Terra (EOS AM-1) is a multi-national scientific research satellite operated by NASA in a Sun-synchronous orbit around the Earth.

The satellite was launched from Vandenberg Air Force Base on December 18th, 1999, aboard an Atlas IIAS vehicle and began collecting data on February 24th, 2000.

Terra carries a payload of five remote sensors designed to monitor the state of Earth's environment and ongoing changes in its climate system:[2] Data from the satellite helps scientists better understand the spread of pollution around the globe.

After launch, operators observed that high energy protons like those found over the South Atlantic Anomaly or the poles could induce single-event upsets that would cause the Motor Drive Assembly (MDA) Built-In Test Equipment (BITE) to turn off the MDA.

With no more such maneuvers, Terra's mean local time has begun to drift starting in April 2021 and with it, its data quality.