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Seasat

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This is an old revision of this page, as edited by 2620:101:f000:eb02:f53e:5c7e:3896:4d0 (talk) at 02:32, 6 August 2018 ('synthetic aperture radar' is not a proper name and should not be capitalized; just because this term can be made into an acronym (with uppercase letters) doesn't make it a proper name). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Seasat
Seasat
Mission typeOceanography
OperatorNASA / JPL / Caltech
COSPAR ID1978-064A Edit this at Wikidata
SATCAT no.10967
Mission duration105 days achieved
Spacecraft properties
BusAgena-D
ManufacturerLockheed
Ball Aerospace
JPL
Launch mass1,800 kilograms (4,000 lb)
Start of mission
Launch date27 June 1978, 01:12:00 (1978-06-27UTC01:12Z) UTC
RocketAtlas E/F Agena-D
Launch siteVandenberg SLC-3W
End of mission
Last contact10 October 1978 (1978-10-11)
Orbital parameters
Reference systemGeocentric
RegimeSun-synchronous
Eccentricity0.00209
Perigee altitude769.0 kilometers (477.8 mi)
Apogee altitude799.0 kilometers (496.5 mi)
Inclination108.0 degrees
Period100.7 minutes
Epoch26 June 1978, 21:12:00 UTC [1]

Seasat[2] was the first Earth-orbiting satellite designed for remote sensing of the Earth's oceans and had on board the first spaceborne synthetic aperture radar (SAR). The mission was designed to demonstrate the feasibility of global satellite monitoring of oceanographic phenomena and to help determine the requirements for an operational ocean remote sensing satellite system. Specific objectives were to collect data on sea-surface winds, sea-surface temperatures, wave heights, internal waves, atmospheric water, sea ice features and ocean topography. Seasat was managed by NASA's Jet Propulsion Laboratory and was launched on 27 June 1978[3] into a nearly circular 800 km orbit with an inclination of 108°. Seasat operated for 106 [4] days until 10 October 1978, when a massive short circuit in the satellite's electrical system ended the mission.

Seasat carried five major instruments designed to return the maximum information from ocean surfaces:

  1. Radar altimeter to measure spacecraft height above the ocean surface
  2. Microwave scatterometer to measure wind speed and direction
  3. Scanning multichannel microwave radiometer to measure sea surface temperature
  4. Visible and infrared radiometer to identify cloud, land and water features
  5. Synthetic aperture radar (SAR) L-band, HH polarization, fixed look angle to monitor the global surface wave field and polar sea ice conditions {the antenna is the light parallelogram in the picture}. The SAR support structure was designed and manufactured by Northrop Grumman Astro Aerospace in Carpinteria, CA. The structure deployed on orbit.

Many later remote sensing missions owe their legacy to Seasat. These include imaging radars flown on NASA's Space Shuttle, altimeters on Earth-orbiting satellites such as TOPEX/Poseidon, and scatterometers on NASA Scatterometer (NSCAT), QuikSCAT, and Jason 1.

Seasat SAR data released in 2013

On the 35th anniversary of Seasat's launch, the Alaska Satellite Facility released newly digitized Seasat synthetic aperture radar (SAR) imagery.[5] Until this release, Seasat SAR data were archived on magnetic tapes, and images processed from the tapes were available only as optical images of film strips or scanned digital images. Neither the tapes nor the film allow the quantitative analysis possible with the new digital archive.[6][7]

Conspiracy theory

Seasat was able to detect the wakes of submerged submarines, a discovery not anticipated before launch.[8] The conspiracy theory holds that once this was discovered, the military shut SEASAT down, with a cover story of a power supply short.[9][10]

See also

References

  1. ^ "NASA - NSSDCA - Spacecraft - Trajectory Details". nssdc.gsfc.nasa.gov. Retrieved 2018-04-30.
  2. ^ "Seasat: Short Description". NASA Jet Propulsion Laboratory. Archived from the original on 14 August 2014. Retrieved 28 June 2013. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  3. ^ https://science.nasa.gov/missions/seasat-1/
  4. ^ "Past Missions - Seasat". NASA Jet Propulsion Laboratory. Retrieved 28 June 2013.
  5. ^ "Trailblazer Sea Satellite Marks Its Coral Anniversary". NASA Jet Propulsion Laboratory. Retrieved 28 June 2013.
  6. ^ Rettig, Molly (2013-06-22). "Old satellite imagery offers new baseline data". Anchorage Daily News. Archived from the original on 2013-06-29. Retrieved 28 June 2013. {{cite news}}: Unknown parameter |dead-url= ignored (|url-status= suggested) (help)
  7. ^ "Alaska Satellite Facility Celebrates Seasat 35th Anniversary". University of Alaska Fairbanks. Archived from the original on 8 July 2013. Retrieved 28 June 2013. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  8. ^ WILLIAM J. BROAD (11 May 1999). "U.S. Loses Hold on Submarine-Exposing Radar Technique". New York Times.
  9. ^ Pat Norris (2008). Spies in the Sky Surveillance Satellites in War and Peace. Praxis. doi:10.1007/978-0-387-71673-2. ISBN 978-0-387-71672-5. p. 172
  10. ^ "The Ship Model Forum". Retrieved 2008-11-18.

Further reading

  • Science, vol. 204, No. 4400, 29 June 1979, cover and papers pp. 1405–1424.
  • IEEE Journal on Oceanic Engineering, vol. OE-5, no. 2, April 1980, Special Issue on SEASAT-1 Sensors.
  • Charles Elachi, "Spaceborne Imaging Radar: Geologic and Oceanographic Applications," Science, vol. 209, No. 4461, 5 September 1980, pp. 1073–1082.
Wikimedia Commons has media related to Seasat.

Template:Space-based meteorological observation

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