The Orbiting Astronomical Observatory (OAO)

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

s were a series of four American

space observatories A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launched ...

launched by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

between 1966 and 1972, managed by NASA Chief of Astronomy

Nancy Grace Roman Nancy Grace Roman (May 16, 1925 – December 25, 2018) was an American astronomer who made important contributions to stellar classification and motions. The first female executive at NASA, Roman served as NASA's first Chief of Astronomy through ...

. These observatories, including the first successful space telescope, provided the first high-quality observations of many objects in

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...

light. Although two OAO missions were failures, the success of the other two increased awareness within the astronomical community of the benefits of space-based observations, and led to the instigation of the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

OAO-1

The first OAO was launched successfully on 8 April 1966, carrying instruments to detect

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

and

gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...

emission. Before the instruments could be activated, a power failure resulted in the termination of the mission after three days. The spacecraft was out of control, so that the solar panels could not be deployed to recharge the batteries that would supply power to the electrical and electronic equipment on board.

OAO-2

OAO-2 was launched on 7 December 1968, and carried 11 ultraviolet

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

s. It observed successfully until January 1973, and contributed to many significant astronomical discoveries. Among these were the discovery that

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

s are surrounded by enormous haloes of

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

, several hundred thousand kilometres across, and observations of

nova A nova (plural novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", which is Latin for "new") that slowly fades over weeks or months. Causes of the dramati ...

e which found that their UV brightness often increased during the decline in their optical brightness.

OAO-B

OAO-B carried a ultraviolet telescope, and should have provided spectra of fainter objects than had previously been observable. The satellite was launched on 30 November 1970 with "the largest space telescope ever launched", but never made it into orbit. The payload fairing did not separate properly during ascent and the excess weight of it prevented the Centaur stage from achieving orbital velocity. The Centaur and OAO reentered the atmosphere and broke up, destroying a $98,500,000 project. The disaster was later traced to a flaw in a $100 explosive bolt that failed to fire."A Faulty Bolt Is Blamed For Failure of Satellite", ''The New York Times'', January 13, 1971, pA43

OAO-3 (Copernicus)

OAO-3 was launched on 21 August 1972, and proved to be the most successful of the OAO missions. It was a collaborative effort between NASA and the UK's Science Research Council (currently known as the

Science and Engineering Research Council The Science and Engineering Research Council (SERC) and its predecessor the Science Research Council (SRC) were the UK agencies in charge of publicly funded scientific and engineering research activities, including astronomy, biotechnology and bi ...

), and carried an X-ray detector built by

University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = ...

's Mullard Space Science Laboratory in addition to an 80 cm UV telescope built by

Princeton University Princeton University is a private university, private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial Colleges, fourth-oldest ins ...

. After its launch, it was named ''Copernicus'' to mark the 500th anniversary of the birth of

Nicolaus Copernicus Nicolaus Copernicus (; pl, Mikołaj Kopernik; gml, Niklas Koppernigk, german: Nikolaus Kopernikus; 19 February 1473 – 24 May 1543) was a Renaissance polymath, active as a mathematician, astronomer, and Catholic Church, Catholic cano ...

. ''Copernicus'' operated until February 1981, and returned high resolution spectra of hundreds of stars along with extensive X-ray observations. Among the significant discoveries made by ''Copernicus'' were the discovery of several long-period

pulsar A pulsar (from ''pulsating radio source'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Ea ...

s, with rotation times of many minutes instead of the more typical

second The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds ...

or less.

Launches

*OAO-1: Atlas-Agena D from

Launch Complex 12 Launch Complex 12 (LC-12) at Cape Canaveral Space Force Station, Florida was a launch pad used by Atlas rockets and missiles between 1958 and 1967. It was the second-most southern of the pads known as Missile Row, between LC-11 to the south and L ...

Cape Canaveral , image = cape canaveral.jpg , image_size = 300 , caption = View of Cape Canaveral from space in 1991 , map = Florida#USA , map_width = 300 , type =Cape , map_caption = Location in Florida , location ...

, Florida *OAO-2, OAO-B and OAO-3:

Atlas-Centaur The Atlas-Centaur was a United States expendable launch vehicle derived from the SM-65 Atlas D missile. Launches were conducted from Launch Complex 36 at the Cape Canaveral Air Force Station (CCAFS) in Florida. Early development Convair, the ...

from

Launch Complex 36 Launch Complex 36 (LC-36)—formerly known as Space Launch Complex 36 (SLC-36) from 1997 to 2010—is a launch complex at Cape Canaveral Space Force Station in Brevard County, Florida. It was used for Atlas launches by NASA and the U.S. Air Force ...

, Cape Canaveral, Florida

References

*Code A.D., Houck T.E., McNall J.F., Bless R.C., Lillie C.F. (1970), ''Ultraviolet Photometry from the Orbiting Astronomical Observatory. I. Instrumentation and Operation'', Astrophysical Journal, v. 161, p.377 *Rogerson J.B., Spitzer L., Drake J.F., Dressler K., Jenkins E.B., Morton D.C. (1973), ''Spectrophotometric Results from the Copernicus Satellite. I. Instrumentation and Performance'', Astrophysical Journal, v. 181, p. L97

External links

OAO-1 at Gunter's Space Page

''Copernicus'' website
{{Space observatories Space telescopes Ultraviolet telescopes 1966 in spaceflight 1968 in spaceflight 1970 in spaceflight 1972 in spaceflight