Testing Completed on NASA's James Webb Space Telescope Backplane
*


The backplane of NASA’s James Webb Space Telescope was mounted to a
structure for static load testing to verify it can withstand the rigors of
launch and hold the weight needed to support the telescope in space.

Image Credit: Northrop Grumman


NASA's James Webb Space Telescope has reached another development milestone
with the completion of static load testing of its primary mirror backplane
support structure (PMBSS) moving the telescope one step closer to its 2018
launch.

The PMBSS is the stable platform that holds the telescope's science
instruments and the 18 beryllium mirror-segments that form the
21-foot-diameter primary mirror nearly motionless while the telescope peers
into deep space. The primary mirror is the largest mirror in the telescope --
the one starlight will hit first.

"Static testing demonstrates the backplane has the structural integrity to
withstand the forces and vibrations of launch and is the final test prior to
starting the integration of the backplane with the rest of the telescope,"
said Lee Feinberg, NASA’s Optical Telescope Element manager at the
agency’s Goddard Space Flight Center in Greenbelt, Maryland.

The Northrop Grumman Corporation and ATK of Magna, Utah, completed the
testing before delivering the structure to Northrop Grumman's facilities in
Redondo Beach, California.

"This is the largest, most complex cryogenically stable structure humans have
ever built," said Scott Texter, Optical Telescope Element manager for
Northrop Grumman. "Completion of the static testing verifies it can hold the
weight it is designed to hold. Now the structural backbone of the observatory
is officially verified and ready for integration."

Despite its size and complexity, the PMBSS is one of the most lightweight
precision-alignment truss structures ever designed and built. When fully
deployed, it measures approximately 24 feet tall by 19.5 feet wide by more
than 11.5 feet deep, and weighs only 2,180 pounds. Once fully assembled and
populated, the PMBSS will support a mission payload and instruments that
weigh more than 7,300 pounds. With a full launch load, it will support the
equivalent of 12 times its own weight.

The PMBSS is designed to minimize changes in the shape of the telescope
caused when one side is hotter than the other. While the telescope is
operating at a range of extremely cold temperatures, between -406 and -343
degrees Fahrenheit, the backplane must not move more than 38 nanometers,
approximately 1/1,000 the diameter of a human hair.

Under contract from NASA, Northrop Grumman is the lead contractor for the
design and development of the Webb telescope's optics, sunshield and
spacecraft. ATK designed, engineered and constructed more than 10,000 parts
for the PMBSS at its facilities in Magna. They used composite parts,
lightweight graphite materials, state-of-the-art material sciences and
advanced fabrication techniques to build the structure.

The next step for the space telescope is to integrate the composite
structures with the deployment mechanisms to create the overall Optical
Telescope Element (OTE) structure. The OTE structure will then be shipped to
Goddard for integration with the mirrors. NASA and Northrop Grumman will
perform cryogenic testing of the PMBSS structure after mirror integration is
complete.

The James Webb Space Telescope is the world's next-generation space
observatory and successor to NASA's Hubble Space Telescope. Designed to be
the most powerful space telescope ever built, Webb will observe the most
distant objects in the universe, provide images of the first galaxies formed
and see unexplored planets around distant stars. The Webb telescope is a
joint project of NASA, the European Space Agency and the Canadian Space
Agency.

For more information about NASA's James Webb Space Telescope, visit:

*http://www.nasa.gov/webb