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Institutional Involvement

The HESSI project is the first of NASA’s Small Explorers to be managed in the PI Mode. In this mode, the Principal Investigator (PI), Professor Robert P. Lin at the Space Sciences Laboratory of the University of California, Berkeley, has full responsibility for most aspects of the mission including not just 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 under the direction of the Office of Space Science at NASA Headquarters in Washington, D.C. Under this arrangement, UC Berkeley is the project general contractor and provider of the spectrometer with its germanium detectors and data processing electronics. The Paul Scherrer Institut in Switzerland has provided the imaging telescope and optical aspect system. NASA's Goddard Space Flight Center has provided the grids and the cryocooler and has supported the alignment of the imaging telescope. General Dynamics (formerly Spectrum Astro Inc.), of Phoenix, Ariz., has provided the spacecraft bus and integration support.

After launch, UC Berkeley will control HESSI in orbit using its on-site Mission Operations Center and 11-meter antenna. It will also receive the telemetered data stream and distribute it for archiving at Goddard. Unlike most other scientific missions, there will be no proprietary data rights; the goal is to have all data and the software needed to analyze them freely available on-line within hours of receipt at the ground station.  Then, many talented scientists around the world can analyze HESSI data along with the complementary observations of the same flares that will be available from other instruments in space and from ground-based observatories.

Roles of Participating Institutions

Management Organization

The HESSI Principal Investigator (PI), Professor Robert P. Lin at UCB, is the point of contact with the SMEX project HESSI Mission Manager, Mr Frank Snow at Goddard. The HESSI Project Manager (PM), Mr. Peter Harvey at UCB, reports directly to the PI. He supervises and coordinates the instrument development at UCB, GSFC, and Paul Scherrer Institute (PSI); the spacecraft development at Spectrum Astro, and the ground system development, integration and test, and mission operations preparation at UCB. Following launch, the PI will direct the Mission/Science Operations at UCB, and lead the overall science analysis effort, with support of the Co-Is, the Education/Outreach and the Ground Observations Coordinators.

Teaming arrangements

The HESSI hardware development team consists of UCB, GSFC, PSI, and Spectrum Astro. UCB was designated as the PI institution and developer of the Spectrometer, based on the solar high-energy (HIREGS, HIREX balloon program) and space-flight experiment expertise of Professor Robert Lin, and on the capabilities of the UCB Space Sciences Laboratory (FAST, SOHO XDL, Polar EFI, Wind, EUVE, etc.). 

GSFC, under lead Co-I Dr. Brian Dennis, was designated to lead the grids and cryocooler effort based on their HEIDI balloon program, their grid characterization expertise, and their cryogenics experience on numerous programs. 

PSI, under lead Co-I Dr. Alex Zehnder, was chosen for the telescope, RAS, and SAS, based on their experience on XMM, EUVITA, and MIR. 

Spectrum Astro, our industry partner, was chosen to provide the spacecraft, based on their outstanding record in small spacecraft (MSTI 1,2,3; New Millenium DS-1, MightySat), and their flight-qualified subsystems useful for HESSI.

Team Members with Hardware Responsibilities 




Spectrum Astro

Project Management 


Instrument Electronics 

Flight Software 

Ground Data System 

Mission I&T

Flight Ops 

Data distribution

Grid Optical 
& X-ray Characterization

Grid Alignment

Cryogenics Thermal Design


Image Analysis Software 

Solar Data Distribution


Imager Tube

Grid Trays

Roll Angle System (RAS)

Solar Aspect System (SAS)

Twist Monitoring System (TMS)

Aspect Solution



Mission I&T support


The division of tasks was chosen to take advantage of the strengths of each partner and to provide straightforward, easily manageable interfaces between the team partners. GSFC tests, characterizes, and qualifies the grids and cryocooler, and delivers them to PSI and UCB, respectively. PSI fabricates the telescope, RAS, and SAS, and integrates them with the grids for the complete Imaging System. UCB fabricates the germanium detectors (GeDs), cryostat, and instrument electronics, and integrates them with the cryocooler for the complete Spectrometer. These are integrated into the spacecraft fabricated by Spectrum Astro (under contract from UCB), and tested at UCB. 

Mission and Science Operations are done at UCB.  Data archiving and distribution are done by GSFC for U.S. researchers and by ETH/Zurich for Europeans. 

Team Members with non-hardware responsibilities

bulletCoI Institutions (US)
bulletMontana State University
bulletU. Alabama in Huntsville
bulletSolar Physics Research Corporation
bulletLawrence Berkeley National Laboratory
bulletCoI Institutions (non-US)
bulletInstitute of Astronomy ETHZ, Zurich, Switzerland
bulletU. Glasgow, Scotland
bulletNational Astronomical Observatory of Japan
bulletISAS, Japan
bulletObservatoire de Paris-Meudon, France

Other Partner Institutions

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This site last updated November 10, 2008.