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

Mission Introduction

Atmosphere Explorer-D

The primary objective of the AE-D spacecraft was to continue investigations of the chemical processes and energy transfer mechanisms, already begun by AE-C, which controlled the Earth’s atmosphere. This mission was planned to sample the high latitude regions at the same time that the AE-E mission was sampling the equatorial and low latitude regions. (Courtesy NASA/GSFC)

The purpose of the AE-D mission was to continue the investigation begun by AE-C of the chemical processes and energy transfer mechanisms that control the structure and behavior of the Earth’s atmosphere and ionosphere in the region of high absorption of solar energy. This mission was planned to sample the high latitude regions at the same time that the AE-E mission was sampling the equatorial and low latitude regions. The same type of spacecraft as AE-C was used, and the payload consisted of the same types of instruments except for deletion of the extreme solar UV monitor and the Bennett ion mass spectrometer, which were part of the AE-E payload. The polar orbit provided the sampling of all latitudes and the perigee moved through all latitudes in 3 months and all local times in 4 months.

Unfortunately, a failure in the solar power panels resulted in the termination of operations on January 29, 1976, after slightly less than 4 months of useful life. However, all the regions at the perigee altitudes were sampled during this time. The spacecraft re-entered the atmosphere about 1 month after cessation of telemetry. To continue the correlated observations with the AE-E mission, AE-C was reactivated on February 28, 1976, to replace AE-D.

LASP Roles

LASP provided:

  • Ultraviolet Nitric-Oxide (UVNO) instrument
  • UVNO Principal Investigator, Charles Barth and Co-Investigator, Ian Stewart

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 data obtained yielded altitude profiles of nitric-oxide density as a function of time and location. 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: October 6, 1975
Launch location: Vandenberg Air Force Base, California
Launch vehicle: Delta
Mission target: Earth orbit
Mission duration: 6 months
Other key dates:

  • AE-D decommissioned: January 29, 1976

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