Palo Alto, Calif. – August 12, 2010 — On 13 July 2010 Space Systems/Loral (SS/L) completed delivery of the last of three sophisticated Ka-band Microwave Assemblies to the Jet Propulsion Laboratory for NASA’s Gravity Recovery and Interior Laboratory (GRAIL) lunar mission. This last unit will serve as a backup to two units previously delivered that are being integrated onto the two GRAIL spacecraft, which are scheduled to launch in September 2011. The design of the precision equipment was derived from the similar hardware that SS/L provided for the highly successful Gravity Recovery and Climate Experiment (GRACE) satellites which have been orbiting the Earth since 2002.
The microwave assemblies, part of JPL’s Ka-band ranging payload, will play a crucial role in allowing the two GRAIL spacecraft to map the moon’s gravity field in great detail, which will allow scientists to derive information about its internal structure from crust to core. As the two spacecraft orbit the moon about 200 kilometers (125 miles) apart, their microwave assemblies continuously communicate with each other by transmitting and receiving ranging signals. They then process those signals to enable determination of the separation distance with about 0.1 millimeter precision, the width of a human hair. Tiny changes in this distance caused by local variations in the moon’s gravity can thus be measured, allowing the gravity variations to be recovered from the data and analyzed.
“SS/L values the opportunity to support U.S. Government missions and to contribute to a better understanding of the universe,” said John Celli, president of Space Systems/Loral. “The capabilities in communications technology, power, and propulsion systems that we have developed over many years of work with commercial spacecraft systems are now helping to enable operational space missions for NASA and other government agencies.”
SS/L has a long history of providing technologies
for NASA’s missions, including the high-gain antennas for Voyager 1 and
2, which are still operating outside the solar system, batteries and high-power
electronics for the International Space Station, ranging equipment and mission
support for GRACE, a high-gain Ka-Band antenna on the Solar Dynamics Observatory,
and the propulsion system for the Lunar Atmosphere Dust Environment Explorer,
which is currently being developed.