Hawkeye 1

Description

The primary mission objective was to conduct particles and fields investigations of the polar magnetosphere of the earth out to 21 earth radii. Secondary objectives were to make magnetic field and plasma distribution measurements in the solar wind, and to study Type-3 radio emissions caused by solar electron streams in the interplanetary medium. To accomplish these objectives, the spacecraft was instrumented with a magnetometer, an energetic plasma analyzer, and an ELF-VLF wave instrument. The spacecraft was spin stabilized with a nominal rotational period of 11 s. In celestial coordinates, the positive spin axis coordinates were right ascension 299.4 deg (plus or minus 1.1 deg) and declination 8.6 deg (plus or minus 1.5 deg). There was no onboard orientation or spin rate control, but the orientation of the spin axis was stable. An optical aspect system operated from launch until September 3, 1974. After this period, aspect had to be determined from magnetometer measurements. The complete spacecraft with instruments had a mass of 22.65 kg. Power of 22 to 36 W, depending on solar aspect, was obtained from solar cells. Hawkeye 1 participated in the International Magnetospheric Study (IMS) and during the first half of 1977 data acquisition was confined to IMS special intervals. Data were obtained in real time only, at frequencies of 136 MHz and 400 MHz at 100 bps (or 200 bps with convolutional coding) plus wideband VLF data. For more details see "Hawkeye 1," U. of Iowa 77-6, January 1977 (TRF B29176).