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Discovery's astronauts
Take a behind-the-scenes look at the seven astronauts who will fly aboard the space shuttle return-to-flight mission in this movie that profiles the lives of the STS-114 crew. (10min 04sec file)

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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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Shuttle history: STS-3
This retrospective remembers the third voyage of space shuttle Columbia. The March 1982 mission served as another developmental test flight for the reusable spacecraft, examining performance of its systems while also conducting a limited science agenda. STS-3 is distinguished by making the first landing at Northrup Strip in White Sands, New Mexico.
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LISA and the search for elusive gravity waves
Posted: April 5, 2005

For almost 100 years, scientists have been searching for direct evidence of the existence of gravity waves - faint ripples in the fabric of spacetime predicted in Albert Einstein's theory of General Relativity.

An artist's concept shows the search for gravitational waves with LISA. Credit: ESA
Today, the hunt for gravity waves has become a worldwide effort involving hundreds of scientists. A number of large, ground-based facilities have been developed in Europe, the United States and Japan, but the most sophisticated search of all will soon take place in space.

Speaking on Tuesday 5 April at the RAS National Astronomy Meeting in Birmingham, Professor Mike Cruise will describe a joint ESA-NASA project called LISA (Laser Interferometric Space Antenna),

Scheduled for launch in 2012, LISA will comprise three spacecraft flying in formation around the Sun, making it the largest scientific instrument ever placed in orbit.

"LISA is expected to provide the best chance of success in the search for the exciting, low frequency gravity waves," said Professor Cruise. "However, the mission is one of the most complex, technological challenges ever undertaken."

According to Einstein's theory, gravity waves are caused by the motion of large masses (e.g. neutron stars or black holes) in the Universe. The gravitational influence between distant objects changes as the masses move, in the same way that moving electric charges create the "electromagnetic waves" that radio sets and TV's can detect.

In the case of a very light atomic particle such as the electron, the motion can be very fast, so generating waves at a wide range of frequencies, including the effects we call light and X-rays. Since the objects which generate gravity waves are much larger and more massive than electrons, scientists expect to detect much lower frequency waves with periods ranging from fractions of a second to several hours.

The waves are very weak indeed. They reveal themselves as an alternating stretching and contracting of the distance between test masses which are suspended in a way that allows them to move.

If two such test masses were one metre apart, then the gravity waves of the strength currently being sought would change their separation by only 10(-22) of a metre, or one ten thousandth of a millionth of a millionth of a millionth of a metre.

This change in separation is so small that preventing the test masses being disturbed by the gravitational effect of local objects, and the seismic "noise" or trembling of the Earth itself, is a real problem that limits the sensitivity of the detectors.

Since each metre length in the distance between the test masses gives rise separately to the tiny changes being searched for, increasing the length of the separation between the masses gives rise to a greater overall change that could be detected. As a consequence, gravity wave detectors are made as large as possible.

Current ground-based detectors cover distances of a few kilometres and should be able to measure the millisecond periods of fast-rotating objects such as neutron stars left over from stellar explosions, or the collisions between objects in our local galactic neighbourhood.

There is, however, a strong interest in building detectors to search for the collisions between massive black holes that take place during mergers of complete galaxies. These violent events would generate signals with very low frequencies- too low to be observed above the random seismic noise of the Earth. The answer is to go into space, away from such disturbances.

In the case of LISA, the three spacecraft will fly in formation, 5 million kilometres apart. Laser beams travelling between them will measure the changes in separation caused by gravity waves with a precision of about 10 picometres (one hundred thousandth of a millionth of a metre).

Since the test masses on each spacecraft will have to be protected from various disturbances that are caused by charged particles in space, they must be housed in a vacuum chamber in the spacecraft. The precision required is 1,000 times more demanding than has ever been achieved in space before and so ESA is preparing a test flight of the laser measurement system in a mission called LISA Pathfinder, due for launch in 2008.

Scientists from the University of Birmingham, the University of Glasgow and Imperial College London are currently preparing the instrumentation for LISA Pathfinder in collaboration with ESA and colleagues in Germany, Italy, Holland, France, Spain and Switzerland.

"When LISA is operating in orbit, we expect to observe the Universe through the new window offered by gravity waves," said Cruise. "In addition to neutron stars and massive black holes, we may be able to detect the echoes of the Big Bang from gravity waves emitted tiny fractions of a second after the event that started our Universe on its current evolution."

The 2005 RAS National Astronomy Meeting is hosted by the University of Birmingham, and sponsored by the Royal Astronomical and the UK Particle Physics and Astronomy Research Council (PPARC).