A newly released
photo from a German radar satellite has revealed the International Space
Station (ISS) like never before, depicting the massive orbiting laboratory as
an eerie apparition glowing in blue.
The photo, taken by
Germany's TerraSAR-X satellite, shows
the space station from above as an incomplete space outpost. It was taken
on March 13, 2008, but Germany's space agency released the unique view this
month.
"The orbital
configuration that provides the opportunity for a picture like this occurs
between 10 and 11 times each month, but there is absolutely no risk of a
collision because TerraSAR-X and the ISS are on very different orbits,"
officials with the German Aerospace Center (DLR) said in an update.
The TerraSAR-X view
reveals the $100 billion space
station as it appeared two years ago, when the outpost did not yet have its
final set of huge, wing-like solar arrays. As a result, the station looks
off-kilter, with one set of solar arrays on the left side and two on the right.
Since 2008,
astronauts have delivered the final set of solar wings, as well as new modules
and laboratories. The station is currently home to five astronauts – two
Americans, two Russians and one Japanese astronaut.
TerraSAR-X is an
Earth-observation satellite that travels around the planet in a polar orbit,
and records X-band radar data about the planet using its active antenna.
TerraSAR-X is not affected by weather conditions, cloud cover or the absence of
daylight.
The station image
taken by TerraSAR-X was recorded on March 13, 2008 during a brief, three-second
flyby using the satellite's synthetic aperture radar.
A
few hours before this image was taken, NASA's space shuttle Endeavour arrived
at the space station carrying a storage room for the station's Japanese Kibo
laboratory during the STS-123 mission. At the time, the Russian and
American modules, as well as the European "Columbus" laboratory, all
had been installed. Six of the station's eight solar panels had already been
placed.
The satellite whizzed
past the space station as it flew 122 miles (195 km) over the orbiting
laboratory. The station typically flies about 220 miles (354 km) above Earth.
TerraSAR-X and the station passed each other at a relative speed of about
22,000 mph (34,540 kph).
This ghostly image
does not show light reflecting from the surfaces of the space station like an
optical photograph.
In fact, radar does
not detect surfaces, which deflect the radar beam, at all. Rather, edges and
corners reflect the microwave signals transmitted by the radar more strongly.
Thus, the solar power generators of the ISS and the radiator panels used to
dissipate excess heat appear as dark areas. The ISS, then, is drawn from bright
spots which clearly outline the space station. The central element of the ISS,
on which modules are docked, possesses a lattice grid structure featuring
multiple surfaces to reflect the radar beam, so it stands out clearly.
This image resolves
objects of about one meter, with separation of at least 3 feet (1 meter).
Structures more closely spaced are merged into a single block. Items smaller
than one meter can be identified, if they are very reflective. However, they
will be enlarged to at least 1 meter in the image.
Today, the space
station's exterior structure is as long as an American football field and it
has about the same internal living space as a Boeing 747 jumbo jet.
In February, NASA's
shuttle Endeavour visited the space station to deliver a new room called
Tranquility and an observation deck that provides stunning views
of Earth from space. They left the orbiting laboratory about 98 percent
complete after 11 years of construction.
NASA's next mission
to the space station is slated to launch April 5 aboard the shuttle Discovery,
which will haul a cargo pod filled with new science gear and other equipment to
stock up the space station. A new Russian room is due to launch in May on the
shuttle Atlantis, with a $1 billion space experiment to follow in July on
Endeavour.
The final flight in
September will deliver more supplies and leave a storage room permanently
attached to the space station. NASA currently plans to retire the shuttle fleet
after just four more missions to complete
the space station.
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