I also favor centrifugal gravity. Weightlessness produces effects similar to prolonged bedrest and aging: oseoporosis, cardiovascual weakening, muscular weakness, etc. Millions of dollars is being poured into ameliorating those conditions.
Zubrin also notes that many spinning spacecraft have performed midcourse corrections without despinning first; the correction is chopped into a series of computer-controled short bursts and are timed for the moment the engine is pointed the right way. He favors putting useless weight at the other end of the tether, not a vital part of the mission.
-- Rob S
]]>This is why I believe we should start practicing with a Soyuz/Progress duo as soon as possible. I suspect any university or national space agency (the ESA?) could raise the relatively modest money needed to "borrow" a Progress and a Soyuz after their ISS duties are complete and attempt tethered flight manuevers, especially as such an experiment would have zero impact on any ongoing ISS operations.
As far as the Earth to Mars transit, Kim Stanley Robinson had the best idea of all, in my opinion. Start out at .95 gee and steadily decrease the spin rate to end up at .4 gee about 10 days before Mars arrival. (Ending up somewhat higher than .38 may give the astronauts an early stamina advantage upon Mars arrival. Also, wouldn't aerobraking require termination of tethered flight with at least several days (?) of zero gee before landing).
I also agree that a counterweight for the return trip would be highly desirable. You could also "spin up" slowly and steadily starting at .4 gee and hitting 1.0 gee a few weeks before Earth aerocapture.
If the Mars - Earth counterweight could be "parked" in LEO, it could be re-used on the next Earth - Mars mission to save the cost of lifting the mass from Earth to LEO. A more radical idea would be to rendevouz the ERV with the Shuttle and refit the ERV for a subsequent mission.
Mars SCHEME envisions re use of ERVs parked in LEO as future Earth - Mars crew vehicles.
Thoughts?
]]>I've never seen what the plan is for the Mars Direct Project's return. Astronauts have spent six months in zero gee before and they adjust fine over a week or two (well, some have longer term problems, but minor ones). I was wondering whether the burnt out upper stage of the ERV could be used as a counterweight vis a vis the crew cabin. One could gradually spin up the rotation rate from Mars gee to Earth gee, so that the astronauts gradually adjust to the higher gravity.
-- RobS
]]>I recall that they linked two parts of the Mars craft with a solid/rigid strut made from aluminum or perhaps a more exotic alloy. I also recall that the total radius needed to establish .38 g was way less than I had thought. Their paper explicitly discusses the advantages of a rigid strut in favor of a flexible tether.
At another forum, I proposed that we could today tether a used Progress resupply rocket to a Soyuz after it completed its ISS escape vehicle service and practice tethered flight with two vehicles otherwise scheduled for re-entry. (The Progress are intended to burn up upon re-entry and a Soyuz capsule cannot be re used after landing on Earth).
So, the next time you read about a new Soyuz being sent up (with a tourist?) to serve as the new emergency crew return capsule for the ISS, keep in mind that the old Soyuz and a trash filled Progess module should be available, essentially for free, for tether experiments.
Bill White
]]>http://www.spacefuture.com/archive....s.shtml
if you are interested in AG specs.
Wim
Webmaster
Mars Society Belgium
I'm glad that the Mars Society is heading this up, too. We have got to start learning what it will be like to live on mars. This project will show us if mammals can reproduce and grow up successfully in .38 g.
Mice today, grandchildren tomorrow!
sax
]]>