CAPE CANAVERAL, Fla. - A star-crossed NASA solar science mission is being delayed yet again -- this time to give engineers time look into a national missile defense system test failure that took place last month in California.
The eight-day slip until at least Feb. 1 represents a fourth delay for NASA's High Energy Solar Spectroscopic Imager, or HESSI, spacecraft, which originally had been slated for launch in July 2000.
Mission managers want to make certain that the satellite's launcher -- an Orbital Sciences Corp. Pegasus rocket -- will not suffer the same fate as a prototype missile defense booster that veered off course and was destroyed shortly after a Dec. 13 launch.
Launched from Vandenberg Air Force Base, that booster -- which was deliberately destroyed by range safety officers after it swerved off course -- was equipped with a first stage made by Alliant Techsystems Inc., a company headquartered in Edina, Mn.
The Pegasus rocket slated to carry HESSI into orbit also is outfitted with an Alliant rocket stage, and engineers want to finish a review of common components and systems to guard against a similar failure.
"They're looking for similarities in the composition and components of that (failed) vehicle and the Pegasus, and that analysis will be going on for another week," said George Diller, a spokesman for NASA's Kennedy Space Center.The Pegasus and HESSI most recently had been slated for launch Jan. 24. The booster-satellite combination is to be flown out over the Atlantic Ocean by an OSC L-1011 and then dropped from the belly of the aircraft.
The Pegasus then will be ignited, hurling the HESSI satellite into an orbit about 373 miles (597 kilometers) above Earth, where it will carry out an extensive study of solar flares over the subsequent two to three years.
The $85 million mission suffered an initial delay in March 2000 when the spacecraft was severely damaged during vibration testing at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The satellite was rebuilt and rescheduled for launch in March 2001, but the flight was pushed back to June 2001 after problems cropped up on a different Pegasus flight.
Another Pegasus rocket carrying NASA's X-43 hypersonic test vehicle then was destroyed during a failed June 2, 2001, launch over the Pacific Ocean, and the HESSI mission has been on hold ever since.
Once aloft, HESSI will study gigantic explosions in the atmosphere of the sun, producing the first high-fidelity color movies of solar flares during their highest energy emissions.
The spacecraft's sole instrument -- an imaging spectrometer -- is expected to give scientists new insight into solar flares and coronal mass ejections, which can disrupt satellite and radio communications and cause power outages on Earth.
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