October 16, 1997
The two Small Explorer missions and the alternate will be launched aboard a U.S. expendable launch vehicle to be selected under the Small Expendable Launch Vehicles Services contract, yet to be awarded.
The first mission, High Energy Solar Spectroscopic Imager (HESSI), will observe the Sun to study particle acceleration and energy release in solar flares. The Principal Investigator is Dr. Robert P. Lin, University of California, Berkeley. The science team includes scientists from the U.S., Switzerland, France, Japan, the United Kingdom and The Netherlands. HESSI, which is scheduled for launch in 2000 aboard an Orbital Sciences Corp. Pegasus rocket, will cost $67 million including launch.
The second mission, called Galaxy Eolution Explorer (GALEX), will use an ultraviolet telescope during its two-year mission to explore the origin and evolution of galaxies and the origins of stars and heavy elements. The Principal Investigator is Dr. Christopher Martin, California Institute of Technology, Pasadena. GALEX will detect millions of galaxies out to a distance of billions of light years and also will conduct an all-sky ultraviolet survey. The mission will cost $65 million including launch, and will be launched aboard a Pegasus rocket in 2001.
Selected as an alternate mission in case one of the primary missions does not progress to launch, the Broadband Observatory for Localization of Transients (BOLT) mission will pinpoint locations of gamma ray bursters, the most energetic objects known in the universe. Bursters emit in a few seconds as much energy as an entire galaxy emits in a year. BOLT, which will cost $66 million including launch, will detect the positions of gamma ray bursters and immediately radio this information to telescopes on the ground, enabling visual identification of these quickly-disappearing events. The Principal Investigator of the Broadband Observatory for Localization of Transients (BOLT) mission is Dr. Charles Hailey of Columbia University, New York City.
The missions were selected under the Small Explorer (SMEX) program. This program provides frequent flight opportunities for highly focused and relatively inexpensive science missions that typically weigh around 500 pounds or less.
Selected as a mission of opportunity, the $15 million Two Wide-Angle Neutral-Atom Spectrometers (TWINS) mission will be launched in 2001 or 2003 aboard a currently undesignated U.S. Government mission. TWINS will provide stereo imaging of the Earth's magnetosphere, the region surrounding the planet controlled by its magnetic field and containing the Van Allen radiation belts and other energetic charged particles. TWINS will enable three- dimensional global visualization of this region, which will lead to greatly enhanced understanding of the connections between different regions of the magnetosphere and their relation to the solar wind. Dr. David McComas, Los Alamos National Laboratory, NM, is the Principal Investigator.
The Small Explorer Program is managed by NASA's Goddard Space Flight Center, Greenbelt, MD, for the Office of Space Science, Washington, DC.