Originally Posted by
Krupski
Unfortunately, a manned trip to Mars where the astronauts go there and come back is not and will not be possible with the current chemical propulsion systems we have.
The moon is "easy" to get to because it stays with the earth, it's not very far away and it's surface gravity is only 1/6 of earths.
But Mars is in it's own independent orbit, so a mission to Mars would need to wait for the proper time when Earth and Mars are close to each other (which is still far away). The CLOSEST approach is around 34 million miles or about 142 times the distance to the moon. The furthest is around 250 million miles or over 1000 times as far away as the moon!
Getting there is a tradeoff. If you go as fast as possible (say by doing an earth or venus slingshot), then you arrive at a high velocity and need a lot of propellant to burn off that speed and go into orbit.
Then, the Mars "lander" would have to do a de-orbit burn and finally make a powered landing. But Mars has double the gravity of the Moon, so the lander would need to be around 10 times larger than an Apollo style LM to hold all the extra propellant for landing (and taking back off to return).
After the Mars lander returned to orbit and docked with it's command spacecraft, it would then need to do another engine burn to leave Mars orbit and come home. The burn would need to be enough so that it escaped Mars gravity field and crossed the point where the earth's gravity became dominant. So, after leaving Mars, the spacecraft would go slower and slower, almost to a crawl, before crossing the point where earth took over and started pulling it in.
Flying so slowly (literally 1000 to 3000 mph) for such a long time would make the return trip unbearably long.
And we haven't even mentioned that every drop of water, every drop of fuel, every piece of food, all the support equipment (CO2 scrubbers, GH2 and GOX for fuel cells, etc..) would need to be carried on board. Plus the astronauts would need to be able to stand being cooped up in a smelly, dirty spacecraft, stuck with their colleagues, no peace or privacy, literally for several YEARS.
That is, if EVERYTHING worked flawlessly and kept working flawlessly for probably 3 years or more.
With chemical propulsion, the spacecraft would need to be THOUSANDS of times larger than an Apollo moon rocket, and be 100% man rated reliable for years. Never gonna happen.
And if some new means of travel is eventually invented, Mars will be so close as to not being worth the bother to visit......... (other than to grab one of the old rovers and bring it back for the Smithsonian).
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