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RADARSAT-1 is Canada's first commercial Earth observation satellite. It was launched at 14h22 UTC on November 4, 1995 from Vandenberg AFB in California, into a sun-synchronous (dawn-dusk) orbit above the Earth with an altitude of 798 kilometers and inclination of 98.6 degrees. Developed under the management of the Canadian Space Agency (CSA) in cooperation with Canadian provincial governments and the private sector, it provides images of the Earth for both scientific and commercial applications. RADARSAT-1's images are useful in many fields, including agriculture, cartography, hydrology, forestry, oceanography, geology, ice and ocean monitoring, arctic surveillance, and detecting ocean oil slicks.

RADARSAT-1 uses a Synthetic Aperture Radar (SAR) sensor to image the Earth at a single microwave frequency of 5.3 GHz, in the C band (wavelength of 5.6 cm). Unlike optical satellites that sense reflected sunlight, SAR systems transmit microwave energy towards the surface and record the reflections. Thus, RADARSAT-1 can image the Earth, day or night, in any atmospheric condition, such as cloud cover, rain, snow, dust or haze.

Each of RADARSAT-1's seven beam modes offer a different image resolution. The modes include Fine, which covers an area of 50km by 50km (2500km²) with a resolution of 10 meters; Standard, which covers an area of 100km by 100km (10,000km²) and has a resolution of 30 meters; and ScanSAR wide, which covers a 500km by 500km (250,000 km²) area with a resolution of 100 meters. RADARSAT-1 also has the unique ability to direct its beam at different angles.

With an orbital period of 100.7 minutes, RADARSAT-1 circles the Earth 14 times a day. The orbit path repeats every 24 days, this means that the satellite is in exactly the same location and can take the same image (same beam mode and beam position) every 24 days. This is useful for interferometry and detecting changes at that location that took place during the 24 days. Using different beam positions, a location can also scanned every few days.

RADARSAT-1 is a right-looking satellite, meaning that microwave beam transmits and receives on the right side of the satellite, relative to its orbital path. As it descends in its orbit from the North Pole, it faces west, and when it ascends from the South Pole, it faces east. Locations can therefore be imaged from opposite sides. Combined with the different beam modes and positions, this provide users with many possible perspectives from which to image a location.

National Aeronautics and Space Administration (NASA) provided the Delta II rocket to launch RADARSAT-1 in exchange for access to its data. Estimates are that the project, excluding launch, cost $620 million (Canadian). The Canadian federal government contributed about $500 million, the four participating provinces (Quebec, Ontario, Saskatchewan and British Columbia) about $57 million, and the private sector about $63 million.

RADARSAT International, Inc. (RSI), a Canadian private company, was created in 1989 to process, market and distribute RADARSAT-1 data. (Radarsat International, Inc. (RSI) was later acquired by MacDonald Dettwiler and Associates.) In 2006, RSI was rebranded MDA Geospatial Services International or MDA GSI

As of Nov. 2006, RADARSAT-1 continues to operate, well beyond its planned five-year lifetime. RADARSAT-2 is under development and is scheduled for launch in March 2007.

RADARSAT-1 covers the Arctic daily, and most of Canada every 72 hours depending on where the instruments are pointing, and what they are monitoring. It covers the entire Earth every 24 days.

• RADARSAT from the Canada Centre for Remote Sensing
• RADARSAT-1 from the CSA