On February 17, 2007, NASA launched a number of satellites named Temis launched to discover the science behind the most colorful auroras on Earth.
About the spacecraft
TEMIS stands for Time History of Macroscale Events and Interactions During Substorms.
Substorms occur when Earth’s magnetism is disturbed by the solar wind, or energetic particles coming from the Sun. This phenomenon makes the aurora borealis bright and wavy in the sky. Themis helped scientists understand what causes these substorms.
All five Temis satellites were launched on a Delta-2 rocket before splitting into Earth orbit in formation. Among these five spacecraft, three of these satellites orbit the Earth in the magnetosphere, while two satellites have been transferred to orbit around the Moon.
Each satellite carries five identical instruments, including a flux magnetometer, electrostatic analyzer, solid-state telescope, magnetometer and coil seeker, and an electric field instrument.
The arrivals of Tamis
In 2007, Themis found evidence of magnetic strings connecting the Earth’s upper atmosphere directly to the Sun, reconfirming the theory of solar-Earth electrical interaction proposed by Christian Birkeland in 1908.
Two of the five probes, about a third of the way from the Moon, measured events indicating a magnetic reconnection event just 96 seconds before the auroral intensification.
On May 19, 2008, the Space Science Laboratory at the University of California, San Francisco announced that NASA had extended the TEMIS mission until 2012. THMIS’ three internal probes continue to collect valuable data on the Sun’s interaction with Earth’s magnetosphere. The other two probes moved into lunar orbit and were renamed Artemis.
As of October 2019, both lunar probes are in stable orbits and are expected to remain active for a long time.