During the 9-day ATLAS-1 mission (March 24--April 2, 1992), a significant database was acquired on the temperature, pressure, and composition of the atmospheric regions between approximately 15 km and 300 km, together with measurements of the total solar irradiance and the solar spectral irradiance between 1200 ¿ and 3.2 &mgr;m. Six remote sensing atmospheric instruments covered a scope in altitude and species that has not been addressed before from a single mission. The atmospheric composition dataset should serve as an important reference for the determination of future global change in these regions. Both the solar and atmospheric instruments made observations that were coordinated with those made from other spacecraft, such as the UARS, the NOAA, and the ERB satellites. The objective of these correlative measurements was both to complement the measurements made by the other payloads and also to update the calibration of the instruments on the long-duration orbiting vehicles with recent, highly accurate calibrations. Experiments were conducted in space plasma physics. Most important of these was the generation of artificial auroras by firing a beam of energetic electrons into the atmosphere.

The induced auroras were observed with a photometric imaging camera. In addition, measurements were made of the precipitation of energetic neutrals from the ring current. ATLAS-1 also carried an UV instrument to gather wide field observations of astronomical sources. A subset of these instruments is planned to fly once a year for the duration of a solar cycle. Both the ATLAS-1 mission and the ongoing series represent an important element of the Mission to Planet Earth and the Global Change Program. The papers in this special issue give a summary of the results obtained in the first 4 months following the mission.