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Quick Facts: Atmosphere Explorer-C (AE-C)

Mission Introduction

Atmosphere Explorer-C

The primary objective of the AE-C spacecraft was to study the energy transfer, atomic and molecular processes, and chemical reactions in atmosphere. The study of photochemical processes accompanying the absorption of solar UV radiation in the Earth's atmosphere was accomplished by making closely coordinated measurements of reacting constituents and the solar input. (Courtesy NASA/GSFC)

The purpose of the AE-C mission was to investigate the thermosphere, with emphasis on the energy transfer and processes that govern its state. The study of photochemical processes accompanying the absorption of solar UV radiation in the Earth’s atmosphere was accomplished by making closely coordinated measurements of reacting constituents and the solar input. The AE-C spacecraft was a multi-sided polyhedron with a diameter of approximately 1.4 m. It weighed about 660 kg including 85 kg of instrumentation.

The spacecraft could be operated in either of two modes: spinning at a nominal 4 rpm or despun to 1 revolution per orbit. The spin axis was perpendicular to the orbit plane. Power was supplied by a solar cell array. The spacecraft used a Pulse Code Modulation telemetry data system that operated in real time or in a tape recorder mode. The payload included instrumentation for the measurement of solar UV; the composition of positive ions and neutral particles; the density and temperature of neutral particles, positive ions and electrons; the measurement of airglow emissions, photoelectron energy spectra, and proton and electron fluxes up to 25 keV.

LASP Roles

LASP provided:

  • Ultraviolet Nitric-Oxide (UVNO) instrument
  • UVNO Principal Investigator, Charles Barth

LASP Instrument

The Ultraviolet Nitric-Oxide Experiment (UVNO) consisted of a two-channel fixed-grating Ebert-Fastie spectrometer which measured the airglow in the (1, 0) Gamma band in a 15-A region centered at 2149 A. The observed intensity was produced by resonance fluorescence of sunlight by the nitric-oxide molecules in the instrument’s field of view. The intensity profiles obtained yielded altitude profiles of nitric-oxide density as a function of time and location. Profiles were measured along the track of the satellite at times when it was on the sunlit side of the earth. The remote sensing character of the UVNO experiment permitted measurements of nitric-oxide to be made at altitudes both above and below satellite perigee.

Quick Facts

Launch date: December 16, 1973
Launch location: Kennedy Space Center, Cape Canaveral, Florida
Launch vehicle: Delta
Mission target: Earth orbit
Mission duration: 5 years
Other key dates:

  • AE-C decommissioned: December 12, 1978

Other organizations involved:

  • NASA Goddard Space Flight Center
  • Johns Hopkins University/Applied Physics Laboratory
  • University of Texas, Dallas
  • Phillips Laboratory
  • University of Minnesota
  • University of Michigan
  • Aerospace Corporation