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Delta 4-Heavy launch
The Boeing Delta 4-Heavy rocket is launched from Cape Canaveral on its demonstration flight. (4min 35sec file)
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Onboard the Heavy
An onboard camera records the launch of Boeing's Delta 4-Heavy rocket from liftoff through separation of the outer boosters. (4min 40sec file)
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Launch of Atlas 5
The Lockheed Martin Atlas 5 rocket launches at 7:07 a.m. EST from Cape Canaveral carrying the AMERICOM 16 communications spacecraft. (6min 22sec file)
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Press site view
The sunrise launch of Atlas 5 is shown in this view from the Kennedy Space Center press site at Complex 39. (QuickTime file)
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Rocket rollout
Riding on its mobile launching platform, the Atlas 5 rocket is rolled from its assembly building to the launch pad at Complex 41 just hours before the scheduled liftoff time carrying AMC 16. (4min 41sec file)
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Deep Impact overview
Rick Grammier, NASA's Deep Impact project manager from the Jet Propulsion Laboratory, provides a detailed overview of the spacecraft and its mission. (4min 54sec file)
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Science preview
Deep Impact principal investigator Michael A'Hearn explains how the comet collision will occur and what scientists hope to learn. (7min 11sec file)
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Pre-flight news briefing
The pre-flight news conference is held at NASA Headquarters on December 14 to preview the Deep Impact mission to intercept a comet and blast a projectile into it. (54min 19sec file)
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Stars of wonder, stars of infrared and X-ray light
Posted: December 29, 2004

This montage shows three clusters of bright, young stars in X-ray (blue) and infrared (green) light that lie in the direction of the center of the Galaxy. Like many stars in the disk of the Galaxy, they are difficult, if not impossible, to see with an optical telescope because of interstellar dust that blocks the visible light.

Credit: X-ray: NASA/CXC/Northwestern U./C.Law & F.Yusef-Zadeh; Infrared: 2MASS/UMass/IPAC-Caltech/NASA/NSF
Infrared and X-ray data provide evidence for a large amount of dust and gas along the line of sight to the cluster, DB01-42. Invisible to optical telescopes, it is located near the Galactic Center, about 25,000 light years from Earth. Most of the stars in the image produce infrared radiation from their surfaces which have temperatures of several thousand degrees Celsius. The X-radiation from the two bright X-ray sources near the center of the cluster requires gas with temperatures of millions of degrees.

Such extremely hot gas may be due to the collision of stellar winds from two closely orbiting stars. The two bright X-ray sources in the image are likely close binary stars with high-speed stellar winds. The diffuse X-ray glow could be caused by the combined heating of gas in the cluster by winds from many stars.

The light from the stars in the two clusters, DB00-58 and DB00-6 show much less X-ray and infrared absorption. This lower absorption, which still blocks much of the visible light, indicates that these star clusters are not in the Galactic Center, but are foreground objects. The way in which the X-rays are produced in these clusters is likely to be similar to DB01-42.