PAGEOS: Difference between revisions
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==Orbit== |
==Orbit== |
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The PAGEOS spacecraft was placed into a [[polar orbit]] (inclination 85–86°) with an initial height of 4200km,<ref name="deorbit" /> which had gradually lowered during its 9 years of operation.{{Citation needed|date=March 2024}} The satellite partly disintegrated in July 1975, which was followed by a second break-up that occurred in January 1976 resulting in the release of a large number of fragments. Most of these re-entered during the following decade.<ref name=":2">{{cite web|title=PAGEOS 1|url=http://space.skyrocket.de/doc_sdat/pageos.htm|website=Gunter's Space Page|accessdate=16 March 2017}}</ref>{{Better citation needed|reason=The current source is insufficiently reliable ([[WP:NOTRS]]).|date=March 2024}} In 2016, one of the largest fragments of PAGEOS de-orbited.<ref name="deorbit">{{cite web|url=http://www.unoosa.org/documents/pdf/copuos/stsc/2017/tech-15E.pdf |title=USA Space Debris Environment, Operations, and Research Updates |publisher= 54th Session of the Scientific and Technical Subcommittee, Committee on the Peaceful Uses of Outer Space, United Nations, 30 January – 10 February 2017, Vienna |author=J.-C. Liou |date=February 1, 2017|access-date= February 5, 2017}}</ref> |
The PAGEOS spacecraft was placed into a [[polar orbit]] (inclination 85–86°) with an initial height of 4200km,<ref name="deorbit" /> which had gradually lowered during its 9 years of operation.{{Citation needed|date=March 2024}} The satellite partly disintegrated in July 1975, which was followed by a second break-up that occurred in January 1976 resulting in the release of a large number of fragments. Most of these re-entered during the following decade.<ref name=":2">{{cite web|title=PAGEOS 1|url=http://space.skyrocket.de/doc_sdat/pageos.htm|website=Gunter's Space Page|accessdate=16 March 2017}}</ref>{{Better citation needed|reason=The current source is insufficiently reliable ([[WP:NOTRS]]).|date=March 2024}} In 2016, one of the largest fragments of PAGEOS de-orbited.<ref name="deorbit">{{cite web|url=http://www.unoosa.org/documents/pdf/copuos/stsc/2017/tech-15E.pdf |title=USA Space Debris Environment, Operations, and Research Updates |publisher= 54th Session of the Scientific and Technical Subcommittee, Committee on the Peaceful Uses of Outer Space, United Nations, 30 January – 10 February 2017, Vienna |author=J.-C. Liou |date=February 1, 2017|access-date= February 5, 2017}}</ref> |
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The satellite's orbital period was approximately three hours.<ref name="NSSDC Master Catalog" /> It was about as bright as [[Polaris]], and appeared as a slow-moving star.<ref name=":5">{{Cite book |last=Dicati |first=Renato |url=https://books.google.com/books?id=O4LgDQAAQBAJ&newbks=0&printsec=frontcover&pg=PA44&dq=PAGEOS&hl=en |title=Stamping the Earth from Space |date=2017-01-10 |publisher=Springer |isbn=978-3-319-20756-8 |language=en}}</ref> Thanks to its high orbit and its polar inclination, it did not pass through the Earth's shadow and was visible any time of night, unlike lower-orbit satellites which had to be viewed exclusively just before sunrise and after sunset.<ref name=":5" /> |
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==See also== |
==See also== |
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Revision as of 02:35, 26 March 2024
 Test inflation of PAGEOS, 5 August 1965 | |
| Names | PAGEOS-A |
|---|---|
| Operator | NASA Office of Space Applications |
| COSPAR ID | 1966-056A |
| SATCAT no. | 02253 |
| Spacecraft properties | |
| Launch mass | 56.7 kg (125 lb) |
| Dimensions | 30.48 m (100.0 ft) diameter[1] |
| Start of mission | |
| Launch date | 00:14:00, June 24, 1966 (UTC) |
| Rocket | Thrust augmented Thor-Agena D |
| Launch site | Vandenberg AFB |
| End of mission | |
| Destroyed | partially disintegrated July 1975 |
| Orbital parameters | |
| Reference system | Geocentric[2] |
| Eccentricity | 0.00301 |
| Perigee altitude | 4,207 km (2,614 mi) |
| Apogee altitude | 4,271 km (2,654 mi) |
| Inclination | 87.14° |
| Period | 181.43 min |
| Epoch | 24 June 1966 |
PAGEOS (PAssive Geodetic Earth Orbiting Satellite) was a balloon satellite which was launched by NASA in June 1966.[1] It was the first satellite specifically for use in geodetic surveying,[3] or measuring the shape of the earth, by serving as a reflective and photographic tracking target. At the time, it improved on terrestrial triangulations of the globe by about an order of magnitude.[4] The satellite, which carried no instrumentation, broke up between 1975 and 1976.[5] One of the largest fragments of the satellite finally deorbited in 2016.[6]
PAGEOS was part of a larger program of inflatable satellites that grew from the original concept by William J. O'Sullivan of a 30-inch diameter inflatable satellite in 1956 to measure air drag at high altitudes, called the Sub-Satellite.[7] While the Sub-Satellite failed, the idea of a visible US satellite became very attractive after Sputnik launched in the Cold War, resulting in a program of similar, larger satellites.[7] These included satellites Echo 1 and Echo 2 under Project Echo, which were also used for experiments in geodetic surveying;[3] the Explorer satellites; and eventually PAGEOS.[7]
Design
PAGEOS had a diameter of exactly 100 feet (30.48 m), consisted of a 0.5 mils (12.7 μm) thick mylar plastic film coated with vapour deposited aluminum enclosing a volume of about 524,000 cubic feet (14,800 m3)[8][9] The metal coating both reflected sunlight and protected the satellite from damaging ultraviolet waves. The satellite was launched in a canister, which explosively separated as it was ejected from the rocket. Then, the balloon was inflated by benzoic acid and anthraquinone placed inside, which turned to gas when the satellite was exposed to the heat of the sun, as well as some residual air left inside.[9] The satellite carried no instrumentation.[9]
Usage
PAGEOS was placed into a polar orbit, about 200 nautical miles above the earth, so that the U.S. Coastal and Geodetic Survey could practically apply triangulation techniques developed from experiments with Echo 1. Over five years, 12 mobile tracking stations tracked the satellite during good weather in a few minutes of twilight each evening, resulting in the fixing of the precise locations of 38 different points around the world. This could be used to help determine the precise locations of the continents relative to each other, and to help determine the precise shape and size of the earth. Some unclassified data was used by scientists studying continental drift, and more classified data was used by US military planners studying intercontinental ballistic missiles.[7]
The satellite also formed the base of the Weltnetz der Satellitentriangulation (Worldwide Satellite Triangulation Network).[4] Finished in 1974, the network connected around 45 intercontinental stations, each around 3000–4000km from each other, reaching an accuracy about an order of magnitude better than terrestrial triangulations at the time.[4]
Orbit
The PAGEOS spacecraft was placed into a polar orbit (inclination 85–86°) with an initial height of 4200km,[6] which had gradually lowered during its 9 years of operation.[citation needed] The satellite partly disintegrated in July 1975, which was followed by a second break-up that occurred in January 1976 resulting in the release of a large number of fragments. Most of these re-entered during the following decade.[5][better source needed] In 2016, one of the largest fragments of PAGEOS de-orbited.[6]
The satellite's orbital period was approximately three hours.[2] It was about as bright as Polaris, and appeared as a slow-moving star.[10] Thanks to its high orbit and its polar inclination, it did not pass through the Earth's shadow and was visible any time of night, unlike lower-orbit satellites which had to be viewed exclusively just before sunrise and after sunset.[10]
See also
References
- ^ a b "PAGEOS 1". National Aeronautics and Space Administration. Retrieved March 16, 2017.
- ^ a b "NSSDCA – PAGEOS 1 – Trajectory Details". nssdc.gsfc.nasa.gov. NASA. Retrieved June 22, 2016.
- ^ a b "Modern Surveying". Encyclopaedia Britannica. Retrieved March 24, 2024.
- ^ a b c Kleusberg, Alfred (2003). "Satelliten im Dienst der Geodäsie und Geoinformatik" (PDF). University of Stuttgart. Archived from the original (PDF) on May 23, 2006.
- ^ a b "PAGEOS 1". Gunter's Space Page. Retrieved March 16, 2017.
- ^ a b c J.-C. Liou (February 1, 2017). "USA Space Debris Environment, Operations, and Research Updates" (PDF). 54th Session of the Scientific and Technical Subcommittee, Committee on the Peaceful Uses of Outer Space, United Nations, 30 January – 10 February 2017, Vienna. Retrieved February 5, 2017.
- ^ a b c d Hansen, James (March 12, 2013). Spaceflight Revolution: NASA Langley Research Center from Sputnik to Apollo. Cia Publishing.
- ^ Teichman, L. A. (June 1, 1968). "The fabrication and testing of Pageos 1". NASA Technical Reports Server
- ^ a b c "Pageos Satellite to Girdle Globe for Earth Mapping". NASA Technical Reports Server. June 19, 1966.
- ^ a b Dicati, Renato (January 10, 2017). Stamping the Earth from Space. Springer. ISBN 978-3-319-20756-8.