''S-1'' (satellite)

S-1
Technical drawing of a satellite with labels
The Juno II rocket carrying S-1 destroyed by Range safety 5.5 seconds after liftoff
Names
  • Explorer S-1
  • Explorer 7X
Mission type Geoscience
Operator NASA
Mission duration 5.5 seconds
Spacecraft properties
Launch mass 41.5 kilograms (91 lb)
Dimensions 76 cm × 71 cm (30 in × 28 in)
Start of mission
Launch date July 16, 1959 16:37 (1959-07-16UTC16:37) UTC
Rocket Juno II AM-16
Launch site Cape Canaveral LC-5
End of mission
Destroyed July 16, 1959 16:37 (1959-07-16UTC16:38) UTC

S-1, also known as Explorer S-1 and Explorer 7X, was a geoscience satellite equipped with a suite of scientific instruments to study the environment around the Earth. The spacecraft and its Juno II launch vehicle were destroyed five seconds after launch on July 16, 1959, in a spectacular launch failure caused by complications with the rocket's power supply. A relaunch of the mission in October 1959, Explorer 7 (S-1A), was successful.

Mission

The S-1 mission was planned to be the sixth flight of the Explorers program, designated Explorer S-1, and Explorer 7X retrospectively.[1] The objectives of the mission were to measure the Earth's radiation balance, and the abundance of Lyman-alpha x-rays and cosmic rays, including heavy primary cosmic rays.[1] The spacecraft was also designed as a test bed for satellite capabilities, being equipped with instruments to measure the spacecraft's temperature, micrometeorite impacts, and the erosion of solar cells exposed to the vacuum of space.[1] The spin-stabilized spacecraft was 76 by 71 centimetres (30 by 28 inches) in size, and had a launch mass of 41.5 kilograms (91 pounds).[1][2] The spacecraft's power was drawn from a bank of fifteen nickel–cadmium batteries recharged by 3,000 solar cells mounted on the exterior of the spacecraft.[2]

Launch

The S-1 spacecraft was mounted atop a Juno II launch vehicle with the serial AM-16.[3] It was launched on July 16, 1959, at 16:37 UTC, from Cape Canaveral Air Force Station Launch Complex 5.[4] Immediately after liftoff, a short circuit of the rocket's guidance system caused the Rocketdyne S-3D engines to gimbal, tilting the rocket sharply to the west before almost flipping upside down.[2][5] Five-and-a-half seconds after launch, the Range Safety Officer destroyed the rocket. The rocket's payload impacted the ground 76 metres (249 feet) northwest of the launch site, resulting in a massive fireball.[2][5]

Aftermath

In an investigation conducted after the launch failure, it was found that the short circuit occurred between two diodes in the rocket's power supply inverter voltage regulator, cutting off power to the guidance system and causing a full gimbal.[5] Circuit board designs for the Juno II, and similar rockets, subsequently used conformal coating to reduce the chances for a recurrence.[5]

The launch, described by commentators as "infamous" and "one of the most spectacular failures ever seen at [Cape Canaveral]",[2][5][6] was the third of the Juno II rocket, after it failed to carry Pioneer 3 into heliocentric orbit in December 1958,[7][8] but succeeded in the same objective in March 1959, carrying the United States' first interplanetary mission, Pioneer 4.[9][10] S-1 was the first geocentric orbit launch attempt for the rocket; its second attempt on August 14, 1959, carrying the Beacon 2 inflatable sphere experiment to low Earth orbit, also failed.[5][11] Eventually, both the Juno II and a re-launch of the S-1 mission, designated Explorer 7 or S-1A, found success on October 13, 1959.[12][13] The satellite, which ended its mission in August 1961, is still orbiting the Earth today.[11][14]

See also

References

  1. 1 2 3 4 NSSDCA staff (March 21, 2017). "Explorer 7X - Details". NASA Space Science Data Coordinated Archive. Goddard Space Flight Center. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  2. 1 2 3 4 5 LePage, Andrew (September 3, 2015). "Vintage Micro: The Second-Generation Explorer Satellites". Drew Ex Machina. Mellarium. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  3. ↑ Krebs, Gunter Dirk (December 12, 2017). "Juno-2". Gunter's Space Page. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  4. ↑ NSSDCA staff (March 21, 2017). "Explorer 7X - Trajectory Details". NASA Space Science Data Coordinated Archive. Goddard Space Flight Center. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  5. 1 2 3 4 5 6 Kyle, Ed (July 16, 2011). "KING OF GODS: The Jupiter Missile Story, Part 5". Space Launch Report. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  6. ↑ Kyle, Ed (July 31, 2011). "KING OF GODS: The Jupiter Missile Story, Part 6". Space Launch Report. Archived from the original on May 5, 2018. Retrieved May 5, 2018. Only two months after the infamous Juno II AM-16 failure off LC 5 ...
  7. ↑ "In Depth - Pioneer 3". NASA Solar System Exploration. National Aeronautics and Space Administration (NASA). January 25, 2018. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  8. ↑ NASA Archives (March 3, 2014). "Space History Photo: Pioneer III Probe". Space.com. Purch Group. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  9. ↑ Granath, Bob (February 20, 2014). "Pioneer 4 Marked NASA's First Exploration Mission Beyond Earth". Kennedy Space Center. National Aeronautics and Space Administration (NASA). Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  10. ↑ Marshall Space Flight Center staff. "Background on the Juno II". Marshall Space Flight Center. National Aeronautics and Space Administration (NASA). Archived from the original (PDF) on May 5, 2018. Retrieved May 5, 2018.
  11. 1 2 NSSDCA staff (March 21, 2017). "Beacon 2 - Details". NASA Space Science Data Coordinated Archive. Goddard Space Flight Center. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  12. ↑ SSEC staff (October 12, 2009). "50 Year Anniversary of Explorer 7 Launch". Space Science and Engineering Center. University of Wisconsin–Madison. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  13. ↑ NSSDCA staff (March 21, 2017). "Explorer 7 - Details". NASA Space Science Data Coordinated Archive. Goddard Space Flight Center. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  14. ↑ "Space Objects Listed by International Designator". U.S. Space Objects Registry. United States Department of State. Archived from the original on October 30, 2007. Retrieved May 5, 2018.
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