Explorer 43
 Explorer 43 satellite in space | |||||||||||||||||||||||||||||||
| Names | IMP-I IMP-6 Interplanetary Monitoring Platform-6 | ||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mission type | Space physics | ||||||||||||||||||||||||||||||
| Operator | NASA | ||||||||||||||||||||||||||||||
| COSPAR ID | 1971-019A | ||||||||||||||||||||||||||||||
| SATCAT no. | 05043 | ||||||||||||||||||||||||||||||
| Mission duration | 3.5 years (achieved) | ||||||||||||||||||||||||||||||
| Spacecraft properties | |||||||||||||||||||||||||||||||
| Spacecraft | Explorer XLIII | ||||||||||||||||||||||||||||||
| Spacecraft type | Interplanetary Monitoring Platform | ||||||||||||||||||||||||||||||
| Bus | IMP | ||||||||||||||||||||||||||||||
| Manufacturer | Goddard Space Flight Center | ||||||||||||||||||||||||||||||
| Launch mass | 635 kg (1,400 lb) | ||||||||||||||||||||||||||||||
| Dimensions | 135.64 cm (53.40 in) in diameter by 182.12 cm (71.70 in) high | ||||||||||||||||||||||||||||||
| Start of mission | |||||||||||||||||||||||||||||||
| Launch date | 13 March 1971, 16:15:00 GMT [1] | ||||||||||||||||||||||||||||||
| Rocket | Thor-Delta M6 (Thor 562 / Delta 083) | ||||||||||||||||||||||||||||||
| Launch site | Cape Canaveral, LC-17A | ||||||||||||||||||||||||||||||
| Contractor | Douglas Aircraft Company | ||||||||||||||||||||||||||||||
| Entered service | 13 March 1971 | ||||||||||||||||||||||||||||||
| End of mission | |||||||||||||||||||||||||||||||
| Decay date | 2 October 1974 | ||||||||||||||||||||||||||||||
| Orbital parameters | |||||||||||||||||||||||||||||||
| Reference system | Geocentric orbit [2] | ||||||||||||||||||||||||||||||
| Regime | Highly elliptical orbit | ||||||||||||||||||||||||||||||
| Perigee altitude | 242 km (150 mi) | ||||||||||||||||||||||||||||||
| Apogee altitude | 196,574 km (122,145 mi) | ||||||||||||||||||||||||||||||
| Inclination | 28.70° | ||||||||||||||||||||||||||||||
| Period | 5626.00 minutes | ||||||||||||||||||||||||||||||
| Instruments | |||||||||||||||||||||||||||||||
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Explorer program | |||||||||||||||||||||||||||||||
Explorer 43, also called as IMP-I and IMP-6, was a NASA satellite launched as part of Explorer program. Explorer 43 was launched on 13 March 1971 from Cape Canaveral Air Force Station (CCAFS) (restored to its old name of Cape Canaveral in 1974), with a Thor-Delta M6 launch vehicle. Explorer 43 was the sixth satellite of the Interplanetary Monitoring Platform.[3]
Spacecraft and mission
Explorer 43 continued the study, begun by earlier IMPs, of the interplanetary and outer magnetospheric regions by measuring energetic particles, plasma, electric fields and magnetic fields. Its orbit took it to cislunar space during a period of decreasing solar activity.[4]
A Radio astronomy experiment was also included in the spacecraft payload. The 16-sided spacecraft was 182.12 cm (71.70 in) high by 135.64 cm (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 1600 bps information bit rate.[3]
The second transmitter was used for transmission of Very low frequency (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 Radio astronomy 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 × 27.6 m (80 × 91 ft), respectively. All four elements perpendicular to the spin axis were to have extended 45.5 m (149 ft).[3]
Experiments
Electrostatic Fields
Two dipole antennas were mounted orthogonally in the spin plane of the spacecraft while a third dipole antenna was mounted along the spacecraft spin axis. Antenna element lengths were -X, 27.6 m (91 ft); +X, 24.4 m (80 ft); -Y and +Y, 45.5 m (149 ft); -Z and +Z (spin axis), 2.9 m (9 ft 6 in). Electrometers measured the analog potential difference between the elements in each pair of antennas simultaneously every 5.12 s. The potential differences were sampled digitally through a 14-bit analog/digital converter every 0.64-seconds. The DC sensitivity was 100 microvolts per meter.[5]
Electrostatic Waves and Radio Noise -- Project
This experiment, as originally defined by NASA Headquarters, has been separated at NSSDC into its Iowa (71-019A-03), Minnesota (71-019A-12), and GSFC (71-019A-16) components. Initial experiment performance was normal.[6]
Electrostatic Waves and Radio Noise -- GSFC
The AC electric field intensity in 12 narrow channels was measured from 0.1 to 100-Hz. The experiment had an optimum noise threshold of 10 microvolts per meter. Each channel was sampled once every 5.12-seconds at the high bit rate. The antennas used in the dc field experiment (71-019A-02) were also utilized in this experiment.[7]
Atmospheric entry
The spacecraft reentered the Earth's atmosphere on 2 October 974, after a highly successful mission.[3][8]
References
- ^ McDowell, Jonathan (21 July 2021). "Launch Log". Jonathan's Space Report. Retrieved 14 November 2021.
- ^ "Trajectory: Explorer 43 (IMP-I) 1971-019A". NASA. 28 October 2021. Retrieved 14 November 2021.
This article incorporates text from this source, which is in the public domain.
- ^ a b c d "Display: Explorer 43 (IMP-I) 1971-019A". NASA. 28 October 2021. Retrieved 14 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Explorer Spacecraft Series". History of NASA. NASA. Retrieved 30 March 2019. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: Electrostatic Fields". NASA. 28 October 2021. Retrieved 14 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: Electrostatic Waves and Radio Noise (Project)". NASA. 28 October 2021. Retrieved 14 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ "Experiment: Electrostatic Waves and Radio Noise -- GSFC". NASA. 28 October 2021. Retrieved 14 November 2021. This article incorporates text from this source, which is in the public domain.
- ^ IMP. Encyclopedia Astronautica. 2011. Retrieved 19 June 2018.
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