Explorer 9
Explorer 9
Explorer 9 before launch |
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Mission type |
Air density |
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Operator |
NASA |
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Harvard designation |
1961 Delta 1 |
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SATCAT № |
81 |
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Start of mission |
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Launch date |
16 February 1961, 13:05:00 (1961-02-16UTC13:05Z) UTC |
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Rocket |
Scout X-1 ST-4 |
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Launch site |
Wallops LA-3 |
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End of mission |
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Decay date |
April 9, 1964 (1964-04-10) |
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Orbital parameters |
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Reference system |
Geocentric |
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Regime |
Medium Earth |
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Perigee |
635 kilometers (395 mi) |
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Apogee |
2,581 kilometers (1,604 mi) |
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Inclination |
38.8 degrees |
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Period |
118.4 minutes |
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Explorer 9, known as S-56A before launch, was an American satellite which was launched in 1961 to study the density and composition of the upper thermosphere and lower exosphere.[1] It was a reflight of the failed S-56 mission, and consisted of a 7-kilogram (15 lb), 3.7-meter (12 ft) balloon which was deployed into a medium Earth orbit.[2] The mission was conducted by NASA's Langley Research Center.
The launch of Explorer 9
Explorer 9 was launched from Launch Area 3 at the Wallops Flight Center, atop a Scout X-1 rocket with the serial number ST-4. It was the first spacecraft launched from Wallops Island to achieve orbit, with one previous attempt having failed. The launch occurred at 13:05:00 UTC on 16 February 1961, and resulted in Explorer 9 being deployed into an orbit with an apogee of 2,581 kilometres (1,604 mi), a perigee of 635 kilometres (395 mi), 38.8 degrees of inclination and a period of 118.4 minutes.[3] It was assigned the Harvard designation 1961 Delta 1.[4]
The second of six identical air density research satellites to be launched, Explorer 9 was the first to successfully reach orbit. It was still operational when the next satellite, Explorer 19, was launched, allowing simultaneous readings to be taken and compared.[5] It decayed from orbit on 9 April 1964.[3]
References
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- Italics indicates probes that failed to deploy or otherwise malfunctioned
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| | | Payloads are separated by bullets ( · ), launches by pipes ( | ). Manned flights are indicated in bold text. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in brackets. |
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