Explorer 43


Explorer 43, also called as IMP-I and IMP 6, was a U.S. satellite launched as part of Explorers program. Explorer 43 as launched on March 13, 1971 on Cape Canaveral, with a Delta rocket. Explorer 43 was the sixth satellite of the Interplanetary Monitoring Platform.

Spacecraft and mission

Explorer 43 continued the study, begun by earlier IMPs, of the interplanetary and outer magnetospheric regions by measuring energetic particles, plasma, and electric and magnetic fields. Its orbit took it to cislunar space during a period of decreasing solar activity.
A radioastronomy experiment was also included in the spacecraft payload. The 16-sided spacecraft was high by in diameter. The spacecraft spin axis was normal to the ecliptic plane, and its spin rate was 5 rpm, with propulsion Star-17A. The initial apogee point lay near the earth-sun line. The solar-cell and chemical-battery powered spacecraft carried 2 transmitters. One continuously transmitted PCM encoder data at a 1,600 bps information bit rate.
The second transmitter was used for transmission of VLF data and for ranging information. Three orthogonal pairs of dipole antennas were used for the electric fields experiments, and one of these pairs was also used for the radioastronomy experiment. The members of the antenna pair along the spacecraft spin axis extended, the members of the pair used in both the electric field and radio astronomy experiments extended, and the members of the third pair were slightly unbalanced, extending, respectively. All four elements perpendicular to the spin axis were to have extended.
The spacecraft reentered the earth's atmosphere October 2, 1974, after a highly successful mission.