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NOAA pre-launch
Officials from NASA, NOAA, the Air Force and Boeing hold the pre-launch news conference at Vandenberg Air Force Base to preview the mission of a Delta 2 rocket and the NOAA-N weather satellite. (29min 54sec file)

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Countdown culmination
Watch shuttle Discovery's countdown dress rehearsal that ends with a simulated main engine shutdown and post-abort safing practice. (13min 19sec file)
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Going to the pad
The five-man, two-woman astronaut crew departs the Operations and Checkout Building to board the AstroVan for the ride to launch pad 39B during the Terminal Countdown Demonstration Test countdown dress rehearsal. (3min 07sec file)
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Suiting up
After breakfast, the astronauts don their launch and entry partial pressure suits before heading to the pad. (3min 14sec file)
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Astronaut breakfast
Dressed in festive Hawaiian shirts, Discovery's seven astronauts are gathered around the dining room table in crew quarters for breakfast. They were awakened at 6:05 a.m. EDT to begin the launch day dress rehearsal at Kennedy Space Center. (1min 57sec file)
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Training at KSC
As part of their training at Kennedy Space Center, the Discovery astronauts learn to drive an armored tank that would be used to escape the launch pad and receive briefings on the escape baskets on the pad 39B tower. (5min 19sec file)
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Discovery's crew
Shuttle Discovery's astronauts pause their training at launch pad 39B to hold an informal news conference near the emergency evacuation bunker. (26min 11sec file)

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Astronaut Hall of Fame
The 2005 class of Gordon Fullerton, Joe Allen and Bruce McCandless is inducted into the U.S. Astronaut Hall of Fame at the Saturn 5 Center on April 30. (1hr 24min 55sec file)
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'Salute to Titan'
This video by Lockheed Martin relives the storied history of the Titan rocket family over the past five decades. (4min 21sec file)
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Titan history
Footage from that various Titan rocket launches from the 1950s to today is compiled into this movie. (6min 52sec file)
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Canada's space telescope cracks open a massive star
UNIVERSITE DE MONTREAL NEWS RELEASE
Posted: May 18, 2005

The MOST space telescope has given astronomers new clues about an exotic star, at least ten times more massive than our Sun, spewing gas into space at a rate of more than 100 trillion tonnes per second.

And according to results presented at the Canadian Astronomical Society meeting in Montreal, Canada, the star - with the misleadingly bland name of WR123 - is even weirder than astronomers ever suspected.

The new findings, by Laure Lefevre and Anthony Moffat (Universite de Montreal), Sergey Marchenko (Western Kentucky University) and the international MOST science team, are based on over five weeks of non-stop monitoring of the light variations of WR123. WR123 is a member of the relatively rare class of Wolf-Rayet stars (named after two French astronomers who discovered their telltale strong plasma winds using a simple spectroscope in the Paris suburbs in 1867, ironically the same year Canada became a nation).

Wolf-Rayet stars like WR 123 have long been known to exhibit complex - seemingly chaotic - brightness variations associated with the turbulent high-speed winds they eject into space. But the nearly continuous coverage possible with the MOST (Microvariability & Oscillations of STars) satellite has revealed a clock in the chaos - a stable variation repeating every 10 hours (see figure illustrating WR123 variations).

"Finding a clock in a star like WR123 is like finding the Rosetta stone for astronomers studying massive stars," explained Ms. Lefevre, a PhD student at the Universite de Montreal. "However, although WR123 may vary like clockwork, it must be a very strange mechanism indeed."

The only theories to explain the 10-hour clock in WR123 would be: (1) the rotation of the star itself, (2) the orbit of another small star around WR123, or (3) vibrations in the structure of WR123 that are transmitted to its dense enveloping wind. All of these ideas are equally strange. If WR123 is spinning at that rate, the surface would be moving so fast (about 2000 kilometres per *second*, or over 7 million kph) that the star should throw itself apart, unless that is the actual source of the wind! If the star is in a tight binary system, it's so tight that its companion would be orbiting *inside* the star itself. If pulsations are the right answer, theoreticians will have to completely revise their current understanding of this class of massive stars.

The same period was hinted at in spectroscopic data obtained from an Earthbound observatory a year earlier, but the MOST results leave little doubt as to the bizarre timing of this stellar clock.

One hundred times fainter than what the unaided eye can see, WR123 is located about 19,000 light-years from Earth, in the direction of the constellation Aquila ("the Eagle"). WR123 and other similar Wolf-Rayets (see the Hubble image of WR124) are believed to have had very violent births, ejected by a supernova explosion in a binary system, or by a gravitational slingshot from a dense star cluster. "Either way, WR123 was probably kicked out from the nest rather abruptly," jokes Dr. Moffat, who helped develop these formation theories in the late 1970's.

Stars that start off their lives with ten or more times the Sun's mass are capable of "burning" hydrogen into helium, helium into carbon, and so on up to the final nuclear ash, iron, before the iron-rich core collapses on itself in less than a second and produces the greatest of all stellar explosions, a supernova. Since H-burning lasts by far the longest, some 90% of stars that shine are actually consuming hydrogen in their cores at a prodigious rate. Then, somewhat under 10% of stars are in the next stage, that of He-burning, while only a miniscule fraction occurs in the subsequent, ever-faster evolving stages. WR123 represents the fleeting final stages of helium-burning, before the rapid death-spiral to supernova.

The gases ejected from stars like WR123 will enrich the interstellar medium, and contribute to future generations of stars. Understanding such stars is vital if we are to properly understand the evolution of the Milky Way and other galaxies. "We may be seeing an example of one of the key stages in the stellar lifecycle that led to the Sun, Earth, and us, being here," noted Ms. Lefevre.

The MOST mission was financed by the Canadian Space Agency and supported by the Natural Sciences and Engineering Research Council of Canada.