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Distant space explosion
Astronomers announce the detection by NASA's Swift satellite of the most distant explosion yet, a gamma-ray burst from the edge of the visible universe, during this media teleconference held Monday, September 12. (54min 01sec file)

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Hill-climbing Mars rover
The Mars Exploration Rover Spirit has reached the summit of Husband Hill, returning a spectacular panorama from the hilltop in the vast Gusev Crater. Scientists held a news conference Sept. 1 to reveal the panorama and give an update on the twin rover mission.

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Planes track Discovery
To gain a new perspective on space shuttle Discovery's ascent and gather additional imagery for the return to flight mission, NASA dispatched a pair of high-flying WB-57 aircraft equipped with sharp video cameras in their noses.

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Rocket booster cams
When space shuttle Discovery launched its two solid-fuel booster rockets were equipped with video cameras, providing dazzling footage of separation from the external fuel tank, their free fall and splashdown in the sea.

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Discovery ferried home
Mounted atop a modified Boeing 747, space shuttle Discovery was ferried across the country from Edwards Air Force Base, California, to Kennedy Space Center, Florida.

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Shuttle tank returned
Shuttle fuel tank ET-119 is loaded onto a barge at Kennedy Space Center for the trip back to Lockheed Martin's Michoud Assembly Facility in New Orleans. The tank will be used in the investigation to determine why foam peeled away from Discovery's tank on STS-114 in July.

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Delta 4 launch delayed
Launch of the GOES-N weather observatory aboard a Boeing Delta 4 rocket is postponed at Cape Canaveral, Florida.

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Mars probe leaves Earth
The Mars Reconnaissance Orbiter lifts off aboard a Lockheed Martin Atlas 5 rocket from Cape Canaveral's Complex 41.

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Launch pad demolition
Explosives topple the abandoned Complex 13 mobile service tower at Cape Canaveral Air Force Station. This video was shot from the blockhouse roof at neighboring Complex 14 where John Glenn was launched in 1962.

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Big ground telescopes eye the Deep Impact comet
Posted: September 15, 2005

When NASA's Deep Impact mission ploughed into comet 9P/Tempel 1 on July 4th of this year, the giant telescopes on Mauna Kea had a unique view of the massive cloud of dust, gas and ice expelled during the collision.

Mid-infrared images of comet 9P/Tempel 1 after the Deep Impact collision. Red shows carbon-rich dust from the comet surface, and green shows silicate-rich fresh dust from underneath the comet surface. The fresh comet material is dispersed into space over several hours of time. Credit: Subaru Telescope, National Astronomical Observatory of Japan
A series of coordinated observations, made under ideal conditions by the world's largest collection of big telescopes, delivered surprising new insights into the ancestry and life cycles of comets. Specifically, materials beneath the comet's dusty skin reveal striking similarities between two families of comets where no relationship had been suspected.

The observations also allowed scientists to determine the mass of material blasted out by the collision, which is estimated to be as much as 25 fully-loaded tractor trailer-trucks.

The findings are based on the composition of rocky dust detected by both the Subaru and Gemini 8- meter telescopes and ethane, water and carbon- based organic compounds revealed by the 10-meter W.M. Keck Observatory. The results from these Mauna Kea observations were made available today in a special section in the journal Science highlighting results from the Deep Impact experiment.

Comet Tempel 1 was selected for the Deep Impact experiment because it circles the Sun in a stable orbit that allows its surface to be gently baked with solar radiation. As a result, the comet has an old, weathered protective layer of dust that covers the icy material beneath - much like a snowbank builds up dirt on its surface as it melts in the springtime sunlight. The Deep Impact mission was designed to dig deep beneath this crusty exterior to learn more about the true nature of the comet's dust and ice components. "This comet definitely had something to hide under its veneer of rock and ice and we were ready with the world's biggest telescopes to find out what it was," said Chick Woodward of the University of Minnesota and part of the Gemini observing team.

The combined observations show a complex mix of silicates, water and organic compounds beneath the surface of the comet. These materials are similar to what is seen in another class of comets thought to reside in a distant swarm of pristine bodies called the Oort Cloud. Oort Cloud comets are well preserved fossils in the frozen suburbs of the solar system that have changed little over the billions of years since their formation. When they are occasionally nudged gravitationally toward the Sun they warm up and release a profuse amount of gas and dust on a one-time visit to the inner solar system.

Returning comets like Tempel 1 (known as periodic comets) were believed to have formed in a colder nursery distinctly different from the birthplaces of their Oort Cloud cousins. The evidence for two distinct "family trees" lies in their vastly different orbits and apparent composition. "Now we see that the difference may really be just superficial: only skin deep," said Woodward. "Under the surface, these comets may not be so different after all."

This similarity indicates that both types of comets might have shared a birthplace in a region of the forming solar system where temperatures were warm enough to produce the materials observed. "It is now likely that these bodies formed between the orbits of Jupiter and Neptune in a common nursery," said Seiji Sugita of the University of Tokyo and Subaru team member.

"Another question that the Mauna Kea telescopes were able to address is the amount of mass ejected when the comet was impacted by the chunk of copper about the mass of a grand piano from the Deep Impact spacecraft," Sugita commented. At the time of impact the spacecraft was traveling at about 23,000 miles per hour or nearly 37,000 kilometers per hour.

This observation from Gemini South in Chile of Comet P9/Tempel was obtained at mid-infrared wavelengths. This type of light acts as a tracer of the extended distribution of dust in the coma of the comet. A comet's coma is the fuzzy haze of gas and dust that surrounds, and is produced by, the comet's true nucleus. In this picture, Comet Tempel's coma is seen to extend to sizes larger than 9 arcseconds (5800 km or 3700 miles) in diameter, which is larger than the continental United States (2450 miles). Credit: Gemini Observatory
Because the spacecraft was unable to study the size of the crater created after it was formed, the high- resolution Mauna Kea observations provided the necessary data to get a firm estimate of the mass ejection, which was about 1000 tons. "To release this amount of material, the comet must have a fairly soft consistency," Sugita said.

"The splash from NASA's impact probe freed these materials and we were in the right place to capture them with the biggest telescopes on Earth," said W.M. Keck Director Fred Chaffee. "The close collaboration among Keck, Gemini and Subaru assured that the very best science was done by the best telescopes in the world, demonstrating that the whole is often greater than the sum of its parts."

All three of Mauna Kea's largest telescopes observed the comet in the infrared part of the spectrum which is light that can be described as "redder than red." The Deep Impact spacecraft was not designed to observe the comet in the mid- infrared (or thermal infrared) part of the spectrum, which is what Subaru and Gemini were able to do. The Keck observations used a near-infrared, high- resolution spectrograph. Large instruments of this sort would have been impossible to fit on the Deep Impact spacecraft.

"These observations give us the best glimpse yet at what's under the dusty skin of a comet," said David Harker of the University of California, San Diego who led the Gemini team. "Within an hour of impact, the comet's glow was transformed and we were able to detect a whole host of fine dusty silicates propelled by a sustained gas geyser from under the comet's protective crust. These included a large amount of olivine, similar in composition to what you would find at the beaches below Mauna Kea. This incredible data was really a gift from Mauna Kea!"

Subaru Telescope is Japan's largest optical-infrared telescope located on Mauna Kea, Hawaii, and operated by the National Astronomical Observatory of Japan.

The W. M. Keck Observatory is run by the California Association for Research in Astronomy (CARA), a nonprofit scientific partnership among Caltech, the University of California, and NASA.

The Gemini Observatory is an international collaboration that has built two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, in Hawai'i (Gemini North) and the Gemini South telescope is on Cerro Pachon in central Chile. Together, the telescopes provide full coverage of both hemispheres of the sky. Both telescopes incorporate new technologies that allow large, relatively thin mirrors under active control to collect and focus both optical and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in each partner country with state-of- the-art astronomical facilities that allocate observing time in proportion to each country's contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the UK Particle Physics and Astronomy Research Council (PPARC), the Canadian National Research Council (NRC), the Chilean Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT), the Australian Research Council (ARC), the Argentinean Consejo Nacional de Investigaciones Científicas y Tecnicas (CONICET) and the Brazilian Conselho Nacional de Desenvolvimento Científico e Tecnologico (CNPq).

The Observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.