THE ATMOSPHERE EXPLORER SATELLITES AE-C, AE-D, AND AE-E ------------------------------------------------------- D. Bilitza, N. Papitashvili, J. King --- 04/19/1995 The AE satellites were launched in the mid-seventies (see table below for times and orbit parameters) to study in great detail the ionosphere and thermosphere (upper atmosphere) and the coupling processes between the two. Sat. Launch-Reentry Data on CD Alt Range/km Incl/deg. -------------------------------------------------------------------------- AE-C 73/12/13-78/12/12 73/12/16-78/12/11 130-4300 68.1 AE-D 75/10/06-76/01/29 75/10/06-76/01/29 150-3800 90.1 AE-E 75/11/20-81/06/10 75/12/01-81/06/06 160-3000 19.7 -------------------------------------------------------------------------- Flying almost identical sets of insitu experiments (see table below) in complementary orbits, the AE satellites have collected a large data base of ionospheric and thermospheric densities, temperatures, winds/drifts, and emissions over close to a full solar cycle. An onboard propulsion system allowed orbit adjustment and changes throughout the missions. The AE-C satellite was kept in an elliptical orbit for the first 8 months with brief excursions deep into the atmosphere (down to 129 km). These excursion occurred approximately in a 2-week interval and lasted about 24 hours; the spacecraft was than returned to the normal perigee altitudes. The orbit plane itself precessed around the Earth (in latitude) very slowly allowing measurements at particular altitudes at a variety of local times. After this period the orbit was changed to a circular orbit at about 300 km and was kept in this orbit mode from March 1975 to December 1976. The satellite was than raised to about 400 km and remained in a circular orbit at this height for the rest of its lifetime. AE-C operated well beyond its expected lifetime. After June 1975 it was operated only twice a week to supplement the AE-D and AE-E data. After the failure of AE-D, AE-C was brought back to normal operations. AE-D was the Explorer with the highest-inclination orbit permitting the study of both polar regions. In February 1976 the signals from AE-D ended abruptly due to a short in the satellite power supply system. This malfunction most likely was caused by insufficient insulation. During the interval of operation the AE-D perigee moved once across the north pole and than to the south pole just before the system failure. The AE-D satellite was also affected by a nutation problem that made data reduction more difficult. AE-E's elliptical orbit phase lasted for about one year and changed in early to mid 1977 to the near circular orbit phase (350 - 450 km). AE-E was highly successful with all instruments fully operational. By the end of 1977, it had completed over 10,000 orbits and was gathering data on only one orbit each day. Like AE-C, AE-E had provided data far beyond its nominal life expectancy when it finally re-entered in June of 1981. During the elliptical orbit phase data collection was mostly scheduled during the period of perigee passage (low altitudes). In general, the tape-recorded telemetry was played back once per orbit for a orbit coverage of about 30%. ATMOSPHERE EXPLORER PROJECT PERSONNEL ------------------------------------- AE Program Scientist: E.R. Schmerling, NASA HQ AE Program Manager: F.W. Gaetano, NASA HQ AE Project Scientist: N.W. Spencer, GSFC AE Project Manager: D.W. Grimes, GSFC AE- Experiment Principal Investigator C D E ----------------------------------------------------------------------- Cylindrical Electrostatic Probe, CEP L. Brace, GSFC X X X Benett Ion Mass Spectrometer, BIMS H. Brinton, GSFC X X Atmospheric Density Accelerometer, MESA K. Champion, ARCRL X X X Photoelectron Spectrometer, PES J. Doering, JHU X X X Retarding Plasma Analyzer, RPA W. Hanson, UTD X X X Visible Airglow Experiment, VAE P. Hays, U Mich. X X X Solar EUV Filter Photometer, PSUM D. Heath, GSFC X X X Solar EUV Spectrophotometer, EUVS H. Hinteregger, ARCRL X X X Magnetic Ion Mass Spectrometer, MIMS J. Hoffman, UTD X X Low-Energy Electron Spectrometer, LEE R. Hoffman, GSFC X X Open-Source Neutral Mass Spec., OSS A. Nier, U Min. X X X Closed-Source Neutral Mass Spectrometer D. Pelz, GSFC X X X Neutral Atmosphere Temp. Exp.,NATE N. Spencer, GSFC X X X Backscatter Ultraviolet Experiment, BUV D. Heath, GSFC X Ultraviolet Nitric Oxide Exp., UVNO C. Barth, U Col. X X ----------------------------------------------------------------------- All experiments operated flawlessly, except for the Close-Source Neutral Mass Spectrometer on AE-C. During the first low-perigee excursion (March 6, 1974) the instrument failed due to a faulty filament connection; this was corrected in subsequent instruments. In addition to the experiments listed here, several other instruments were carried by the AE satellites for housekeeping, engineering measurements and test purposes: Cold Cathode Pressure Gage, PSB (C,D,E), Capacitance Press Gage, PSA (C,D,E), Magnetometer, MAG (C), Temperature Alarm, TAL (C,E), Electric Fields, SIDS (D), Reflected Gas, MRMU (D), Planar Atmosphere Composition Test, PACT (D), He & H Airglow, SIDS (E), Nitric Oxide Airglow (E), Radiation Damage Experiment, CREM (E), Energy Analyzer Spectrometer Test, EAST (E). Data from these experiments were not included on the project-generated Unified Abstract (UA) tapes and therefore are not part of this CD-ROM. The list of references (in the AEDOC directory), however, includes also references that were keyed to these additional experiments. An interested user can thus find information about relevant articles and personnel. A detailed description of the AE experiments can be found in the scientific journal: Radio Science, Volume 8, Number 4, 263-405, April 1973 The AE mission, the experiments and the most important results are described in the book: Into the Thermosphere - The Atmosphere Explorers E. Burgess, D. Torr, and AE Investigators, NASA, 1987, US Gov. Printing Office, Washington, DC 20402, USA. -------------------------------------------------------------------------- ACKNOWLEDGMENT: We thank Alan E. Hedin, William D. Pesnell, Joseph M. Grebowsky, and Walter R. Hoegy of Goddard's Planetary Atmospheres Branch for their support in providing the data. --------------------------------------------------------------------------