Press Release

Re-scheduled launch of HESSI on Feb. 5 leaves scientists optimistic that satellite can meet scientific objectives despite delay

By SpaceRef Editor
February 1, 2002
Filed under , ,

NOTE: Check below for a detailed agenda of pre-launch press briefings
and launch-day activities.

Berkeley – The long-delayed launch of a UC Berkeley/NASA satellite to
study violent explosions on the sun is now set for next Tuesday, Feb.
5, from the belly of an Orbital Sciences Corp. plane over the
Atlantic Ocean.

The High Energy Solar Spectroscopic Imager, or HESSI, designed, built
and operated by an international consortium led by scientists at the
University of California, Berkeley, will embark on a two- to
three-year mission to look at high-energy X-ray and gamma ray
emissions from solar flares. Though various satellites have made
X-ray and gamma ray observations of flares, which are enormous
explosions in the solar atmosphere, HESSI will be the first to snap
pictures in gamma rays and the highest energy X-rays.

HESSI was originally scheduled for launch in July 2000, but was
postponed after the satellite suffered damage during vibration
testing. Since then, flight delays due to launch vehicle failures
have affected the launch date. However, officials have since cleared
the way for next Tuesday’s scheduled launch.

Robert P. Lin, professor of physics in the College of Letters &
Science at UC Berkeley and principal investigator for the mission, is
optimistic that HESSI will achieve its original scientific goals.

“We were aiming for the peak of solar activity in mid-2000, so we
have been lucky that, with the slip of our launch date by a year and
a half, solar activity has continued to stay high,” Lin said. “The
sun had another peak of activity at the end of 2001. We still think
we will image around a thousand solar flares, though whatever we see
will be new and interesting.”

HESSI, whose total mission cost is $85 million, is the sixth Small
Explorer (SMEX) spacecraft scheduled for launch under NASA’s
Explorers program.


NOTE: Details of the mission and the physics of solar flares can be
found on the Web at UC Berkeley’s news site,
NASA’s HESSI press kit is available at

Robert Lin can be reached at (510) 642-1149 or Brian Dennis can be reached at the
Laboratory for Astronomy and Solar Physics, Goddard Space Flight
Center, (301)286-7983 or at

For information from NASA Goddard, contact Susan Hendrix at (301) 286-7745.

Also check out UC Berkeley’s HESSI Mission Web site at

Hessi’s education Web site is at



WHAT: At Kennedy Space Center, a combination mission and science
briefing. Participants will discuss the overall mission, the launch
vehicle, spacecraft health, and timeline between separation from the
Pegasus rocket through start of science operations. Scientists will
discuss details of the science payload and science objectives for the

NASA will provide live broadcast via NASA-TV. The news conference
also will be streamed through the web from the KSC Web site at

WHO: Robert P. Lin, UC Berkeley principal investigator for HESSI

Brian Dennis, HESSI mission scientist at Goddard

Bill Wagner, NASA’s Sun-Earth Connection program manager

NOTE: West Coast reporters may view the Florida news briefing from
the conference room at the University of California, Berkeley’s Space
Sciences Laboratory beginning at 10:30 a.m. PST. Several HESSI
scientists will be at the lab. The lab is at the top of Centennial
Drive near its intersection with Grizzly Peak Boulevard. Please check
in at the front office for parking permit.



WHAT: Live NASA-TV coverage and commentary of the HESSI launch,
including L-1011 take-off from Cape Canaveral, Fla., and drop of the
Pegasus rocket. The launch as seen from a chase plane will be on
NASA-TV or on the Web at

WHEN: Coverage begins at about 2:00 p.m. EST. L-1011 take off is at
2:30 p.m., with Pegasus drop scheduled for 3:26 p.m. EST.


WHAT: Viewing of the launch at UC Berkeley’s Space Sciences
Laboratory via live satellite feed from NASA-TV. HESSI scientists in
the Mission & Science Operations Center (MSOC) will provide regular
updates. The main update will be given after the satellite’s first
pass over Berkeley, at about 2 p.m. PST. By then, HESSI scientists
should have information about the health of the spacecraft.


Robert P. Lin, HESSI principal investigator, UC Berkeley professor of
physics, director of UC Berkeley’s Space Sciences Laboratory

Manfred Bester, lead scientist in HESSI Mission Operations Center, UC Berkeley

David Smith, spectrometer development scientist, UC Berkeley

WHEN: 10:30 a.m. – 3 p.m. PST

WHERE: Conference room, first floor of Silver Laboratory Addition,
UC Berkeley.


NOTE: Recorded status reports will be available beginning Sunday,
Feb. 3, at (321) 867-2525 or (301) 286-NEWS.

SpaceRef staff editor.