Don Savage
Headquarters, Washington, DC                  April 10, 1996
(Phone:  202/358-1547)

Jim Sahli/Fred Brown
Goddard Space Flight Center, Greenbelt, MD
(Phone:  301/286-8955)


RELEASE:  96-68

INVESTIGATIONS SELECTED FOR INITIAL MIDEX MISSIONS

       NASA's Office of Space Science has selected the first 
two science missions for the new Medium-class Explorer 
(MIDEX) program.  The two missions, selected for definition 
studies leading to confirmation and development, are the 
Microwave Anisotropy Probe (MAP) and the Imager for 
Magnetopause-to-Aurora Global Exploration (IMAGE).

       The MAP mission will make a detailed investigation of 
the cosmic microwave background to help understand the large 
scale structure of the universe, such as galaxies and 
clusters of galaxies, which result in enormous walls and 
voids in the cosmos.  The Principal Investigator is Dr. 
Charles L. Bennett of the Goddard Space Flight Center, 
Greenbelt, MD.  Information about the MAP mission is 
available on the World Wide Web at URL:  
http://map.gsfc.nasa.gov.

       The IMAGE mission will use three-dimensional imaging 
techniques to study the global response of the Earth's 
magnetosphere to variations in the solar wind, the steam of 
electrified particles flowing out from the Sun.  The 
magnetosphere is the region surrounding the Earth controlled 
by its magnetic field and containing the Van Allen radiation 
belts and other energetic charged particles.  The IMAGE 
Principal Investigator is Dr. James L. Burch, Southwest 
Research Institute, San Antonio, TX.

       "These selections are the beginning of a key 
component of our program of scientific exploration of space 
into the next century," said Dr. Wesley T. Huntress Jr., 
Associate Administrator for Space Science at NASA 
Headquarters, Washington, DC.  "We received many outstanding 
proposals for the first two MIDEX missions, and it was an 
extremely difficult choice.  It's exciting that such 
remarkable science can be accomplished within the MIDEX cost 
constraints."

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       In addition to the two primary missions, two 
alternate missions were chosen to receive minimal funding 
for study in the event that the primary missions are not 
able to proceed to development.  The alternate mission for 
MAP is The Hopkins Ultraviolet Background Explorer (HUBE).  
Dr. Richard Henry, Johns Hopkins University, is Principal 
Investigator.  The alternate for IMAGE is the High Energy 
Solar Spectroscopic Imager (HESSI). Professor Robert Lin, 
University of California, Berkeley, is Principal 
Investigator.

       The MIDEX program is intended to provide research 
opportunities in the areas of astrophysics and space 
physics.  Plans call for about one MIDEX mission to be 
launched per year, with development cost capped at no more 
than $70 million (FY 1994 dollars) each, excluding the costs 
of the launch vehicle and mission operations and data 
analysis.  Mission operations are expected to be completed 
within two years.  

       The space science investigations in the MIDEX program 
will use spacecraft launched on NASA's Med-Lite expendable 
launch vehicles, with launch anticipated to be late 1999 and 
2000.  The launch dates and order of launch will be 
determined in the near future, followed by confirmation for 
development of the first mission in about a year.

       The MIDEX missions are a new component of NASA's 
Explorer program, designed to complement the Small Explorer 
and the proposed University Explorer Programs, and are a 
follow-on to the more than 70 successful missions beginning 
with the launch of Explorer 1 in 1958.  The Explorer program 
was restructured in 1994 to permit more frequent, low-cost 
launch opportunities, with no more than three years from the 
design and development phase to launch.

       The Explorer Project Office at the Goddard Space 
Flight Center will manage MIDEX mission development for 
NASA's Office of Space Science, Washington, DC.  The Med-
Lite Expendable Launch Vehicle program is managed by 
Goddard's Orbital Launch Project Office.  McDonnell Douglas 
Aircraft Company will provide the Med-Lite launch vehicle.

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