NASA bows out of Lockheed Martin shuttle-replacement project.(Knight Ridder Newspapers)

WASHINGTON _ Beset by financial and technical problems putting people in space, NASA on Thursday shot down its proposed space plane after spending nearly $1 billion on it.

The announcement effectively killing the X-33 space plane, which was supposed to replace the aging space shuttle fleet, came a day after the space agency announced it would dramatically prune its plans to expand the International Space Station because the program is $4 billion over budget. And that came on the heels of the demotion of a high-ranking official who had been the godfather of the human space program.

"It's 52-card pickup time," space analyst John Pike, director of GlobalSecurity.org, a Washington policy group, said of the NASA human spaceflight program. "It's in greater disarray than it's been in some decades."

The X-33 program, over-budget and behind schedule, needed money from NASA to stay alive. On Thursday, NASA announced it would spend no more on the plane, which was being built by Lockheed Martin Corp. of Bethesda, Md. NASA also canceled an experimental unmanned-rocket program called X-34.

Without NASA money, "I can't see us pressing forward alone," Lockheed Martin spokesman Evan McCollum said Thursday.

"This has been a very tough decision, but we think it is the right business decision," said Art Stephenson, the director of NASA's Marshall Space Flight Center in Huntsville, Ala., which oversaw the program.

He said NASA learned from the space plane and the X-34 "that our technology has not yet advanced to the point that we can successfully develop a new reusable-launch vehicle that substantially improves safety, reliability and affordability."