Explorer 24 (also called AD-B, Air Density experiment-B and S-56C) was a NASA satellite designed for atmospheric studies. Explorer 24 was launched on 21 November 1964 from Vandenberg Air Force Base, Lompoc, California, with a Scout X-4. Explorer 24 was launched along with its successor satellite, Explorer 25.[6]
![]() Explorer 24 satellite | |
Names | AD-B Air Density experiment-B |
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Mission type | Air density |
Operator | NASA |
COSPAR ID | 1964-076A ![]() |
SATCAT no. | 00931 |
Mission duration | 1426 days (achieved) [1] |
Spacecraft properties | |
Spacecraft | Explorer XXIV |
Spacecraft type | Explorer |
Bus | AD |
Manufacturer | Langley Research Center |
Launch mass | 8.6 kg (19 lb) |
Dimensions | 3.6 m (12 ft) diameter |
Power | Solar cells and rechargeable batteries |
Start of mission | |
Launch date | 21 November 1964, 17:09:39 GMT[2][3] |
Rocket | Scout X-4 (S-135R) [4] |
Launch site | Vandenberg, PALC-D |
Contractor | Vought |
Entered service | 21 November 1964 |
End of mission | |
Decay date | 18 October 1968 |
Orbital parameters | |
Reference system | Geocentric orbit[5] |
Regime | Low Earth orbit |
Perigee altitude | 525 km (326 mi) |
Apogee altitude | 2,498 km (1,552 mi) |
Inclination | 81.40° |
Period | 116.30 minutes |
Instruments | |
Nonsystematic Changes of Air Density Systematic Changes of Air Density | |
Explorer program |
Explorer 24 was placed in orbit together with Explorer 25 from a single launch vehicle. Explorer 24 was identical in configuration to the previously launched balloon satellites Explorer 9 and Explorer 19. The spacecraft was 3.6 m (12 ft) in diameter, was built of alternating layers of aluminum foil and plastic film, and was covered uniformly with 5.1 cm (2.0 in) white dots for thermal control. It was designed to yield atmospheric density near perigee as a function of space and time from sequential observations of the sphere's position in orbit. To facilitate ground tracking, the satellite carried a 136-MHz tracking beacon.[6]
This experiment was designed to determine nonsystematic changes of the density of the upper atmosphere from studies of the drag on a 3.6 m (12 ft) diameter low-density sphere caused by short-term differences in solar activity. Density values near perigee were deduced from sequential observations of the spacecraft position, using optical (Baker-Nunn camera network) and radio and/or radar tracking techniques. This experiment resulted in the successful determination of reasonable density values until spacecraft re-entry.[7]
This experiment was designed to determine systematic changes of air density as a function of altitude, latitude, and time of day, by measuring the drag on a 3.6 m (12 ft) diameter low-density sphere with ground tracking.[8]
Explorer 24 helped determine the variation in density between the day and night of the Earth and gave rise to studies on the zone winds in the exosphere, at an altitude of between 450 km (280 mi) and 620 km (390 mi).[9][10]
The satellite reentered the Earth's atmosphere on 18 October 1968.[6]
Explorers Program | |||
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List of Explorers Program missions | |||
Missions | ![]() | ||
Proposals |
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← 1963 · Orbital launches in 1964 · 1965 → | |
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Poppy 3 · GGSE-1 · SOLRAD 7A · SECOR 1 | OPS 3367A · OPS 3367B | Relay 2 | Echo 2 | Jupiter Nosecone | Elektron 1 · Elektron 2 | Ranger 6 | OPS 3444 | Zond 3MV-1 No.2 | Kosmos 25 | OPS 2423 | OPS 3722 | OPS 3435 | Kosmos 26 | BE-A | Luna E-6 No.6 | OPS 3467 | Kosmos 27 | Ariel 2 | Zond 1 | Kosmos 28 | Gemini 1 | Polyot 2 | Luna E-6 No.5 | Transit 5BN-3 · Transit 5E-4 | OPS 3743 | Kosmos 29 | OPS 2921 | Kosmos 30 | OPS 3592 | Apollo AS-101 | OPS 4412 | OPS 3483 | Molniya-1 No.2 | Kosmos 31 | Kosmos 32 | OPS 3236 | OPS 4467A · OPS 4467B | OPS 3754 | Kosmos 33 | ESRS | Atlas-Centaur 3 | Kosmos 34 | OPS 3395 | OPS 3684 · OPS 4923 | Elektron 3 · Elektron 4 | OPS 3491 | Kosmos 35 | Vela 2A · Vela 2B · ERS-13 | Ranger 7 | Kosmos 36 | OPS 3042 | Kosmos 37 | OPS 3802 · OPS 3216 | Kosmos 38 · Kosmos 39 · Kosmos 40 | Syncom 3 | OPS 2739 | Kosmos 41 | Kosmos 42 · Kosmos 43 | Kosmos 44 | Titan 3A-2 | OGO-1 | Kosmos 45 | OPS 3497 | Apollo AS-102 | OPS 4262 | Kosmos 46 | Explorer 21 | OPS 3333 | Kosmos 47 | OPS 5798 · Dragsphere 1 · Dragsphere 2 | OPS 4036 | Explorer 22 | Voskhod 1 | Kosmos 48 | OPS 3559 | Strela-1 No.6 · Strela-1 No.7 · Strela-1 No.8 | OPS 4384 · OPS 5063 | Kosmos 49 | Kosmos 50 | OPS 5434 | OPS 3062 | Mariner 3 | Explorer 23 | OPS 3360 | Explorer 24 · Explorer 25 | Mariner 4 | Zond 2 | DS-2 No.2 | OPS 4439 | Kosmos 51 | Titan 3A-1 | Surveyor Mass Model | OPS 6582 · Transit 5E-5 | San Marco 1 | OPS 3358 | Explorer 26 | OPS 3762 | |
Payloads are separated by bullets ( · ), launches by pipes ( | ). Crewed flights are indicated in underline. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in brackets. |