I think artificial gravity is cool, but for Mars it might not be necessary.You would not need artificial gravity if the flight to mars was short enough. I would rather spend the weight (and monetary) budget on more fuel or a better engine that shortens the trip time.
For missions beyond mars or for orbital stations, it is a different matter, though. Also, if I may suggest, you could rotate the habitats at the end of the trusses by 90 degrees (using the truss as a rotation axis) and give the inhabitants and longer straight floor. Unless you just rotate the entire spacecraft, you might want to consider counter rotating something (more habitats?) in the other direction?
I think artificial gravity is cool, but for Mars it might not be necessary.You would not need artificial gravity if the flight to mars was short enough. I would rather spend the weight (and monetary) budget on more fuel or a better engine that shortens the trip time. For missions beyond mars or for orbital stations, it is a different matter, though. Also, if I may suggest, you could rotate the habitats at the end of the trusses by 90 degrees (using the truss as a rotation axis) and give the inhabitants and longer straight floor. Unless you just rotate the entire spacecraft, you might want to consider counter rotating something (more habitats?) in the other direction?
I am of course talking about Mars missions with transit times much shorter than 100 days. There are several concepts, using advanced propulsion systems with trip times as short as 30 days. Once your trip times get significantly over 30 days, everything starts to get much more complicated and the lack of gravity is only one of those problems. This is why I am saying that it would be a good idea to further investigate those propulsion concepts and invest money and launch weight into those, rather than artificial gravity. This is just my personal opinion of course and I understand that some people might think differently.
Whilst those propulsion systems may be some years/decades away, artificial gravity would still be required for longer trips to the outer planets. So both will be needed I suspect.
I think NASA should build a rodent habitat with some male and female mice for the ISS that rotates and can simulate Mars gravity. Maybe put it inside the BEAM if they are short on space. That would be to verify that mammals can reproduce successfully in Mars gravity. They may start with lower animals such as insects or worms first.
Quote from: Jcc on 05/15/2016 03:02 amI think NASA should build a rodent habitat with some male and female mice for the ISS that rotates and can simulate Mars gravity. Maybe put it inside the BEAM if they are short on space. That would be to verify that mammals can reproduce successfully in Mars gravity. They may start with lower animals such as insects or worms first.I think NASA does not want that as it might interfere with microgravity experiments. They would have to shift the entire focus of what is done on the ISS.I have been thinking for a while they may do that on MCT. I imagine they will want to verify the ECLSS of MCT with a crew in orbit for at least 6-8 months. Time enough to do such an experiment. If they are generous they may do the experiment with moon gravity in parallel, the same centrifuge but nearer to the center. The experiment could run long enough that space born mice can reproduce.
Quote from: Elmar Moelzer on 05/01/2016 03:43 amI think artificial gravity is cool, but for Mars it might not be necessary.You would not need artificial gravity if the flight to mars was short enough. I would rather spend the weight (and monetary) budget on more fuel or a better engine that shortens the trip time.The availability of fuel for refueling spaceships in space means that over time we can go faster and faster to our destinations, so while artificial gravity would be nice, passengers may be able to make a multi-month trip in 0G without too much physical degradation. But we will need to ship enough people to Mars so that we can understand what the actual effects are.QuoteFor missions beyond mars or for orbital stations, it is a different matter, though. Also, if I may suggest, you could rotate the habitats at the end of the trusses by 90 degrees (using the truss as a rotation axis) and give the inhabitants and longer straight floor. Unless you just rotate the entire spacecraft, you might want to consider counter rotating something (more habitats?) in the other direction?Artificial gravity through the use of rotating structures will require more much more mass than we'll be able to push between Mars and Earth in the early years. That's because mass requires fuel, and fuel requires rockets from Earth (at least for the trip from Earth to Mars). It's going to be a while until fuel is that cheap that we can build large spaceships with rotating gravity.But when that time comes I have some ideas...
Quote from: JamesH65 on 05/10/2016 06:15 amWhilst those propulsion systems may be some years/decades away, artificial gravity would still be required for longer trips to the outer planets. So both will be needed I suspect.The video is about a trip to Mars. I think for that particular application, trips can be shortened enough to remove the need for artificial gravity. Now for longer trips, this is a different matter all together.
Of course, if all of NASA's budget is simply meant to spent on propulsion and capsules, and ignoring the Grand Challenges of the past decades, then by all means continue to spend the next decade spending all the cash on multiple engine, capsule, and LV development efforts.
SpaceX could do it on an automated DragonLab if NASA or other ISS partners are not interested. NASA does want to go to Mars, so it is relevant, and it could be very interesting basic science. They can call it SpaceSex, that should grab people's attention.
Quote from: muomega0 on 05/15/2016 01:24 pmOf course, if all of NASA's budget is simply meant to spent on propulsion and capsules, and ignoring the Grand Challenges of the past decades, then by all means continue to spend the next decade spending all the cash on multiple engine, capsule, and LV development efforts.Better to have the means to get there and current gen life support, than no means to get there and a significantly better life support.We have the resources to keep people alive on mars now. The focus (and it's a vital one) is mitigating health risks and making everything cheaper, more sustainable and easier to expand using primarily martian resources - but one fiscal challenge at a time. You don't start fireproofing a building if the basic structure is impossible.Probably more important than artificial gravity on mars is getting general healthcare fixed. How do I grow basic tissues on a martian environment? If someone gets cancer can we treat that without having to send them back to Earth? Somebody has inhaled martian dust? How do we look after their lungs?
I like to point out that a third of the people who went to the moon on moon landing missions stayed in orbit. The same makes sense for a Mars mission
Quote from: Lee Jay on 05/15/2016 02:10 pmI like to point out that a third of the people who went to the moon on moon landing missions stayed in orbit. The same makes sense for a Mars missionWith modern automated docking maneuvers, is it really necessary to keep somebody on orbit? I was under the impression that NASA had been planning on this when they were considering new manned lunar missions as part of Constellation before it was cancelled. If separate command and decent modules are used, why not have the orbiting command module run by computer?
Gas stations in space with prepositioned supplies and propellant are the fastest way to send crew to Mars, but it appears to be limited to about 3 months one way with existing technology.
Quote from: muomega0 on 05/15/2016 02:03 pmGas stations in space with prepositioned supplies and propellant are the fastest way to send crew to Mars, but it appears to be limited to about 3 months one way with existing technology. I think there was a concept for a VASIMIR based mission with a slightly over 30 day trip time. MSNW is also working on a new fusion drive that could result in 30 day trip times with a space craft that fits into a single BFR launch (with payload to spare) or a single SLS launch (with no margin).
There's a 39-day VASIMR mission described here:http://www.adastrarocket.com/Andrew-SPESIF-2011.pdfIf I'm reading the paper correctly, the 39 day mission requires a 200MW nuclear reactor with power density of around 0.8kg/kW. It mentions in passing that 4kg/kW is the best that's currently achievable.
(snip) One interesting speculation they mentioned, based on animal studies, is that Mars' 0.38G gravity field might not be strong enough to prevent harm to human health over long stays on the planet.
For the record I want to go to Mars but it just freaking does my head in why we will not simulate the Mars environment in a reasonably safe manner in Earth orbit, close enough for a quick trip home should any problems occur. I mean, you can make an argument for just about anything but surely what is reasonable should prevail.
Quote from: WindyCity on 05/16/2016 10:33 pm(snip) One interesting speculation they mentioned, based on animal studies, is that Mars' 0.38G gravity field might not be strong enough to prevent harm to human health over long stays on the planet.And this is why we must have at least a system whereby we can simulate Mars gravity for extended stays. I mentioned this in the past but it is only reasonable to assume that if you sent people somewhere knowing it MAY BE HARMFUL then surely you open yourself up to legal claims. I can see the lawyers standing in the court rooms showing all the wonderful concept pictures of idyllic mars bases, of how the believers got the hopes up of the decieved thereby condemning them to a sorry end..........on mars! :-)For the record I want to go to Mars but it just freaking does my head in why we will not simulate the Mars environment in a reasonably safe manner in Earth orbit, close enough for a quick trip home should any problems occur. I mean, you can make an argument for just about anything but surely what is reasonable should prevail.
Quote from: Aussie_Space_Nut on 05/17/2016 06:21 amQuote from: WindyCity on 05/16/2016 10:33 pm(snip) One interesting speculation they mentioned, based on animal studies, is that Mars' 0.38G gravity field might not be strong enough to prevent harm to human health over long stays on the planet.And this is why we must have at least a system whereby we can simulate Mars gravity for extended stays. I mentioned this in the past but it is only reasonable to assume that if you sent people somewhere knowing it MAY BE HARMFUL then surely you open yourself up to legal claims. I can see the lawyers standing in the court rooms showing all the wonderful concept pictures of idyllic mars bases, of how the believers got the hopes up of the decieved thereby condemning them to a sorry end..........on mars! :-)For the record I want to go to Mars but it just freaking does my head in why we will not simulate the Mars environment in a reasonably safe manner in Earth orbit, close enough for a quick trip home should any problems occur. I mean, you can make an argument for just about anything but surely what is reasonable should prevail.Everyone going to Mars will know EXACTLY what they are letting themselves in for. The lawyers will have their signatures in blood confirming it. I'm not seeing any lawsuits in the near future.
Exploration missions to Mars will be dangerous and everyone knows that. No lawsuits afterwards.
The big issue is whether or not it is possible to colonize Mars. We need to know if 0.38g is enough for long term health before we start building a colony. Artificial gravity studies will be important.
Why do we NEED to do artificial grav studies in LEO before Mars?
Quote from: philw1776 on 05/17/2016 11:57 pmWhy do we NEED to do artificial grav studies in LEO before Mars?NASA is cautious is my guess. (Isn't astronaut health and safety the agency's preeminent concern?)
That's why I am somewhat surprised that they plan orbital missions.
These fellows have detailed knowledge of the history of artificial gravity research, especially from the point of view of the physiological effects of weightlessness and artificial grav's ameliorative value.
I think that before planners talk seriously about what the challenges are in colonizing Mars they ought to have some idea of whether 0.38G is enough gravitational force to prevent harm to human health.
Quote from: WindyCity on 05/19/2016 05:49 pmThese fellows have detailed knowledge of the history of artificial gravity research, especially from the point of view of the physiological effects of weightlessness and artificial grav's ameliorative value.Be wary of experts promoting "further studies" in their field; it is in their interests after all!
Once there's sufficient capacity on Mars they can do their own biomedical research.
Mice on the Moon. Land a colony there for a few mouse generations, monitor them, and then bring them back for study. Seems straightforward, and a lot faster and cheaper than a human mission to Mars.
Quote from: llanitedave on 05/20/2016 03:07 pmMice on the Moon. Land a colony there for a few mouse generations, monitor them, and then bring them back for study. Seems straightforward, and a lot faster and cheaper than a human mission to Mars.On the moon you have the same problem as in orbit. Without humans tending the habitat it will be difficult to maintain it for such a long time.Plus a habitat with artificial gravity for mice is not that hard, you don't need a large diameter. It would not even be too hard to have two levels with moon and Mars gravity.
You'll need to get those mice back too. Can't tell much from just remote observation.It's kinda sad that sending mice to the surface of the Moon and returning them safely to Earth is beyond our capabilities.
I am of the firm opinion that artificial gravity on a large scale has no place in such a scenario. We can and should build a base on Mars regardless. That base is the place to find out about long term health, including reproduction. First with animals and then soon with humans.
What about mice bred in a centrifuge on the ISS?
Are we mice or men? Animal studies can help point the way, but their usefulness goes only so far. I should think that human studies will be required to reach a deeper, more reliable understanding of the issue.
Quote from: scienceguy on 05/21/2016 04:40 pmWhat about mice bred in a centrifuge on the ISS?Are we mice or men? Animal studies can help point the way, but their usefulness goes only so far. I should think that human studies will be required to reach a deeper, more reliable understanding of the issue.
You can't (for several reasons) breed several sequential generations of humans in varying levels of gravity just to see what happens.
Quote from: Robotbeat on 05/22/2016 07:03 pmYou can't (for several reasons) breed several sequential generations of humans in varying levels of gravity just to see what happens.Aw, why not? I will gladly volunteer to spend the rest of my life on the Moon, with as many other volunteers as may arise, to help perform such studies.Of course, I imagine they would want someone younger than 60 as their starting point... ah, well.
These are significant complications. Might as well just solve them as well as you can with animal models and just go for it. After all, if the purpose of these experiments is to reduce risk and cost, the experiment would be just as risky and cost just as much as just trying the real thing and so would be pointless.
<snip>Plus a habitat with artificial gravity for mice is not that hard, you don't need a large diameter. It would not even be too hard to have two levels with moon and Mars gravity.
Quote from: guckyfan on 05/20/2016 04:12 pm<snip>Plus a habitat with artificial gravity for mice is not that hard, you don't need a large diameter. It would not even be too hard to have two levels with moon and Mars gravity.Why wouldn't you need the same diameter as for humans? Mice are subject to motion sickness and tend to turn their heads a lot faster than humans do I think.
The gravity gradient sure, but from everything I've read, the limit for diameter/rpm is motion sickness caused by turning the subject's head around any axis other than the rotational axis of the environment.When you (or your mouse) turn your head in a rotating environment, the angular velocity of the centrifuge and the angular velocity of your head cross multiply, resulting in a perceived rotation around a different axis than the one you're turning your head at. Since that's not what your eyes are seeing, if the perceived angular velocity is too high, the result is motion sickness. The size of the head isn't important, what matters is its angular velocity and that of the environment.
About humans reproducing under lower gravity. I am sure scientists would be very, very interested. But doing such a program from beginning of pregnancy to at least adolescence would be a long term program. Even with very optimistic cost estimates any space agency could not do that below 20 billion $. Chance of that money provided? Exactly ZERO. A lower cost estimate anyone?Would Elon Musk be interested? Certainly. Would he do it? Chance again exactly ZERO. He would build his Mars base and let people have children there.
My understanding is different. What causes motion sickness is the difference of angular movement between head and feet. Which is a lot bigger for humans than mice. So a centrifuge can be as much smaller as the body of a mouse is.
Interesting, wouldn't a smaller animal with a higher metabolic rate like a mouse, be already used to higher angular velocities because they rotate their heads through much smaller circles (1cm radius vs 10 or 15 for a human) more quickly?
Quote from: nadreck on 06/01/2016 08:29 pmInteresting, wouldn't a smaller animal with a higher metabolic rate like a mouse, be already used to higher angular velocities because they rotate their heads through much smaller circles (1cm radius vs 10 or 15 for a human) more quickly?The issue isn't how fast you (or your mouse) turn your head on the earth or in any other non-rotating environment. There, your vestibular system perceives the same rotation your eyes do, so everything is cool.However, in a rotating environment, the rotation of the environment and the rotation of your head produce a "cross coupling", a vector cross product rotation, that has a component at right angles to both rotations. Your vestibular system thinks you are rotating your head around a different axis than your eyes do which is bad.For example, if you are standing upright on the inside of a centrifuge and nod forward and back, your inner ear will think you twisted it with a shoulder to shoulder side wise motion as well. Since your eyes don't see that, if the effect is strong enough, you'll experience motion sickness.Apparently in high rotational rate centrifuges they sometimes use head restraints to avoid this.
But, how pronounced that cross coupling must depend on the relative diameters of the two circular motions and the relative amounts of angular momentum. The mouses motion is a much smaller circle than a humans.
Quote from: nadreck on 06/01/2016 10:13 pmBut, how pronounced that cross coupling must depend on the relative diameters of the two circular motions and the relative amounts of angular momentum. The mouses motion is a much smaller circle than a humans.No, it's just angular velocity, rpm, and has nothing to do with the mass of the object.Consider a penny glued to the center of a truck tire on the end of the axle. As the truck goes down the road, the penny and the tread on the tire rotate at exactly the same rpm, angular velocity. Actually, if you glue the penny on the sidewall just in from the edge, it still rotates at the same angular velocity as well.
But the penny is not making these coupled motions you speak of where there are intersecting planes of rotation. I still don't accept this argument without some experimental data on mice at >1g in a centrifuge here on earth, have you got some links to such?
Quote from: nadreck on 06/01/2016 10:26 pmBut the penny is not making these coupled motions you speak of where there are intersecting planes of rotation. I still don't accept this argument without some experimental data on mice at >1g in a centrifuge here on earth, have you got some links to such?Follow the link I gave earlier, it explains the problem in terms of angular velocity.https://books.google.com/books?id=Z5VTZGRQvFoC&pg=PA38#v=onepage&q&f=falseIf you're unsure of how angular velocity vectors interact, there are a bunch of videos and explanations in the various physics lessons online. They tend to use calculus or linear algebra notation however. There are also some discussions and illustrations of the "right hand rule" that may be more accessible.
No it does not contain what I asked about, it describes gravity + centrifugal tests with humans at speeds up to 23rpm (which is less than needed for the mouse experiments in space with the 2 meter radius device at 1g) but it did not describe anything about testing with mice in those environments. It did discuss mice and other animals in microgravity.
Quote from: nadreck on 06/01/2016 10:43 pmNo it does not contain what I asked about, it describes gravity + centrifugal tests with humans at speeds up to 23rpm (which is less than needed for the mouse experiments in space with the 2 meter radius device at 1g) but it did not describe anything about testing with mice in those environments. It did discuss mice and other animals in microgravity.Hmm, you might want to do some of your own research, but here's a reference to rat motion sickness testing. Notice that they only talk about rotational rate, and it's in the same range as for humans 10-25 rpm or so.https://books.google.com/books?id=Jr-m3bMy7IUC&pg=PA100&lpg=PA100#v=onepage&q&f=false
I don't get it. The record stay in space is 438 days. Mars would be 900 days. There are demonstrable health effects which increase with time in zero g. For humanity to go to Mars, or space, rotating habitats are a must. Why not develop this technology? It's difficult but necessary.
No, I don't get it. Rotating habitats are not a must. They are not difficult, they are unnecessary. That's what Charles Bolden said in a Congress hearing. They have learned enough about mitigating zero gravity problems for a Mars mission duration.
Quote from: guckyfan on 06/04/2016 04:09 pmNo, I don't get it. Rotating habitats are not a must. They are not difficult, they are unnecessary. That's what Charles Bolden said in a Congress hearing. They have learned enough about mitigating zero gravity problems for a Mars mission duration.Only if there's a fast transit, only if everyone goes to the surface, and only if Mars gravity is safe for two years, none of which has been demonstrated.
Quote from: Lee Jay on 06/04/2016 04:40 pmQuote from: guckyfan on 06/04/2016 04:09 pmNo, I don't get it. Rotating habitats are not a must. They are not difficult, they are unnecessary. That's what Charles Bolden said in a Congress hearing. They have learned enough about mitigating zero gravity problems for a Mars mission duration.Only if there's a fast transit, only if everyone goes to the surface, and only if Mars gravity is safe for two years, none of which has been demonstrated.Wrong. He talked about a full mission. And remember the first mission planned by NASA is an orbital mission. Without rotating habitats.
Quote from: guckyfan on 06/04/2016 05:17 pmQuote from: Lee Jay on 06/04/2016 04:40 pmQuote from: guckyfan on 06/04/2016 04:09 pmNo, I don't get it. Rotating habitats are not a must. They are not difficult, they are unnecessary. That's what Charles Bolden said in a Congress hearing. They have learned enough about mitigating zero gravity problems for a Mars mission duration.Only if there's a fast transit, only if everyone goes to the surface, and only if Mars gravity is safe for two years, none of which has been demonstrated.Wrong. He talked about a full mission. And remember the first mission planned by NASA is an orbital mission. Without rotating habitats.Poor Scott Kelly. They subjected him to almost of year of microgravity, but they had it all figured out. I'm sure he'll relish that thought as he's going through the significant amount of rehab he need's from his mission.
Poor Scott Kelly.
Quote from: stoker5432 on 06/04/2016 05:23 pmPoor Scott Kelly. Ask him if he would reverse his decision to quit when he is offered a microgravity trip to Mars in 3 years.Unfortunately he is probably going to be too old in 10 years.
The cosmonaut actually walked from the capsule on his own two legs, stole a cigarette from his comrade, and said, "We can fly to Mars."
Not sure how long they are planning to keep people there initially. That will be interesting to learn (probably in September).
My best guess, some will return, when the next crew arrives, some will stay.
Quote from: guckyfan on 06/04/2016 08:19 pmMy best guess, some will return, when the next crew arrives, some will stay.Well that would imply at least 2 years stay, which I find a rather risky proposition for a first mission. The long stay would also require a lot more consumables, habitats, etc. I would assume that they would only stay for a few weeks initially (as long as practical given return trajectories, etc). I might be wrong, though.
In this discussion it seems relevant that Musk said at RecodeDotNet that they are aiming for 90 day trips times to mars (and back I presume) and 30 days later. Which is interestingly very much in line with what I was hoping for. Such short trip times (if they can indeed make them happen), should make artificial gravity unnecessary. Of course there is still the problem of the low Martian gravity for the duration of the stay. Not sure how long they are planning to keep people there initially. That will be interesting to learn (probably in September).
The challenge is that any station big enough to provide refuge for a colony is currently too big to build or move using our current abilities and cost structures. And it's mainly the cost of moving mass to space that needs to come down, since I believe that we have the technology necessary to build at least the 1st generation of rotating space stations.
Quote from: Elmar Moelzer on 05/15/2016 07:34 pmQuote from: muomega0 on 05/15/2016 02:03 pmGas stations in space with prepositioned supplies and propellant are the fastest way to send crew to Mars, but it appears to be limited to about 3 months one way with existing technology. I think there was a concept for a VASIMIR based mission with a slightly over 30 day trip time. MSNW is also working on a new fusion drive that could result in 30 day trip times with a space craft that fits into a single BFR launch (with payload to spare) or a single SLS launch (with no margin).There's a 39-day VASIMR mission described here:http://www.adastrarocket.com/Andrew-SPESIF-2011.pdfIf I'm reading the paper correctly, the 39 day mission requires a 200MW nuclear reactor with power density of around 0.8kg/kW. It mentions in passing that 4kg/kW is the best that's currently achievable.
Quote from: SpacedX on 06/04/2016 03:32 pmI don't get it. The record stay in space is 438 days. Mars would be 900 days. There are demonstrable health effects which increase with time in zero g. For humanity to go to Mars, or space, rotating habitats are a must. Why not develop this technology? It's difficult but necessary.No, I don't get it. Rotating habitats are not a must. They are not difficult, they are unnecessary. That's what Charles Bolden said in a Congress hearing. They have learned enough about mitigating zero gravity problems for a Mars mission duration.
Could many of the muscular/skeletal problems of low Mars G be mitigated by just wearing a weight suit? I know it might not have a impact on other areas, but just curious.
Quote from: Robotbeat on 06/04/2016 05:38 pmThe cosmonaut actually walked from the capsule on his own two legs, stole a cigarette from his comrade, and said, "We can fly to Mars."Not saying your wrong, but I really dislike this rational. People walk out of hospitals everyday that are in terrible shape and have no business doing anything strenuous. Kelly himself is confirming this with his recent comments on his overall health. We don't know the detailed medical records of any of these people.In Mars's case I think speed is the best solution as of now. I really like that Elon has indicated he wants 3 months travel time to Mars.
Quote from: launchwatcher on 05/15/2016 10:47 pmQuote from: Elmar Moelzer on 05/15/2016 07:34 pmQuote from: muomega0 on 05/15/2016 02:03 pmGas stations in space with prepositioned supplies and propellant are the fastest way to send crew to Mars, but it appears to be limited to about 3 months one way with existing technology. I think there was a concept for a VASIMIR based mission with a slightly over 30 day trip time. MSNW is also working on a new fusion drive that could result in 30 day trip times with a space craft that fits into a single BFR launch (with payload to spare) or a single SLS launch (with no margin).There's a 39-day VASIMR mission described here:http://www.adastrarocket.com/Andrew-SPESIF-2011.pdfIf I'm reading the paper correctly, the 39 day mission requires a 200MW nuclear reactor with power density of around 0.8kg/kW. It mentions in passing that 4kg/kW is the best that's currently achievable.A Molten Salt reactor could probably do <1kg/kw. Read up on the "fireball" reactor designed for a nuclear powered plane.http://energyfromthorium.com/pdf/ORNL-2387.pdf
Mark Kelly also spent twice as long in microgravity as you would in even a NASA-esque 6 month trip to Mars.
Quote from: Robotbeat on 06/13/2016 05:16 pmMark Kelly also spent twice as long in microgravity as you would in even a NASA-esque 6 month trip to Mars.Scott Kelly was the one who spent 340 days in space.
In a recent Congress hearing NASA administror Bolden stated that the present theory on the causes of vision impairment is high CO2 content in the ISS atmosphere. They have reduced CO2. Final results are not yet in though.
Quote from: stoker5432 on 06/04/2016 07:49 pmQuote from: Robotbeat on 06/04/2016 05:38 pmThe cosmonaut actually walked from the capsule on his own two legs, stole a cigarette from his comrade, and said, "We can fly to Mars."Not saying your wrong, but I really dislike this rational. People walk out of hospitals everyday that are in terrible shape and have no business doing anything strenuous. Kelly himself is confirming this with his recent comments on his overall health. We don't know the detailed medical records of any of these people.In Mars's case I think speed is the best solution as of now. I really like that Elon has indicated he wants 3 months travel time to Mars.Scott (edited) Kelly also spent twice as long in microgravity as you would in even a NASA-esque 6 month trip to Mars.A 100 day or 3 month trip would be no problem.
Specifically, Mr. Hale was interested in how artificial gravity might help address some of the issues facing long-duration microgravity missions.Mr Gerstenmaier responded that NASA had no studies showing the need for artificial gravity, leading Mr. Hale to point out “you’ve got a lot of really critical things that you’re trying to investigate, and if it pans out that you can’t mitigate one of those risks” with what is currently under development, might artificial gravity be something to consider.Mr. Gerstenmaier responded that all microgravity considerations are currently mitigatable with the systems in place or under development.Further, Mr. Gerstenmaier noted that “you’re never gonna provide a partial gravity environment throughout the entire vehicle.“I think the changes associated with trying to provide partial gravity are so fundamental and large … that I don’t think that’s an area that’s really a problem. [We have] real problems that need to be addressed, and partial gravity isn’t something that we should be spending quality time on right now.”
They are doing research on astros coming back from micro-g all the time:Terry W. Virts @AstroTerry 4h4 hours agoMy last day in the magnet- today was my landing+1 year final MRI, studying my brain and eyesight changesBut yeah, back on to the topic of artificial gravity.
During the NAC teleconference, Gerst mentionned that partial gravity may create additionnal problems. He said that you could likely not have gravity in the entire ship. So you could have vestibular problems when going from zero G to a partial gravity module. Gerst sounded pretty negative on the idea of partial gravity. But he said that the testing of partial gravity on mice on ISS should let them know if partial gravity can be helpful. But he didn't seem to think that it was necessary or helpful for Mars.
SEP
Quote from: stoker5432 on 08/11/2016 06:44 pmSEPEven scaled up several powers of 10 any low thrust SEP acceleration gravity would be inconsequential.
Quote from: philw1776 on 08/13/2016 02:26 pmQuote from: stoker5432 on 08/11/2016 06:44 pmSEPEven scaled up several powers of 10 any low thrust SEP acceleration gravity would be inconsequential. I thought I had deleted that post. Oh well. This was in reference to the spinning of the entire spacecraft which would not be possible using SEP. NASA and SEP are joined at the hip.
Quote from: stoker5432 on 08/13/2016 04:20 pmQuote from: philw1776 on 08/13/2016 02:26 pmQuote from: stoker5432 on 08/11/2016 06:44 pmSEPEven scaled up several powers of 10 any low thrust SEP acceleration gravity would be inconsequential. I thought I had deleted that post. Oh well. This was in reference to the spinning of the entire spacecraft which would not be possible using SEP. NASA and SEP are joined at the hip.Not sure why you think SEP and spin gravity are mutually exclusive? The thrust vector is radial/perpendicular to the axis of spin, which works because your trajectory is spiraling out at a tangent to the sun anyway.
No the thrust vector can swing around a good deal in order to capture into a planets gravity well, though the thrust vector is always confined to the 2D plane of the heliocentric orbit. Your design would need to be modified by having a hinged 'wrist' under the engine count to gimbal them along with long boom arms to the propellant plumes don't strike the craft.Personally I would go with a non rotating structural axis perpendicular to the orbital plane, on both ends are the solar arrays which remain pointed at the sun, habitation, propellant and engine pods are in stacks of rings along the central axis, this allows a clear path for thrust in any direction.
It's ironic that space fans have no problem assuming all kinds of advances in aerospace enabling a Mars mission which we can't do today while they ignore the incredible biotech and medicine revolution ongoing which has at least the possibility of mitigating both radiation and zero gee problems with primates.
The open question is whether lunar or martian gravity is enough, or whether we will regularly have to return to spin gravity (higher g-levels) to compensate.
The ITS spacecraft is big enough to spin at 2 RPM and produce .25 m/s of acceleration at the rim.Is that enough gravity to be useful for things like eating, showing, using a toilet, settling dust, and other things that are a giant pain in 0 g?
About 1/15 of Mars gravity. A 70kg man could wear a 969kg suit to acclimatise to Mars gravity.
Quote from: envy887 on 10/03/2016 04:58 pmThe ITS spacecraft is big enough to spin at 2 RPM and produce .25 m/s of acceleration at the rim.Is that enough gravity to be useful for things like eating, showing, using a toilet, settling dust, and other things that are a giant pain in 0 g?About 1/15 of Mars gravity. A 70kg man could wear a 969kg suit to acclimatise to Mars gravity. It would help with muscle atrophy. Tungsten has a density of 19.25 g/cm3, an average man is said to have a surface area of 19,000 cm2. A Tungsten suit would have to average a thickness of 2.65 cm.To approximate Earth weight would require an almost 2.7 ton suit with a thickness of 7.32 cm. Not so practical.Such a suit might also help with radiation shielding.
Gravity is one of the reasons why I prefer Venus as a destination over Mars; if 8.7 m/s at flight altitude isn't enough then there's no hope for the Moon, Mars, or almost anywhere else in our solar system. Likewise, if Venus's natural atmospheric radiation shielding isn't enough, then that makes the shielding requirements on other celestial bodies painfully great.Not that I'm not hopeful that Mars's gravitational issues can be shown to be tolerable or worked around
Gravity is one of the reasons I prefer spin-gravity habitats on/around asteroids ahead of the moon, Mars and Venus
Spin gravity habitats which can provide 1xg will need to be large, and therefore must be built in microgravity environments with access to resources (ie around asteroids).
Quote from: mikelepage on 03/02/2017 07:48 amGravity is one of the reasons I prefer spin-gravity habitats on/around asteroids ahead of the moon, Mars and Venus Re, Venus: What, ~8.7 m/s^2 isn't close enough to 9.81 for you?
QuoteSpin gravity habitats which can provide 1xg will need to be large, and therefore must be built in microgravity environments with access to resources (ie around asteroids).You're talking something vastly into the future if you're talking about building whole habitats in space from asteroid materials.Given that tether experiments in space have had a less than stellar track record, I'd say that counterweighted rollable trusses look to probably be the best option at this point in time.
But I think building habitats from asteroid regolith can happen sooner than you're expecting, it's just that you can't do anything clever with it. I'm thinking something along the lines of a mold that takes loose regolith and stamps/sinters it into segments of a large scale torus. You use the regolith as your compressive component, and import (steel) cables from Earth as your tensile component when you want to fuse the whole thing together. Such massive structures will be much easier to work with in microgravity.
Quote from: mikelepage on 03/04/2017 08:50 amBut I think building habitats from asteroid regolith can happen sooner than you're expecting, it's just that you can't do anything clever with it. I'm thinking something along the lines of a mold that takes loose regolith and stamps/sinters it into segments of a large scale torus. You use the regolith as your compressive component, and import (steel) cables from Earth as your tensile component when you want to fuse the whole thing together. Such massive structures will be much easier to work with in microgravity.How about using basalt fibers to reinforce some form of concrete?http://novitsky1.narod.ru/babv1.html.htmOr even basalt fiber to reinforce sintered basalt? The fiber has higher strength because of the low defects, and the sintered basalt serves as fill.
Not quite sure what you mean by counterweighted rollable trusses (I'm assuming you mean baton-stations/tumbling pigeons?)
There is a third option I'm calling DEployable Spin Gravity Array (DeSGA - small animation attached), which I would put on space craft intended to support humans working out at asteroids.
But I think building habitats from asteroid regolith can happen sooner than you're expecting, it's just that you can't do anything clever with it. I'm thinking something along the lines of a mold that takes loose regolith and stamps/sinters it into segments of a large scale torus.