International Space Station Solar Arrays Fully Unfurled and Tensioned Following Spacewalk Repair
Both
International Space Station (ISS) solar array wings, built at Lockheed
Martin Space Systems in Sunnyvale, have been fully unfurled and
tensioned following a spacewalk this morning by shuttle astronauts Joe
Tanner and Carlos Noriega. The astronauts successfully repositioned
tensioning wires on the starboard solar array that was deployed on
Sunday, December 3, 2000. The wires slipped from their reels during
the initial deployment.
Procedures to effect the repair were developed by the Lockheed
Martin solar array team in consultation with NASA astronauts who
traveled here to examine identical flight hardware, which will be
delivered to the International Space Station on an upcoming shuttle
mission. The astronauts here practiced the procedure on a deployed
solar array blanket and found it satisfactory. It was further
simulated and practiced by astronauts in a massive pool, called the
Neutral Bouyancy Laboratory, at the Johnson Space Center in Houston.
“The whole team is absolutely delighted to see that the final
tensioning procedures worked just as we believed they would,” said Sid
Bourgeois, Lockheed Martin International Space Station program
manager. “We look forward to continuing work here on getting the
remaining six solar array wings ready for flight.”
The first of four pairs of massive solar arrays for the
International Space Station, were launched aboard the space shuttle
Endeavour to the International Space Station on November 30, 2000.
Subsequent pairs of arrays will be delivered on shuttle flights
currently scheduled for 2002, 2003, and 2006.
The functional testing of the solar array flight hardware has
involved several extension and retraction cycles of the 107-foot
deployment mast and solar array blankets. Additionally, all individual
solar panel circuits have been flash-tested with simulated sunlight to
verify output power. Further, a close inspection has ensured that
individual solar cells can withstand the harsh environment of space
while converting sunlight into electricity. Arrays have also been
exposed to harsh vacuum and thermal environments that simulate
conditions 200 miles above the Earth’s surface, and tested further in
an acoustic chamber to simulate the violent shaking vibrations that
accompany launch aboard the Space Shuttle. The technology has already
been flight proven in a demonstration prototype solar array
replacement flown by NASA and Space Systems on the Russian MIR space
station.
The Space Systems ISS solar arrays are the largest deployable
space structure ever built and will be by far, the most powerful
electricity-producing arrays ever put into orbit. When the Station is
completed a total of eight flexible, deployable solar array wings will
generate the reliable, continuous power for the on-orbit operation of
the ISS systems. The eight array wings were designed and built under a
$450 million contract from the Boeing-Rocketdyne Division in Canoga
Park, Calif., for delivery to the Boeing Company and NASA.
Each of the eight wings consists of a mast assembly and two solar
array blankets. Each blanket has 84 panels, of which 82 are populated
with solar cells. Each panel contains 200 solar cells. The eight
photovoltaic arrays thus accommodate a total of 262,400 solar cells.
When fully deployed in space, the active area of the eight wings, each
107 by 38-feet, will encompass an area of 32,528-sq. ft., and will
provide power to the ISS for 15 years.
In addition to the arrays, Space Systems in Sunnyvale has also
designed and built other elements for the Space Station that will be
launched on future shuttle missions. Rotary mechanical joints for the
ISS will move the solar arrays and thermal radiators into positions
relative to the Sun that will optimize their individual functions.
These mechanical joints are the largest mechanisms ever designed to
operate in a space environment.
The two Solar Alpha Rotary Joints (SARJ) are each 10.5 ft diameter
and 40 inches long. Their purpose is to maintain the solar arrays in
an optimal orientation to the Sun while the entire Space Station
orbits the Earth once every 90 minutes. Drive motors in each SARJ will
move the arrays through 360 degrees of motion at four degrees per
minute.
The Thermal Radiator Rotary Joints (TRRJ) are each five and a half
feet long and three feet in diameter. Their purpose is to maintain the
Space Station thermal radiators in an edge-on orientation to the sun
that maximizes the dissipation of heat from the radiators.
Space Systems has also produced the Trace Contaminant Control
System, an advanced air processing and filtering system that will
ensure that over 200 various trace chemical contaminants, generated
from material off-gassing and metabolic functions in the Space Station
atmosphere, remain within allowable concentration levels. It will
become an integral part of the Space Station’s Cabin Air
Revitalization Subsystem.
Lockheed Martin Space Systems in Sunnyvale, CA, is a leading
supplier of satellites and space systems to military, civil government
and commercial communications organizations around the world. These
spacecraft and systems have enhanced military and commercial
communications; provided new and timely remote-sensing information;
and furnished new data for thousands of scientists studying our planet
and the universe.
Hi- and low-resolution electronic images of an ISS solar array
blanket at Lockheed Martin Space Systems in Sunnyvale are available
at:
http://lmms.external.lmco.com/photos/civil_space/space_station/
space.stat.html
For more information about Lockheed Martin Space
Systems-Sunnyvale, see our website at http://lmms.external.lmco.com
