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March
17, 2009: Talk about a big construction project...
Astronauts
are about to add a pair of 115-foot-long solar wings to the
International Space Station. The station's solar arrays are
the largest deployable space assemblies ever built and the
most powerful electricity producing arrays in orbit. Each
wing weighs 2,400 pounds, uses 32,800 individual solar cells,
and adds about 4000 sq. feet of light-collecting surface area
to the ISS. When the work is done, the space station will
have enough usable electricity to light up 42 houses.
Amateur
astronomers can see it happen with their own eyes.
The
International Space Station is so large, its outlines are
visible in backyard telescopes. Here, for instance, is the
view through a 10-inch Newtonian reflector:
"In
December, the space station made a nice pass over my backyard
observatory," says photographer Ralf Vandebergh of the
Netherlands. "It was about as bright as Venus—you couldn't
miss it." He hand-guided his telescope to keep the ISS
centered in the field of view and captured the image using
a digital video camera attached to the eyepiece.
Vandebergh's
snapshot shows six previously-installed solar wings--four
port and two starboard. The new arrays will go on the starboard
side, rounding out the eight-wing set.
Once
complete, the station's power system will generate between
80 and 120 kilowatts of usable electric power. Some of that
electricity is
needed to operate basic space station systems, but once that
is figured in, the addition of the new arrays will nearly
double the amount of power available to perform scientific
experiments--from 15 kilowatts to 30 kilowatts. The extra
power will also double the number of full-time crew the station
can support from three to six.
Above:
The ISS fully-powered by all eight solar wings,
an artist's concept. Credit: NASA [larger
image] [press
kit]
The
new wings are en route to the ISS onboard space shuttle Discovery,
which left Earth on Sunday, March 15, in a beautiful twilight
launch from Kennedy Space Center. In addition to the solar
arrays, Discovery is also bringing a 31,000-lb truss segment
to complete the station's massive backbone and a thermal radiator
to shed heat from newly-powered electronics. If all goes according
to plan, the arrays, truss segment, and radiator will be installed
during a spacewalk on mission Day 5 (March 19); the arrays
will be unfurled accordian-style on mission Day 8 (March 22).
The
timing of these events favors sky watchers in the USA and
Canada. The ISS (with Discovery docked) is due to fly over
many North America towns and cities after sunset in mid- to
late-March. Shining brighter than any star, the ISS-Discovery
combo takes a leisurely 5 minutes to glide across the sky--plenty
of time to point a telescope, take a picture, or just soak
up some of the station's growing luminosity.
Check
NASA's ISS tracker for flyby times: link.
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Author: Dr.
Tony Phillips | Credit: Science@NASA
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