TIMED Science: First Light

he goal of the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) mission is to characterize the physical, dynamic, energetic, and thermal struc-ture of Earth’s mesosphere, lower thermosphere, and ionosphere (MLTI) between 60 and 180 km and to understand quantitatively the processes that govern its temporal and spatial variability. Because the MLTI is at the interface between interplanetary and lower-atmospheric processes, it plays a uniquely important role in the solar-terrestrial system. This article presents the “fi rst light” results from TIMED’s suite of four instruments. TIMED has allowed the Sun-Earth Connection research community to observe for the fi rst time the cause-and-effect chains linking the Sun, heliosphere, and magnetosphere to the Earth’s upper atmosphere. This is highlighted in preliminary results from TIMED observed during a period of intense solar and geomagnetic activity in April 2002.