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The Wednesday Report TWR17v18
Canada's Aerospace and Defence Weekly Last Week ~ Next Week ~ Ten years Ago ~ Appendix A

Volume 18, Number 17, April 21, 2004

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Testing Einstein's Theory: Gravity Probe B Away after 24Hr Delay

Gravity Probe B, a NASA satellite that will validate two key aspects of Einstein's general theory of relativity, was launched yesterday aboard a Boeing Delta II rocket.

Boeing and NASA officials had halted the countdown Monday approximately three minutes before liftoff after it was determined that there was insufficient time to confirm that the correct wind profile data had been loaded aboard the Delta II based on a weather balloon that was monitoring upper level winds.

The Delta II lifted off precisely at its rescheduled time at 9:57:24 a.m. PDT from Space Launch Complex 2W at Vandenberg Air Force Base, California.

Following a 75-minute flight, the two-stage rocket deployed the spacecraft to a circular-polar orbit, approximately 400 nautical miles above the Earth.

Our Delta team did a great job in preparing and launching this extraordinary mission, said Will Trafton, vice president and general manager, Boeing Expendable Launch Systems. We're proud to continue our support for NASA in their quest to learn more about our universe, and we're looking forward to hearing the results of this important science experiment.

A Delta II 7920-10 configuration launch vehicle was used for the mission and features the Boeing Rocketdyne RS-27A main engine, nine solid rocket boosters and a 10-foot diameter payload fairing.

Gravity Probe B will test two predictions made by Albert Einstein in 1916 as part of his general theory of relativity.

The two predictions are the Geodetic effect the amount by which the Earth warps local space time in which it resides, and the frame-dragging effect the amount by which the Earth drags local space time with it as it rotates.

The spacecraft will send back data on changes in the spin axis direction of four onboard, ultra-precise gyroscopes in relation to the spacecraft's guide star, IM Pegasi, that will enable scientists to determine if space time is distorted by the Earth's presence and rotation.

The mission will be conducted over a 16-month period, and scientists also hope to learn more about the structure of the universe in terms of the relationship between space and matter.

NASA's Marshall Space Flight Center, Stanford University and Lockheed Martin Space Systems developed the Gravity Probe B spacecraft.

The next mission for the Delta team is the launch of a U.S. Air Force Global Positioning System satellite, GPS IIR-12, in June aboard a Delta II rocket from Cape Canaveral Air Force Station, Fla.

Boeing's Integrated Defense Systems is one of the world's largest space and defense businesses. Headquartered in St. Louis, Boeing Integrated Defense Systems is a $27 billion business. It provides systems solutions to its global military, government and commercial customers. It is a leading provider of intelligence, surveillance and reconnaissance; the world's largest military aircraft manufacturer; the world's largest satellite manufacturer and a leading provider of space-based communications; the primary systems integrator for U.S. missile defense; NASA's largest contractor; and a global leader in launch services.

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