Far from being ready for space, NASA’s billion-dollar space plane, a critical transitional craft in replacing the Space Shuttle, is in deep trouble. The maiden test flights of the X-33 hypersonic plane were scheduled for the middle of this year. But NASA now says the prototype will not fly until at least the end of 2001.

Indeed, if the critics have their way, the X-33 may never leave the ground. At congressional hearings in April, House space subcommittee chairman Dana Rohrabacher criticized NASA’s strategy for replacing the Space Shuttle. “By resisting the philosophy of build a little, test a little, NASA had put all of our cheap-access-to-space eggs in one fragile technology basket.”

The X-33 has been an ambitious-and controversial-project from the start. The plane, being built by a NASA-Lockheed Martin partnership, is meant to demonstrate the feasibility of “single-stage-to-orbit” (SSTO) technology. If the X-33 proves the credibility of the SSTO strategy, the technology could be used in a privately funded spaceship, Venture Star, to replace the Space Shuttle.

At stake is more than just a suitable replacement for the Space Shuttle. The X-33 will be NASA’s first new space-related flight test program in two decades. And many observers are watching to see whether the sometimes beleaguered space agency has any technology magic left.