CAPE CANAVERAL, Florida (Reuters) - NASA on Tuesday delayed the test flight of an unmanned prototype moon rocket due to poor weather.

The attempt to launch the 327-foot (100-meter) Ares 1-X rocket was reset for 8 a.m. EDT on Wednesday.

The flight is the centerpiece of a $445 million NASA technology demonstration program aimed at replacing the space shuttles. The shuttles, which began flying in 1981, are due to be retired next year after six more flights to complete construction of the International Space Station.

NASA planned to launch the demo rocket on Tuesday but was stymied by cloudy skies over the Kennedy Space Center and by a boat that wandered into the launch danger zone. Pilots and mariners who violate restricted zones can face jail terms and fines of up to $250,000.

Ares 1-X, currently the world’s tallest rocket, is a modified space shuttle booster outfitted with a faux second stage and a simulated Orion crew capsule. It is the first new rocket developed by NASA since the 1970s-era space shuttle. The test flight is intended to verify computer models used to design rockets.

Ares 1-X’s motor was made by Alliant Techsystems Inc as part of a $1.8 billion Ares development contract for NASA.

NASA hopes to develop two Ares rockets to return U.S. astronauts to the moon sometime in the 2020s. The program, however, is under review.

(Editing by Jane Sutton, Editing by Sandra Maler)