April is a historic month for noteworthy missions controlled
by JSC’s flight controllers—STS-1, the first flight
of the Space Shuttle Program, and the safe return of the Apollo
13 astronauts. Few are probably aware of other significant
human spaceflight missions that flew this month. STS-37, which
launched and landed in April 1991, is just one example that
illustrates the importance of flight crew training and contingency
planning.
JSC’s Mission Operations Directorate’s (MOD) mantra
is plan, train, fly. Astronauts fly as they train, and crews
simulate on-orbit activities through realistic ground simulations.
In April 1991, the five-member crew of STS-37 encountered
a problem deploying the Gamma Ray Observatory (GRO), one of
four of NASA’s Great Observatories which also included
the Hubble Space Telescope (HST), the Chandra X-ray Observatory,
and Spitzer Space Telescope.
GRO followed the launch of the Hubble Space Telescope by one
year. Weighing just over 35,000 pounds, the GRO was—at
the time—the heaviest astrophysical payload to be deployed
by a Shuttle flight crew. STS-37 Mission Specialist Jerry
Ross likened the observatory to a “diesel locomotive.”
The satellite was big; GRO weighed more than Hubble and was
denser. Astronomers hoped that the GRO would provide answers
to gnawing questions about the origins and history of the
universe, as well as the birth, evolution, and death of stars,
and supply vital information about quasars, pulsars, and black
holes.
On the third day of the flight Mission Specialist Linda Godwin
used the Shuttle’s arm to move the GRO out of the payload
bay. The solar array panels unfolded as expected, and Crew
Commander Steve Nagel remembered telling Ross, “Well,
we’re out of the woods now.” But the GRO’s
high-gain antenna would not open, even after the crew fired
the Orbiter’s reaction control jets and shook the observatory
with the Canadarm. After several efforts to free the antenna
failed, Mission Specialists Ross and Jay Apt donned their
spacesuits to complete the first unscheduled spacewalk in
six years. Coincidentally Ross had participated in the last
Shuttle spacewalk before the Challenger accident occurred.
Ross remembered being nervous about going outside, not because
it had been six years since his last EVA but because, “I
didn’t know what was wrong with it. I didn’t know
if we could fix it or not.” Because the solar arrays
had been deployed, it was possible that the crew would not
be able to bring the observatory home. The agency needed the
satellite to work. Just a year earlier astronomers found that
the HST’s primary mirror had been ground improperly,
and NASA became a lightning rod. Astronaut Jeff Hoffman explained,
“Hubble was the butt of jokes on late-night talk shows.
It was denounced in the US Congress. There were cartoons of
the great disasters of history. Right next to the Hindenburg
was Hubble.”
Ross might have thought about the HST but fixing the GRO antenna
was his greatest concern as he entered the payload bay. He
pushed the observatory a few times, and after only a few minutes,
the antenna came loose and Ross locked the antenna into position.
“And that was a really good feeling,” he explained,
“demonstrating where the man in the loop can help a
robotic system and let it go off and do some really great
science.”
MOD and the crew had planned for a contingency spacewalk and
Ross and Apt had spent hours training in JSC’s Weightless
Environment Training Facility. Ross later recalled thinking,
“‘Yeah, they’ll never need any of these,’”
when training in the water tank, “but we ended up needing
it.” After the crew landed at Ellington Field Nagel
explained how training had paid off for the STS-37 crew. “No
matter what nook and cranny we got into, we had been there
before or in a similar place in training." When the antenna
failed to open, Nagel said, “It was just like running
a sim over again. Except with much higher stress levels.”
The GRO
went on to provide valuable scientific data to scientists.
On June 4, 2000, the observatory stopped gathering data when
it re-entered the Earth's atmosphere.
For more
information on this exciting mission, be sure to read the
interviews conducted with Ross and Nagel, available on the
JSC History Portal: http://www.jsc.nasa.gov/history/oral_histories/oral_histories.htm.
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