The Mars Problem

Getting to Mars -- more specifically, getting people to Mars -- is challenging enough, but it seems that one of the really hard parts is that very last step: getting them from a Mars parking orbit down to the surface. Mars's atmosphere is so thin that big parachutes only work up to a point. Bigger weights, bigger landers, and they're just not able to slow the craft enough to prevent a really hard landing. The thinness of the Mars atmosphere also means that our usual way of slowing incoming spacecraft -- by wasting their kinetic energy as heat -- is not terribly effective for Mars. So, up to now, most Mars mission planning has assumed that you'll need to slow for a landing by burning fuel. Retro-rockets. The advantage is that we have a pretty good idea how to do this. The disadvantage is that you have to lug a whole bunch of fuel all the way to Mars just so that you can land. Then you might want to take off again, so more fuel wanted there, and quite a lot of it. One way to handle this is to send it on ahead in its own spacecraft, park it in Mars orbit, and refuel the human-carrier upon arrival. All doable.

I think there's a better way, though it does rather presume that we intend going to Mars lots and lots, otherwise it is probably just not worth all the trouble. I think we should, send a robot factory ahead to build a space-elevator from orbit to the Martian surface. Sure, we don't really know how to build such a thing yet, but we also lack the technology to get really bulk shipments from here to Mars in the first place, so there's some time to work on the problem (and there are people actively working on it, anyway.)

Then, too, Mars is a much less challenging target for building a space-elevator than Earth is. In building our first space-elevator Mars's thin atmosphere is a positive advantage, as is its lower gravity. We'd get to build a useful, working elevator under slightly less challenging, but still real, conditions than if we try to build one for Earth, so good practise for us, and we simultaneously solve the problem of getting people down from Mars orbit to the surface. And back again, if they want. Plus it gets us past a whole horde of technical unknowns that we need to overcome if we're ever going to make access to space from down our gravity wells and an easy (for some value of easy) and cheap (relatively) prospect.

Let's go.