It was not a surprise, but nevertheless was a disappointment, that the National Aeronautics and Space Administration told contractors this week to expect cancellation of the Constellation program, an effort to return American astronauts to the moon.

There’s a two-fold problem with NASA’s decision, which is apparently based on the president’s distaste for the moon program. First, an enormous amount has already been spent; $10 billion over the past five years. Most, if not all, of that will be wasted with the program’s cancellation. Perhaps more importantly, the cancellation will be yet another giant step backward for America’s space program, one of the few efforts our nation is making to prepare for the future.

Lunar exploration, except for the groundbreaking days of the Apollo missions, has always been a hard sell, as has been the need for a manned mission to Mars. Both are important because experience has shown, throughout all of recorded history, that exploration brings uncountable benefits, often benefits that can not be predicted. To sit on the island of Earth, when we have the capability to do more, is to gradually wither as a society.

The United States can find money for many costly projects, from utterly useless “bailouts” of struggling economic sectors to foreign entanglements that offer no tangible benefits. It doesn’t make sense to stop work on one of the few projects, admittedly expensive, that is almost certain to pay rich results.