Studying the gateway between Earth and Space
The NASA TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics) mission provides valuable insight into the influences of the Sun and humanity on the least-explored and least-understood region of Earth’s atmosphere — the mesosphere and lower thermosphere/ionosphere. TIMED probes this critical region to advance our knowledge of the dynamic interplay between the Earth’s upper atmosphere, the near-Earth space environment and the Sun.
For nearly two decades, the TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics) mission has provided valuable insight into the influences of the Sun and humanity on the least-explored and least-understood region of Earth’s atmosphere — the mesosphere and lower thermosphere/ionosphere. Located approximately 40-110 miles (60-180 kilometers) above Earth, this region is the gateway between Earth’s atmosphere and space, where the Sun’s energy is first deposited into Earth’s atmosphere and where auroras are generated. TIMED probes this critical region to advance our knowledge of the dynamic interplay between the Earth’s upper atmosphere, the near-Earth space environment and the Sun.
TIMED remains healthy and is proposed to continue operating though 2025.
Spacecraft and Instruments
TIMED, a low-cost spacecraft, was built and is operated by APL for NASA. The original design criteria aimed to lower mission operations costs by enabling the four onboard instruments to operate at their full capacity around the clock without constant intervention. Several technological innovations that were incorporated into TIMED’s design include an increased autonomy system, an integrated electronics module and a GPS navigation system.
TIMED was designed so that all of the instruments can be commanded into any of their respective operating modes at any time without regard for the state of the other instruments or the spacecraft, thus allowing instrument principal investigators better control and more freedom to target science observations.
December 7, 2001
David Grant, Johns Hopkins APL
Sam Yee, Johns Hopkins APL
Don Carson, NASA Goddard Space Flight Center
Craig Pollock, NASA Headquarters
Results and Expectations
For almost two decades and nearly two solar cycles, TIMED has transformed our understanding of the ionosphere-thermosphere-mesosphere (ITM) region as an integrated geospace system, through improved understanding of the internal coupling with Earth’s lower atmosphere and external coupling to the Sun and the solar wind via the magnetosphere.
For example, TIMED measurements have shown the direct connection between the variability of the lower atmosphere and ocean due to changes in the ITM structure. Other missions in NASA’s Heliophysics fleet now enhance TIMED observations to better predict our environment: aeronautics, communications, space launch and reentry, and tracking and avoidance of space debris are a few of the applications dependent on ITM models that must account for the effects of geomagnetic disturbances.
TIMED has provided 14 TB of data so far and has accomplished 113 yaw maneuvers. As of 2020, nearly 2,700 peer-reviewed papers have been written on data provided by TIMED, including 75 dissertations or theses and 1,900 science presentations.