MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
Contacts: Mary Beth Murrill, JPL, (818) 354-6478
Dolores Beasley, NASA Headquarters, Washington, D.C.,
Mark Hess, NASA Goddard Space Flight Center, Greenbelt,
MD, (301) 286-8982
FOR IMMEDIATE RELEASE
March 24, 2000
HESSI SUSTAINS DAMAGE DURING VIBRATION TESTING
NASA's High Energy Solar Spectroscopic Imager spacecraft --
an international mission to explore the basic physics of particle
acceleration and energy release in solar flares -- has sustained
substantial damage during vibration testing. Repairs to the
spacecraft, known as HESSI, will likely delay its launch to no
earlier than January 2001.
The damage was caused when a test device that simulates
vibrations the spacecraft can expect during launch delivered
approximately 20G's, 10 times the appropriate levels for the
test. As a result, the spacecraft's structure was damaged and two
of the four solar arrays were cracked. The status of the HESSI
instrument is not currently known.
Engineers are optimistic that the structure, instrument
boxes and detectors were not harmed, but further analysis will be
required to determine the full extent of the damage. Both damaged
solar arrays need to be replaced.
The incident occurred March 21 while the spacecraft was
undergoing vibration testing in facilities at NASA's Jet
Propulsion Laboratory, Pasadena, CA.
The spacecraft and vibration facility are impounded pending
an independent failure review board that will be chaired by
NASA's Marshall Space Flight Center, Huntsville, AL, and
supported with experts from NASA's Goddard Space Flight Center,
Greenbelt, MD; NASA Headquarters, Washington, DC; and other NASA
centers as required. This board will begin investigating in the
next several days, and is expected to conclude its efforts in six
to eight weeks.
After the spacecraft is released from the vibration
facility, the HESSI team will disassemble it, re-inspect it, and
perform needed repairs. It is expected replacement of the solar
arrays will take four to six months.
HESSI was scheduled to be launched on a Pegaus rocket in
July 2000. While a new launch date is not known, current
estimates, depending on the amount of work that will have to be
done, put a launch no earlier than January 2001. The cost to
repair the satellite, which will determine how long the mission
will be delayed, has not yet been determined. NASA's cost for the
HESSI spacecraft was budgeted at $40 million. Development,
launch vehicle and mission operations costs bring the total
to $75 million.
HESSI is a Small Explorer mission and is managed by Goddard
under the Explorer Program. The science team includes co-
investigators from Switzerland, Scotland, Japan, France and the
More information on the HESSI mission can be found on the
Internet at http://hesperia.gsfc.nasa.gov/hessi/ or