Aura (satellite)

Aura (EOS CH-1) is a multi-national NASA scientific research satellite in orbit around the Earth, studying the Earth's ozone layer, air quality and climate. It is the third major component of the Earth Observing System (EOS) following on Terra (launched 1999) and Aqua (launched 2002). Aura follows on from the Upper Atmosphere Research Satellite (UARS). Aura is a joint mission between NASA, the Netherlands, Finland, and the U.K. The Aura spacecraft is healthy and is expected to operate until at least 2028, possibly beyond, however only two of its four instruments are functioning nominally.

The name "Aura" comes from the Latin word for air. The satellite was launched from Vandenberg Air Force Base on July 15, 2004, aboard a Delta II 7920-10L rocket.

The Aura spacecraft has a mass of about 1,765 kg (3,891 lb). The body is 6.9 m (23 ft) long with the extended single solar panel about 15 m (49 ft) long.

Aura originally flew in a Sun-synchronous orbit, in formation with three other satellites, collectively known as the "A Train"; it is last in the formation. The other satellites in the formation are:

All satellites have an equatorial crossing time at about 1:30 in the afternoon, thus the name 'A (Afternoon) Train'.

Aura's orbital inclination of 98.2° and right ascension of ascending node (RAAN, or longitude of ascending node) of 96.8126°, has its ascending node in daylight. With an orbital period of 98.83 minutes, it has a sixteen-day repeat cycle and 233 revolutions per cycle. Since 2023, Aura has been allowed to drift to save fuel.