ATS satellite prototype at SNASM.jpg
ATS satellite prototype
Mission typeWeather Satellite
COSPAR ID1968-068A
SATCAT no.03344
Mission duration38 days
Spacecraft properties
ManufacturerHughes Aircraft
Launch mass305 kilograms (672 lb)[2]
Power350 W (peak)[3]
Start of mission
Launch dateAugust 10, 1968, 22:33:00 (1968-08-10UTC22:33Z) UTC[4]
RocketAtlas SLV-3C Centaur-D
Launch siteCape Canaveral[2] LC-36A [4]
End of mission
DisposalAugust 10,1968
Decay dateOctober 17, 1968 (1968-10-18)[5]
Orbital parameters
Reference systemGeocentric
Perigee altitude185.99 kilometres (115.57 mi)[4]
Apogee altitude766.89 kilometres (476.52 mi)[4]
Inclination29.141º [4]
Period94.131 minutes[4]

ATS-4 (Applications Technology Satellite) also known as ATS-D was a communications satellite launched by NASA on August 10, 1968[5] from Cape Canaveral through an Atlas-Centaur rocket.[2]


The objective of ATS-4 was to investigate the possibilities of a gravity gradient stabilization system (the method of stabilizing artificial satellites).[5]


The satellite has a cylindrical shape with a 142cm diameter and 183cm (about 360 cm considering the motor cover) with the surface covered by solar panels, and stabilized by gravity gradient.


A total of four experiments were conducted during the mission:

  • Microwave Transponder
  • Gravity Gradient Stabilization
  • Image Orthicon (Day/Night) Camera
  • Ion Thruster


The Atlas and Centaur stages performed satisfactorily and placed the Centaur/ATS-4 in an elliptical parking orbit, the Centaur stage, however, failed to re-ignite after a 61 minute coast. The failure was determined to be caused freezing of the hydrogen peroxide supply lines to the Centaur engines.[4] High atmospheric drag due to the low altitude of the achieved orbit precipitated the orbital decay of the spacecraft, yet, still achieved good results in some of the experiments. The primary objective to put a spacecraft stabilized by gravity gradient in orbit was not reached. The satellite reentered the atmosphere on 17 October 1968.[5]


  1. ^ 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.
  2. ^ 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.
  3. ^ Fairchild Hiller Space Systems Divsion (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.
  4. ^ 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.
  5. ^ a b c d Garner, Robert (2010-01-22). "ATS". Goddard Space Flight Center. Greenbelt, MD: NASA. Archived from the original on 2021-04-21. 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.

External links

  • ATS, Past NASA Missions
  • ATS, NASA Science Missions