Elon Musk's space ship Dragon 'can land on Mars' | Hacker News Reader

Elon Musk's space ship Dragon 'can land on Mars'

theregister.co.uk

103 pointssasvari32 comments

Note that a crew escape system, what the article treats as an absolute minimum for a manned vehicle, doesn't exist on the space shuttle for budgetary reasons. The space shuttle has many, many abort modes[1], but absolutely nothing can be done while the solid boosters are firing, since you can't shut them off or detach them from the stack.

Maciej Cegłowski (pinboard.in) complains at length about this in an essay[2] about the space shuttle.

[1]: http://en.wikipedia.org/wiki/Space_Shuttle_abort_modes

[2]: http://www.idlewords.com/2005/08/a_rocket_to_nowhere.htm

This is excellent.

Many human Mars mission architectures use an Earth return vehicle that is separate from the outbound vessel. The requirements are very different, and there's an overwhelming advantage to placing an Earth return vehicle on the surface ahead of time to produce the methane fuel for its return flight in situ ahead of time, so a vessel that can get astronauts out to Mars without being able to return them is still an important contribution.

On a poignant side note, the article notes that the only feature Dragon now lacks to become qualified for carrying humans is a launch abort system; the original Space Shuttle was designed without a launch abort system.

It's nice that it has this capability, but it's still not an ideal Mars lander, and I think the economics work out that it's cheaper to design a new ship than to send a non-ideal ship all the way to Mars.

For instance, the Dragon's heat shield is (I assume) far heavier than it needs to be for a Mars entry. A purpose-built Mars lander could be made significantly lighter than a purpose-built Earth lander, and sending unneccessary weight to Mars winds up expensive.

Besides, there's going to be a lot of custom hardware needed for a manned Mars mission anyway. At a minimum you'll need a large "Command Module" for the astronauts to travel in (sitting in a Dragon ain't gonna cut it for a one-year voyage) and a custom-built Mars takeoff craft.

I went and carefully read the statement. It says the capsule can carry crew, and that the capsule can land on Mars. It did not say that the capsule can carry crew to Mars, which is a wildly different thing. I think the Register added that accidentally.

I don't think that's possible, because solving the equations to carry enough supplies to get the crew to Mars alive while still being able to stop when you get there almost certainly has no solution with any capsule primarily designed to get to Earth orbit. On the other hand, merely getting hardware to Mars if you don't care how long it takes can be relatively low energy [1], which would also be an orbit not requiring a lot of propellant to enter Mars orbit.

[1]: http://en.wikipedia.org/wiki/Hohmann_transfer_orbit

The discussion of not yet having a return vehicle for a trip to Mars reminds me of a Reddit AMA with a Russian engineer through his grandson. There he claims his Grandfather worked on a plan to send an astronaut to Mars orbit then return, but there was a second and favored plan with which the astronaut would land on the surface, walk around, then die.

http://www.reddit.com/r/IAmA/comments/etu2s/i_was_born_in_sh...

I wonder how it would be received if the goal was to create a permanent settlement on Mars rather than returning.

I think if we are technologically capable of it, it's a much better plan than return. A kind of 6 months on the surface, return ASAP mission would probably go down like Apollo in that those funding it would be like well that's done now and building on that one mission could take decades again.

The other benefit to a settlement plan, is that you could send the habitat and tools ahead of time, to be assembled by robots. Which implies multiple missions, which lowers per-mission weight requirements, and allows for habitat tests prior to having human life (and larger, more temperamental resources) on the line and for fixes to be bundled in subsequent missions.

SpaceX stories always read like they were written by Ben Bova.

Why do people assume that the people we send to Mars need to come back? Could we not send large supply stores first and then send people on a one way trip? I would guess people would sign up even knowing that the trip to Mars is one way.

As always, landing is the easy part. Escaping the gravity well is not. (Looks like they plan to make it a one way trip, setup a colony, then mfg fuel before the return trip.)

I suggest you read "The Moon is a Harsh Mistress" and think about why any Earth-bound government would hate the idea of allowing space based travel or settlement by any agency not under their direct control.

I'm sure it will be done by governments and/or big business, and will be under their control...

at first...

Does anyone know any details of the thrust and delta-v capabilities of the proposed combined launch abort / retro landing system?

Is it going to be just a bunch more Draco thrusters, or something else?

Landing is the relatively easy part. Surviving the journey is harder. The necessary shielding is too heavy to launch, so we need some new ideas there.

I hate how the British use single quotes. It's sometimes ambiguous and relatively hard to parse.

Like JavaScript?

The convention is that double quotes are for actual quotes, while single quotes are for paraphrasing things that others have said.

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