New Mars Forums

And even bring an asteroid in Moon orbit is not so easy for the robot, unless it has some kind of Jedi superpower: we need to develpoed an appropriate unmanned vehicle able to dock the asteroid, despin it, and move it with some kind of high efficient electric propulsion. All this hardware will not magically apper clapping the hands, but it need to be founded, projected, developed and tested.

I couldn't realize why they pretend to use xenon, when argon is more and more abundant and cheaper. An electric propulsion using xenon is doomed to reamain forever on the paper.

The problem of compress gas engines is that douring adiabatic expansion temperature drops very much, so if there are some traces of water vapor inside, the ice blocks the tubes. So the gas has to be completely water vapor free.

Or reaching L1 slow spiraling with a cheap solar electric propulsion, and then the crew reach the spaceship and leave for Mars.

I this article, NASA thinks to use SEP to achive an higly elliptical orbit ( http://images.gizmag.com/gallery_lrg/so … brid-2.png ) and chemichal for depart from perigee.

but I dont know how a HEO can be achived with a continous SEP, that theorically have to spirally out, as you said.

If the cargo truck is unmanned, why not using an electric engine powered by a 100 KW SAFE 400 nuclear reactor?
It may be simpler than develop a new technology for an ICE adapt to Mars environment.

Rendez-vous in higly elliptical orbits are difficoult or can be performed without trouble?

It would not be difficoult to performe some tests, mixing duricrete and fiberglass, or duricrete and sawdust, or duricrete and iron mosquito net.

Diphosphonates reduce bone mass loss, blocking osteoclast activity, but this "frozen bone", even if it has a good mass, may also be fragile because trabeculae may not be perfectly oriented to counteract the loads. This effect may be particulary critical in high stressed zones like the Ward triangle of the femour neck. So we have still very few data to realy on this kind of drugs in a long term space mission.
Considering also that bone mass loss is not the only negative effect of microgravity on human body: there are also retinal damage for fluid body shift ocular hypertension, anemy, cardiac hypotrophy...

It may also be possible to use a short arm internal centrifugue for high gee cicles of exercise in a microgravity travel, but we have no data. So we need a space centrifugue for testing and exercise protocol optimization.

We have very few data and we absolutely need an artificial gravity module in space to test and verify the RMP limits, the ability to adapt at high rotation rate and the long term effects of a reduced gravity environment.
At this time, the only well prooved evidence is that microgravity is very unhealty and it has to be avoided in a more than two years Mars mission, because it would be very dangerous for an astronaut to break the thighbone during a surfare excursion. So, if you compare the risk of some drizzle douring trasfer for an high rotation rate to the risk of a femour fracture or a vertebral collapse douring exploration, the second is more and more mission critical.

The best compromise is one gee with 56 m radius and 4 RPM, but astronauts can adapt even at shorter radius and faster rotation (i.e. 35 m and 5 RPM and probably up to 20 m and 7 RPM) if RPM increment is gradual. Probably some drugs like scopolamine will be necessary in the first days, but it's still better than six months in microgravity.
Even a low cost 4.5 m radius internal centrifugue, that can be easly fitted in a 10 m diameter SLS launced module, may be an interesting tool of study adaptation at high RPM rate, body modification in low gravity environment and may be useful to optimize training protocols.

The NTR of Copernicus are the old Rover-Pewee rockets developed tested and qualified in Los Alamos, plus a Stirling electric generator. I think there are no problems on rebuilding it if we want. On Mars we can go well also with chemical rockets, but if we want to go beyond, we need nuclear.