Quote from: guckyfan on 05/13/2017 11:53 amQuote from: mikelepage on 05/13/2017 10:26 amThe complexity with spin gravity is minor compared to the whole Mars endeavour anyway, so I find the resistance to the concept puzzling.I find it puzzling how people insist on AG without a trace of evidence it is needed.I'm curious what you think the threshold is then? We have strong evidence that long term zero-gravity exposure is harmful long-term in spite of regular exercise, and three centuries of biology research will tell you these effects always exist on a sliding scale.So if you're sure enough that Mars (38.9%) gravity is okay to plan a long-term mission without spin-g, do you think Moon-gravity (16.6%) is okay long term? What about Ceres surface gravity (2.8%)? Or Phobos surface gravity (0.6%)?
Quote from: mikelepage on 05/13/2017 10:26 amThe complexity with spin gravity is minor compared to the whole Mars endeavour anyway, so I find the resistance to the concept puzzling.I find it puzzling how people insist on AG without a trace of evidence it is needed.
The complexity with spin gravity is minor compared to the whole Mars endeavour anyway, so I find the resistance to the concept puzzling.
Aussie_space_nut:what do you think about this arrangement:
I am not sure Mars gravity is enough. But I think there is a very good chance. Humans have proven over and over to be very adaptable. With moon gravity I am less confident but whoever is interested in settling the moon can try that.I just say doing a multi year test with humans in spin gravity is absurd and absurdly expensive in money and time. It needs to be done on Mars.Spin gravity for pregnancies on Mars may technically not the biggest obstacle. But it would be a severe disruption of social life and much harder to justify and find people willing to go there. Spin gravity for in space settlements no doubt is needed. Multi year manned expeditions to the outer solar system may or may not require it. I guess yes it will be needed with flight times beyond 2 or 3 years.
Emphasis mine, just to point out that you can't say I have no evidence that low gravity on Mars is harmful, and then come out with a statement like that
<snip>For that matter, there's never been life (that we know of) that didn't have 1xg.<snip>
Quote from: mikelepage on 05/13/2017 08:08 am<snip>For that matter, there's never been life (that we know of) that didn't have 1xg.<snip>Except of course all aquatic life.
Quote from: mikelepage on 05/15/2017 06:13 amEmphasis mine, just to point out that you can't say I have no evidence that low gravity on Mars is harmful, and then come out with a statement like that This is getting annoying. My statements are totally consistent. I I never said we have positive proof either direction. It is you who demands a huge cost layout in money and time to try this in AG that IMO are better done in the real martian environment. Just imagine having an AG environment set up and maintained long enough that children can be born and raised there, just to prepare for getting to Mars, on the assumption it will fail.
Quote from: Welsh Dragon on 05/15/2017 09:38 amQuote from: mikelepage on 05/13/2017 08:08 am<snip>For that matter, there's never been life (that we know of) that didn't have 1xg.<snip>Except of course all aquatic life. Neutral buoyancy !=! zero gravity.
Quote from: mikelepage on 05/15/2017 10:11 amQuote from: Welsh Dragon on 05/15/2017 09:38 amQuote from: mikelepage on 05/13/2017 08:08 am<snip>For that matter, there's never been life (that we know of) that didn't have 1xg.<snip>Except of course all aquatic life. Neutral buoyancy !=! zero gravity.Of course not. But as far as adaptations required for it, it's effectively the same.
A small base on the Moon would allow research into medical effects of 1/6 gee in addition to lunar exploration. It would be interesting to see if such a low gravity reduces or eliminates the issues we have in microgravity. It would provide a third data point to extrapolate the effects of Mars gravity to give us an idea before we run experiments on Mars.There's international support for some sort of gateway station in lunar orbit. A gateway station and reusable lander would make lunar exploration easier.SpaceX could land an ITS ship on the Moon, let it sit for a few months as a temporary base, and go back to Earth. They probably want to do some cislunar testing before heading to Mars anyway.
Of course not. But as far as adaptations required for it, it's effectively the same.
Counterpoint: After spending 437 days in space (on Mir in 1994-1995) Valeri Polyakov got out of his Soyuz capsule and walked to the recovery couch.
In short, there's little reason to spend billions designing, building, testing a rotating spacecraft to go to Mars
PAUL 451:AGREE WITH YOU .CHECK THIS ARRANGEMENT
Very belated response:Quote from: whitelancer64 on 05/01/2017 08:28 pmCounterpoint: After spending 437 days in space (on Mir in 1994-1995) Valeri Polyakov got out of his Soyuz capsule and walked to the recovery couch.The test for orthostatic intolerance is not walking a short distance while still on an adrenalin high from a high-g EDL. Rather, it is a measure of the length of time you can stand upright, with a heart-rate around your resting BPM. Ten minutes is the minimum to be considered free of the condition.Most astronauts experience some degree of orthostatic intolerance. Typically requiring one day of recovery time per mission day. However, the susceptibility varies wildly between individuals and is largely unpredictable on the ground in advance. And even recovery is kind of random, some astronauts will be considered fully recovered and cleared, but weeks later will have a random fainting spell. (And it may be worse than reported because it might damage your chances of reflight, so there's a cultural tendency to hide such issues.)Flight surgeons I've seen speak on the subject consider micro-g adaptation to be a significant problem. Essentially, "the more we learn, the worse we realise it is."[Worse, astronauts are strongly selected against anything that might be considered a health risk or susceptibility, based on very ad hoc standards created since the '50s (which are as much gut-feel educated guesses as actual science-based.) Long duration spaceflight research therefore has a strong selection bias that is out of the hands of researchers. So what we are "learning" may be garbage due to the lack of ability to do a proper cohort selection.]Quote from: whitelancer64 on 05/01/2017 08:28 pmIn short, there's little reason to spend billions designing, building, testing a rotating spacecraft to go to MarsWe're already spending billions/yr on a micro-g station which isn't capable of producing high quality human weightlessness research.As for the cost of an AG Mars transfer vessel: Because of the lack of research into low gravity and spin gravity, we don't know what the optimum numbers are (G-load/RPM). If humans only need a trace of artificial gravity, and can adapt to a fairly high RPM, then it may be that a simple tumbling-pigeon rotation of any MTV would be enough. Or for a large ship like ITS-BFS, even rotation around the long axis could be enough. No giant wheels or risky tethers required.And such rotation may also simplify systems engineering. Water processing, air circulation and filtering, fuel transfer, sanitary systems, etc. (Prop-tank ullage only needs a milli-g load to settle the liquids. Other systems may be the same.) Simplified engineering, lower costs.Spending a relatively small amount now to produce data on AG, might save money in the long run.
AG is also possible on Mars.
You seem to have missed these parts of my comment: " [...] all the evidence suggests [...] "
Quote from: gospacex on 06/06/2017 02:59 pmAG is also possible on Mars.While true, I think artificial gravity would be significantly more complex to do on a planet with a partial gravity than it would in zero gravity.