NASA’S X-RAY TIMING EXPLORER SHIPPED TO LAUNCH SITE
Don Savage, Jim Sahli
The X-ray Timing Explorer (XTE) spacecraft is being
shipped to its launch site in Florida today from the Goddard
Space Flight Center in Greenbelt, MD. When it is launched
this August, XTE will gather data about X-ray emitting star
systems and other sources within the Milky Way galaxy and
beyond.
The satellite has completed its environmental testing
program and is being flown to the Cape Canaveral Air Station
launch site by an Air Force C-5 aircraft from Andrews AFB in
Maryland.
The 6,700-pound (3,045-kilogram) spacecraft currently
scheduled for launch August 31 aboard a Delta II Expendable
Launch Vehicle was integrated and tested at Goddard, which is
managing this mission. After several months of preparing the
X-ray observatory for flight in Florida, XTE will be launched
into a 360-mile (580-km) low-Earth orbit.
Spacecraft engineers and scientists from the three XTE
instrument teams gathered at Goddard this month for a final
rehearsal of mission operation activities before shipping the
spacecraft to the launch site. The instruments are being
provided by science and engineering teams at Goddard, the
University of California at San Diego, and the Massachusetts
Institute of Technology.
“It is great to see the whole spacecraft shipped to the
Cape after several years of pulling the different pieces
together,” said Dale Schulz, Project Manager for the XTE
mission in Goddard’s Flight Projects Directorate.
“XTE will carry three instruments for studies of the
variable X-ray sky: the Proportional Counter Array, the High
Energy X-ray Timing Experiment and the All Sky Monitor. A
two-year prime mission is scheduled, with extended operations
for four to five years possible,” said Dr. Jean Swank, project
scientist for the XTE at Goddard.
“XTE will carry out in-depth timing and spectral
studies of X-ray sources across a wide range of X-ray energies
to answer questions about collapsed compact stars — white
dwarfs, neutron stars, and black holes, and about very large
black holes in quasars and galaxies,” she said.
“The X-ray sky is highly variable. Suddenly an obscure
faint star lost in the crowd can become the brightest X-ray
source in the sky, revealing where a black hole is likely to
be found. Neutron stars emit beams of X-rays that sweep
across our view as the stars rotate. XTE is tuned to watch
the action and study it. These data will allow us to study
the strongest gravitational and magnetic fields that we think
exist in the universe,” she said.
Observations of specific targets to be studied with XTE
will be proposed by scientists from the United States and
abroad. Selected observations will be implemented by
scientists at the XTE Science Operations Center (SOC) at
Goddard. XTE will transmit data via two of NASA’s Tracking
and Data Relay Satellites, which will then relay the data to a
ground station in White Sands, NM, and then to the SOC.
Scientists can monitor observations from the SOC. Data are
sent to their home institutions for detailed analysis.
Goddard manages the X-ray Timing Explorer for the
Office of Space Science at NASA Headquarters in Washington,
DC.