01.31.2002 - UC Berkeley space scientists team with NASA to launch satellite to study solar flares

UC Berkeley/NASA launch HESSI satellite, continued:

The HESSI mission
31 January 2002

Rendering of HESSI spacecraft in orbit around Earth. Hi-res version. Spectrum Astro Inc. graphic

HESSI is the first Small Explorer (SMEX) spacecraft to be managed in a way that gives the principal investigator — in this case, Robert P. Lin — responsibility for most aspects of the mission. This includes not only the scientific instrument but also the spacecraft, integration, all environmental testing, and operations and data analysis after launch. The Explorers Program Office at Goddard provides management and technical oversight for the HESSI mission under the direction of the Office of Space Science at NASA headquarters in Washington, D.C.

Other mission facts:

UC Berkeley scientists built the spectrometer with its germanium detectors and data processing electronics;

The Paul Scherrer Institut in Switzerland provided the imaging telescope and optical aspect system.

Goddard Space Flight Center provided the grids and the cryocooler and supported the alignment of the imaging telescope.

Spectrum Astro Inc., of Phoenix, Ariz., provided the spacecraft electronics, the satellite skeleton (called the spacecraft bus) and integration support.

Tecomet, a subsidiary of Thermo Electron, Inc., Waltham, Mass., and van Beek Consultancy, The Netherlands, supplied the tungsten and molybdenum imaging grids for the instrument. Tecomet used new microfabrication techniques to create slits in the grids as narrow as 20 microns — less than one thousandth of an inch.

One of HESSI's two grid trays. The nine pairs of grids collimate X-rays and gamma rays to produce pictures of solar flares. NASA photo

The ORTEC division of PerkinElmer Instruments provided the largest and most advanced array of germanium detectors ever flown in space. The nine germanium crystals, one under each pair of grids, were artificially grown to be pure to over one part in a trillion. They are maintained at a temperature of -324 degrees Fahrenheit (-198 Celsius) using a new type of mechanical cooler manufactured by Sunpower, Inc., that has never before been flown in space.

HESSI links: