There have been eight landing attempts over 36 years at Mars. Six different designs, or five if you count MPL/Phoenix as being more-or-less the same.
Just a thought:In terms of extraction, Dragon (and likely any Mars derivative) has a CBM sized opening on top. Could some of the landing legs be designed to be extendable/retractable, to tip the capsule onto its side after landing?
There have been attempts to standardise Mars landers. In fact, they have all been born of the same development program already, leading to a standardised but scalable basic entry vehicle shape and parachute. That is already much more standardisation than you will find in most spacecraft designs given the spread of time and different purposes and payloads.For MER, it was initially proposed to reuse the MPF lander design, but in the end they had to scale it all up to fit the payload.Anyway, as to Dragon- I think some of the technologies behind it are sound, and applicable to a Mars lander. But it would be ridicuolous to handicap the design by basing it on the Dragon capsule itself. Firstly, why restrict the diameter to 3.6m? Why not take it out to the maximum that the LV can cope with? Landed mass scales closely with vehicle diameter. Secondly, why put everything inside a sealed capsule? The basic design should be more flexible than that, allowing a multitude of different payloads to be flown.
The manned Dragon and Dragonlab have a side hatch. It may be simpler for surface equipment to exit through that.http://www.spacex.com/downloads/dragonlab-datasheet.pdf
A fresh design for a general purpose lander would be much more elegant, no doubt, but who is going to do it? And who is going to finance it? And how much time is going to take? After all, "they" had at least since 1975, 37 years, and I see no indication of any will to build anything remotely similar.
And who said to restrict ourselves to 3.6 m? That's just a starting point. The fairing for a Falcon Heavy is 5.2 m in diameter. I see no reason to, at the very least, try to use that. But that is phase 2. Start humble, prove yourself, and then, maybe, you'll get farther.
Does "detived" in include he possibility of modifying the side hatch to be much larger, or perhaps to also include a folding/extensible ramp? I'd think that would be a good derivation jumping off point. Might also want to reduce the height to lower the c/g. The pressure vessel is made up of welded panels so ISTM mods like this would be a CNC w/plasma cutter away for a decent fabricator
I think the basic premise is wrong. I believe it will be far better and cheaper in the long run to start with a blank sheet of paper and design the vehicle for its particular purpose.
I think the basic premise is wrong. I don't think that planetary landers are general purpose. I think they are specialized vehicles and should be custom designed for the mission and the planetary environment they are going to land in.So first we should decide what the mission is. Is it a manned lander? Is it for cargo? Is it for science? I believe it will be far better and cheaper in the long run to start with a blank sheet of paper and design the vehicle for its particular purpose. Rather than taking something like Dragon and go through all sorts of permutations to modify it for another purpose we should start from the bottom up.Now if SpaceX wish to design a Mars lander for a specific purpose, there is no reason why they cannot use Dragon technology and systems for it. But that is very different from starting with an already mature design and trying to morph it into something else.
Why not get SpaceX to do it? They are not averse to altering their designs. Of their seven launches, how many have been the exact same configuration?The benefits of creating a dedicated lander rather than a modified LEO taxi would be huge, and the increased payload would probably pay for itself fairly quickly in terms of $/kg landed.
well, SpaceX are quite clear that they want to put people on Mars. so there is a pretty reasonable chance that some thought has been applied to using Dragon for that purpose - they've already repeatedly said the heat shield was designed to be capable of Earth reentry from Mars, for example.
Imagine how much payload SpaceX might be able to land with a PICAX heat shield scaled up to 4.5 Meters (Scaled up to fill their fairing), Draco thrusters hinged to allow for no cosine losses, and an airframe optimized for Mars entry.
That's exactly the point: Dragon designed as an Earth lander, not a Mars lander. It's quite feasible to imagine it being used to bring members of a Mars expedition back to Earth on the last stage of their journey. But it isn't a Mars lander (despite what Musk says). Just what I was arguing: a Mars lander designed from the ground up, but using Dragon technology, makes much more sense. I believe it could actually be cheaper than "hacking" the current vehicle's configuration.
I don't think that planetary landers are general purpose. I think they are specialized vehicles and should be custom designed for the mission and the planetary environment they are going to land in.