Why Lasso an Asteroid?

The answer involves politics and money. Although the moon is just three days away and offers valuable resources such as water ice, the White House canceled NASA's Constellation program, and its plan to return to the moon, in 2010. At this point there is no chance the Obama administration will reverse course and adopt this Bush administration goal.

So, NASA had to find another nearby destination for future exploration, and the capture-an-asteroid mission gives the agency a near-term target just beyond the moon. NASA thinks it can get astronauts there on a month-long mission by the early 2020s. Given current budgets, the asteroid mission is the only realistic astronaut destination NASA can reach before 2025—a manned trip to Mars just isn't going to happen that soon.