AZUR/EI-88: Medium-energy low-altitude trapped proton and alpha-particle data (1969–1970)

AZUR

The magnetically aligned spacecraft AZUR (also called GRS-A), launched into a near-polar orbit on 08 Nov 1969, was a product of a joint effort by NASA-GSFC and the German Bundesministerium fuer Wissenschaftliche Forschung (BMWF) and had as its primary purpose the acquisition of terrestrial radiation belt data. The instrument complement included detectors to measure the directional and omnidirectional fluxes of protons and electrons. These instruments and the high quality of the resulting measurements made the AZUR mission particularly well suited for the study of the trapped radiation environment, despite the short duration of the mission.

Experiment EI-88

The energetic proton measurements, which were collected during the maximum of Solar Cycle 20, were the basis for the low altitude part of the NASA model AP-8 MAX Sawyer & Vette, 1976. The payload consisted of seven instruments. Descriptions of each instrument package can be found in Achtermann et al., 1970 (see also Hovestadt et al., 1972). The EI-88 experiment consisted of two identical proton-alpha particle telescopes, one oriented perpendicular and one oriented at 45 degrees with respect to the local magnetic field vector. In the northern hemisphere, the 45 degree telescope pointed upwards. The telescopes detected protons and alpha particles in the Earth's trapping region. Unfortunately, the data gathered after 5 March 1970 have been lost.

Principal Investigator: D.K. Hovestadt, Max Planck Institut fuer Extra-Terrestrische Physik

Dataset

In the framework of the ESA/ESTEC TREND-2 study, D. Heynderickx restored the data from the original NSSDC magnetic tapes 69-097A-02A,04A, performed detailed data checks and removed bad and suspicious data records. In the framework of the ESA/ESTEC TREND-3 study, magnetic parameters were computed using UNILIB.

Acknowledgment

• National Space Science Data Center, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
• D.K. Hovestadt, Max Planck Institut fuer Extra-Terrestrische Physik
• ESA/ESTEC TREND studies