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With its post-launch engineering checkouts complete, NASA’s TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics) spacecraft is now globally studying one of Earth’s final atmospheric frontiers.

Since its launch on Dec. 7, 2001, TIMED principal investigators and mission operations personnel at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and the spacecraft instrument teams located in Colorado, Michigan, Virginia and Maryland, have been conducting routine engineering checkouts of the spacecraft and its four instruments and preparing TIMED for data collection.

The spacecraft has since been declared operational and is beginning its two-year science mission to study the influences of the sun and humans on the least explored and understood portion of Earth’s atmosphere — the Mesosphere and Lower Thermosphere/Ionosphere (MLTI), a gateway between Earth’s environment and space. TIMED is focusing on a portion of this atmospheric region located approximately 40-110 miles (60-180 kilometers) above the surface, studying its basic structure and how energy is transferred into and out of this area.

“We’re very excited that our science mission is underway,” says Dr. Sam Yee, APL TIMED project scientist and the mission’s science team leader. “TIMED’s observations will provide us with the first-ever global picture of this critical region of our atmosphere, which will allow scientists to form a baseline for future studies of this area. TIMED will characterize the physical properties of this region, enabling the scientific community to make future ‘space weather’ predictions and determine how it affects things like communications, satellite tracking, spacecraft lifetimes and spacecraft reentering Earth’s atmosphere.”

TIMED is the first mission in NASA’s Solar Terrestrial Probes Program. The Solar Terrestrial Probes Program Office at NASA’s Goddard Space Flight Center, Greenbelt, Md., oversees the TIMED mission for the Office of Space Science in Washington, D.C. The Johns Hopkins University Applied Physics Laboratory built and now operates the spacecraft, leads the project’s science effort and manages the mission’s Science Data Center for NASA.

For more information about the status and location of the TIMED spacecraft and its mission, visit .