In July, the final shuttle, STS-135, landed, and the U.S. had no next-generation vehicle waiting on a nearby launchpad. The planned Constellation program has been killed, so U.S. astronauts must rely on the Russian Soyuz craft or possibly commercial craft to get to the International Space Station until the next vehicle is ready. Although NASA is currently designing and testing that vehicle, Wired has a great article breaking down exactly what obstacles NASA will have to overcome to get humans on Mars.
The Mars Science Laboratory is scheduled to launch soon. It weighs one ton, and that’s about the limit of what we can safely land on Mars. A manned mission will require 40-80 tons of material (water, food, air, power supplies, tools, etc.). First off, that’s a lot of stuff to launch. But landing is also terribly difficult because Mars barely has an atmosphere. It’s 100 times thinner than ours–the equivalent of being 100,000 feet above the surface of the Earth. The lack of atmosphere makes it harder to slow down an incoming lander because there is less friction. So even if you pull a parachute, while the lander would slow, it would still be moving faster than someone in free fall above Earth. And to slow a 40 ton lander, the parachute would have to be as big as a stadium, which could mean that it would be too big to deploy before landing.
And parachutes really come into play late in the descent stage. When the lander first hits Mars’s atmosphere, it’s moving so fast that any parachute would be torn to shreds. The Wired article talks about lightweight structures that (hopefully) could be rapidly inflated to become rigid. These structures would be attached to the bottom of the lander and fan out like an inverted umbrella to greatly increase drag and slow the lander down. The article also discusses “supersonic retropropulsion”–retrorockets that can be fired to slow the lander down while it’s still moving at supersonic speeds. This is an interesting concept, but we still have very little data on the sort of shock waves they would produce (and how those waves could affect the human passengers).
Check out the article. It will give you a new appreciation of the difficulties of safely landing astronauts on Mars. NASA is planning on a manned mission to Mars by 2032. Unless we want to send 40-80 one-ton missions, we need to develop new technology. Sadly, NASA’s budget has repeatedly been the victim of cuts. While you can argue about the value of manned vs. unmanned missions, I’d hate to see the U.S. surrender its position as leaders in space exploration. Besides, new tech means new jobs and new kids studying science. And in a generation, a new class of heroes. What’s not to like?