NASA Spacecraft Provides Critical Link in Sun–Earth Chain

NASA’s TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics) spacecraft recently observed our atmosphere’s response to a series of strong solar storms, providing important new information on the final link in the Sun–Earth Connection (SEC) chain of physical processes connecting the Sun and Earth.

“Several NASA spacecraft measured this strong activity coming from the Sun. Now TIMED provides the critical link between what happened on the Sun and Earth’s response,” says Dr. Sam Yee, TIMED project scientist, from the spacecraft’s operations center at The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., and leader of the mission’s science team.

“TIMED allows us to observe the global reaction of our upper atmosphere to solar activity,” says Dr. Mary Mellott, TIMED program scientist from NASA Headquarters in Washington. “One of the current puzzles for the Sun–Earth Connection community is determining why some solar activity has significant geospace impact and some does not. Being able to monitor the impact so well with TIMED should allow the scientific community to make significant progress toward solving this SEC mystery.”

Preliminary TIMED data will be featured in a special session at the Spring 2002 American Geophysical Union meeting, May 31, in Washington, D.C., which is open to the media.

Since TIMED’s science mission began in January 2002, science team members say it has made great strides in helping them learn more about one of Earth’s least understood atmospheric regions-the Mesosphere and Lower Thermosphere/Ionosphere-a gateway between Earth’s environment and space. TIMED is the first of NASA’s Solar Terrestrial Probes missions to globally study the influences of the Sun and humans on the MLTI region, located approximately 40-110 miles (60-180 kilometers) above the surface.

“TIMED’s study of short-term events, such as the recent solar storms, will help us gain a better understanding of the dynamics of this gateway region,” says Dr. Yee. “But our main goal is to understand the region’s overall climate through a comprehensive set of global measurements we’re collecting using TIMED’s 4-instrument suite. With the core data we’ve already collected, we’ve taken the first step in assessing the region’s global characteristics and seasonal variations-information that will help us establish a baseline for future studies.”

Space weather in Earth’s upper atmospheric regions can change as suddenly as our weather patterns on the ground. It can affect satellite communications and orbital tracking, spacecraft lifetimes and the reentry of piloted vehicles. “When a change occurs in one region of our atmosphere, it affects other regions,” Dr. Yee says. “It’s important that we better understand how this gateway region responds to various solar inputs, which affect our atmosphere’s overall energy balance.”

Images and videos of preliminary TIMED data can be downloaded from www.timed.jhuapl.edu/press2/images.htm.

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 at NASA Headquarters in Washington, D.C. The Johns Hopkins University Applied Physics Laboratory, in Laurel, Md., 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 TIMED, visit the APL Web site.