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Ariel 1



Ariel 1 (1962 Omicron 1) was designed to contribute to the current knowledge of the ionosphere and of sun-ionosphere relationships. The satellite was a 62-kg cylinder with a 58-cm diameter and a height of 56 cm. A tape recorder and instrumentation for one cosmic-ray, two solar emissions, and three ionospheric experiments were on board the satellite. Except for failure at launch of the solar Lyman-alpha experiment, the spacecraft operated nominally until July 9, 1962, when it fell victim to the Starfish Prime nuclear test.

Spacecraft and subsystems

Ariel 1 was a short cylinder, rounded on both ends, with a diameter of 58 cm (23 in.) and a height of 56 cm (22 in.). Four solar array paddles extended from the lower rounded section. Two inertia booms, part of a steel spring despin system, were extended radially outward on opposite sides of the lower rounded section. Extending radially and perpendicular to these was a 122 cm (4 ft.) boom holding the electron temperature probe, and a 122 cm boom opposite that holding the electron density probe.

Mounted on top of the upper rounded section was a spherical experiment package holding the mass spectrometer probe mounted on a short column. A two-antenna turnstile array also extended at an angle from the upper section. The spacecraft shell was constructed of epoxy-bonded fiberglass painted gold, black, and white for thermal control. Total mass was 62 kg (136 lbs).

The solar arrays provided power to NiCd batteries. A PFM transmitter operated ast 136.410 MHz and 250 mW power. The spacecraft carried six British experiments comprising a Cerenkov cosmic ray detector, Geiger tube detector, ion mass sphere electron density sensor, two electron temperature gauges, three Lyman-Alpha detectors, and two proportional X-ray counters. The data were read onto an onboard 100 minute tape recorder and played back for transmission to Earth on ground command.

Mission Profile

Ariel 1 was launched from Cape Canaveral on a Thor-Delta at 18:00 UT on 26 April 1962. It was put into a 389 x 1214 km altitude orbit with an inclination of 53.85 degrees and a period of 100.86 minutes. It was spin stabilized at 12 to 36 rpm. The Lyman-Alpha solar experiment failed at launch.

Otherwise operation was nominal until the Starfish Prime high altitude (400 km) nuclear test explosion on 9 July 1962. Ariel 1 was the closest satellite to the blast, and its Geiger counter was saturated within about 20 seconds of detonation, and the Cerenkov counter 7 minutes after that. Although Ariel 1 was able to send back data, the energetic particles generated by the blast caused severe damage to the solar cells and command system electronics, resulting in power loss and intermittent electronic failures.

Between that date and September 8, 1962, spacecraft operation was limited. transmission became intermittant in November, 1963, and tracking of the spacecraft was stopped on 30 June 1964. The spacecraft was operated again from August 25, 1964, to November 9, 1964, to obtain data concurrent in time with Explorer 20 (64-051A). The orbit decayed on 24 May 1976.

Also known as International Ionosphere satellite, Ariel 1 was named for the airy spirit of Shakespeare's "The Tempest". The U.K./U.S. collaboration made it the first international satellite.

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

  • UK1
  • 00285
  • 1962 Omicron 1
  • S 51
  • Ariel1

Facts in Brief

Launch Date: 1962-04-26
Launch Vehicle: Thor-Delta
Launch Site: Cape Canaveral, United States
Mass: 62 kg

Funding Agencies

  • NASA-Office of Space Science Applications (United States)
  • Science Research Council, UK (United Kingdom)


  • Space Physics
  • Solar Physics
  • Astronomy

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. Dieter K. Bilitza



NameRoleOriginal AffiliationE-mail
Dr. E. B. DorlingProject CoordinatorUniversity College, London
Mr. Robert C. BaumannProject ManagerNASA Goddard Space Flight
Mr. M. O. RobbinsProject ManagerScience Research Council
Mr. John T. SheaProject ScientistNASA Goddard Space Flight Center
Sir Robert L. F. BoydProject ScientistMullard Space Science Laboratory
Dr. Kenneth BulloughMission Principal InvestigatorUniversity of Sheffield
Mr. Robert E. BourdeauProject ScientistNASA Goddard Space Flight Center
Sir Harrie MasseyProgram ScientistUniversity College, London

[Ariel 1 Diagram]

[Ariel 1 Model]
Ariel 1 model at the Smithsonian Air and Space Udvar-Hazy Center

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