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Hey, that's a link for Brian walker's website. He's using a hydrogen peroxide rocket to get up to 50 miles. I was thinking something like what he's got could be used on mars to get back to on orbit components.
Let's say the mission goes like this: you have a surface nuclear reactor, separately stored fuel rods or pebbles for a pebble bed design (my personal preference), and various "luxury" items that you would ONLY need on the surface, packed in a frame and on one end of a tether. In addition to this equipment, the crew habitat, crew return vehicle, and life support systems would be on the other end. This would be equipped with a propulsion module and tankage for the return trip.
Once you got to the surface, assuming you got there safely, you would set up a rocket much like the one depicted in the site linked above. ISPP would be easily used to get the vehicle up to about 90 or 100 miles altitude over mars, and a tether catch system could be used to capture with the orbiter. three or four of these would be available, and very lightweight since they'd be shipped empty. In any case, you'd hop in, fire up, and a computer would guide you to the on orbit crew return vehicle, which would have just enough fuel to get on a long slow free return path back to earth. You'd link up, and transfer your extra propellant, and then one or two of the other rockets would be carrying extra fuel and your fellow crew member(s), and one would carry nothing but a few hundred extra pounds of fuel, so you could have enough fuel to get all the way back to earth.
If someone works out JLN lab's lifter, or our electrokinetic thruster, then the propellant required to get back to earth could be significantly reduced, so you'd just get out of mars orbit, and accelerate over a few weeks back to earth, but barring that, you'd use a fusion type propulsion system, or Ion propulsion.
What do you think? Do you think we should take the CRV all the way to the surface, only to have to heft all that weight back up, or should we use an unpressurized capsule like walker's design with our intrepid explorers in pressure suits? I think it's risky to take your way back home all the way down and up, in case something screws up, you don't lose your way back home completely. Something like this system would potentially preclude sending an advance CRV and hab, like in mars direct. Anyhow, let me know what you think, this might just be another brain fart...
Rion
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oh yeah, blah, the other idea was to just make a fuel that could react with your regolith, instead of extracting fuel and oxidizer... i read from the viking missions that the soil is supposed to contain alot of peroxides or something that are quite reactive, which is why viking put up so much fuss for signs of microbial life on mars... somthing about the way UV reacts with iron oxide to make highly energetic reactants, so when you mix it with water it goes fizz.... who knows. We need some more data, so maybe i'll add that to moltov's sensor package....
anyone else have some data on what I'm talking about with the soil? I think it was in Malin's mars book.
Later,
Rion
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well, this is on the getting back home topic:
if we launched a nuclear propulsion (say ion) ship, couldnt we use the same drive to get us back home? As you said, leaving the engines and other components in orbit, just reattach an ascent vehicle to the other section, and blast back the other way.
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yeah, that's the idea.
I was just thinking if you could use ISPP effectively, say without having to process anything but the fuel, and use packed martian regolith for oxidizer (just for fun, get a chlorine tablet for pool water conditioning, drill a hole in the middle- you can use an xacto knife- and put it in a coffee can away from flammables, then arrange for a dixie cup to fall down on it, filled with brake fluid- so it tips over and spills the fluid into the hole- you'll get a hypergolic reaction similar to what i'm thinking of) you could just pack regolith into a chamber with a hole down the middle, pop out whatever form you need, and then use methanol or whatever you create from your hydrogen and CO2 with the ISPP rig. Then you're back home. You'd have to get from the surface to mars orbit no matter what methods you use, unless you build a really really big vehicle on the surface and launch direct.
anyhow, my idea was to simply load your vehicle with enough engine and propellant to get back to earth on a free-return type trajectory, just barely getting out of mars orbit, but to try and make enough propellant on the surface to get you back at whatever rate you wanted to be able to design to. I'm not sure that the mass advantage would be significant if you're using nuclear ion propulsion, but i'm thinking what i could buy off the shelf yesterday, not what might be proven in ten years... so chemical/solar ion would be it, and i don't think there's quite enough raw power to get the thrust numbers you'd need. with chemical you could brake quickly and powerfully, so you could go faster for longer, and cut your transit time by quite a bit, but if that would really be a benefit, say cutting a week or two off transit, or would it just be an unneccesary improvement, say taking a day or two off transit time, who's to know?
I'd have to do too much math for a hohmann transfer, but i can fire up my old copy of STK and probbably figure it out in a week or two, when i have some time.
Till later y'all,
Rion
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As far as I know, even the most reactive regolith is only 1 or 2% peroxide compounds, so I doubt a regolith rocket could even lift itself. But if you have a water supply, you could use it to make the reaction in a chamber on the surface, capture the oxygen produced, store it as liquid oxygen, then reuse the water to process more peroxide. The system might be able to make oxygen for rockets and for sure oxygen for breathing.
The big danger of separating the men and the earth return cabin is that if the latter doesn't work, the men are stuck. If you take a reasonably light weight crew return cabin to the surface, you have to lift it all the way back to Earth, but with ISPP you only have to supply an eighteenth of the propellant (the liquid hydrogen). On the surface it serves as backup housing; and this might be useful in all sort of non emergency situations, or maybe I should "social emergency situations" as well (two crew members get in a fist fight; two lovers break up). If the crew cabin blows up on launch from the surface, it kills the astronauts as well, so at least it doesn't strand them on Mars (and the risk of it blowing up is the same as any Mars ascent vehicle blowing up).
If you leave the cabin in orbit, some sort of accident might disable it and no one would be there to use a fire extinguisher or perform some other quick action that would save the day. That's the big danger of separating the crew from the return cabin. Mars Direct is quite elegant in this regard; it minimizes the risks inherent in the return trip, thanks to a nuke and some hydrogen on the surface, and Mars's weaker gravitational field.
-- RobS
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I was sort of envisioining something akin to a modified lunar plan, where your crew return vehicle (command module) orbits, and you can transfer crews from the orbital station to the surface and back, and the orbital crew can manage incoming supplies and new crew members, since you may not want to bring your folks back if things are going well and they're cool about staying for another six months. Otherwise, when the new crew module gets there, you simply use the old crew module to take everyone home, and the orbital lab module would be left behind to link up with the new lab module, so you can send mars rocks up and check 'em out before a return mission. I would assume lifting a few pounds at a time from the surface wouldn't be anything huge, and with the thin martian atmosphere an empty lift rocket would be able to use a very thin/light reusable heat shield to go up and down four or five times?
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i think that adds a lot of unncecessary complexity to the mission, which we dont want. if they want to stay, then we can leave them on the surface, and just send more supplies with a booster launch.
now, we could send part of the ship, maybe the tether, as an orbiting satellite, which would not destroy the mission if it was damaged. the satellite could be unlatched in orbit, perhaps during aerobraking, and the ship could touch down without it.
i dont see why we cant inspect rocks on the surface, to send them to orbit seems like a bit of a waste of time, fuel, and power.
i wonder if we have options to send return vehicles based on nuclear propulsion-with a lot less fuel than chemical propulsion ships. we could bring a lot more back, and faster. then your power from say, your nuclear reactor, could be directed to higher level lab activities, or digging for water.
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well, i'm thinking of having a pre-colonization gear-up with the first few missions. If you were to use a fuel tank from the space shuttle as your craft to get to mars, you'd have to add your hab module and your crew return vehicle with associated heat shields, but I'm not sure how you'd get the tank to the surface. If you could work out a tether that would work in martian gravity, you could do that much sooner than one for earth gravity. Then your astronauts could just climb the thing if it comes down to it, and though they may spend weeks and weeks climbing, they'd still be able to get to their ship. That would add complexity to an initial mission, but there's no reason that once we get enough equipment to do good science there, we couldn't send one of the follow on missions to GMO and drop a carbon tether. Heck, kevlar might work since the loads would be less, and you could simply have an electric lift mechanism big enough to carry three crew members and about a hundred pounds of rocks. In the mean time, a small, rather chintzy unpressurized, no-life-support systems rocket could carry one astronaut and some rocks that needed to be run through a zero-g mass spectrometer or something. AND, you could leave all your systems on orbit without the risk of landing damage. You'd really be saving weight if you didn't supply the crew return module with a heat shield, since you could always dock with the space station to get back home on a shuttle flight, instead of bringing the CRV all the way down through the atmosphere. The small rockets i'm speaking of could be made to weigh very little, and you could use biologicals to produce the components to many fuels, as long as you have some sort of distilling facility for alcohol, and ISPP could be used to produce oxygen.
Anyhow, take it easy y'all
Rion
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