Astronomy:Orbiting Astronomical Observatory 2

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Orbiting Astronomical Observatory 2
Orbiting Astronomical Observatory 2.jpg
Technicians in a clean room at NASA’s Kennedy Space Center in Cape Canaveral, Florida, check out the Orbiting Astronomical Observatory 2 before the mission’s Dec. 7, 1968, launch.
Mission typeAstronomy
OperatorNASA
COSPAR ID1968-110A
SATCAT no.3597
Spacecraft properties
ManufacturerGrumman
Dry mass2,012 kilograms (4,436 lb)
Start of mission
Launch date7 December 1968, 08:40:09 (1968-12-07UTC08:40:09) UTC
RocketAtlas SLV-3C Centaur-D
Launch siteCape Canaveral Air Force Station Cape Canaveral Air Force Station Space Launch Complex 36
End of mission
DisposalTelescope issues
DeactivatedFebruary 1973 (1973-03)[1]
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Perigee altitude768 kilometres (477 mi)
Apogee altitude777 kilometres (483 mi)
Inclination35.0 degrees
Period100.30 minutes
Epoch6 January 1969[2]
 

The Orbiting Astronomical Observatory 2 (OAO-2, nicknamed Stargazer) was the first successful space telescope (first space telescope being OAO-1, which failed to operate once in orbit), launched on December 7, 1968.[3] An Atlas-Centaur rocket launched it into a nearly circular 750-kilometre (470 mi) altitude Earth orbit.[4] Data was collected in ultraviolet on many sources including comets, planets, and galaxies.[3][5] It had two major instrument sets facing in opposite directions; the Smithsonian Astrophysical Observatory (SAO) and the Wisconsin Experiment Package (WEP).[5] One discovery was large halos of hydrogen gas around comets,[5] and it also observed Nova Serpentis, which was a nova discovered in 1970.[3]

Celescope: Smithsonian Astrophysical Observatory

The Smithsonian Astrophysical Observatory, also called Celescope, had four 12 inch (30.5 cm) Schwarzschild telescopes that fed into Uvicons.[6] The Uvicon was an ultra-violet light detector based on the Westinghouse Vidicon.[7] Ultraviolet light was converted into electrons which were in turn converted to a voltage as those electrons hit the detection area of the tube.[8] There has been a Uvicon in the collection of the Smithsonian Institution since 1973.[7]

Various filters, photocathodes, and electronics aided in collecting data in several ultraviolet light passbands.[6] The detectors showed a gradual loss of sensitivity[9] and the experiment was turned off in April 1970.[6] By the time it finished about 10 percent of the sky was observed[6] resulting in a catalog of 5,068 UV stars.[9]

Wisconsin Experiment Package

The Wisconsin Experiment Package had seven different telescopes for ultraviolet observations.[10] For example, there was a nebular photoelectric photometer fed by a 16-inch (40.64 cm) telescope with a six-position filter wheel[10] that unfortunately failed a few weeks after launch.[9]

Construction was supervised by Arthur Code of the University of Wisconsin-Madison. [9] WEP observed over 1200 targets in ultraviolet light before the mission ended in early 1973.[5]

Discoveries

In addition to the Celescope's catalog of UV stars, the WEP observed comet Tago-Sato-Kosaka and found it to be surrounded by a cloud of hydrogen, confirming that the comet was largely made up of water, and detected the 2175-angstrom bump, an increase in UV absorption at that wavelength that is still not fully explained.[9]

Spacecraft bus

The observatory was built in the shape of an octagonal prism. It measured about 10 by 7 ft (3.0 by 2.1 m) and weighed 4,400 lb (2,000 kg).[11]

See also

References

  1. ↑ "NASA's First Stellar Observatory, OAO 2, Turns 50". NASA. 11 December 2018. https://www.nasa.gov/feature/goddard/2018/nasa-s-first-stellar-observatory-oao-2-turns-50. 
  2. ↑ McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. http://www.planet4589.org/space/log/satcat.txt. 
  3. ↑ 3.0 3.1 3.2 Joseph A. Angelo (2014). Spacecraft for Astronomy. Infobase Publishing. p. 20. ISBN 978-1-4381-0896-4. https://books.google.com/books?id=y8BMepjeciEC&pg=PA20. 
  4. ↑ Gunter – OAO-2
  5. ↑ 5.0 5.1 5.2 5.3 Orbiting Astronomical Observatory OAO-2
  6. ↑ 6.0 6.1 6.2 6.3 High-Resolution Telescopes
  7. ↑ 7.0 7.1 "Detector, Uvicon, Celescope" (in en). National Air and Space Museum. 2016-11-24. https://airandspace.si.edu/collection-objects/detector-uvicon-celescope-1. 
  8. ↑ "Detector, Uvicon, Celescope | National Air and Space Museum". https://airandspace.si.edu/collection-objects/detector-uvicon-celescope-1. 
  9. ↑ 9.0 9.1 9.2 9.3 9.4 Reddy, Francis (11 Dec 2018). "NASA's First Stellar Observatory, OAO 2, Turns 50". https://www.nasa.gov/feature/goddard/2018/nasa-s-first-stellar-observatory-oao-2-turns-50. 
  10. ↑ 10.0 10.1 Wisconsin Experiment Package
  11. ↑ "OAO-2". https://draperspacetelescopes.weebly.com/oao-2.html. 

External links




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