Where will NASA's next giant step take us?

As space agency rolls out a new rocket, its long-range mission remains unclear

It emerged just after midnight last Tuesday, bolted down and gleaming under the floodlights. This was the biggest debut since King Kong, joked the aerospace folks. The Ares I-X is the world's tallest rocket, 327 feet high, and it began the long crawl toward the launch pad at the Kennedy Space Center, where it will blast off Oct. 27 if weather permits.

This is a test rocket, a crude approximation of the Ares I, the rocket that NASA has said will replace the aging commuter bus known as the space shuttle. But the Ares I may turn out to be a rocket to nowhere.

A blue-ribbon committee has said the Ares I is part of a NASA program that doesn't make sense given current and future budgets. The commission would like NASA to get out of the business of ferrying astronauts to low Earth orbit and let commercial companies handle that task. Now the Obama administration may try to kill the Ares I.

The space shuttle is old and unsafe and is supposed to be put out to pasture by the end of 2010. The United States will then find itself in the unfamiliar position of being incapable of launching humans into orbit. For five, six, seven years, American astronauts will probably have to buy a seat on a Russian spacecraft.

It's an awkward time for NASA. The most basic questions are on the table: Where to go? How to get there? And to what end?

There are billions of dollars at stake. The technological questions are complicated.

Um, yes, it's rocket science.

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The whither-NASA issue was supposed to have been decided already. After the Columbia disaster of 2003, an investigative commission declared that NASA lacked clear direction and purpose. By early 2004 the Bush White House put together a sweeping blueprint for NASA that it called the "Vision for Space Exploration."

The plan called for returning astronauts to the moon for extended stays as preparation for what would someday be a manned mission to Mars. Under a new NASA administrator, Michael Griffin, the agency put together the Constellation program, which called for two new rockets, a new crew capsule, a lunar lander and a lunar habitat. Crew and cargo would no longer ride to orbit together in a huge space truck such as the shuttle. Instead, NASA would return to an Apollo-style architecture, with astronauts in a capsule on top of a rocket. The capsule would parachute into the sea at the end of the mission. NASA's new crew capsule, dubbed Orion, is being designed to ride atop the Ares I rocket to reach low Earth orbit, or LEO. A heavy-lift rocket called the Ares V, to be built later, could take Orion moonward.

It was an ambitious plan. Too ambitious, apparently.