CAPE CANAVERAL, Fla. — The name of the new vehicle that NASA hopes will take astronauts back to the moon was supposed to be hush-hush until next week. But apparently an American astronaut, Jeff Williams, floating 220 miles above Earth at the international space station, did not get the memo. Mr. Williams let it slip yesterday that the new vehicle’s name is Orion.

“We’ve been calling it the crew exploration vehicle for several years, but today it has a name — Orion,” Mr. Williams said, taping a message in advance for the space agency that was transmitted accidentally over space-to-ground radio.

NASA planned to release the name August 31, when the space agency also announces which contractor will build the vehicle. Competing for the award are Lockheed Martin and a team made up of Northrop Grumman and Boeing.

The crew exploration vehicle will replace the space shuttle program after it ends in 2010. Earlier this summer, NASA announced the names of the rockets that will propel the crew exploration vehicle and a cargo vehicle, respectively Ares I and Ares V.

A NASA spokesman, Michael Braukus, in Washington said nothing was official until the formal announcement next week, adding: “My next phone call is to Houston asking, ‘What’s going on?'”