Seasat
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.
Out
of service
|
10
Oct 1978 (106 days of returning data)
|
Cause
|
a
short circuit drained all power from its batteries
|
Prime
contractor
|
Lockheed
|
Platform
|
Agena
|
Mass
at launch
|
2300
kg
|
Dimension
|
1.5
m diameter x 21 m length
|
Solar
array
|
2
panels,
|
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.
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
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
Frequency
|
1.275
GHz (L-band)
|
Accuracy
|
windspeed
+/- 2 m/s; direction better than 20°
|
Mission: windspeed and direction
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
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