Michael Crichton once wrote that if you had told a physicist in 1899 that within a hundred years humankind would, among other wonders (nukes, commercial airlines), "travel to the moon, and then lose interest ... the physicist would almost certainly pronounce you mad." In 2000, I quoted these lines expressing Crichton's incredulity at America's abandonment of the moon. It is now 2009 and the moon recedes ever further.

Next week marks the 40th anniversary of the first moon landing. We say we will return in 2020. But that promise was made by a previous president, and this president has defined himself as the anti-matter to George Bush. Moreover, for all Obama's Kennedyesque qualities, he has expressed none of Kennedy's enthusiasm for human space exploration.

So with the Apollo moon program long gone, and with Constellation, its supposed successor, still little more than a hope, we remain in retreat from space. Astonishing. After countless millennia of gazing and dreaming, we finally got off the ground at Kitty Hawk in 1903. Within 66 years, a nanosecond in human history, we'd landed on the moon. Then five more landings, 10 more moonwalkers, and, in the decades since, nothing.

The shuttle is now too dangerous, too fragile and too expensive. Seven more flights and then it is retired, going — like the Spruce Goose and the Concorde — into the museum of Things Too Beautiful And Complicated To Survive.

America's manned space program is in shambles. Fourteen months from today, for the first time since 1962, the U.S. will be incapable not just of sending a man to the moon but of sending anyone into Earth orbit. We'll be totally grounded. We'll have to beg a ride from the Russians or perhaps even the Chinese.

So what, you say? Don't we have problems here on Earth? Oh please. Poverty and disease and social ills will always be with us. If we'd waited for them to be rectified before venturing out, we'd still be living in caves.

Yes, we have a financial crisis. No one's asking for a crash Manhattan Project. All we need is sufficient funding from the hundreds of billions being showered from Washington — "stimulus" monies that, unlike Eisenhower's interstate highway system or Kennedy's Apollo program, will leave behind not a trace on our country or our consciousness — to build Constellation and get us back to Earth orbit and the moon a half-century after the original landing.

Why do it? It's not for practicality. We didn't go to the moon to spin off cooling suits and freeze-dried fruit. Any technological return is a bonus, not a reason. We go for the wonder and glory of it. Or, to put it less grandly, for its immense possibilities. We choose to do such things, said JFK, "not because they are easy, but because they are hard." And when you do such magnificently hard things — send sailing a Ferdinand Magellan or a Neil Armstrong — you open new human possibility in ways utterly unpredictable.

The greatest example? Who could have predicted that the moon voyages would create the most potent impetus to — and symbol of — environmental consciousness here on Earth: Earthrise, the now iconic Blue Planet photograph brought back by Apollo 8?

Ironically, that new consciousness about the uniqueness and fragility of Earth focused contemporary imagination away from space and back to Earth. We are now deep into that hyper-terrestrial phase, the age of iPod and Facebook, of social networking and eco-consciousness.

But look up from your BlackBerry one night. That is the moon. On it are exactly 12 sets of human footprints — untouched, unchanged, abandoned. For the first time in history, the moon is not just a mystery and a muse, but a nightly rebuke. A vigorous young president once summoned us to this new frontier, calling the voyage "the most hazardous and dangerous and greatest adventure on which man has ever embarked." We came, we saw, we retreated.

How could we?

Charles Krauthammer is a columnist for The Washington Post Writers Group. Reach him at letters@charleskrauthammer.com.