RADARSAT-1 was Canada's first commercial Earth observation satellite. It utilized synthetic aperture radar (SAR) to obtain images of the Earth's surface to manage natural resources and monitor global climate change. As of March 2013, the satellite was declared non-operational and is no longer collecting data.

Mission

RADARSAT-1 was launched at 14:22 UTC on 4 November 1995, from

Vandenberg Air Force Base Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in Key West, Florida * Vandenberg S ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

, into a

Sun-synchronous orbit A Sun-synchronous orbit (SSO), also called a heliosynchronous orbit, is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time. More technically, it is ...

(dawn-dusk) above the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

with an

altitude Altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum (geodesy), datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometr ...

of and inclination of 98.60°. Developed under the management of the

Canadian Space Agency The Canadian Space Agency (CSA; ) is the national space agency of Canada, established in 1990 by the ''Canadian Space Agency Act''. The President of the Canadian Space Agency, president is Lisa Campbell (civil servant), Lisa Campbell, who took ...

(CSA) in co-operation with Canadian provincial governments and the private sector, it provided images of the Earth for both scientific and marketing purposes. RADARSAT-1's images were useful in many fields, including agriculture, cartography, hydrology, forestry, oceanography, geology, ice and ocean monitoring, arctic surveillance, and detecting ocean oil slicks.

History

The Canadian Space Agency (CSA) RADARSAT-1 project was conceived in the early 1980s and included discussions with NASA.

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

provided the

Delta II Delta II was an expendable launch system, originally designed and built by McDonnell Douglas, and sometimes known as the Thorad Delta 1. Delta II was part of the Delta rocket family, derived directly from the Delta 3000, and entered service in ...

launch vehicle to launch RADARSAT-1 and access to the NASA Deep Space Network (NASA DSN) in exchange for access to its data. Estimates are that the project, excluding launch, cost CA$620 million. The Canadian federal government contributed about CA$500 million, the four participating provinces ( Québec,

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Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...

and

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

) about CA$57 million, and the private sector about CA$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.

Payload

RADARSAT-1 used a synthetic aperture radar (SAR) sensor to image the Earth at a single

microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...

frequency of 5.3 GHz, in the C band (wavelength of 5.6 cm). The SAR support structure was designed and manufactured by Northrop Grumman Astro Aerospace and deployed to in length on orbit. Unlike optical satellites that sense reflected sunlight, SAR systems transmitted microwave energy towards the surface and recorded the reflections. Thus, Radarsat-1 imaged 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 offered a different image resolution. The modes included Fine, which covers an area of () with a resolution of ; Standard, which covered an area of () and had a resolution of ; and ScanSAR wide, which covered a () area with a resolution of . RADARSAT-1 also had the unique ability to direct its beam at different angles.

Orbit

With an orbital period of 100.70 minutes, RADARSAT-1 circled the Earth 14 times a day. The orbit path repeated every 24 days, meaning that the satellite was in exactly the same location and could take the same image (same beam mode and beam position) every 24 days. This was useful for

interferometry Interferometry is a technique which uses the ''interference (wave propagation), interference'' of Superposition principle, superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important inves ...

and detecting changes at that location that took place during the 24 days. Using different beam positions, a location could also be scanned every few days. RADARSAT-1 was a right-looking satellite, meaning that the 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 The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's rotation, Earth's axis of rotation meets its surface. It is called the True North Pole to distingu ...

, it faces west, and when it ascends from the

South Pole The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is the point in the Southern Hemisphere where the Earth's rotation, Earth's axis of rotation meets its surface. It is called the True South Pole to distinguish ...

, it faces east. Locations could therefore be imaged from opposite sides. Combined with the different beam modes and positions, this provided users with many possible perspectives from which to image a location.

End of service

On 4 November 2010, RADARSAT-1 celebrated its 15-year service anniversary. It outlived its planned five-year lifetime by a wide margin. Radarsat-2 was launched on 14 December 2007 from

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Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...

RADARSAT-1 covered the

Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...

daily, and most of Canada every 72 hours depending on instrument orientation and mode. It covered the entire Earth every 24 days. On 29 March 2013, RADARSAT-1 experienced a technical problem. The Canadian Space Agency (CSA) assembled a team of engineers, who conducted an extensive investigation. Following numerous attempts to resolve the problem, the CSA, in consultation with its commercial data distributor MDA Geospatial Services Inc. concluded that RADARSAT-1 was no longer operational.

References

External links

RADARSAT-1 from the CSA
{{Orbital launches in 1995 Earth observation satellites of Canada Spacecraft launched in 1995 Spacecraft launched by Delta II rockets Space synthetic aperture radar