It's not the fall that kills you...

Popping off to Mars for a vacation may actually be a little more complicated than we'd first thought. It turns out that even once you've dealt with issues such as getting there (how many frequent flyer points do you get for 60 million kilometres?), finding water and fashionable spacesuits, there is the small problem of actually stopping (via /.). In the past when we've sent stuff to Mars, we've done things like wrap them in airbags. As any eBayer will tell you, you can wrap even the most delicate collectables to survive the hellish conditions of Australia Post transportations, so why can't the brightest brains of NASA find enough bubble wrap to secure Mars-bound astronauts? The only problem is that you can design robots to survive a 10-20G impact, but squishy humans are unlikely to fare quite so well.

For anything bigger than R2D2, Mars is a tricky spot to land on in one piece. There is not enough of an atmosphere to allow parachutes to be useful (they'd have to be 100 metres in diameter and unreasonably strong, and even then they wouldn't slow you down quickly enough), but there is too much atmosphere to easily allow landing thrusters like the moon landings (unlike the moon, Mars has weather, and lots of it). The space shuttle uses the resistance of Earth's atmosphere against its heat shields to slow it down during its decent, but again that's not going to work on Mars.

This slowing down and stopping business isn't a trivial problem. According to the article, a heavy spaceship wanting to land on Mars has to slow down from Mach 5 (about 6,000 km/h) to less than a thousand kilometres an hour in about 90 seconds. To do this, they'll probably need a combination of something called a Hypercone, which sounds a little like one of those inflatable donuts used behind water-ski boats, to slow down to below Mach 1, then a parachute of some description for a couple of seconds, and then some sort of landing legs to actually get you onto the ground. Piece of cake, really. Unfortunately, until fairly recently, no one has actually been thinking about it. Maybe NASA needs to steal back some of Google's PhDs.

Interestingly they note that the best solution for getting out of Mars orbit and onto the surface of the red planet is a space elevator. Basically, that's just a great big elevator that hangs in the sky, counter-balanced by some sort of space station. This just goes to show that the boffins have been busy reading Kim Stanley Robinson. Of course, we haven't actually worked out even the first couple of hurdles to making a space elevator on Earth, so that's sort of putting the cart before the horse.

So maybe we humans wont actually make it to Mars in my lifetime. I guess I can live with that. But it's good to see people seriously thinking about what it would take to get there.