Quote from: meekGee on 07/03/2012 03:33 amAn airship (or any other form of LTA vehicle) in 1% atmosphere is quite a challenge. (Even if it is a CO2 atmosphere...)LTAs look soft and fluffy, but they are incredibly difficult to tame, especially if you're thinking full automation. Every time you come near the surface, it's a game of Russian roulette.nope, the airship is not for lifting the probe/lander, but for mounting and lifting huge solar array and uplift system. the lander is hanged on light weight cable, and lift off ground only when uplift system is on, like a helicopter.
An airship (or any other form of LTA vehicle) in 1% atmosphere is quite a challenge. (Even if it is a CO2 atmosphere...)LTAs look soft and fluffy, but they are incredibly difficult to tame, especially if you're thinking full automation. Every time you come near the surface, it's a game of Russian roulette.
Quote from: cordor on 07/08/2012 03:01 amQuote from: meekGee on 07/03/2012 03:33 amAn airship (or any other form of LTA vehicle) in 1% atmosphere is quite a challenge. (Even if it is a CO2 atmosphere...)LTAs look soft and fluffy, but they are incredibly difficult to tame, especially if you're thinking full automation. Every time you come near the surface, it's a game of Russian roulette.nope, the airship is not for lifting the probe/lander, but for mounting and lifting huge solar array and uplift system. the lander is hanged on light weight cable, and lift off ground only when uplift system is on, like a helicopter.Have to agree with meekGee. Although I think airships are cool in general, I think this idea has formidable difficulties. To lift a useful payload in the tenuous Martian atmosphere the envelope would have to be very large indeed. This would make the vehicle very prone to winds and turbulence (which isn't much of a problem for other types of equipment, apart from the dust problem.) I think deployment and control of such a large structure makes this idea inferior to other means of Mars surface exploration.And again: this topic should be another thread (unless someone can cite some evidence that SpaceX is working on Martian hoppers and airships.)
ya? show me the press release about spacex is going to build a mars explorer. They talked about visiting mars many times, but all gave me impression, it's based on assumption, someone like nasa is willing to pay for their delivering service. They never mention explorering mars out of their own pocket.
Well that makes a little more sense that the initial suggestion.However, any serious science mission starts not with a cool bit of hardware, but with a scientific objective.I would suggest that landing a vehicle of the suggested complexity and ability would be in the same league technically as a sample return mission. If the two were head-to-head which do you think would actually get funded?
What would be the best power source for a rocket hopper while in ISRU mode (other than broadcast power)? Nuclear? Solar?
Quote from: go4mars on 03/15/2013 04:49 amWhat would be the best power source for a rocket hopper while in ISRU mode (other than broadcast power)? Nuclear? Solar? NTR with compressed C02 as the reaction mass. Refueling is running a pump.
Even the general question of how to power a stationary ISRU (or anything for that matter) has not been answered yet.I can't imagine a hopper that's carrying the power source and ISRU plant with it. It will be less hassle to carry more fuel from the stationary ISRU plant to suffice for a longer trip.Neither a nuclear plant nor a solar field are something you want to carry with you...
Quote from: meekGee on 03/15/2013 05:13 amEven the general question of how to power a stationary ISRU (or anything for that matter) has not been answered yet.I can't imagine a hopper that's carrying the power source and ISRU plant with it. It will be less hassle to carry more fuel from the stationary ISRU plant to suffice for a longer trip.Neither a nuclear plant nor a solar field are something you want to carry with you...It depends which planet you are on. For Mars use solar power to split CO2 into 2CO and O2 at your base camp. Burn them to fuel the hopper.
A rocket with a propellant mass ratio of 2 and an exhaust velocity of 3km/s could hover above Mars surface for just 9 minutes before running out of fuel, I don't see any way of getting the vehicles surface to surface range up to a distance that would make it economic enough to compete against surface rovers.
Quote from: Andrew_W on 03/16/2013 10:40 pmA rocket with a propellant mass ratio of 2 and an exhaust velocity of 3km/s could hover above Mars surface for just 9 minutes before running out of fuel, I don't see any way of getting the vehicles surface to surface range up to a distance that would make it economic enough to compete against surface rovers.Well, that's half the delta-V required for orbit... With a decent mass ratio you can do quite a distance semiballistic, much faster than a rover, and if you've got a nuclear CO2 engine you can refill directly from the atmosphere without having to power a cracking plant.It was Zubrin's idea, I believe...