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NASA communications satellite From Wikipedia, the free encyclopedia
ATS-4 (Applications Technology Satellite) also known as ATS-D was a communications satellite launched by NASA on August 10, 1968[3] from Cape Canaveral through an Atlas-Centaur (AC-17) rocket.[1][2]
Mission type | Weather Satellite |
---|---|
Operator | NASA |
COSPAR ID | 1968-068A |
SATCAT no. | 03344 |
Mission duration | 38 days |
Spacecraft properties | |
Bus | HS-306 |
Manufacturer | Hughes Aircraft |
Launch mass | 305 kilograms (672 lb)[1] |
Power | 350 W (peak) |
Start of mission | |
Launch date | August 10, 1968, 22:33:00 UTC |
Rocket | Atlas SLV-3C Centaur-D (AC-17) |
Launch site | Cape Canaveral[1] LC-36A[2] |
End of mission | |
Disposal | August 10, 1968 |
Decay date | October 17, 1968[3] |
Orbital parameters | |
Reference system | Geocentric |
Regime | LEO |
Eccentricity | 0.042372[2] |
Perigee altitude | 185.99 kilometres (115.57 mi)[2] |
Apogee altitude | 766.89 kilometres (476.52 mi)[2] |
Inclination | 29.141º [2] |
Period | 94.131 minutes[2] |
The objective of ATS-4 was to investigate the possibilities of a gravity gradient stabilization system (the method of stabilizing artificial satellites).[3]
The satellite has a cylindrical shape with a 142-centimetre (56 in) diameter and 183-centimetre (72 in) height (about 360 centimetres (140 in) considering the motor cover) with the surface covered by solar panels that generated a maximum of 350 W of power,[4] and stabilized by gravity gradient. It was based on the Hughes Aircraft HS-306 bus.[5]
A total of four experiments were conducted during the mission:
The Atlas and Centaur stages performed satisfactorily and placed the Centaur/ATS-4 in an elliptical parking orbit. However the Centaur stage failed to re-ignite after a 61-minute coast. The failure was determined to be freezing of the hydrogen peroxide supply lines to the Centaur engines.[2]
High atmospheric drag due to the low altitude of the achieved orbit (186 km perigee) precipitated the orbital decay of the spacecraft. ATS-4 still achieved good results in some of the experiments, but the primary objective of achieving gravity gradient stabilization of a satellite was not reached.
ATS-4 reentered the atmosphere on 17 October 1968.[3]
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