Remote Sensing of the Environment : Sensors: Image Processing Library

Sensors: Image Processing Library

RADARSAT

Launch of RADARSAT on Delta II rocket on November 4, 1995.

The RADARSAT Concept

Background

RADARSAT is an advanced Earth observation satellite project developed by Canada to monitor environmental change and to support resource sustainablility. With RADARSAT's launch on Nov. 4, 1995, Canada and the world now have access to the first radar satellite system capable of large scale production and timely delivery of data. RADARSAT will provide useful information to both researchers and operational users working in fields such as agriculture, cartography, hydrology, forestry, oceanography, ice studies and coastal monitoring over the satellite's expected life span of five years. These data is meeting the needs of commercial, government and scientific programs and provides a new source of reliable and cost-effective data for environmental and resource professionals worldwide.

First image collected by RADARSAT
on November 28, 1995.
The RADARSAT project, led by the Canadian Space Agency, builds on the history of achievements in remote sensing and space technologies by the Canada Centre for Remote Sensing (CCRS), part of Natural Resources Canada. With its creation in 1989, the Canadian Space Agency took over the implementation and operation of the RADARSAT project as a key component of the Canadian space program. CCRS continues to participate in the RADARSAT project through the Radar Data Development Program (RDDP) and is responsible for data collection and archiving.

Sensor

Optical satellite remote sensing depends on sunlight illuminating the Earth in order to obtain useful imagery. As such, its performance is restricted by the presence of clouds, fog, smoke or darkness. However, RADARSAT will not have those limitations. At the heart of RADARSAT is an advanced radar sensor called Synthetic Aperture Radar (SAR). SAR is a microwave instrument which sends pulsed signals to Earth and processes the received reflected pulses. RADARSAT's SAR-based technology provides its own microwave illumination and thus will operate day or night, regardless of weather conditions. RADARSAT's dawn-dusk orbit will place the satellite's solar arrays in almost continuous sunlight. The major advantage of this orbit is that the RADARSAT SAR will primarily rely on solar rather than battery power, providing users with the optimum number of viewing opportunities.

Using a single frequency, C-Band, the RADARSAT SAR will have the unique ability to shape and steer its radar beam over a 500 kilometre range. Users will have access to a variety of beam selections that can image swaths from 35 kilometres to 500 kilometres with resolutions from 10 metres to 100 metres respectively. Incidence angles will range from less than 20 degrees to more than 50 degrees. RADARSAT will provide complete global coverage with the flexibility to support specific requirements. The satellite's orbit will be repeated every 24 days. RADARSAT will provide daily coverage of the Arctic, view any part of Canada within three days, and achieve complete coverage at equatorial latitudes every six days using a 500 kilometre wide swath.

Orbital Characteristics

Orbits	Circular,sun-synchronous
Inclination Angle	98.6 degrees
Altitude	793-821 km
Orbital period	101 minutes
Orbits per day	14
Orbit repeat cycle	every 24 hours
Equator Crossing Time	06:00
Ascending Node	18:00 hours
Swath	30-500 km

Sensor Applications

As the world's first operational spaceborne SAR, RADARSAT will be an important, cost-effective source of environmental and resource information worldwide. For example, RADARSAT will provide the first routine surveillance of the entire Arctic region, offering daily coverage regardless of weather conditions. This information will be useful to shipping companies in North America, Europe and Asia, and to government agencies with ice reconnaissance and mapping mandates. SAR also is a valuable tool for mapping the Earth's structural features such as faults, folds and lineaments. These features provide clues to the distribution of ground water, mineral deposits and oil and gas in the Earth's crust. RADARSAT will facilitate the mapping and planning of land-use and will accurately monitor disasters such as oil spills, floods and earthquakes. The use of satellite remote sensing technology is growing, driven by the need to better monitor the environment and the availability of more affordable information integration systems, including Geographic Information Systems (GIS). Major natural resource industries such as mining, fishing, farming and forestry can be better managed if monitored effectively and accurately. RADARSAT will fulfill that need by providing high-quality and cost-effective data.

RADARSAT SAR Characteristics

Frequency / Wavelength	5.3GHz/C-band 5.6 cm
Antenna Polarization	HH
RF Bandwidth	11.6, 17.3 or 30.0 Mhz
Transmitter Power (peak)	5 kW
Transmitter Power (average)	300 W
Maximum Data Rate	85 Mb/s (recorded) - 105 Mb/s (R/T)
Antenna Size	15m x 1.5m
Ground Resolution	10 - 100 m

Data Acquisition

RADARSAT will be placed in a sun-synchronous orbit at an altitude of 798 kilometres above the Earth, at an inclination of 98.6 degrees to the equatorial plane. Because it will be placed in a dawn-dusk orbit, RADARSAT's solar arrays will be in almost continuous sunlight, enabling it to primarily rely on solar rather than battery power. The sun-synchronous orbit also means that the satellite overpasses are always at the same local mean time, which is important to many users.

RADARSAT will offer users a variety of beam selections. The satellite's SAR will have the unique ability to shape and steer its beam from an incidence angle of less than 20 degrees to more than 50 degrees, in swaths of 35 to 500 kilometres, using resolutions ranging from 10 to 100 metres. RADARSAT will cover the Arctic daily and most of Canada every 72 hours depending on the swath selected. The entire Earth will be covered every 24 days using the standard 100-kilometre beam mode. Data will be down-linked in real time, or stored on one of the two tape recorders until the spacecraft is within range of a receiving station. Processed data is expected to be available to on-line users within a few hours after the satellite passes over an area.

Imaging Beam Modes

Mode	Resolution (m) Range 1x azimuth (m)	Looks2	Width (km)	Incidence Angle 3 (degrees)
Standard	25 x 28	4	100	20-49
Wide - 1	48-30 x 28	4	165	20 - 31
Wide - 2	32-25 x 28	4	150	31 - 39
Fine resolution	11-9 x 9	1	45	37 - 48
ScanSAR narrow	50 x 50	2 - 4	305	20 - 40
ScanSAR wide	100 x 100	4 - 8	510	20 - 49
Extended (H)	22-19 x 28	4	75	50 - 60
Extended (L)	63-28 x 28	4	170	10 - 23

1. Nominal; ground range resolution varies with range
2. Nominal; range and processor dependent
3. Incidence angle depends on sub-mode

Sensors

Last Modified: Wed Apr 14, 1999
CSR/TSGC Team Web