Explorer: IMP F, G

IMP F (Explorer 34, Interplanetary Monitoring Platform) was placed into a high-inclination, highly eccentric earth orbit. The apogee point was located near the ecliptic plane and had an initial local time of about 1900 h. The spacecraft was spin-stabilized and had an initial spin period of 2.6 s. The spin vector was approximately perpendicular to the ecliptic plane. Like the earlier IMPs, this spacecraft was instrumented to study interplanetary magnetic fields, energetic particles, and plasma. The spacecraft optical aspect system failed on March 4, 1969. Otherwise, useful data were acquired until just before spacecraft reentry, which occurred on May 3, 1969. 

IMP-G (Explorer 41) was a spin-stabilized spacecraft placed into a high-inclination, highly elliptic orbit to measure energetic particles, magnetic fields, and plasma in cislunar space. The line of apsides and the satellite spin vector were within a few degrees of being parallel and normal, respectively, to the ecliptic plane. Initial local time of apogee was about 1300 h. Initial satellite spin rate was 27.5 rpm. The basic telemetry sequence was 20.48 s. The spacecraft functioned very well from launch until it decayed from orbit on December 23, 1972. Data transmission was nearly 100% for the spacecraft life except for the interval from November 15, 1971, to February 1, 1972, when data acquisition was limited to the vicinity of the magnetotail neutral sheet. 

Source: NSSDC Master Catalog website

Last update: 27.09.2009
Contact: gunter.krebs@skyrocket.de
© Gunter Dirk Krebs