New X-ray spacecraft launched

By Diane Ainsworth, Public Affairs

Peter Schroeder, left, Robert Lin, center, Andre Csillaghy, right, and other staff at Samuel Silver Space Sciences Laboratory applaud as the launch of the HESSI spacecraft is announced. Noah Berger photo

06 February 2002 | Whoops of joy and applause erupted in the halls of Berkeley’s Space Sciences Laboratory multimedia conference room at 12:58 p.m. on Feb. 5, as the long-awaited High Energy Solar Spectroscopic Imager (HESSI) was air-launched from a L-1011 jetliner and blasted into space 40,000 feet over the Atlantic Ocean.

In keeping with the satellite’s record of delays to date, the first launch attempt was aborted two minutes and seven seconds before HESSI’s scheduled drop from the belly of the commercial airplane, keeping the science and operations team in limbo for an additional 30 minutes. Communications problems prompted the action. After looping around and returning to the launch location, HESSI was dropped from the sky and blasted into orbit by its Pegasus booster.

“It was fabulous, my virgin launch,” said an elated Beth Burnside, vice chancellor of research, who watched the televised launch from the Space Sciences Laboratory.

“Terrific,” said Robert Lin, director of the lab and HESSI’s principal investigator. “We couldn’t have asked for a better launch.”

The launch came just six days after another Berke-ley/NASA satellite — the Extreme Ultraviolet Explorer — re-entered Earth’s atmosphere, ending an eight-year mission to explore space in the extreme ultraviolet, a portion of the electromagnetic spectrum never before studied.

Studying solar flares
The HESSI mission was designed to study high-energy X-ray and gamma-ray eruptions and solar flares spewing from the sun’s atmosphere during solar maximum, the height of the sun’s activity, which peaked in mid-2000. However, launch delays — caused by damage to the spacecraft during testing and subsequent Pegasus rocket booster failures — kept the spacecraft grounded for nearly 18 months. Despite the setback, solar activity has remained high this year, and the HESSI science team believes the new solar probe will be able to image a thousand or more solar flares during its two-year mission.

HESSI is the first NASA mission in more than a quarter of a century to be designed, built and operated by a university and its partners. NASA made that decision as a way to lower the cost of the mission, which is estimated to be $85 million, said Peter Harvey, HESSI project manager.

Manfred Bester, HESSI mission operations scientist, designed the lab’s 36-foot-diameter antenna dish, which will send commands to the four-winged spacecraft as it passes over Berkeley six times a day.

“What a perfect flight,” he exclaimed as a fax from NASA’s Kennedy Space Center, with the coordinates of the newly orbiting spacecraft, arrived.

Faster than a speeding bullet
Once HESSI is in its final orbit, the spacecraft will be traveling faster than the speed of a bullet — at 16,900 miles per hour.

HESSI’s X-ray and gamma- ray vision will allow it to take snapshots of solar flares and “see inside of a solar flare,” Lin said. These flares are seen in visible light as the sudden and intense brightenings of the sun’s surface near sunspots.

Scientists believe solar flares release as much energy as a billion megatons of TNT, but nobody knows how the sun is able to release this much energy or why up to half of the energy that is released is in the form of high-energy particles.

Sister satellite reenters atmosphere
While one astrophysics mission was going up, another had just come down. The Extreme Ultraviolet Explorer, a sister satellite that had charted new discoveries in the extreme ultraviolet, concluded its eight- year voyage, burning up in the atmosphere over Egypt Jan. 30.

The ultraviolet probe went off line in the operations center nearly a week before HESSI spread its wings. Shutdown of operations freed Berkeley operations engineers to begin tracking HESSI and preparing for another launch in late 2002.

The 7,000-pound satellite, built and operated by a consortium that was led by Berkeley, allowed scientists to observe distant objects in the Milky Way galaxy that were impossible to see at other wavelengths. During its long lifetime, the satellite observed more than 1,000 celestial sources inside and outside of the Milky Way.