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Walking with Discovery
Walk alongside space shuttle Discovery as the motorized transporter hauls the ship a quarter-mile from the Orbiter Processing Facility to the Vehicle Assembly Building. (3min 21sec QuickTime file)
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Discovery leaves hangar
This time-lapse movie captured from an overhead camera shows space shuttle Discovery's middle-of-the-night departure from its processing hangar at Kennedy Space Center to the roll to the Vehicle Assembly Building. (4min 30sec file)
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Rolling into VAB
Discovery arrives in the Vehicle Assembly Building as viewed in this time-lapse movie. The shuttle will be mated to the redesigned external fuel tank and twin solid rocket boosters in the VAB before rolling to the launch pad for the first post-Columbia mission. (5min 00sec file)
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Nanosat toss overboard
A foot-long Russian nanosatellite is flung overboard by the spacewalking International Space Station Expedition 10 crew. Station cameras watched the hand-launched deployment and the nanosat as it floated away. (4min 52sec file)
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Spacewalk highlights
Highlights of the second spacewalk of the International Space Station's Expedition 10 crew is compiled into this movie. The crew completed external outfitting of gear that will guide European cargo ships to the outpost during dockings starting in 2006. (5min 00sec file)
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ISS EVA preview
Mission managers preview the next spacewalk by the Expedition 10 crew aboard the International Space Station, which will install external equipment on the Russian segment and hand-launch a tiny nanosatellite. (37min 00sec file)

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Shuttle history: STS-49
This video retrospective remembers the first flight of space shuttle Endeavour. The maiden voyage set sail in May 1992 to rescue the Intelsat 603 communications spacecraft, which had been stranded in a useless orbit. Spacewalkers attached a rocket booster to the satellite for the critical boost to the correct altitude.
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Shuttle history: STS-109
This video retrospective remembers the 2002 mission of Columbia that made a long distance service call to the Hubble Space Telescope, giving the observatory a new power system and extending its scientific reach into the Universe. Astronauts performed five highly successful spacewalks during the mission.
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New image of Earth, seen through gamma-ray eyes
Posted: March 30, 2005

A NASA-funded scientist has produced a new type of picture of the Earth from space, which complements the familiar image of our "blue marble". This new picture is the first detailed image of our planet radiating gamma rays, a type of light that is millions to billions of times more energetic than visible light.

Here we see a false-color image of the Earth in three gamma-ray energy bands, analogous to the colors red (lower energy), green (mid energy) and blue (higher energy) in the visible spectrum. For the complete caption and print-resolution versions, see the links at the end of this article. Credit: NASA/CGRO/EGRET/ Dirk Petry
The image portrays how the Earth is constantly bombarded by particles from space. These particles, called cosmic rays, hit our atmosphere and produce the gamma-ray light high above the Earth. The atmosphere blocks harmful cosmic rays and other high-energy radiation from reaching us on the Earth's surface.

"If our eyes could see high-energy gamma rays, this is what the Earth would look like from space," said Dr. Dirk Petry of NASA Goddard Space Flight Center in Greenbelt, Md. "Other planets -- most famously, Jupiter -- have a gamma-ray glow, but they are too far away from us to image in any detail."

Petry assembled this image from seven years of data from NASA's Compton Gamma-Ray Observatory, which was active from 1991 to 2000. The Compton Observatory orbited the Earth at an average altitude of about 260 miles (420 km). From this distance, the Earth appears as a huge disk with an angular diameter of 140 degrees. The long exposure and close distance enabled Petry to produce a gamma-ray image of surprisingly high detail. "This is essentially a seven-year exposure," Petry said.

The gamma rays produced in the Earth's atmosphere were detected by Compton's EGRET instrument, short for Energetic Gamma-Ray Experiment Telescope. In fact, 60 percent of the gamma rays detected by EGRET were from Earth and not deep space. Although it makes a pretty image, local gamma-ray production interferes with observations of distant gamma-ray sources, such as black holes, pulsars, and supernova remnants.

Petry created this gamma-ray Earth image to better understand the impact of "local" cosmic-ray and gamma-ray interactions on an upcoming NASA mission called GLAST, the Gamma-ray Large Area Space Telescope. GLAST is planned for launch in 2007. Its main instrument, the Large Area Telescope, is essentially EGRET's successor.

In 1972 and 1973 the NASA satellite SAS-II captured the first resolved image of the Earth in gamma rays, but the detectors had less exposure time (a few months) and worse energy resolution

Petry, a member of the GLAST team at NASA Goddard, is an assistant research professor at the Joint Center for Astrophysics of the University of Maryland, Baltimore Country.