# Spaceship: Minimum Gs for health? **URL:** \ **Category:** Factual Questions\ **Created:** [January 8, 2017, 7:01pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643 "2017-01-08T19:01:33Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [January 8, 2017, 7:01pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/1 "2017-01-08T19:01:33Z")
I’ve been fiddling around with another spaceship model. This one is going to be an ocean liner of space, designed to proceed at constant boost (to provide a semblance of gravity for passenger comfort). Also, I don’t want to postulate both a space-drive and artificial gravity; I’d prefer to keep my improbabilities to a minimum 😉 The problem is that, if I boost at 1G, the ship is too fast; I can make it to Mars in 3 or 4 days and Neptune in a couple weeks. Which means I don’t need a ballroom and a gymnasium and a lounge and all those other beloved ocean liner accoutrements, and who’d want to build a model without 'em? So I can cut the boost. At 0.25G, Mars is 6 to 10 days away and Neptune about a month, and at least on the Neptune run, I need a ballroom and lounges and all those other lovely things to keep the passengers occupied on the long trip. But now a question arises, and I put it to you guys. I know at zero g, your bones start to lose mass and you get vision problems and heaven knows what else. So what’s the minimum G I can use and still have my passengers arrive in reasonably good health? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 8, 2017, 8:36pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/2 "2017-01-08T20:36:37Z")
We have extensive experience of human health at 1 g. And we’ve had people go for over a year in 0g, so we have a decent amount of experience with that, too. But for any g value in between, the longest data we have are from the Apollo astronauts on the Moon. That’s it, just a few days. So the short answer is, nobody knows. ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [January 9, 2017, 2:07pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/3 "2017-01-09T14:07:48Z")
In my opinion, figuring out the effects of long-term simulated gravity ought to be one of the top priorities for NASA. We already know that long-term zero G living causes some pretty severe health issues, and that only some can be improved with rigorous exercise routines. That’s tolerable when you start with astronauts in peak physical condition, and they return to Earth where they can recover with the best modern treatments. That’s not so good when the astronauts have to immediately perform physical tasks, like they’d face on any kind of Mars mission. Unfortunately, none of the proposals to test centrifugal artificial gravity have gone anywhere. ---
**Author:** ![boffking](https://avatars.discourse-cdn.com/v4/letter/b/858c86/32.png) [@boffking](https://boards.straightdope.com/u/boffking)\ **Post date:** [January 9, 2017, 3:40pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/4 "2017-01-09T15:40:15Z")
A better question is, how are you going to stop the ship when it reaches the destination? 0.25G acceleration for weeks is going to lead to ridiculous speeds. ---
**Author:** ![mbh](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@mbh](https://boards.straightdope.com/u/mbh)\ **Post date:** [January 9, 2017, 3:45pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/5 "2017-01-09T15:45:43Z")
> [@boffking](#): > > A better question is, how are you going to stop the ship when it reaches the destination? 0.25G acceleration for weeks is going to lead to ridiculous speeds. Spend the first half of the trip accelerating. At the midpoint, flip the ship 180 degrees. Spend the second half of the trip decelerating. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [January 9, 2017, 3:46pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/6 "2017-01-09T15:46:38Z")
My conspiracy theory regarding NASA and low G is that they have some inkling that anything other than 1 G leads to total bone “decay” over a period of years…and once that got out…well people living on the moon and mars is pretty much a no go…and that would be bad… ---
**Author:** ![iiandyiiii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iiandyiiii/32/7924_2.png) [@iiandyiiii](https://boards.straightdope.com/u/iiandyiiii)\ **Post date:** [January 9, 2017, 3:49pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/7 "2017-01-09T15:49:04Z")
> [@billfish678](#): > > My conspiracy theory regarding NASA and low G is that they have some inkling that anything other than 1 G leads to total bone “decay” over a period of years…and once that got out…well people living on the moon and mars is pretty much a no go…and that would be bad… But how would they know? No one has spent any more time than a few days in constant gravity between 0 and 1 g. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [January 9, 2017, 3:50pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/8 "2017-01-09T15:50:59Z")
> [@iiandyiiii](#): > > But how would they know? No one has spent any more time than a few days in constant gravity between 0 and 1 g. Well, like many things…don’t ask any question you might not like the answer to. Or more on point. Don’t try to find the answer IF you might not like the answer. IMO NASA NOT finding this out is one serious failure of our manned space program. With as much money as we have spent messing around in low earth orbit we should have SOME idea if 1/3 a G is okay or not. Prediction. ---
**Author:** ![iiandyiiii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iiandyiiii/32/7924_2.png) [@iiandyiiii](https://boards.straightdope.com/u/iiandyiiii)\ **Post date:** [January 9, 2017, 3:51pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/9 "2017-01-09T15:51:04Z")
Do we know enough to say that a 150 lb man feels about half the effects from gravity as a 300 lb man? Or is there more to it than this sort of simple calculation? ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [January 9, 2017, 3:52pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/10 "2017-01-09T15:52:11Z")
We have ample evidence that even at 1 g your bones will eventually “decay” - that’s what osteoporosis is, after all, it’s just that at 1 g is doesn’t get hazardous (usually) until a fairly advanced age. Short answer, as noted, is that “we don’t really know”. On the other hand, with 3-4 days to Mars it probably doesn’t matter much and gravity will be more important for passenger comfort (less nausea, cocktails stay in the martini glass, etc.) than overall health because the health effects of even microgravity for that time period is pretty minimal. ---
**Author:** ![iiandyiiii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iiandyiiii/32/7924_2.png) [@iiandyiiii](https://boards.straightdope.com/u/iiandyiiii)\ **Post date:** [January 9, 2017, 3:52pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/11 "2017-01-09T15:52:33Z")
> [@billfish678](#): > > Well, like many things…don’t ask any question you might not like the answer to. I would like to know the answer to this question. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [January 9, 2017, 3:55pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/12 "2017-01-09T15:55:17Z")
> [@lazybratsche](#): > > In my opinion, figuring out the effects of long-term simulated gravity ought to be one of the top priorities for NASA. We already know that long-term zero G living causes some pretty severe health issues, and that only some can be improved with rigorous exercise routines. That’s tolerable when you start with astronauts in peak physical condition, and they return to Earth where they can recover with the best modern treatments. That’s not so good when the astronauts have to immediately perform physical tasks, like they’d face on any kind of Mars mission. > > Unfortunately, none of the proposals to test centrifugal artificial gravity have gone anywhere. The designs for those toroidal space stations proposed by Werner von Braun for the US Space Program in the fifties (although they had been conceived of by others much earlier) were never intended to rotate fast enough to produce 1 g, a detail they n ever really told us about in those popularizations. (Although the Space Wheel and the Discovery centrifuge apparently produced 1 g in the film **2001** , they were too small and/or rotating too slowly to actually deliver this. It’s one of those sneaky secrets of space engineering) the conceptual Stanford Torus, proposed at 1.8 km in diameter, would have rotated at a stately one rotation per minute, which gives 1 g of artificial gravity at an angular rate thought to be imperceptible. For obvious reasons, no one has built one yet. Coming up with a design to give an acceptable level of gravity without being too big (the Stanford Torus would require a million tons of material) or without unacceptably fast rotation rates (they’re still debating what this is) is the big problem of tradeoffs. > **[Stanford torus](https://en.wikipedia.org/wiki/Stanford_torus)** > > The Stanford torus is a proposed NASA design for a space settlement capable of housing 10,000 to 140,000 permanent residents. > The Stanford torus was proposed during the 1975 NASA Summer Study, conducted at Stanford University, with the purpose of exploring and speculating on designs for future space colonies (Gerard O'Neill later proposed his Island One or Bernal sphere as an alternative to the torus). "Stanford torus" refers only to this particular version of the design, as the concept of a rin... Anything smaller would either have to rotate at an angular rate that would make Coriolis forces noticeable, or would rotate too slowly to give you a gee. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [January 9, 2017, 4:13pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/13 "2017-01-09T16:13:49Z")
Based on the OP’s description of his ship, it seems to have the ability to accelerate indefinitely (magic fuel?). If that’s the case, go ahead and run at 1 G, just turn the ship around 180 degrees for a while when you want to slow down. You’ll still be getting 1 G all the way. ---
**Author:** ![JRDelirious](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jrdelirious/32/9531_2.png) [@JRDelirious](https://boards.straightdope.com/u/JRDelirious)\ **Post date:** [January 9, 2017, 4:15pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/14 "2017-01-09T16:15:25Z")
Right, it’s not a question of fearing the answer, it’s that they already know the engineering/cost considerations make “build it just to find out what happens” a No Go at the appropriations committee. Hard enough to keep a manned program flying as it is, they’re not going to pop for a reduced-G environment experiment for its own sake. Mind you, they could do a long term exposure to 0.17G research, w/o building spinning stations, by building a long duration Moon Base. But again: Apollo scale budget, the committee is gonna want more bang for those bucks. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [January 9, 2017, 4:23pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/15 "2017-01-09T16:23:21Z")
> [@JRDelirious](#): > > Right, it’s not a question of fearing the answer, it’s that they already know the engineering/cost considerations make “build it just to find out what happens” a No Go at the appropriations committee. Hard enough to keep a manned program flying as it is, they’re not going to pop for a reduced-G environment experiment for its own sake. . But it is not for it’s OWN sake. That may be the most important manned space flight question we need to know… There will be no Mars exploration/colonization program if a few years in zero G and another one or two at Mars gravity level’s results in human blobs that can never return to Earth. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [January 9, 2017, 5:36pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/16 "2017-01-09T17:36:06Z")
> [@lazybratsche](#): > > (snip)Unfortunately, none of the proposals to test centrifugal artificial gravity have gone anywhere. Technically they’ve gone places, it’s just that they always end up coming around to where they started. It’s kind of in the nature of the thing. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 9, 2017, 6:03pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/17 "2017-01-09T18:03:39Z")
> [@billfish678](#): > > IMO NASA NOT finding this out is one serious failure of our manned space program. The International Space Station is a zero-G science laboratory. You can’t do zero-G experiments on a rotating space station. Rotating a _part_ of a station is difficult to do safely. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [January 9, 2017, 6:15pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/18 "2017-01-09T18:15:19Z")
> [@scr4](#): > > The International Space Station is a zero-G science laboratory. You can’t do zero-G experiments on a rotating space station. Rotating a _part_ of a station is difficult to do safely. Well, of course. But we have known for about 30 to 40 years now that long term zero G is BAD for you. At some point you kinda need to figure out what level isn’t so much. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [January 9, 2017, 7:36pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/19 "2017-01-09T19:36:45Z")
> [@Rocketeer2](#): > > So I can cut the boost. At 0.25G, Mars is 6 to 10 days away and Neptune about a month, and at least on the Neptune run, I need a ballroom and lounges and all those other lovely things to keep the passengers occupied on the long trip. > > But now a question arises, and I put it to you guys. I know at zero g, your bones start to lose mass and you get vision problems and heaven knows what else. So what’s the minimum G I can use and still have my passengers arrive in reasonably good health? 6-10 days or even a month at zero G isn’t going to harm anyone. You’ll want to know this stuff before your trip to Andromeda though. That constant acceleration is going to cause hell with your fuel budget, however. You’ll want to keep those ticket prices high. ---
**Author:** ![levdrakon](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@levdrakon](https://boards.straightdope.com/u/levdrakon)\ **Post date:** [January 9, 2017, 7:54pm UTC](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643/20 "2017-01-09T19:54:19Z")
> [@scr4](#): > > The International Space Station is a zero-G science laboratory. You can’t do zero-G experiments on a rotating space station. Rotating a _part_ of a station is difficult to do safely. Why is that? Would it introduce a dangerous wobble to the whole station or something? I was wondering if we could make a rotating drum large enough for astronauts to sleep in, so they’d get 8 hrs of simulated gravity per day. [Next page](https://boards.straightdope.com/t/spaceship-minimum-gs-for-health/776643.md?page=2)