Gravity Probe B
Also named GP-B
Worth $750 million. Scientists first proposed what became Gravity Probe B in
1959. Over the decades, it weathered more than a half-dozen attempts at
cancellation amid concerns over cost overruns and technical hurdles.
Attempted to verify two subtle physical effects predicted by Albert Einstein's
General Theory of Relativity. It actually managed to prove that space and time
bend!
The first result from the Gravity Probe B satellite confirms a prediction of
Einstein's general theory of relativity to a precision of better than 1%.
Status: confirmed 2 predictions of Albert Einstein's general theory of
relativity.
http://einstein.stanford.edu/
http://www.gravityprobeb.com/
sat-index articles
Prime
contractor
|
Stanford
University
|
Platform
|
|
Mass
at launch
|
3145
kg
|
Mass
in orbit
|
|
Dimension
|
|
Solar
array
|
|
Stabilization
|
|
DC
power
|
|
Design
lifetime
|
16
months
|
Integrated and tested by Lockheed Martin.
The payload is made of two parts: the dewar (structural component) and the
flight probe (2.7 m long vacuum chamber) which contains the Science Instrument
Assembly.
When the Gravity Probe B experiment begins, the instrument apparatus will
measure minute changes in spin axis orientation of four ultra-precise
gyroscopes contained within. The gyros will be so free of disturbances that
they will provide a nearly perfect space-time reference system. 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.
Carries 4 gyroscopes kept at 1.8 Kelvin by a liquid helium dewar, laser
retroreflectors and 2 GPS receivers for orbit determination, a drag
compensation system, and a 14 cm aperture quartz telescope. Will lock on its
guide star IP Pegasi (precision of 1/100,000th of a degree).
Downlinks via
TDRS
and specific earth stations.