Astronomy:Explorer 43

Explorer 43

Explorer 43 in space.
Mission type	Space physics
Operator	NASA
COSPAR ID	1971-019A
SATCAT no.	5043
Mission duration	3 ​1⁄2 years
Spacecraft properties
Manufacturer	GSFC
Launch mass	635 kg (1,400 lb)
Start of mission
Launch date	March 13, 1971, 16:15 (1971-03-13UTC16:15) UTC
Rocket	Delta M6 562/D83
Launch site	Cape Canaveral Air Force Station LC-17A
End of mission
Decay date	October 2, 1974 (1974-10-03)
Orbital parameters
Reference system	Geocentric
Regime	Highly Elliptical
Eccentricity	0.93678
Perigee altitude	242 km (150 mi)
Apogee altitude	196,574 km (122,145 mi)
Inclination	28.7°
Period	5,626.0 minutes
Epoch	March 13, 1971
Instruments
Instruments Measurement of Magnetic Fields Electrostatic Fields Measurement of Solar Plasma Low-Energy Protons and Electrons Medium-Energy Solar Protons and Electrons Solar Proton Monitoring Experiment Solar and Galactic Cosmic-Ray Studies Nuclear Composition of Cosmic and Solar Particle Radiations Study of Cosmic Ray, Solar, and Magnetospheric Electrons Measurement of Solar Plasma Interplanetary Long-Wavelength Radio Astronomy Experiment Radio Astronomy Electrostatic Waves and Radio Noise
Explorers

Explorer 43, also called as IMP-I and IMP 6, was a United States satellite launched as part of Explorers program. Explorer 43 as launched on March 13, 1971 on Cape Canaveral Air Force Station , 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 182.12 centimetres (71.70 in) high by 135.64 centimetres (53.40 in) 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 2.9 m (9 ft 6 in), the members of the pair used in both the electric field and radio astronomy experiments extended 45.5 m (149 ft), and the members of the third pair were slightly unbalanced, extending 24.4 m × 27.6 m (80 ft × 91 ft), respectively. All four elements perpendicular to the spin axis were to have extended 45.5 m (149 ft).

The spacecraft reentered the earth's atmosphere October 2, 1974, after a highly successful mission.