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Genesis recovered
Workers recover the Genesis solar wind samples from the impact crater and take the equipment into a facility for examination. (2min 08sec file)
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Tour of KSC hurricane damage
Martin Wilson, manager of the Thermal Protection System Facility, gives a tour of the highly damaged building at Kennedy Space Center in the wake of Hurricane Frances. (2min 31sec file)
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Inside the VAB
Go inside Kennedy Space Center's hurricane-battered Vehicle Assembly Building and also see the damage to the 52-story tall facility's roof. (2min 51sec file)
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Post-impact news briefing
Officials hold a post-landing news conference in Utah a couple hours after Genesis returned to Earth on Sept. 8. (40min 52sec file)
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Capsule first spotted
Powerful tracking cameras spot the Genesis capsule for the first time a couple hundred thousand feet above Earth, prompting applause in the control centers. But just moments later, that joy turned to heartbreak. (1min 02sec file)
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Genesis crash lands
The Genesis sample return capsule tumbles through the sky and impacts the desert floor in Utah after its speed-slowing chute and parafoil failed to deploy for a mid-air recovery by a helicopter. (2min 29sec file)
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This slow-motion video shows the Genesis capsule slamming into the ground. (1min 06sec file)
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Aerial views of crater
Aerial views show the Genesis capsule half buried in the Utah desert floor after its landing system suffered a failure. (1min 53sec file)
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Recovery helicopters
The primary and backup recovery helicopters take off with escort from a Blackhawk in preparation for the mid-air retrieval of Genesis. (1min 01sec file)
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The original plan
Animation shows how the Genesis spacecraft was supposed to return. Expert narration provided by JPL entry, descent and landing expert Rob Manning. (5min 29sec file)
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Tuesday's hurricane news briefing
The Kennedy Space Center director and 45th Space Wing commander from Cape Canaveral Air Force Station hold a news conference Tuesday to describe damage from Hurricane Frances. (46min 15sec file)
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Footage of KSC damage
This movie takes you on a tour of hurricane damage to Kennedy Space Center's Vehicle Assembly Building, shuttle tile manufacturing facility and press site. (3min 11sec file)
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Scientists follow doomed matter around black hole
Posted: September 9, 2004

Scientists have pieced together the journey of a bundle of doomed matter as it orbited a black hole four times, an observational first. Their technique provides a new method to measure the mass of a black hole; and this may enable the testing of Einstein's theory of gravity to a degree few thought possible.

Seyfert I galaxy NGC 3516, as seen in optical light with the Hubble Space Telescope. The observation by Iwasawa et al. is of a region no larger than our Solar System within this galaxy -- by scale, a mere pinpoint within the center of this HST image. The Iwasawa et al. observation relied on spectroscopy, however, not imaging. Credit: HST/UCLA/M. Malkan
A team led by Dr. Kazushi Iwasawa at the Institute of Astronomy (IoA) in Cambridge, England, followed the trail of hot gas over the course of a day as it whipped around the supermassive black hole roughly at the same distance the Earth orbits the Sun. Quickened by the extreme gravity of the black hole, however, the orbit took about a quarter of a day instead of a year.

The scientists could calculate the mass of the black hole by plugging in the measurements for the energy of the light, its distance from the black hole, and the time it took to orbit the black hole -- a marriage of Einstein's general relativity and good old-fashioned Keplerian physics.

Iwasawa and his colleague at the IoA, Dr. Giovanni Miniutti, present this result today during a Web-based press conference in New Orleans at the meeting of the High Energy Astrophysics Division of the American Astronomical Society. Dr. Andrew Fabian of the IoA joins them on an article appearing in an upcoming issue of the Monthly Notices of the Royal Astronomical Society. The data is from the European Space Agency's XMM-Newton observatory.

The team studied a galaxy named NGC 3516, about 100 million light years away in the constellation Ursa Major, home to the Big Dipper (or, the Plough). This galaxy is thought to harbour a supermassive black hole in its core. Gas in this central region glows in X-ray radiation as it is heated to millions of degrees under the force of the black hole's gravity.

XMM-Newton captured spectral features from light around the black hole, displayed on a spectrograph with spikes indicating certain energy levels, similar in appearance to the jagged lines of a cardiograph. During the daylong observation, XMM captured a flare from excited gas orbiting the black hole as it whipped around four times. This was the crucial bit of information needed to measure the black hole mass.

An artist's concept of a black hole, surrounded by an accretion disk. The gas in the accretion disc is heated to millions of degrees and emits X-ray radiation, particularly close to the black hole. The black hole's event horizon, it's theoretical border, is represented here as a black sphere, although a black hole has no surface. Credit: NASA
The scientists already knew the distance of the gas from the black hole from its spectral feature. (The extent of gravitational redshift, or energy drain revealed by the spectral line, is related to how close an object is to a black hole.) With an orbital time and distance, the scientists could pin down a mass measurement -- between 10 million and 50 million solar masses, in agreement with values obtained with other techniques.

While the calculation is straightforward, the analysis to understand the orbital period of an X-ray flare is new and intricate. Essentially, the scientists detected a cycle repeated four times: a modulation in the light's intensity accompanied by an oscillation in the light's energy. The energy and cycle observed fit the profile of light gravitationally redshifted (gravity stealing energy) and Doppler shifted (a gain and loss in energy as orbiting matter moves towards and away from us).

The analysis technique implies, to this science team's surprise, that the current generation of X-ray observatories can make significant gains in measuring black hole mass, albeit with long observations and black hole systems with long-lasting flares. Building upon this information, proposed missions such as Constellation-X or XEUS can make deeper inroads to testing Einstein's math in the laboratory of extreme gravity.