ATS-4
 ATS-4 | |
| 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] |
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]
Objectives
The objective of ATS-4 was to investigate the possibilities of a gravity gradient stabilization system (the method of stabilizing artificial satellites).[3]
Features
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]
Instruments
A total of four experiments were conducted during the mission:
- Microwave Transponder
- Gravity Gradient Stabilization
- Image Orthicon (Day/Night) Camera
- Ion Thruster
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]
References
- ^ a b c Bell, Ed. "1968-068A". NASA Space Science Data Coordinated Archive. NASA. Archived from the original on 2021-01-21. Retrieved 22 April 2021.
- ^ a b c d e f g h Lewis Research Center (1972-05-01). "Atlas-Centaur AC-17 performance for applications technology satellite ATS-D mission" (PDF). NTRS - NASA Technical Reports Server. Cleveland, Ohio: NASA. Archived (PDF) from the original on 2021-04-22. Retrieved 22 April 2021.
- ^ a b c d Garner, Robert (2010-01-22). "ATS". Goddard Space Flight Center. Greenbelt, MD: NASA. Archived from the original on 2021-02-26. Retrieved 22 April 2021.
ATS-4 was to investigate the possibilities of a gravity gradient stabilization system. A launch vehicle failure stranded ATS-4 in a much lower than planned orbit, making the satellite nearly useless. Despite this, NASA engineers successfully turned on several of the experiments to collect as much information as possible during the craft's short life. The low orbit and resulting atmospheric drag caused ATS-4 to re-enter Earth's atmosphere and break apart on Oct. 17, 1968.
- ^ Fairchild Hiller Space Systems Division (1 December 1966). "ATS-4 study program, volume 4 Final report" (PDF). NTRS - NASA Technical Reports Server. Germantown, Maryland: NASA. p. 64. Archived (PDF) from the original on 22 April 2021. Retrieved 22 April 2021.
- ^ Hughes Aircraft Company Space and Communications Group (1972-09-29). "Tracking and data relay satellite system configuration and tradeoff study. Volume 5: TDRS spacecraft design, part 1" (PDF). NTRS - NASA Technical Reports Server. El Segundo, California: NASA. p. 269. Archived (PDF) from the original on 22 April 2021. Retrieved 22 April 2021.