For Sen. Barack Obama, space really is the final frontier. The debate over space exploration is, in large part, between folks who see those dollars better spent elsewhere and others who get butterflies when they think of space exploration. While President Bush introduced plans for the next generation of space exploration, conforming to his pattern, he left it to the next president to pay for it.

Obama says he’ll put off that bill by five years to pay for his pre-K proposal. Hillary thinks she can do both. And it appears the stakes will be high for the next president on this issue.

After NASA’s three space shuttles are retired in late 2010, the United States will have no spacecraft capable of launching astronauts into orbit — although the international space station will be reaching completion at that time. American officials have made plans to pay Russia to supply the space station, with the possibility that a private American company or the French Ariane spacecraft may also play a role.

The Constellation program was proposed by Bush in 2004 as a way to return Americans to space. His plan envisions the establishment of a settlement on the moon, in part to prepare for the lengthy voyage to Mars.

Contracts have been let to build several key components of the new launch system, and NASA has put together an elaborate timetable for building, testing and launching the spacecraft by 2015.

Is a delay in space exploration something that will turn off voters? No. But it’s the kind of prideful federal program that’s hard to say no to. Obama’s argument has been that kids need to learn math and science or we’ll have no one to explore space. That’s fair. But so is Hillary’s note that a lack of space exploration may cause a “brain drain” in NASA’s ranks.