Seasat

Seasat
Seasat
Mission typeOceanography
OperatorNASA / JPL / Caltech
COSPAR ID1978-064A Edit this at Wikidata
SATCAT no.10967
Mission durationOperational:
3 months and 13 days
Spacecraft properties
BusAgena-D
ManufacturerLockheed
Ball Aerospace
JPL
Launch mass2,290 kg (5,050 lb)
Power700 watts
Start of mission
Launch date27 June 1978, 01:12 (1978-06-27UTC01:12) UTC
RocketAtlas E/F Agena-D
Launch siteVandenberg SLC-3W
End of mission
Last contact10 October 1978 (1978-10-11) UTC
Orbital parameters
Reference systemGeocentric
RegimeSun-synchronous
Eccentricity0.00209
Perigee altitude769 kilometers (478 mi)
Apogee altitude799 kilometers (496 mi)
Inclination108.0 degrees
Period100.7 minutes
Epoch26 June 1978, 21:12:00 UTC
Instruments
 

Seasat was the first Earth-orbiting satellite designed for remote sensing of the Earth's oceans and had on board one of 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 into a nearly circular 800 km (500 mi) orbit with an inclination of 108°. Seasat operated until 10 October 1978 (UTC), when a massive short circuit in the Agena-D bus electrical system ended the mission.

Instruments

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, California. The structure deployed on orbit.

Many later remote sensing missions benefited from Seasat's legacy. These include imaging radars flown on NASA's Space Shuttle, altimeters on Earth-orbiting satellites such as TOPEX/Poseidon, and scatterometers on ADEOS I, QuikSCAT, and Jason-1.

2013 data release

On the 35th anniversary of Seasat's launch, the Alaska Satellite Facility released newly digitized Seasat synthetic aperture radar (SAR) imagery. 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.

Conspiracy theory

Seasat is claimed to have been able to detect the wakes of submerged submarines. This supposed capability was unexpected. The conspiracy theory holds that when this capability was discovered, the mission was ended for national security reasons, and the end of the mission was falsely blamed on catastrophic failure of the satellite's electric power system. Subsequent ocean-observing SAR satellites with higher resolutions and sensitivities have not exhibited this claimed capability.

See also


This page was last updated at 2024-01-16 02:48 UTC. Update now. View original page.

All our content comes from Wikipedia and under the Creative Commons Attribution-ShareAlike License.


Top

If mathematical, chemical, physical and other formulas are not displayed correctly on this page, please useFirefox or Safari