Seasat 1

USA

Launch data:

Designation	10967 / 78064A
Launch date	27 Jun 1978
Launch site	Va, SLC-3W
Launch vehicle	Atlas-F Agena-D
Mission	Remote sensing
Earth orbit:
Perigee/Apogee	761/764 km
Inclination	108°
Period	100.1 min

Seasat was designed to demonstrate techniques for global monitoring of oceanographic phenomena and features, to provide oceanographic data, and to determine key features of an operational ocean-dynamics monitoring system. The major difference between Seasat and previous Earth observation satellites was the use of active and passive microwave sensors to achieve an all-weather capability.

Dedicated ocean monitoring satellite that carried the first spaceborne synthetic aperture radar (SAR) and other microwave instruments.

Specifications

Prime contractor	Lockheed
Platform	Agena
Mass at launch	2300 kg
Length	21 m
Stabilization	3 axis (momentum wheel/horizon sensing system)
Design lifetime	2 years

The second stage of the Atlas-Agena launch vehicle served as the satellite bus and provided attitude control, power, guidance, telemetry, and command functions. Attached to the Agena was a sensor module which carried the payload of five microwave instruments and their antennas. Together, the two modules were about 21 meters long with a maximum diameter of 1.5 m without appendages deployed. After burnout of the Agena stage and injection into orbit, Seasat-A weighed 2300 kg. In orbit the satellite appeared to stand on end with the sensor and communications antennas pointing toward Earth and the Agena rocket nozzle and solar panels pointing toward space.

End of life

Out of service	10 Oct 1978 (106 days of returning data)
Cause	a short circuit drained all power from its batteries

SAR (Synthetic Aperture Radar)

Frequency	1.275 GHz (L-band)
Resolution	25 m
Swath width	100 km

Mission: deep ocean wave pattern imaggery, coastal sea/land interaction, ice and snow imagery

ALT (Radar Altimeter)

Frequency	Ku-band
Accuracy	10 cm

Mission: measure satellite altitude above sea surface, significant wave height at sub-satellite point, establish characteristics of marine geoid

SASS (Seasat-A Satellite Scatterometer) - Wind scatterometer

Frequency	1.275 GHz (L-band)
Accuracy	windspeed +/- 2 m/s; direction better than 20°

Mission: windspeed and direction

SMMR (Scanning Multichannel Microwave Radiometer) (passive)

Frequencies	6.6, 18, 37, 10.7 & 21 GHz (H & V polarization)
Swath width	600 km
Accuracy	ocean surface temperature 2 K ocean surface windspeed 2 m/s

Mission: ocean surface temperature and windspeed, water vapor, icecover, rain rate, propagation corrections for other instruments

VIRR (Visible and IR Radiometer)

Wavebands	0.25-0.73 µm 10.5-12.5 µm
Field of view	2-5 km
Swath width	1900 km

Mission: image feature identification in support of other instruments, thermal images of ocean

Downlink frequency: 2287.5 MHz

Ref: #15 - update: 24.10.04