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starcanuck64
2012-Nov-28, 09:42 PM
I'm reading Bob Berman's "The Sun's Heartbeat" right now and he mentions how astronauts on a mission to Mars would suffer greater neuron loss than Alzheimer's patients do that would leave them with about 40% fewer neurons after 2 years, a pretty significant loss.

What kind of protection is available for penetrating particles and radiation that are usually redirected by the magnetosphere and stopped by the atmosphere.

He also describes how muons which are produced by the collision of energetic particles from space with the atmosphere can live long enough to reach the Earth's surface and hit us due to Special Relativity.

antoniseb
2012-Nov-28, 10:16 PM
If the spacecraft had two meters thickness of water tanks surrounding the crew quarters, that would go a long way toward protecting the crew... it still wouldn't completely stop the radiation but it should bring it down to a tiny fraction. Personally I'd be more comfortable sending people inside something with ten meters of asteroid or Moon dust on the outside. This would add a large amount of mass to the vehicle, but it would make the trip less devastating.

cjameshuff
2012-Nov-28, 11:59 PM
An artificial magnetosphere may be able to do the job more effectively and with far less mass.

Jens
2012-Nov-29, 12:14 AM
I'm reading Bob Berman's "The Sun's Heartbeat" right now and he mentions how astronauts on a mission to Mars would suffer greater neuron loss than Alzheimer's patients do that would leave them with about 40% fewer neurons after 2 years, a pretty significant loss.


That seems pretty extreme. I would assume that other cells in the body would be affected as well, in fact more so since they have no skull to protect them. Does that mean that the astronauts would lose 40% of their heart muscle as well? If so, it seems to make a mission to Mars pretty tricky unless you have very good shielding.

NEOWatcher
2012-Nov-29, 04:33 PM
... in fact more so since they have no skull to protect them. Does that mean that the astronauts would lose 40% of their heart muscle as well?
I wouldn't think the skull would be a factor. If water is a good shield, then I would guess that it has more to do with tissue depth.
It's a matter of density rather than hardness. Isn't bone lighter than flesh?

Noclevername
2012-Nov-29, 05:15 PM
Generally hydrogen works best for particle shielding materials. So anything with a high content of hydrogen seems like a good idea. Conversely, since the human body is made mostly of water and hydrocarbons, it absorbs a lot of particles. So better fill up those water tanks.

starcanuck64
2012-Nov-29, 06:56 PM
That seems pretty extreme. I would assume that other cells in the body would be affected as well, in fact more so since they have no skull to protect them. Does that mean that the astronauts would lose 40% of their heart muscle as well? If so, it seems to make a mission to Mars pretty tricky unless you have very good shielding.

Maybe he was referring to the astronauts being on the planet surface where they would be receiving most of the incoming particles in the head first. In space then the tissue damage would be more evenly distributed.

starcanuck64
2012-Nov-29, 06:58 PM
An artificial magnetosphere may be able to do the job more effectively and with far less mass.

I guess the question then becomes would the generator be more massive than the mass of shielding material it was replacing.

IsaacKuo
2012-Nov-29, 07:52 PM
Just a couple weeks ago, there was this story: http://www.universetoday.com/98509/can-humans-live-on-mars/

Curiosity has been measuring radiation levels on Mars, and so far has found the levels to be in the same ballpark as those on the ISS. Mars's atmosphere halves the radiation dose. The radiation environment may be a concern for cancer risk, but not the sort of physiological effects suggested in the OP.

Furthermore, it's not like the astronauts are going to be walking around outside all the time. They've got to sleep. They may plausibly sleep within their solar radiation storm shelter--which they need anyway even if it may be too cramped for anything else. This could cut their dose by another third or more.

There's also the possibility of using regolith or other ISRU for larger scale habitat shielding, but the Curiosity results so far suggest this isn't a requirement.

starcanuck64
2012-Nov-29, 08:07 PM
Thanks Isaac, I kind of wondered about the 40% loss of neurons on a two year stay on Mars, I hadn't read that anywhere else.

TooMany
2012-Nov-29, 08:16 PM
These issues cast serious doubt on the practicality of sending men to Mars. Sure we could probably do it, but the expense would be, well astronomical. Better to work on robots. It's always been our fantasy that men would personally travel to other planets, but as mechanical probes become more autonomous, it's going to be hard to find a good argument that we need to send men.

Lifetime costs of the space shuttle program are said to be close to $200 billion dollars. The question is what did we get of value of scientific value that was worth that kind of money, not to mention the loss of 14 astronauts? I'm certainly happy that astronauts repaired and upgraded the Hubble telescope a few times, but maybe it would have been cheaper to just send up a new telescope.

publiusr
2012-Dec-01, 05:44 PM
There's some debate about that: http://www.space.com/18322-mars-sample-return-humans-robots.html
Otherwise we wouldn't have anyone in the field here. Man-rated Protons and R-7 allowed for larger robots to so that's a both and, not either or.

neilzero
2012-Dec-02, 04:20 AM
Perhaps the best reason for humans in space is a back up for humans on Earth. Near term the off planet humans would die a few years after the Earth stopped sending supplies and advice. To get self sufficient humans in space we need to practice for perhaps a century with dependent humans in space. Lots of dependent humans in space may get us to self sufficiency sooner. One way to get lots of humans in space is to develop robot nannies and artificial wombs, then we can send embryos and later sperm to space with mass of micro grams instead of 70 kilogram astronaughts.
Possibly robot colonies on Mars by 2020, first children reach adult age in 2039. Is it doable? The children need to live beneath the surface to minimise ionizing radiation. The children on Mars can communicate on bautform and answers.yahoo and similar forums where the several minutes delay hardly matters. Neil

Ara Pacis
2012-Dec-02, 04:25 AM
These issues cast serious doubt on the practicality of sending men to Mars. Sure we could probably do it, but the expense would be, well astronomical. Better to work on robots. It's always been our fantasy that men would personally travel to other planets, but as mechanical probes become more autonomous, it's going to be hard to find a good argument that we need to send men.It doesn't cast anything. Scientists have known about radiation from the beginning. These new results appear to be better than expected so they are actually encouraging, not discouraging.


Lifetime costs of the space shuttle program are said to be close to $200 billion dollars. The question is what did we get of value of scientific value that was worth that kind of money, not to mention the loss of 14 astronauts? I'm certainly happy that astronauts repaired and upgraded the Hubble telescope a few times, but maybe it would have been cheaper to just send up a new telescope.No, the question is what did we get of military value that was worth that kind of alteration for military demands when they designed the thing.

JCoyote
2012-Dec-02, 02:26 PM
Possibly robot colonies on Mars by 2020, first children reach adult age in 2039. Is it doable? The children need to live beneath the surface to minimise ionizing radiation. The children on Mars can communicate on bautform and answers.yahoo and similar forums where the several minutes delay hardly matters. Neil

Your first generation of children are going to have severe emotional issues in the social interaction range. Lack of a prior generation's mirror neuron feedback to guide the social development process... subconsciously... could be a very severe problem.

Sardonicone
2012-Dec-02, 02:33 PM
These issues cast serious doubt on the practicality of sending men to Mars. Sure we could probably do it, but the expense would be, well astronomical. Better to work on robots. It's always been our fantasy that men would personally travel to other planets, but as mechanical probes become more autonomous, it's going to be hard to find a good argument that we need to send men.

Lifetime costs of the space shuttle program are said to be close to $200 billion dollars. The question is what did we get of value of scientific value that was worth that kind of money, not to mention the loss of 14 astronauts? I'm certainly happy that astronauts repaired and upgraded the Hubble telescope a few times, but maybe it would have been cheaper to just send up a new telescope.

The hilarious thing is just two posts above yours it's explained how the initial numbers cited in the article are completely wrong, and how the radiation itself is easily mitigated. Did you read the rest of the thread before replying or are you just going off the OP?

TooMany
2012-Dec-02, 11:45 PM
There's some debate about that: http://www.space.com/18322-mars-sample-return-humans-robots.html
Otherwise we wouldn't have anyone in the field here. Man-rated Protons and R-7 allowed for larger robots to so that's a both and, not either or.

Keeping that in mind, perhaps both sides of the argument can get what they need want with shared funding. Are shuttle-type manned flights to EO part of planned manned visit to Mars?

TooMany
2012-Dec-03, 12:13 AM
The hilarious thing is just two posts above yours it's explained how the initial numbers cited in the article are completely wrong, and how the radiation itself is easily mitigated. Did you read the rest of the thread before replying or are you just going off the OP?

Where there is a will there is a way. I've heard the suggestions, heavy shielding, surround the module with water (or fuel?), create a strong magnetic field. Practicality is different from possibility. If you are interested in getting samples of Martian rocks, if you want to study geology and search for signs of life, then what's the most efficient way to do that?

It really boils down to this when you decide how to use the space budget: What is your goal? Is it to send men to Mars or is it to learn about Mars?

I'm really haven't looked into proposals for manned Mars vehicles so I don't know to what degree the technical problems have been solved. Without some new means of propulsion, won't it take month's to get there? So exposure has to be keep fairly low. ISS is protected by earth's magnetosphere.

TooMany
2012-Dec-03, 12:16 AM
No, the question is what did we get of military value that was worth that kind of alteration for military demands when they designed the thing.

What were the alterations for military value? (It's something I've haven't heard about before.)

Ara Pacis
2012-Dec-03, 07:55 AM
What were the alterations for military value? (It's something I've haven't heard about before.)

How long have you been on this forum? The question seems to come up at least once a month. (But maybe you're not in those threads.) The military wanted the shuttle to have the ability to launch into a polar orbit (from Vandenberg AFB, IIRC) and land back there, which means it needs to have a large cross range capability (because the earth spins beneath the orbital track) which is why they decided to put big, honking delta wings on the thing... which is part of the reason 7 astronauts died.

Ara Pacis
2012-Dec-03, 07:58 AM
Where there is a will there is a way. I've heard the suggestions, heavy shielding, surround the module with water (or fuel?), create a strong magnetic field. Practicality is different from possibility. If you are interested in getting samples of Martian rocks, if you want to study geology and search for signs of life, then what's the most efficient way to do that?

It really boils down to this when you decide how to use the space budget: What is your goal? Is it to send men to Mars or is it to learn about Mars?

I'm really haven't looked into proposals for manned Mars vehicles so I don't know to what degree the technical problems have been solved. Without some new means of propulsion, won't it take month's to get there? So exposure has to be keep fairly low. ISS is protected by earth's magnetosphere.

Actually, if you want the most efficient way then that might be a tractor beam, or sending small, self-replicating robots that build an aerospace industrial complex on mars that eventually produces the vehicles capable of bringing samples back. That may sound pedantic, but we've had Looong threads on that very subject.

TooMany
2012-Dec-05, 01:06 AM
How long have you been on this forum? The question seems to come up at least once a month. (But maybe you're not in those threads.) The military wanted the shuttle to have the ability to launch into a polar orbit (from Vandenberg AFB, IIRC) and land back there, which means it needs to have a large cross range capability (because the earth spins beneath the orbital track) which is why they decided to put big, honking delta wings on the thing... which is part of the reason 7 astronauts died.

On and off in Astronomy for a year or so. I'm new to the space exploration forum and no I was not aware of the polar orbit requirement.

Did the shuttle as-built actually have that capability? I'm pretty sure it was never tried. Can't you time the reentry to avoid the problem? Also isn't there a pretty significant gain from launching in the direction of earth's rotation, so they would have to overbuild the engines as well as the wings?

You gotta please the military to get money. Look what they get compared to the space program. The interstate highway system was built to military specs to assure they could drive tanks around on the bridges and whatnot.

TooMany
2012-Dec-05, 01:10 AM
Actually, if you want the most efficient way then that might be a tractor beam, or sending small, self-replicating robots that build an aerospace industrial complex on mars that eventually produces the vehicles capable of bringing samples back. That may sound pedantic, but we've had Looong threads on that very subject.

I don't know about the tractor beam, since they don't exist. However, some more modest plans for a manned trip to Mars do include a robotic lander that provides living space and perhaps makes and stores fuel for the return trip. Sorry but I have not read years worth of threads.

Ara Pacis
2012-Dec-05, 08:59 AM
On and off in Astronomy for a year or so. I'm new to the space exploration forum and no I was not aware of the polar orbit requirement.

Did the shuttle as-built actually have that capability? I'm pretty sure it was never tried. Can't you time the reentry to avoid the problem? Also isn't there a pretty significant gain from launching in the direction of earth's rotation, so they would have to overbuild the engines as well as the wings?

You gotta please the military to get money. Look what they get compared to the space program. The interstate highway system was built to military specs to assure they could drive tanks around on the bridges and whatnot.

According to what I've read, the shuttle was capable of that mission, despite not being tasked to do so because it ended up being over-mass. What do you mean by timing re-entry? Do you mean wait 12/24 hours until Vandenberg was under the track again? The Military only wanted it to be a single orbit.

Ara Pacis
2012-Dec-05, 09:00 AM
I don't know about the tractor beam, since they don't exist. However, some more modest plans for a manned trip to Mars do include a robotic lander that provides living space and perhaps makes and stores fuel for the return trip. Sorry but I have not read years worth of threads.

ISRU is different from self-replicating robot systems. Self-replicating robots actually create new robots all by processing native materials. ISRU for fuel only needs the atmosphere as feedstock, but self-replicating machines would actually mine the planetary regolith and bedrock.

TooMany
2012-Dec-05, 10:04 PM
The Military only wanted it to be a single orbit.

Why?

Buttercup
2012-Dec-05, 10:05 PM
So that's what's happened to my sister!!! :(

TooMany
2012-Dec-05, 10:12 PM
ISRU is different from self-replicating robot systems. Self-replicating robots actually create new robots all by processing native materials. ISRU for fuel only needs the atmosphere as feedstock, but self-replicating machines would actually mine the planetary regolith and bedrock.

Yes, I get the difference. I just wanted to point out that there is a robotic role in a manned trip to Mars that is already feasible. You don't need to go all the way to self-replicating robots to find a role for a separate robotic mission as a direct component of a manned-mission plan.

TooMany
2012-Dec-05, 10:22 PM
According to what I've read, the shuttle was capable of that mission, despite not being tasked to do so because it ended up being over-mass. What do you mean by timing re-entry? Do you mean wait 12/24 hours until Vandenberg was under the track again? The Military only wanted it to be a single orbit.

Wiki:
The inaugural polar-orbit flight, designated STS-62-A, and using Discovery with Shuttle veteran Robert Crippen as commander, was planned for October 15, 1986. However, the Challenger Disaster of January 28, 1986 grounded the Shuttle fleet as efforts were concentrated on recovery and returning the program to flight after a two year hiatus.
On July 31, 1986, Secretary of the Air Force Edward C. Aldridge Jr., announced that Vandenberg's space shuttle program would be placed in "operational caretaker status", six months after the space shuttle Challenger accident. A few months later, however, SLC-6 was placed in "minimum caretaker status" on February 20, 1987.

The article talks about the dangers of polar launches from Florida due to debris paths. These guys know how to waste money like nobody else on the planet. I worked in the defense industry for 20 years.

cjameshuff
2012-Dec-05, 11:34 PM
Why?

Because the results of reconnaissance missions can be very time sensitive, and actions against reconnaissance satellites may very well provoke reprisal. How long do you want to hang around in orbit after destroying a Soviet reconnaissance satellite or outright stealing it along with its load of exposed film, or snapping pictures that might show imminent military action?

Ara Pacis
2012-Dec-06, 06:03 AM
Why?

If you worked in the defense industry, you may know better why. There are reasons listed around the web. They may or may not be accurate or comprehensive. The answer you're looking for may be classified.

Ara Pacis
2012-Dec-06, 06:05 AM
Yes, I get the difference. I just wanted to point out that there is a robotic role in a manned trip to Mars that is already feasible. You don't need to go all the way to self-replicating robots to find a role for a separate robotic mission as a direct component of a manned-mission plan.

That's besides the point. You were talking about efficiency, and a small probe with a self-replicating robot, Von Neumann machines as some will call them, are more efficient because you send less mass and provide less input over the course of time devoted to it. It may take A LOT longer to get the result you want, but it would be more efficient from an Earth-centric point of view.

Ara Pacis
2012-Dec-06, 06:07 AM
Wiki:

The article talks about the dangers of polar launches from Florida due to debris paths. These guys know how to waste money like nobody else on the planet. I worked in the defense industry for 20 years.

I'm not sure what you're regarding debris paths. Are you referring to possible failures/interceptions along the east coast and Midwest if the shuttle were to launch on a northward trajectory or do you mean debris in orbit?

Jens
2012-Dec-06, 06:18 AM
I'm not sure what you're regarding debris paths. Are you referring to possible failures/interceptions along the east coast and Midwest if the shuttle were to launch on a northward trajectory or do you mean debris in orbit?

I would assume it would mean things like SRBs? Even if they have parachutes, what if one comes down on a house in the path northward from Florida?