Press Release

Lockheed Martin-Built NASA Gravity Probe B Spacecraft Readied for Launch

By SpaceRef Editor
April 4, 2004
Filed under , ,
Lockheed Martin-Built NASA Gravity Probe B Spacecraft Readied for Launch

NASA’s Gravity Probe
B (GP-B) space vehicle, built, integrated and tested by Lockheed Martin, is undergoing final preparations for launch, scheduled for
April 17, 2004, from Vandenberg Air Force Base, Calif. Stanford University is
the GP-B prime contractor. NASA Marshall Space Flight Center in Huntsville,
Ala. manages the program.

During its 16-month mission, GP-B will attempt to verify two subtle
physical effects predicted by Albert Einstein’s General Theory of Relativity,
which provides the foundations for understanding the large-scale structure of
the Universe.

“We’re now counting the days until launch and are enormously proud of the
close collaboration with our Stanford and NASA colleagues that has brought us
to this exciting point in the GP-B program,” said Jim Crocker, vice president,
civil space, Lockheed Martin. “We look forward to the mission ahead and the
data that will increase our understanding of the fundamental structure of the

“Developing GP-B has been a supreme challenge requiring the skillful
integration of an extraordinary range of new technologies,” said Professor
Francis Everitt of Stanford University, and the GP-B principal investigator.
“It is hard to see how it could have been done without the kind of unique
long-term collaboration that we have had between Stanford, Lockheed Martin and
NASA. It is wonderful to be ready for launch.”

The GP-B space vehicle comprises the spacecraft, built by Lockheed Martin,
and its payload. The payload is made up of the dewar, the key structural
component around which the GP-B space vehicle was built, and the flight probe,
a nine-foot-long cigar-shaped vacuum chamber. Both elements were built at the
Lockheed Martin Advanced Technology Center, Palo Alto. Inside the flight probe
is the very delicate and precise Science Instrument Assembly, built by
Stanford University.

The GP-B experiment must be conducted in an extremely stable environment,
free from all outside forces. To accommodate, Lockheed Martin designed an
enclosure within the spacecraft in which the Science Instrument Assembly can
operate at a temperature near absolute zero.

When Gravity Probe B is launched into a 400-mile-high polar orbit, the
instrument apparatus will measure tiny changes in spin axis orientation of the
four ultra-precise gyroscopes contained within. The gyros will provide a
nearly perfect space-time reference system. Additionally, they will measure
two predicted effects of Einstein’s theory: whether and how space and time
are warped by the presence of Earth, and whether and how the rotating Earth
drags space-time around with it.

This will be by far the most accurate test of any of the predicted effects
of Einstein’s theory.

Small as the two effects measured by Gravity Probe B are, their
measurement will provide an extremely important advance by testing previously
unproven predictions of Einstein’s theory. They may provide critical clues to
modern attempts to unify the four fundamental forces observed in Nature:
electromagnetism, gravity, and the so-called strong and weak interactions that
govern the behavior of atomic nuclei.

“Gravity Probe B is one of the few space missions NASA has conducted with
relevance to fundamental physics,” stated a review of GP-B undertaken in 1995
by the Space Studies Board of the National Research Council. “If successful,
it would assuredly join the ranks of the classical experiments of physics. By
the same token, a confirmed result in disagreement with General Relativity
would be revolutionary.”

Headquartered in Bethesda, Md., Lockheed Martin employs about 130,000
people worldwide and is principally engaged in the research, design,
development, manufacture and integration of advanced technology systems,
products and services. The corporation reported 2003 sales of $31.8 billion.

Media Contact: Buddy Nelson (510) 797-0349, E-mail:

For more information about Lockheed Martin Space Systems, see our web site

SpaceRef staff editor.