There's no accepted global policy on what to do about asteroid impacts.
Asteroids are deep-space bodies orbiting the Sun, not the Earth, and traveling to one would mean sending humans into solar orbit for the very first time. Facing those challenges of radiation, navigation and life support on a months-long trip millions of miles from home would be a perfect learning journey before a Mars trip.
We are going to learn how to relate to the Earth and our own natural environment here by looking seriously at space colony ecologies.
Americans who read the papers or watch Jay Leno have been aware for some time now that there is a slim but real possibility - about 1 in 45,000 - that an 850-foot-long asteroid called Apophis could strike Earth with catastrophic consequences on April 13, 2036.
The frontier in space, embodied in the space colony, is one in which the interactions between humans and their environment is so much more sensitive and interactive and less tolerant of irresponsibility than it is on the whole surface of the Earth.
When you have an asteroid threatening Earth, it's uncertain where it's going to hit until the last minute; the decision to take action has to be coordinated by the international community.