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Mars May Have Been 1/3 Ocean
coondoggie sends in a snippet from Network World, as is his wont: "It's possible that a huge ocean covered one-third of the surface of Mars some 3.5 billion years ago, a finding likely to reignite an old argument about that amount of water on the red planet, according to a new report. The study by the University of Colorado at Boulder is the first to integrate multiple data sets of river deltas, valley networks and topography from a cadre of NASA and European Space Agency orbiting missions of Mars dating back to 2001, the researchers claim." The National Geographic coverage of the news gives some air time to those doubtful that this study will prove definitive.
The National Geographic coverage of the news gives some air time to those doubtful that this study will prove definitive.
3.5 billion years ago is too long ago for us to ever *know* definitively. We won't get to Mars for decades and it would be decades after that before any real "hands on" research could even bring us closer to a "definitive" answer (which will still inly be a best guess).
We don't know if the capsule from Hayabusa does contain material yet. Also note that a sample-return mission to Mars will be much more difficult than a sample-return mission to an asteroid. The gravity of an asteroid is negligible. But Mars has gravity that is around a third that of Earth. That's a lot. So a sampling robot would need to land on Mars and then return fighting against the large Martian gravity well. It would probably need to carry its fuel with it which means it would need to have a lot of mass to start with and which would make a safe landing even more difficult. We'll probably have successful sample-return from Mars before a human mission their but the technical difficulty with even a sample-return mission is immense.
So I finally looked it up. Interesting. http://phoenix.lpl.arizona.edu/mars151.php
I still cannot find the droids I am looking for...
Escape velocity, fuel supply, navigation. People always bring up those pesky problems. Gimme a spaceship that runs on dilithium crystals that you can run a starship at multiples of the speed of light indefinitely (or at least until the episode plot calls for them to be used up).
Serious? Seriousness is well above my pay grade.
Mars has an atmosphere, not much of one to be sure, but it does have one. Why else do you think so many landers used parachutes to help slow their descent?
UNIX? They're not even circumcised! Savages!
Philip K. Dick wrote several short stories about how we lived on Mars and didn't remember to reduce, reuse, recycle, curb our species appetites for violence (war) and sex (overpopulation). So we burned up the oceans when it all went kaboom!. But not before we sent people to live on Earth...
Now there are "billions and billions" of us. (sigh)
Update: it's been opened. It contains material. The report is due six months or so, so set a tickle.
Mars is easier than an asteroid. At Mars you have a planet to cancel your Delta-V with its gravity and atmosphere (limited though Mars' atmosphere is, it does help). Hitting an asteroid and returning is roughly twice as hard as hitting Mars and returning because you have to halt your motion at the asteroid using propulsion. It's a miracle Hyabusa returned at all - and it was three years late - because it missed its return window and had to wait for Earth to come back into position. The efforts of the ground team could be considered heroic - if some blood had been spilled.
Help stamp out iliturcy.
What sort of intelligent life would cause oil pollution?
One plan for Mars sample return I read about involves automatic docking in low Mars orbit. One stage lands and a rover loads it up with material. An ascent stage (really just a missile) lifts off for low orbit. It docks with an orbiter which has enough juice to return to Earth.
All in all it is probably more productive to send better surface labs.
http://michaelsmith.id.au
Let's do the numbers.
The ascent stage (ie the Mars to Low Mars Orbit transport) needs about 4.1 km s^-1 of delta-V. About twice what you need from the Moon, but less than half what you need from Earth. The Mars orbit return vehicle, which doesn't need to land on Mars needs about 2.3 km s^-1 to get into a transfer orbit back to Earth. (figures from wikipedia).
This is definitely challenging, ascent stage most challenging of all. We need a rocket that can survive launch from Earth, 9 months coasting, aerocapture and aerobraking at Mars, impact with the Mars surface, a few months sitting on Mars and then take off with no support systems, deliver 4+kms^-1 of delta-V and automatically dock with the orbiting component of the system. The durability requirement pretty much rules out cryogenic fuels, and even relatively stable liquid fuels like kerosene/nitric acid might give trouble, both due to the cold conditions on Mars and the extra mass of tankage robust enough to survive the journey, so you're probably looking at solids.
A few quick checks reveal that good solid rockets have an ISP of maybe 265s, giving a mass ratio of perhaps 10 for Mars to Low Mars orbit, so we need an ascent stage roughly 90% of which is solid rocket propellant (or multiple ascent stages, adding complexity). Suppose we can get the payload capsule + docking system down to 10kg and our solid rocket motors are 95% propellant (5% nozzles and casing -- this might be optimistic) we get a mass of 200kg launching from Mars. This is actually less bad than I'd feared. Seems that a Viking sized lander could probably do it. A 1 ton or so lander includes a digging tool and maybe a mini-rover to collect 5kg of rock and load them into a 5kg capsule with some tiny thrusters on it. That sits on a 200kg solid fuel rocket that gets into Low Mars Orbit and drops the capsule, which docks with a similar sized vehicle with 100kg of solid fuel some batteries and electronics and a heat shield for Earth reentry.
So we need two launches to Mars transfer, each about 1 ton payload, plus heat shields for aero-braking/aero-capture on Mars. Should be doable as two medium large launches from Earth