US asteroid probe misses summer launch window

CAPE CANAVERAL, Fla, July 8 (Reuters) A science probe making NASA's first foray into the asteroid belt missed its summer launch window, jeopardizing NASA's first attempt to orbit two bodies with a single spacecraft, officials said today.

The Dawn spacecraft was originally scheduled to fly on June 20 but assembly of the Boeing Delta 2 rocket at Cape Canaveral Air Force Station was delayed after a crane failure.

Then the spacecraft needed minor repairs to one of its solar wing panels.

The mission was rescheduled for yesterday, but poor weather at the launch site delayed rocket fueling and then an airplane needed to help track the spacecraft after liftoff developed mechanical problems.

Unable to get firm commitments for launch dates later in the month, due to previously scheduled missions at Cape Canaveral, NASA gave up for the summer and reset Dawn's liftoff for September.

''A September launch for Dawn maintains all the science goals,'' said NASA spokesman George Diller.

September will be NASA's last chance for 15 years to explore its two targets, Vesta and Ceres. After that, the two bodies will begin moving apart from each other and the spacecraft will no longer be able to reach both.

Dawn is intended to be a low-cost mission to explore two of the largest bodies in the asteroid belt, a vast area between Mars and Jupiter littered with primordial remains from the solar system's formation.

The spacecraft will be the first able to go into orbit around more than one target, thanks to its innovative ion-powered engines that can be stopped and restarted during flight using a fraction of the fuel of conventional chemical thrusters.

NASA last year canceled Dawn, citing budget pressures and technical issues, but scientists appealed and won an additional 100 million dollars to continue the program. Total mission costs will now be about 450 million dollars.

REUTERS PD BST1942