Components and specifications

radarsat1

RADARSAT covered the Arctic daily, and most of Canada every 72 hours depending on where the instruments were pointing, and what they were monitoring. It covered the entire Earth every 24 days. (Credit: Canadian Space Agency)

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Synthetic Aperture Radar (SAR) on RADARSAT-1

RADARSAT-1 was equipped with an advanced radar sensor, the synthetic aperture radar SAR. It was a powerful microwave instrument. It transmitted and received signals for capturing high quality images of the Earth night and day and in all weather conditions. As an active sensor, RADARSAT-1's SAR transmitted a microwave energy pulse (C-band at 5.3 GHz frequency) to the Earth, and the SAR measured the amount of energy that is reflected back to the satellite from the Earth's surface.

Spacecraft Characteristics
Launch mass (total) 2,750 kg
Array power 2.5 kW
Batteries 3 x 48 Ah NiCd
Design lifetime 5 years
Synthetic Aperture Radar Characteristics (SAR)
Frequency/wavelength 5.3 GHz/band C, 5.6 cm
Radio frequency bandwidth 11.6, 17.3 or 30 Mhz
Transmitter power (peak) kW
Transmitter power (average) 300 W
Maximum data rate 85 Mb/s (recorded) - 105 Mb/s (R/T)
Antenna size 15 m x 1.5 m
Antenna polarization HH

Imaging modes and beam calibration information

RADARSAT's SAR instrument could shape and steered its radar beam using C-band. A wide variety of beam widths were available to capture swaths of 45 to 500 km, with a range of 8 to 100 m in resolution and incidence angles of 10 to 60 degrees. These images could be downlinked in real-time to the receiving stations or recorded on the on-board recorder for later downlink to Canada.

For technical information of interest to data users, please consult the pages on beam calibration.

Imaging modes
Mode Nominal Resolution (m) No. of Positions / Beams Swath Width (km) Incidence Angles (degrees)
Fine 8 15 45 34 - 47
Standard 30 7 100 20 - 49
Wide 30 3 150 20 - 45
ScanSAR narrow 50 2 300 20 - 49
ScanSAR wide 100 2 500 20 - 49
Extended high 18 - 27 3 75 52 - 58
Extended low 30 1 170 10 - 22
Ground cover of various modes of beam.

Text description of image - Beam mode

(Credit: Canadian Space Agency)

Beam mode ground coverage

RADARSAT could provide nearly complete global landmass coverage, and could support specific requirements. The satellite's orbit path repeated every 24 days. But RADARSAT could also:

  • provide daily coverage of the Arctic,
  • view any part of Canada within three days
  • achieve complete coverage at equatorial latitudes every six days using the 500-km wide swath
Coverage and Frequency Using Maximum Swath Width
North of 70°N Daily
North of 48°N Every 4 days
The Earth (except the centre of Antarctica, 80°S and 90°S) Every 6 days
The Twilight RADARSAT orbit

RADARSAT's dawn- to-dusk path (red line) ensured that the solar arrays were constantly exposed to the Sun, although in June-July, it was in the dark for a few minutes of each orbit over Antarctica. (Credit: Canadian Space Agency)

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Orbit

RADARSAT was in orbit 798 km above the Earth, circling from pole to pole in asun-synchronous orbit. The dawn-to-duskorbit placed its solar panels in sunlight almost constantly ensuring reliable solar power and provided the optimum number of viewing opportunities.

Because of its sun-synchonous orbit, it passed over a given place at the same local time. This minimized the effects of diurnal variations and was key in obtaining data over time as is, for example, data used in predicting harvests. The satellite was rarely in eclipse and could acquire data at any time. The descending equatorial crossing for a dawn-to-dusk orbit was 6 hours.

RADARSAT could acquire up to 28 minutes of data for each 100.7-minute orbit. Data was downlinked in real time to ground receiving stations or stored on the onboard tape recorder until RADARSAT was within range of a receiving station. In critical situations, data could be processed and delivered within 4 hours of acquisition.

Orbit Characteristics
Altitude 793-821 km
Inclinaison 98.6 degrees
Duration of one orbit 100.7 min
Descending node 6 hr
Ascending node 18 hr
Sun-synchronous 14 orbit per day

Ground Segment: Network Stations

Data collected by RADARSAT-1 was transmitted directly to a Data Reception Facility or could be stored onboard for downloading later. The receiving stations provided:

  • complete and reliable real-time coverage around the world
  • consistency in format for high-quality products
  • timely delivery of the requested data

Each new station was gradually integrated into the system in a certification process developed by the Canadian Space Agency (CSA) and MacDonald, Dettwiler and Associates Ltd. (MDA) Geospatial Services (formerly RADARSAT International). This process guaranteed a uniform, high level of performance and data quality.

Many data reception facilities were added and this has created a broad global network. By 2013, the RADARSAT-1 network comprised 33 Data Reception Facilities, including six transportable ones for real-time coverage of nearly all the landmass on Earth.

With such a comprehensive network of receiving stations around the globe, RADARSAT-1 could deliver near-real-time, reliable monitoring services for applications such as monitoring floods, maritime pollution, and oil spills.

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RADARSAT-1 offered global coverage through a ground station network. Additional coverage was provided by portable stations. (Credit: Canadian Space Agency)

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Canadian Data Reception Facilities

The Canada Centre for Remote Sensing (CCRS) operates two Canadian ground-receiving facilities, in Gatineau, Quebec, and Prince Albert, Saskatchewan. CCRS coordinates the acquisition services and is responsible for scheduling and reporting day-to-day operations. Imagery for public use is placed on the Web-accessible CEOCat browser and catalogue service.

International Data Reception Facilities

The network includes two American facilities: one in Fairbanks, Alaska, and one in MacMurdo, Antarctica. Other facilities have been incorporated to ensure coverage of the Earth's landmass in the United States (U.S.), the United Kingdom, Norway, Singapore, China, Australia, Korea, Japan, South Korea, and Saudi Arabia, Puerto Rico, Thailand, Brazil, Argentina, Turkey, Malaysia, Russia, and Kazakhstan.

Six portable ground stations in other parts of the world provide coverage opportunities for applications such as pollution control, oil and gas exploration, surveillance, and emergency response management.