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Telstar 1



Telstar 1, primarily a communications satellite, carried an experiment designed to measure the energetic proton and electron distribution in the Van Allen belts. The spacecraft spin rate varied according to r=(178.2)exp(-t/333) rpm, where t was in days from launch. The spin axis original orientation was right ascension 81.96 deg and declination -65.57 deg. It varied slowly over the lifetime of the spacecraft. For example, on 09 November 1962, the right ascension was 94.05 deg, and the declination was -51.91 deg. Scientific information was transmitted by the spacecraft beacon, which was one of two onboard transmitters, via a PCM/FM/AM encoder. The telemetry sequence required about 1 min. The spacecraft operated normally from launch until November 1962, when the command channel began to behave erratically. The satellite was turned on continuously to circumvent this problem. On 23 November 1962, the command channel ceased to respond. On 20 December, the satellite was successfully reactivated, and intermittent data were obtained until 21 February 1963, when the transmitter failed.

Telstar 1 was launched on 10 July 1962, one day after the Starfish Prime high-altitude nuclear test. The test resulted in energetic charged particles forming an artificial radiation belt. This was encountered by Telstar 1, causing damage to the solar cells, transistors, and other electronic devices. This was the cause of the eventual failure of the spacecraft, as measured by instrumentation on the spacecraft specifically designed to measure radiation damage.

Starfish Prime

Starfish Prime was an American high-altitude nuclear test that took place on 9 July 1962. Launch took place from Johnston atoll in the Pacific Ocean (about 1330 km southwest of Honolulu) at 8:46:28 UT on 9 July 1962 (10:46:28 pm, 8 July local time) on a Thor rocket carrying a W49 thermonuclear warhead. Detonation of the warhead occurred at 09:00:09 UT on 9 July (11:00:09 pm local time, 8 July) at an altitude of 400 km. Total yield was 1.4 megatons. The explosion, occurring at a geomagnetic latitude 10.5 degrees, generated an electromagnetic pulse and generated large amounts of charged particles. These had the effect of damaging many operating satellites, both at the time of the blast and later, as the energetic particles remained trapped in the Earth's magnetic field, forming an artificial radiation belt that persisted for many days after the explosion. These damaged satellites include TRAAC, Transit-4B, Ariel 1, Cosmos 5, Telstar 1, Explorers 14 and 15, and possibly Injun 1, OSO-1, Alouette 1, and ANNA-1B.

Alternate Names

  • 1962 Alpha Epsilon 1
  • 00340
  • A 40
  • Telstar1

Facts in Brief

Launch Date: 1962-07-10
Launch Vehicle: Delta
Launch Site: Cape Canaveral, United States
Mass: 171 kg

Funding Agency

  • AT&T Bell Telephone Laboratories (United States)


  • Communications
  • Space Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Mr. C. P. Smith, Jr.Project ManagerNASA Goddard Space Flight Center
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