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New UC Berkeley/NASA x-ray spacecraft heads for the sun after Feb. 5 launch

5 Feb 2002

HESSI launch team in Berkeley
Bob Lin, director of UC Berkeley's Space Sciences Laboratory, and others applaud as the HESSI spacecraft is launched on Tuesday, Feb. 5, 2002. 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. Pictured left to right are Peter Schroeder, Lin and Andre Csillaghy. (Photo by Noah Berger)

By Diane Ainsworth, Public Affairs

BERKELEY — Whoops of joy and applause erupted in the halls of Berkeley’s Space Sciences Laboratory multimedia conference room at 12:58 p.m. Pacific time 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 past record of delays, 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. Faulty communications prompted the action. However, after looping around and returning to the launch location, HESSI was dropped from the jetliner and blasted into orbit by its Pegasus booster.

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

Bob Lin, director of the Space Sciences lab, and vice chancellor Beth Burnside celebrate following the launch of the HESSI spacecraft on Tuesday, Feb. 5, 2002. (Photo by Noah Berger)

"Terrific," said Robert Lin, director of the Spaces Sciences Lab and HESSI’s principal investigator. "We couldn’t have asked for a better launch."

Now that it is in orbit, the satellite comes under UC Berkeley's control, with commands uplinked and data downlinked through a 36-foot (11 meters) radio dish at the Space Sciences Laboratory, perched in the wooded hills above UC Berkeley. From there, HESSI mission operators will monitor the automatic pointing of the satellite toward the sun, deployment of the four solar panels, and the spin-up of the satellite to about 15 revolutions per minute.

The launch came just six days after another Berkeley/NASA satellite – the Extreme Ultraviolet Explorer (EUVE) – burned up as it 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.

Hessi mission

The HESSI mission will study the high-energy x-ray and gamma-ray eruptions from solar flares, which follow a 11-year cycle that 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 a year and a-half. 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 primary science mission.

HESSI is the first NASA mission in more than a quarter of a century to be designed, built as well as 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 arrived from NASA’s Kennedy Space Center noting the orbital coordinates of the new spacecraft.

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.

Artists concept of HESSI
Artist's concept of HESSI spacecraft in orbit, spinning around an axis pointing at the sun. Hi-res version. NASA picture

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, rapid and intense brightenings of the sun's surface near sunspots.

Scientists believe solar flares release as much energy as several 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, EUVE, reenters atmosphere

While solar physicists begin to probe that mystery, a sister satellite (EUVE) that had charted new discoveries in the extreme ultraviolet concluded its eight-year voyage, burning up in the atmosphere over central Egypt on Jan. 30.

The EUVE went offline in the Science and Mission Operations Center nearly a week before HESSI spread its wings. Shutdown of all EUVE operations freed Berkeley operations engineers to begin tracking HESSI and preparing for the next launch later this year, of the Cosmic Hot Interstellar Plasma Spectrometer.

The 7,000-pound EUVE 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 galaxy.

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