... and shelved it.

Are you talking about the X-38? It was intended as a lifeboat for the ISS. However, when the (economic) decision was made to scale down the ISS complement from 7 to 3, the X-38 became "unnecessary" and funding was ended.




Not intending to sound sarcastic at all, but is that not the jist of what I said? I did not say it was economic in nature, but I did say it was shelved when we decided Core Complete was enough. My reference to "infatuation" was sarcastic in nature, meaning it was cut back when the overruns in the station made it an easy mark for the budget axe.

calliarcale
2003-Feb-06, 05:13 PM
Actually, X-38 isn't quite dead yet. (Visions of Monty Python: "I'm not dead yet!") NASA has quietly managed to keep the project alive with funding from other sources. It's not developing it for the CRV, officially, but it is working on materials, reentry techniques, parafoils, etc. Last year, they even took delivery of its solid-fueled retropack and began acceptance testing. The hope is that once "Core Complete" is acheived, CRV will be put back on official active status. If they keep the project alive in the meantime, it will be easier to restart the effort in a serious way.

One nice feature of CRV is that the designers originally had a requirement to make CRV meet the Hermes project reqs. Specifically, it had to be able to fit on an Ariane V payload adapter, turning it into something very like the cancelled Dynasoar project (or the Soviet Spiral spaceplane concept). This req was dropped fairly early on, but the designers kept everything the right size to fit the spacecraft onto Ariane V. After all, some of its requirements were fairly arbitrary -- why *not* make it fit Ariane V? It also has to fit inside a Shuttle's payload bay, of course.

It might be possible to turn CRV into a rendezvous rescue craft, but this will involve giving it some kind of maneuvering capability. At present, its design only gives it enough maneuvering ability to back away from ISS, orient itself for deorbit, and then fire the retropack. It doesn't have much capacity for maneuvering; in the interest of emergency reliability, it has been designed as simple as possible. So there would be some work involved, but it could still be feasible as a rescue vehicle. Set it up to launch on a decommissioned Titan II, and you can cut its launch processing times down very short indeed because Titan II is, after all, an ICBM. The other major problem would be developing an automated (or remote-controlled) rendezvous and stationkeep system. If possible, it would be nice to outfit it with an RMS grapple fixture so a crippled shuttle could capture it and make the transfer a bit less harrowing. Transfer techniques would also need to be developed; as CRV has no airlock, you couldn't use the old Rescue Ball concept.

JayUtah
2003-Feb-06, 05:44 PM
Two problems I see immediately with this.

First, we're trying to get stuff out of low earth orbit. Especially with the Iridium constellation there's already enough obstacles for launches.

Second, even if we ignore the altitude parameter, there are still an infinite number of orbits. You have a 20-degree range of allowable STS orbit inclinations, and within each of these an infinite number of orientations for the ascending node -- an essentially infinite number of orbital planes in which the orbiter can fly.

You have two choices to deal with this problem. Either launch the shuttle only in predetermined planes where you've cached lifeboats, or flood low earth orbit with lifeboats such that the plane change to get to one of them falls within the orbiter's OMS capacity.

The former option puts a 5-minute, once-daily launch window on every shuttle launch, even those that wouldn't otherwise require it. (HST and ISS rendezvouses already have this constraint, but Columbia did not.)

The latter is Iridium, only with bigger obstacles.

Russ
2003-Feb-06, 06:47 PM
On 2003-02-06 10:33, Mespo_Man wrote:

SHORT TERM:
What other rockets can lift on or near 7 tons?
European Arianne 5 - 10 tons
Chinese Long March IV - 5 tons
American Delta IV - 7 tons

(:raig



I call to your attention to the fact that the Arianne 5 cannot be used. It has been prooven that the only thing it can do is blow up 10 tons at high altitude. /phpBB/images/smiles/icon_wink.gif /phpBB/images/smiles/icon_lol.gif

Doodler
2003-Feb-06, 06:54 PM
On 2003-02-06 13:47, Russ wrote:


On 2003-02-06 10:33, Mespo_Man wrote:

SHORT TERM:
What other rockets can lift on or near 7 tons?
European Arianne 5 - 10 tons
Chinese Long March IV - 5 tons
American Delta IV - 7 tons

(:raig



I call to your attention to the fact that the Arianne 5 cannot be used. It has been prooven that the only thing it can do is blow up 10 tons at high altitude. /phpBB/images/smiles/icon_wink.gif /phpBB/images/smiles/icon_lol.gif



I noticed that a lot of new rockets tend to explode quite a bit with live loads on board. Aren't these things given shakeout flights without multi-million dollar satellites on board? Or is it just not in the budget?

Mespo_Man
2003-Feb-06, 07:07 PM
I noticed that a lot of new rockets tend to explode quite a bit with live loads on board. Aren't these things given shakeout flights without multi-million dollar satellites on board? Or is it just not in the budget?


I believe the operating philosophy is...

If it's successful, it's production.
If it fails, it's a test.

(:raig

Doodler
2003-Feb-06, 07:09 PM
On 2003-02-06 14:07, Mespo_Man wrote:

I believe the operating philosophy is...

If it's successful, it's production.
If it fails, it's a test.

(:raig


How Soviet of them.

Mespo_Man
2003-Feb-06, 08:02 PM
Two problems I see immediately with this.

First, we're trying to get stuff out of low earth orbit. Especially with the Iridium constellation there's already enough obstacles for launches.

Second, even if we ignore the altitude parameter, there are still an infinite number of orbits. You have a 20-degree range of allowable STS orbit inclinations, and within each of these an infinite number of orientations for the ascending node -- an essentially infinite number of orbital planes in which the orbiter can fly.

You have two choices to deal with this problem. Either launch the shuttle only in predetermined planes where you've cached lifeboats, or flood low earth orbit with lifeboats such that the plane change to get to one of them falls within the orbiter's OMS capacity.

The former option puts a 5-minute, once-daily launch window on every shuttle launch, even those that wouldn't otherwise require it. (HST and ISS rendezvouses already have this constraint, but Columbia did not.)

The latter is Iridium, only with bigger obstacles.



If I may press you a bit, Jay.

If LEO is getting too crowded, how about lifeboats in a higher parking orbit? I'm not talking about static platforms, but fully maneuverable robot vehicles. It has been stated on another thread that the "shelf-life" of the Soyuz is about 6 months, based on the volatility of the fuel on board. Does it have to be so? No other fuels for consideration? Not even APBs? (Agitated Pepsi Bottles)?

If the shelf-life of a rescue vehicle can be extended, then what do you consider a "flood" of vehicles? I imagine the number would be based on what mission planners would consider as the safe minumum lifeboat rendevous time. 12 hours? One day? Two days?



(:raig

<font size=-1>[ This Message was edited by: Mespo_Man on 2003-02-06 15:04 ]</font>

Doodler
2003-Feb-06, 08:32 PM
On Dr. Ed Mitchell's forum, I was in a rather lengthy discussion concerning orbital debris. There is a lot, and I mean a LOT of junk up there. Putting a half dozen life boats up there in storage is adding to the alread ugly problem... the station and shuttles are already having to dodge crap that has been discarded from previous missions, now you would ask us to compound the problem by adding more orbiters in already crowded orbit planes? What is to stop them from being rendered useless and stuck in orbit by a massive solar flare, like the Galaxy satellite? What is to prevent it from being hit by a smaller piece of debris and having their supplies bled into space? Or from being destroyed by an impact creating a nice orbitting debris field? If there is a plan to use stand by launch craft, better to keep them grounded till you need them. That way when you launch them, they go right (hopefully) where you want them without the wear and tear associated with being left in space.

Colt
2003-Feb-06, 08:48 PM
An idea on dealing with LEO debri: We could build a giant cannon/EM rail-cannon on the ground and fire nuclear buckshot at LEO to clear out all of the junk! And it would probably be cheaper than launching satellites. /phpBB/images/smiles/icon_biggrin.gif I doubt the Russians would like something of that nature though. /phpBB/images/smiles/icon_wink.gif

Wasn't Enterprise an atmospheric and re-entry test vehicle? What would it take to strip it down and send it up on automatic to then dock with the ISS as a lifeboat? Just shooting in the dark right now. /phpBB/images/smiles/icon_smile.gif -Colt

tjm220
2003-Feb-06, 08:53 PM
Nu-cu-lar buckshot?

John Kierein
2003-Feb-06, 09:06 PM
Putting lifeboats on-orbit doesn't work. It takes too much energy to change planes for a shuttle or a lifeboat to get together unless they are launched to the same inclination. Otherwise, if the Columbia had known it was in trouble, it could have rendezvoused with the Space Station. But the ISS was in a much different orbit. Much better to have a standby vehicle on the ground, but still very expensive. There are current designs for spheres that a crewman could crawl into to transfer from one EVA to another, so a docking port is not absoluelly required so long as both vehicles have EVA capability.

The Iridium constellation is at a higher altitude than the shuttle flies.

<font size=-1>[ This Message was edited by: John Kierein on 2003-02-06 16:07 ]</font>

JayUtah
2003-Feb-06, 09:43 PM
If LEO is getting too crowded, how about lifeboats in a higher parking orbit?

Obviously the farther out you go, the dramatically less crowded it becomes. But then it makes them harder to launch, and also increases the re-entry speed. A Soyuz spacecraft has a maximum altitude governed by its heat-dissipating capacity. Luckily we know that it's at least the ISS altitude, which is pretty high.

Does it have to be so? No other fuels for consideration?

Not really. Something that's going to stay on-orbit for extended periods needs reliable equipment, and reliability derives from simplicity which, for rocket engines, means hypergols. Hypergols by definition are highly reactive, so there you have it.

Ion propulsion is too weak. Solid motors aren't controllable and require external ignition. Cryogenics have a shorter shelf life and require external ignition. It's not just a matter of finding a suitable propellant formulation; it's making it work reliably in an engine that can soak on-orbit for a matter of years.

what do you consider a "flood" of vehicles?

One.

Well, let's be practical. Depending on what you want to do, having one more object up there can halve your available launch windows. But in practice that doesn't happen often.

If we orbit them at 250 nautical miles, casual low earth orbits won't be affected. But you still have to deal with GPS, weather, and communication satellites as well as planetary probes. That constitutes a sizable fraction of commercial and scientific space traffic. This is not an insurmountable problem; it may be the price we'll have to pay for safer manned space flight.

I imagine the number would be based on what mission planners would consider as the safe minumum lifeboat rendevous time.

It's a little bit more complicated than that. Time to rendezvous is an issue, certainly, but fuel margin is the greater concern.

If you don't constrain shuttle launches to certain orbits, you have to orient the lifeboat orbits to fall within shuttle fuel constraints for plane changes as well as altitude changes. Let's say you restrict the shuttle orbit inclinations to 28&deg; at the lowest and 59&deg; at the highest. You would have to establish key orbital planes within this range to accommodate lifeboats. A vehicle in distress would have to be able to change from its current orbital plane to one of the rescue planes as the first step in a rendezvous.

But inclination alone does not determine the orientation of an orbit. You have also the right ascension of the ascending node. Even if a distressed vehicle were at the correct inclination, it might not be in exactly the same orbital plane. Adopting the same strategy as above, for each orbital plane we provide a certain number of nodal orientations to which a vehicle can change.

How many of these we need depends on an engineering analysis I would have to spend a lot of time on before coming up with an answer. But basically it would go like this. The orbiter already has a certain template for fuel budgeting. You have de-orbit fuel plus insertion fuel plus circularization fuel plus a margin. That's your absolute necessity. Everything beyond that is for orbital trim and manuevering. You would need to take away from that to supply a fuel budget for emergency rendezvous. The more you allocate, the less there is for on-orbit maneuvers, and this limits your mission capability. The less you allocate, the more lifeboats you'd need in order to compensate for the orbiter's reduced ability to reach them.

Any lifeboat rendezvous would comprise the following steps, in order:

1. Transfer to 250 nm apogee.
2. Circularization to 250 nm rendezvous orbit.
3. Change of inclination to nearest lifeboat inclination.
4. Change of node to nearest lifeboat node.
5. Trim and final rendezvous.

These manuevers will equate to a certain sum of delta-v, which will in turn translate to a certain amount of fuel.

If A<sub>p</sub> represents the maximum plane change capability in angular degrees, and A<sub>n</sub> is the maximum node change capability in angular degrees, for a given fuel budget, then the minimum number of lifeboats required would be

L = ( (31 / A<sub>p</sub>) / 2 ) * ( (360 / A<sub>n</sub>) ) / 2 )

Now solve this system so that L and (A<sub>p</sub>+A<sub>n</sub>) are minimized.

This is actually a first-order approximation since the orbital mechanics on the list will immediately realize that steps 3 and 4 above could be accomplished with a single maneuver, and perhaps with less total delta-v requirement than as two separate steps. It's the orbital mechanics equivalent of dropping off your dry cleaning on the way to the supermarket.

In any case you have to factor in the two-year construction time for a Soyuz spacecraft.

JayUtah
2003-Feb-06, 09:47 PM
The Iridium constellation is at a higher altitude than the shuttle flies.

I bring up Iridium not because it is a complication for the shuttle, but because it is a complication for any launch to geostationary orbit or points outward. Before we contemplate deploying a lifeboat constellation we have to consider its impact (pun intended) on all space operations, not just on the shuttle.