Three down, two to go
NASA OKs fifth spacewalk for Discovery crew
February 16, 1997
Web posted at: 10:45 a.m. EST
In this story:
JOHNSON SPACE CENTER (CNN) -- They dodged space debris flying
at them at 17,500 miles per hour, weathered a glitch in an
astronaut's spacesuit, and deftly installed equipment that
was never designed to be handled by bulky space gloves.
They even took time out to enjoy some of the most spectacular
pictures of their home planet taken from an orbiting shuttle,
and send messages to loved ones several hundred miles below.
All in a day's work for the shuttle Discovery and its spacewalking telescope repair crew -- but the trickiest task
is yet to come. In a galactic conference call early Sunday
morning, the shuttle's crew told NASA mission managers they
wanted an additional spacewalk to repair some unexpected
damage to the Hubble Space Telescope's protective insulation.
NASA was surprised by the extent of damage -- not seen during
the last repair trip to Hubble in 1993 -- to the Teflon foil
that protects the $2 billion telescope from extreme
temperatures in space. The material is ripped and cracked
badly in places, and engineers fear pieces could tear loose
and contaminate the telescope's delicate optics.
"Basically this thing is just falling apart, cracking all
over the place," astronaut Mark Lee told mission control
while inspecting the damage on spacewalk No. 3 Saturday
night. Lee tried to tape a crack, but the adhesive didn't
"It barely sticks," he said. "It doesn't do anything."
Lee and his spacewalking partner Steve Smith will make Discovery's fifth spacewalk early
Tuesday morning, and will try a complicated series of repairs
to prevent the cracked insulation from flaking off the
One procedure calls for the astronauts to install a wire mesh
around two of the telescope's equipment bays, and another
involves using long poles to rig an insulation blanket around
a larger part of the telescope.
Discovery's crew will manufacture the repair materials from
supplies aboard the shuttle.
Saturday began with an evasive action procedure of sorts -- a
few hours after Commander Ken Bowersox had nudged the shuttle
and its telescope cargo into an orbit two miles further from
the incessant tug of Earth's atmosphere, NASA told him to
boost it another half mile up.
The problem was an 8-inch square piece of an exploded rocket
bearing down on the shuttle at 17,500 miles per hour. The
debris, part of a Pegasus rocket launched in 1994 with a
military research satellite aboard, was expected to pass
within a half-mile of the orbiting shuttle and telescope, but
mission managers wanted no chance of a collision.
Discovery will lift the Hubble another 2 miles before the end
of this mission, settling the telescope into an orbit 375
miles away from the surface of the planet.
Saturday night's spacewalk, the third of a planned four, was
delayed because of a glitch in the computer of Lee's $10.4
million spacesuit, but a reboot apparently solved the
problem, and the astronauts -- anxious to get to work --
stepped into Discovery's open cargo bay.
Lee and Smith completed three
upgrade tasks to the telescope, including the challenging
replacement of a data interface unit that allows the various
parts of Hubble to "talk" with one another.
Astronaut Story Musgrave, who orchestrated
the first Hubble repair three years ago, describes
wearing and moving around in a spacesuit
The job was made difficult by 18 separate cable connections
needed to complete the installation, handled expertly by Lee
despite the bulky spacesuit gloves.
"Great hands, Mark," mission control's Jeff Hoffman told the
astronaut when he finished.
(220K/20 sec. AIFF or WAV sound)
Lee and Smith also swapped a 1970s vintage analog data
recorder with a new digital model, and replaced a wheel
mechanism used to aim the telescope. The astronauts had to
use a little extra power from an electric wrench when bolts
holding the wheel assembly to the telescope refused to budge.
(653K/15 sec. Small frame QuickTime movie)
(1.6M/15 sec. Large frame QuickTime movie)
Lee also took a moment to send a long distance greeting to
his wife, astronaut Jan Davis.
(87K/8 sec. AIFF or WAV sound)
Joe Tanner, who took his first steps in space Friday night,
and Greg Harbaugh are set to take the crew's fourth repair
trip to Hubble Sunday night. The two, who easily replaced a
guidance sensor the size of a baby grand piano during their
first walk, will replace two more old telescope components,
finishing Discovery's original repair mission.
Tanner and Harbaugh will also begin the insulation repair
Mission control added the fifth walk after Bowersox said he
preferred that the scheduled spacewalks take place as
planned. Managers considered delaying the fourth walk by a
day, but settled on the additional time in space.
The crew was to redeploy Hubble on Monday, but that will be
delayed until Tuesday. Discovery is still on schedule to
return to Earth Friday.
Correspondent John Holliman and Reuters contributed to this report.
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