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COUNTDOWN: The one-of-a-kind
probe could launch in April.
Courtesy Lockheed Martin
Space Systems |
It came sooo close to liftoff.
More than 40 years in the planning, Gravity Probe B,
a sophisticated experiment to test Einstein’s
theory of general relativity (Farm
Report, November/December 2001), was ready and waiting
in a clean room at Vandenberg Air Force Base in central
California in early December. NASA and Stanford engineers
were all set to roll the spacecraft out to the launchpad,
hoist it onto the Delta 2 rocket, close up the faring
like a neat clamshell and start the countdown.
But the engineers had been hearing inexplicable noise—make
that “bias”—on an external SQUID (superconducting
quantum interference device). Rather than risk compromising
the efficacy of the one-of-a-kind spacecraft, decision
makers huddled and made the hard call to stand down
and check out the problem. Like auto mechanics searching
for an oil leak, Stanford workers slid underneath the
spacecraft and unbolted the big black box that is the
experimental control unit.
Physics research professor and long-distance runner
Francis Everitt, who has guided the $650 million experiment
since 1962 and weathered previous setbacks and Congressional
threats to terminate funding, compared the latest interruption
to the end of a marathon race. You get to a place where
you can see the finish line, Everitt told colleagues,
and while you’re making your final push, the judges
pick up the finish line and move it five miles down
the road.
The experimental control unit has now been replaced,
and Gravity Probe B is once again good to go, scheduled
for launch sometime between mid-April and the end of
June. A website will be updated with the latest launch details every Friday: einstein.stanford.edu.
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