Dolores Beasley

Headquarters, Washington, DC

(Phone: 202/358-1753)

RELEASE: 00-32

NASA today announced the selection of an investigation
to be flown on the Gamma Ray Large Area Space Telescope
(GLAST) mission, planned for launch in 2005. In addition to
the flight investigation, NASA selected four
interdisciplinary scientist investigations to broaden the
scientific expertise available to the project.

GLAST will explore the most energetic and violent events
in a quest for the ultimate sources of energy in the
Universe. Objects explored will include distant galaxies
fueled by super massive black holes at the center, neutron
stars and individual black holes, remnants of stars that have
ended their life with an explosion (supernova), and many
others at the extremes of mass and energy.

Almost 300 objects have been observed to emit high-
energy gamma rays and yet less than half of these have been
identified with objects seen at other wavelengths. What
mysteries are lurking in these illusive objects? The GLAST
mission will also explore the very high-energy component of
gamma-ray bursts, still one of the greatest mysteries of

Even the dimmest of these bursts is as bright as the
brightest of the steady high-energy gamma-ray sources. The
discovery of high-energy gamma rays from these mostly low-
energy gamma-ray events constrains the models for the gamma-
ray “flash bulbs.” The major improvement in sensitivity and
precision of the observations will provide an opportunity for
new discoveries. One possibility is the search for evidence
for some of the most exotic particles predicted by physicists
to be candidates for the dark matter of the Universe.

The GLAST mission’s primary scientific objectives
require an instrument with large collecting area, imaging
capability over a very large field of view, the ability to
measure the energy of the gamma rays over an unprecedented
range of energies, and time precision to study transient
phenomena characteristic of gamma-ray sources. The
instrument must be carefully designed in order to weed out
the rare gamma rays from the much more abundant cosmic rays,
and other backgrounds such as gamma rays produced by these
cosmic rays slamming into the molecules in the Earth’s

The investigation selected by NASA is the “GLAST Large
Area Telescope Flight Investigation: A Particle-Astrophysics
Partnership to Explore the High-Energy Universe.” The
Principal Investigator is Professor Peter F. Michelson of
Stanford University. The investigation is a collaborative
international effort involving a major contribution from the
U.S. Department of Energy, and contributions from France,
Italy, Japan and Sweden. The instrument covers the energy
range from 10 million to 1 trillion electron volts. It has
about 50 times the sensitivity of any previous gamma-ray
investigation and covers a much broader energy range with
high angular precision.

NASA’s cost to develop the GLAST mission is
approximately $200 million, which includes approximately $70
million for the primary instrument.

The four interdisciplinary scientists selected and their
investigations are:

  • Stephen Thorsett of the University of California at Santa
    Cruz, “Observations of Rotation Powered Pulsars in Support
    of GLAST.” This work will provide important information
    to allow the study of gamma rays from pulsars by the
    primary instrument.

  • Professor Brenda Dingus of the University of Wisconsin,
    Madison, “GLAST: A GeV All-Sky Monitor of Transient
    Phenomena.” The purpose of this investigation is to alert
    other space- and ground-based observers of the occurrence
    of a transient phenomenon, such as a gamma-ray burst or
    gamma-ray flaring quasar, so that the object may be
    observed at many wavelengths simultaneously to obtain the
    most information possible.

  • Dr. Charles D. Dermer of the U.S. Naval Research
    Laboratory, Washington, D.C., “Exploring the Nonthermal
    Universe: Analysis and Modeling to Maximize the Scientific
    Impact of GLAST.” This investigation will provide a
    theoretical framework for the GLAST studies.

  • Dr. Martin Pohl , Ruhr University, Bochum, Germany,
    “Modeling the diffuse galactic gamma-ray emission.” The
    model provided in this work is essential to the analysis
    of GLAST data.