entropic_existence: cman: Khellendros: cman: Not really. We have a lot of technology that can get us there, it is simply a matter of logistics. It takes 6 months to get from the earth to mars and really, stocking enough food, water, oxygen, fuel, and various supplies for human survival is extremely difficult that far away from earth. Plus, there is also the matter of atrophy. In a 0 gravity environment, your muscles that keep you standing upright atrophy. 6 months of that is gonna be extremely harsh on the human body.We still have a ways to go before we can send a man to mars.You do know that people have been on the ISS much longer than 6 months, right? They have quite expanded routines for muscle conditioning and fighting atrophy. And stocking/supplying it is routine for long periods of time. There's entire logistical processes and procedures to manage supply, and they're quite mature. Sure, they'd need to be adapted and altered for a vehicle with different purposes, but it's not like it's far-fetched.I am not saying that it is impossible. All I am saying is that we still have a way to go before we can send mankind to mars. I dont think we are quite ready with the realities of such and we should start getting ready. I would LOVE to see one of our own walk on Mars. I want to have it happen before my lifetime is over, and with the way things are progressing, I dont see that happening.It isn't the duration that is the problem. ISS missions are already months long, and there has been at least one Astronaut who spent over a year in space for single-duration. The real problems for Mars missions right now is dealing with radiation. We aren't entirely sure what the total exposure levels would be and how much shielding is needed for the craft. And that isn't limited to the flight but to the time spent on Mars as well.
dittybopper: All those issues go away when you get there faster, and we can get there faster than six months. In fact, with a modest Project Orion vehicle, boosted to Earth orbit by the equivalent of 3 Saturn V-class rockets and assembled in orbit, you could do a round trip to Mars and back in about 125 days, or just about 4 months. We have experience with that length of time being weightless (and it would actually be half that: There would be time on Mars where they'd have some gravity).
Cythraul: I don't even think we should be trying to do manned missions to Mars with our current level of technology. I keep reading about how extremely dangerous it is. Yes, yes, I know, nothing is discovered without risk.
WelldeadLink: dittybopper: All those issues go away when you get there faster, and we can get there faster than six months. In fact, with a modest Project Orion vehicle, boosted to Earth orbit by the equivalent of 3 Saturn V-class rockets and assembled in orbit, you could do a round trip to Mars and back in about 125 days, or just about 4 months. We have experience with that length of time being weightless (and it would actually be half that: There would be time on Mars where they'd have some gravity).I assume 125 days is the travel time, but that article does not describe the boost/zero-g travel profiles.Using an Orion drive with 2000 impulses (a number mentioned in the link), they'd be under acceleration (aka gravity) for an interesting fraction of the travel time. 2000 impulses / 125 days is 16 boosts per day, if they are evenly spread out. It would make sense to do more of them at the start and end of the trip, so as to accelerate to a cruise speed faster, and I would find it interesting to see how they'd process more than 16 nukes in a day, and how long it would take the shock absorber to release each burst of force. So the zero-G portion may be interrupted by many acceleration events.
dittybopper: President Merkin Muffley: dittybopper: President Merkin Muffley: Bone loss as well and unlike muscle atrophy there seems to be no way to counter it.Then we'll just have to get there faster, won't we?Oh, man that's brilliant! Somebody call NASA, they've got untapped genius right here!We have the technology to get there faster. It's just expensive, and we're not allowed to do it because of an international treaty that is applicable to weapons testing, but was written in such a manner to outlaw *ALL* nuclear explosions in space.If we were to get that out of the way by amending the 1963 test ban treaty, then it would be like that line in "Mad Max": Speed's just a question of money. How fast you wanna go?
dittybopper: MrBallou: Staging, not taking everything with you, etc. I'll let somebody else do the math. My point is that it's not the same as LEO and there are reasons to be there.That makes sense if you do something useful at L2. One could make a better argument for the Moon itself, because there is the possibility of mining it for construction materials and fuel, and the gravity well you have to climb out of is much more modest than that of the Earth. You can't mine local resources at L2, though.Just pulling numbers out of my ass, I find it hard to believe that it would be cheaper to send 5 payloads of 100,000 lbs to L2 for subsequent assembly and launch to than it would be to send 5 payloads of 170,000 lbs to LEO* for the same. In the first case, you get a total vehicle/fuel weight of 500,000 lbs, and in the second, 850,000 lbs.I suppose you could mine and refine on the moon, and shoot it up to L2 for assembly, but then you have a large infrastructure, and that's extra cost. You've got to maintain a presence both on the moon and at L2. If you were going to do something like that, might as well just assemble in lunar orbit: You don't have the problems of drag inherent with LEO on Earth.You don't *NEED* to worry about staging so much from orbit to wherever. You send up the payloads one at a time, assemble them in orbit, then you have a single stage to boost you out of orbit. One large stage from LEO is more efficient than a bunch of smaller ones to boost you to L2 for assembly, and then a subsequent (smaller) booster to get you to your ultimate destination. You could boost the LEO-To-Asteroid-And-Back stage to orbit pressurized but unfueled, and send up subsequent "space tankers" (essentially boosters with a big tank on on top) designed to rendezvous with the empty LTAAB and fill it up. And you could send up the crew module separately also. Obviously, you're going to want to use non-cryogenic fuels.*Numbers based upon throw weights of Apollo CSM/LM combo ...
dwyw: So putting the assembly/refuel point at L2 would give you all the benefits of L2 over LEO (no aerodrag and reboosting required, lower fuel evaporation, and apparently it's a much more favorable environment for the hardware itself) with very little fuel cost.
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