The TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) mission is studying the influences of the Sun and humans on the least explored and understood region of Earth's atmosphere - the Mesosphere and Lower Thermosphere/
Ionosphere (MLTI). The MLTI region is a gateway between Earth's environment and space, where the Sun's energy is first deposited into Earth's environment. TIMED is focusing on a portion of this atmospheric region located approximately 40-110 miles (60-180 kilometers) above the surface.

TIMED Website:

http://www.timed.jhuapl.edu