If you wanted dangerous, you got it.

One week ago today, in response to heavy criticism for killing the Constellation program begun under his predecessor, President Obama presented his revised vision for NASA: To build a new heavy lift spacecraft that will go beyond low Earth orbit and land on an asteroid by around 2025. This goal is far more ambitious than going back to the moon. Space experts say such a voyage could take several months longer than a journey to the moon and entail far greater dangers. “It is really the hardest thing we can do,” NASA Administrator Charles Bolden said [AP].

NASA doesn’t know which of the nearby asteroids it might pick for a visit, but the main candidates are around 5 million miles from Earth. The moon, by contrast, is a little less than a quarter-million miles away. The asteroids are about a quarter-mile across; the moon is more than 2,000 miles in diameter. And a trip to an asteroid could take 200 days, as opposed to the Apollo 11 lunar round-trip, which required little more than a week. That means NASA may have to devise new radiation shields and life-support systems for the asteroid-bound astronauts.

Once you get there, it’s no picnic either. You can’t actually land on an asteroid because it has so little gravity. Astronauts would have to somehow tether themselves to the rock to keep from floating away. (DISCOVER blogger Phil Plait cheered this bit of science fact in the 1998 disaster movie Deep Impact, in which the heroes encounter this problem while visiting a comet.)

Despite the challenge, there are several great reasons to go. The chemical composition of asteroids can give scientists clues about era of the planets’ formation, roughly four and a half billion years ago. And on a practical level, an asteroid mission would be a Mars training ground, given the distance and alien locale. “If humans can’t make it to near-Earth objects, they can’t make it to Mars,” said MIT astronautics professor Ed Crawley [AP].

And then there’s the heroic Hollywood angle: If we can land on an asteroid, we might also be able to blow one up, or nudge one into a new trajectory. NASA’s Near Earth Object Program has identified more than 1,000 “potentially hazardous asteroids.” … Sometimes they come really close — in March 2009 an asteroid passed by Earth at a distance of just about 49,000 miles [ABC News]. Our planet has taken enormous hits from asteroids throughout its geological history, including the 6-mile-wide asteroid that is believed to have wiped out the dinosaurs.

But if humans master the art of asteroid-handling, saving the planet from death from the skies might jump from fodder for terrible movies to reality. That “would demonstrate once and for all that we’re smarter than the dinosaurs and could therefore avoid what they didn’t”, White House science adviser John Holdren said [New Scientist].

So there it is, your ultimate response to people who whine that we shouldn’t spend money on space exploration: We must prove, once and for all, that we’re tougher than T. rex.

Related Content:
DISCOVER: The Science and the Fiction, in which the Bad Astronomer tackles the good and bad of sci-fi science.
DISCOVER: What To Do Before the Asteroid Strikes
80beats: Obama’s Space Speech: We’ll Go To Mars in this Lifetime
80beats: European Spacecraft Buzzes Past an Asteroid, Takes Pictures
Bad Astronomy: Obama lays out bold and visionary revised space policy

Image: NASA