NASA’s GLAST Mission One Step Closer to Launch
NASA's next major space observatory, the Gamma-ray Large Area Space Telescope
(GLAST), is one step closer to unveiling the mysteries of the high-energy
universe. Almost all the components have been assembled onto the spacecraft,
which will undergo a review this week before environmental testing begins at
the primary contractor, General Dynamics Advanced Information Systems in
Image left: This is a photo of the GLAST Observatory at General Dynamics, after the integration of the GLAST Burst Monitor instrument. Credit: NASA and General Dynamics
GLAST will study the universe's most extreme objects, observing physical
processes far beyond the capabilities of earthbound laboratories. GLAST's main
instrument, the Large Area Telescope (LAT), operates like a particle detector
rather than a conventional telescope. It is 30 times more sensitive (and even
more at higher energies) than the best previous missions, enabling it to detect
thousands of new gamma-ray sources while extending our knowledge of previously
unidentified sources. For example, it will study how some black holes
accelerate matter to near light speed and perhaps even reveal the nature of
dark matter. The other instrument, the GLAST Burst Monitor (GBM), will detect
roughly 200 gamma-ray bursts per year. Together with the LAT, the GBM will
enable GLAST to make gamma-ray burst observations spanning a factor of a
million in energy.
"These two instruments and the spacecraft have now been integrated and are
working together as a single observatory," says GLAST project manager Kevin
Grady of NASA's Goddard Space Flight Center, Greenbelt, Md.
"The observatory is getting ready for the final testing in the simulated
environment of space, so that any problems can be fixed to ensure that it will
work when we launch it," adds Kathleen Turner, the LAT program manager at the
United States Department of Energy, in Germantown, Md. The Department of Energy
helped build the LAT in collaboration with other institutions in the United
States, France, Italy, Japan, and Sweden. NASA's Marshall Space Flight Center,
Huntsville, Ala., built the GBM in collaboration with institutes in Germany.
Image right: This is rendering of the GLAST spacecraft in orbit above the Earth by General Dynamics. Credit: General Dynamics
On April 11 and 12, 2007, an independent committee of scientists and engineers
commissioned by NASA will conduct a Pre-Environmental Review (PER). This
committee, chaired by Mark Goans of NASA Goddard, has been monitoring the
development of the mission over the past four years. This review is expected to
last two days, and will make sure that all technical problems and anomalies have
been resolved, and that the 4.7-ton spacecraft is ready to be "shake and baked."
Following the PER, environmental testing will begin. Each individual subsystem
has already passed its own round of environmental testing, but this new set of
procedures will make sure that the integrated observatory can survive the
rigors of launch and the harsh conditions of space.
In the first test, called the Electro-Magnetic Interference test, operators will
bombard the spacecraft with electromagnetic radiation to ensure that certain
systems do not produce signals that interfere with other systems. As project
scientist Steve Ritz of NASA Goddard explains, "If electrical noise from your
beating heart causes a problem with your brain, you'd want to know about it."
Next, GLAST will undergo mechanical tests, which involves exposure to
vibrations, shocks, and acoustic waves. The vibration test will make certain
the entire spacecraft can survive the shaking of a Delta II Heavy rocket
launch. With the tall spacecraft being shaken from its base, some of the
appendages will be exposed to accelerations up to 15 times the force of Earth's
gravity. The shock test ensures it can survive separation from the booster. The
acoustic test examines if the craft can survive the terrific roar of a Delta II
launch. Engineers will bombard the spacecraft with up to about 144 decibels of
noise, louder than being in close proximity to a jet aircraft.
Finally, the team will subject GLAST to the Thermal-Vacuum test, which checks
the spacecraft's ability to withstand the vacuum of space and the extreme
temperature swings it will experience as it goes in and out of sunlight during
each orbit. This procedure will last about six weeks, the longest of all the
In mid-October, GLAST is scheduled to be flown to Cape Canaveral Air Force
Station, Fla., on a C5 airplane. The spacecraft is scheduled to be launched
into a low-Earth circular orbit no earlier than Dec. 14, 2007.
NASA's GLAST mission is an astrophysics and particle physics partnership,
developed in collaboration with the U.S. Department of Energy, along with
important contributions from academic institutions and partners in France,
Germany, Italy, Japan, Sweden, and the United States.
+ GLAST mission site
Goddard Space Flight Center