HOUSTON - NASA mission managers today
announced a risky new plan to fix an injured solar wing at a distant end of the
International Space Station (ISS).
The solar
wing, which tore Wednesday during its remote deployment, is generating plenty
of power, but engineers fear that it is structurally unstable. NASA officials
decided to make the repair their top priority after scrapping previous plans to
inspect worrisome
gears at the other end of the orbital laboratory.
To remedy
the problem, spacewalker Scott Parazynski will ride out to the damaged area on
the end on the space shuttle's 50-foot (15-meter) extension boom, which the
space station's Canadarm2 will grapple - a first in spaceflight history.
"Right
now the crew on orbit is kind of wrapping their brains up around this new
option that we've thrown out there," said Derek Hassmann, lead ISS flight
director for the STS-120 space shuttle mission.
"We're going to work hard to get there and be ready on Friday."
Hassmann
said the spacewalk - the fourth of up to five planned for the mission - could
be pushed back to Saturday morning if teams on the ground need more time to
devise a specific plan of action. Whatever the case, space shuttle and station
crews said they are ready
to help.
Damage
control
Suffredini
said the fix will "detour" physical stress around the 2.5-foot
(0.76-meter) tear in the solar wing. The wing itself is one of two anchored
to a mast projecting off of the Port 6 (P6) solar array truss segment.
"The
objective is to carry the load around the tear," Suffredini said.
Parazynski,
who has six spacewalks under his belt, will thread homemade "cufflinks"
through holes that helped secure the arrays during launch seven years ago.
Astronauts on board the space station will fashion the straps out of wire
before the 6.5-hour spacewalk.
"There
could be as many as seven cufflinks all the way across the wing,"
Suffredini said, as there are seven hole-containing lines running the 115-foot
(35-meter) length of the solar wing.
Astronaut
Doug Wheelock will venture outside of the space station to monitor Parazynski's
handiwork, as well as help reel in a guide wire that snagged and ultimately
caused the tear. Parazynski will clip the troublesome wire while on fully
extended on the end of the boom-arm combination.
Delicate
situation
Complicating
the spacewalk is the delicateness of the solar array material - about as thick
as a vinyl shower curtain but stronger and sturdier - and the dangerous amount
of electricity running through it.
"There's
a lot of power running through this whole thing," Suffredini said.
"So part of our challenge is we don't want to touch the array, we don't
want to bump into the array."
Suffredini
said all the tools used by Parazynski to make the fix will be coated in
non-conductive Kapton tape. Astronaut Dan Tani, who will operate the space
station's robotic arm during the spacewalk, will keep Parazynski at a safe
distance from the orange-and-black solar wing.
"We
want to everything at arm's reach if we can," Suffredini said, noting that
Parazynski will bring something other than 39 hours and 46 minutes of
spacewalking experience to the table. "One of the advantages of Scott is
that he has long arms. It just gives you a little more reach."
NASA
expects the space shuttle and Discovery and its seven-astronaut crew to return
to Earth on Nov. 7, but mission managers said there are enough supplies on
board to last another two days docked with the space station, should they need
the time. The shuttle's original 14-day mission has already been extended once
to 15 days.
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