I've seen a lot written about artificial gravity on the trip to Mars.But ... why? People have stayed in zero-g for more than a year (record 437 days), not just the ~8 months to Mars. And on Mars you only have to function in .38 g; even with spacesuits, that still probably comes out to carrying around less weight than on Earth. (And maybe you can use mechanical counter-pressure suits, which would weigh way less).Is the real problem after return to Earth? Is it something physical therapy can't deal with?(And would something like 'Mars One' need to worry about it at all?)What am I missing?
After all the long duration flights to-date the astronauts (and cosmonauts) have been incapable of getting out of the capsule themselves. Even under .38 g they'd be incapable of completing the mission.
I would say largest effect of 8 month in space is the psychological effects.
Next largest effect is the effects of radiation.
From radiation effects you may never recovery,
So, this quite different than some individual deciding to take such a risk, because one has make a policy, and follow this policy. And with 8 month trip, it seems NASA would have to change it's current policy.
I think these are handleable by proper crew selection alone. People have dealt with much more extreme isolation in much worse conditions (look at some of the guys on early Antarctic expeditions cramped into small winter quarters to conserve heat -- with no strong lighting for months and months) without psychological damage.You have tons of people to choose from. Be very very very selective on the psychological aspects.
Quote from: QuantumG on 11/11/2013 01:33 amAfter all the long duration flights to-date the astronauts (and cosmonauts) have been incapable of getting out of the capsule themselves. Even under .38 g they'd be incapable of completing the mission.But don't they recover in a reasonable time? And you'll probably be on Mars for months and months. So what makes a few weeks of recuperation-only unacceptable? The lander being too small for enough exercise to recuperate?
People laid up in bed can't take care of themselves.. doubly so on Mars.
Is the cost of artificial gravity going to be so great that the inconvenience of zero g and the time to adjust to the return to gravity are justified?
I think we can assume all astronauts have already had some some degree of screening, but you seem to suggest there high level precision about this, and I have no reason to suppose there can be such accuracy.So the skill of such predictions can be tested, and imagine some where and some time it has been tested.But I need the reference or some reason to agree that is such predictive ability of people future behavior which could be adequate to remove this risk. Very very very selective doesn't help unless you can successful select with skill.
We want to make sure we select people who are mentally ready to spend 70 days in bed. Not everyone is comfortable with that. Not every type of person can tolerate an extended time in bed, says Dr Cromwell."Now after all this testing how many finished? If they can get 100% on this that would indicate some skill.Though this is pretty easy in comparison.
Is the effect that extreme? I agree that people who get back from long stays can't just walk away as soon as they get back to Earth... but that's in 1 g, not .38. That should be much more manageable, no?
And how long is the recovery time likely to be? If it's fairly brief, couldn't you set up the necessary controls for the first bit to where they could be operated sitting down?
Yeah but the Antarctic guys were able to do it with basically no formal psychology.
QuoteYeah but the Antarctic guys were able to do it with basically no formal psychology.And in the Antarctic it's a shorter time period- nor are people locked in a small room for months.
"Despite winter-over studies that date back to the 1950s
Quote from: Vultur on 11/12/2013 03:30 amIs the effect that extreme? I agree that people who get back from long stays can't just walk away as soon as they get back to Earth... but that's in 1 g, not .38. That should be much more manageable, no?It's getting less and less "extreme" over time as it is learnt how to keep astronauts healthy in zero-g.
If you stayed sitting down, the recovery time would be forever.
OK but my real question is 'would the severe effects, eg inability to walk, seen when you go from 0g to 1g still apply when you go from 0g to 0.38g'?
Quote from: Vultur on 11/12/2013 06:22 amOK but my real question is 'would the severe effects, eg inability to walk, seen when you go from 0g to 1g still apply when you go from 0g to 0.38g'?Of course not. And they can stand up even in earth gravity if they have to. They just won't jump out of their seats after landing to fight venusian swamp monsters. Anyway they are not on Venus but on Mars which does not have swamp monsters. Just artificial gravity elephants in the room. Edit: fixed quote
AG is nice because as mentioned some things get a lot easier to do. (Zero-G toilets suck.. Pun highly intended However the most often noticed long term "adapation" problem when someone returns to gravity after a long stay in microgravity seems to be habitual... Simply "forgetting" for quite a while that the things you learned to do and adjust to in microgravity no longer apply.For example, Valeri Polyakov was at a formal dinner/party over two years after he came back and while telling a story to several people he habitually, and without thinking set his tea-cup in mid air to free both hands to expound a point. Gravity works Of course even with AG that 'habitual' problem is not going to go away as there are going to be noticable and "adapted-to" issues with most proposed AG schemes.The "main" problem with landing on Mars after a long period in microgravity is the very LACK of time between micro and adverse gravity during landing. Going from nothing to upwards of 6Gs during the landing (possible in some scenerios) might be more than the astronauts can take after a long trip. (This doesn't seem as likely as it once did given the number of times long duration astro/cosmo-nauts have been exposed to purely ballistic recoveries on the Soyuz) But still it would probably take at least a few weeks to fully adapt back to gravity after a long trip. The major reason for AG being needed was for the most part because the STAY on Mars for most early missions was only a few weeks meaning there wasn't enough "adapt" time built in to allow much actual work. This may no longer be the case.Randy
Though AG increases the complexity of the vehicle in some ways it can simplify the design of other parts.Even partial G makes liquid gas separation a lot easier.This would simplify at lot of the ECLSS design eliminating a lot of small high speed centrifuges and small passageways increasing it's reliability.