THEMIS (constellation)

The THEMIS (Time History of Events and Macroscale Interactions during Substorms) constellation is a NASA mission consisting of exactly five identical satellites. They were successfully launched together into orbit in 2007.

The primary goal of the THEMIS constellation is to study the timing and physical causes of auroral substorms near the Earth's polar regions. By measuring magnetic fields and particles, scientists aimed to understand how solar wind energy is released into the magnetosphere.

In 2010, two of the original five spacecraft were redirected from their orbits to study the Moon's interaction with the solar wind. This extended mission phase was renamed ARTEMIS (Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun).

The mission was managed by the Space Sciences Laboratory at the University of California, Berkeley, under NASA's Explorer program. The data collected by the constellation continues to be vital for modern space weather research.