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26 August 1997
For Immediate Release

ACE Launched to Study Solar Particles

The Advanced Composition Explorer (ACE) spacecraft, designed and built by The Johns Hopkins University Applied Physics Laboratory, Laurel, Md., was successfully launched Aug. 25, at 10:39 a.m., from Cape Canaveral Air Station in Florida on a Delta II rocket.

The spacecraft is now on its way to a point one million miles from the Earth and 92 million miles from the sun, where it will use its nine instruments to collect and examine particles from the sun and interstellar and galactic sources. The instruments are designed to provide 10 to 100 times more data than collected by previous experiments.

Today ACE is performing flawlessly with its solar arrays deployed. The spacecraft's magnetometer has been turned on and systems evaluation is underway. Each instrument is being turned on and tested to assure all systems are functional.

For the next four months ACE will travel at 25,000 miles per hour to a point of equal gravitational pull from the Earth and the sun, where it will settle into a halo orbit, staying just off center of direct solar activity to protect its instruments. There it will orbit for up to five years as the spacecraft samples solar particles that stream toward Earth, looking for clues to the formation of the solar system. While in orbit, the spacecraft will also be able to provide advance warning of solar flare activity heading to Earth that could damage communication systems and knock out power grids on Earth, and endanger astronauts in space.

ACE mission operations are the responsibility of the NASA Goddard Space Flight Center in Greenbelt, Md.

For more information contact:

Helen Worth, JHU/APL Public Affairs Office,

Lynn Jenner, Goddard Space Flight Center Office of Public Affairs,
(301) 286-0045
e-mail: .