The Thermosphere Ionosphere Mesosphere Energetics and Dynamics spacecraft was transported Nov. 8 to the NASA Goddard Space Flight Center in Greenbelt, Md., from the Applied Physics Laboratory in Laurel, where it was designed and built. Final environmental testing will now begin in preparation for the spacecraft's launch, currently scheduled for May 18, 2000, from Vandenberg Air Force Base, Calif., aboard a Delta II 7920-10 launch vehicle.
In late October the TIMED spacecraft underwent vibration testing at APL to verify structural integrity. "The tests went smoothly and all systems performed as expected," said Dave Grant, APL TIMED program manager. While at Goddard, the spacecraft will undergo acoustic and thermal vacuum testing, which is scheduled to conclude in February 2000. In the spring, TIMED will be shipped to Vandenberg, where it will undergo final launch preparations.
Once launched, TIMED will begin a two-year mission to study the influences of the sun and humans on the Mesosphere and Lower Thermosphere/Ionosphere, the least explored and understood region of Earth's atmosphere. TIMED will be the first mission to conduct a global study of the MLTI region, located between 60 and180 kilometers (40-110 miles) above the Earth's surface. The MLTI region is where a significant portion of the sun's energy is first deposited into Earth's atmosphere and where the solar soft X-ray and ultraviolet radiation, the most variable part of the solar spectrum, is absorbed.
TIMED's payload consists of four instruments, which were built by organizations from around the country. The Global Ultraviolet Imager, a collaborative effort between APL and the Aerospace Corporation, will measure composition and temperature profiles of the MLTI region, as well as high-latitude auroral energy inputs.
Hampton University will lead the science team for the Sounding of the Atmosphere using Broadband Emission Radiometry experiment, built by Utah State University for NASA's Langley Research Center. SABER will measure atmospheric cooling rates, as well as pressure, temperature and chemical constituents of the MLTI region. The Solar Extreme Ultraviolet Experiment, built by the University of Colorado, will measure solar X-ray, ultraviolet and far ultraviolet radiation, the primary energy source of the MLTI region. The TIMED Doppler interferometer, built by the University of Michigan, will measure the region's winds and temperature profiles.
The TIMED spacecraft will be the initial launch in NASA's Solar Terrestrial Probe Program, part of NASA's initiative to lower mission costs and provide more frequent access to space. The TIMED program is cost-capped at approximately $130 million (FY99) dollars with a maximum three-year development cycle.
The TIMED mission is sponsored by NASA Headquarters, Office of Space Science, Washington, and is managed by NASA Goddard Space Flight Center. The mission operations and science data centers, located at APL, will support data analysis for an additional two years after the conclusion of the mission.