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{{Short description|Canadian Earth observation satellite (1995–2013)}}
{{Use Canadian English|date=November 2021}}
{{Use dmy dates|date=November 2021}}
{{Infobox spaceflight
| name              = RADARSAT-1
| names_list        = 
| image             = Radarsat-1.gif
| image_caption     = RADARSAT-1 satellite
| image_size        = 300px

| mission_type      = [[Earth observation satellite|Earth observation]]
| operator          = [[Canadian Space Agency]]
| COSPAR_ID         = 1995-059A 
| SATCAT            = 23710
| website           = {{url |http://www.asc-csa.gc.ca/eng/satellites/radarsat1/}}
| mission_duration  = 5 years (planned)<br/>{{time interval|4 November 1995 14:22|29 March 2013|show=ymd|sep=,}} (achieved)

| spacecraft_bus    = [[RADARSAT]]
| manufacturer      = [[MacDonald Dettwiler|MDA]] (formerly [[Spar Aerospace]])<br/>[[Ball Aerospace]]
| launch_mass       = {{cvt|2750|kg}} <ref name=characteristics>{{Cite web|url=http://www.asc-csa.gc.ca/eng/satellites/radarsat/radarsat-tableau.asp|title=Satellite Characteristics|date=21 January 2011 |access-date=20 October 2014 |publisher=Canadian Space Agency}}</ref>
| power             = 2.1 [[Watt|kW]]

| launch_date       = 4 November 1995, 14:22 [[Coordinated Universal Time|UTC]]
| launch_rocket     = [[Delta II]] 7920-10
| launch_site       = [[Vandenberg Space Force Base|Vandenberg]], [[Vandenberg Space Launch Complex 2|SLC-2W]]
| launch_contractor = [[Boeing]]

| entered_service   = 
| last_contact      = 29 March 2013
| deactivated       = 
| decay_date        =

| orbit_reference   = [[Geocentric orbit]]
| orbit_regime      = [[Low Earth orbit]]
| orbit_periapsis   = {{cvt|793|km}}
| orbit_apoapsis    = {{cvt|821|km}}
| orbit_inclination = 98.60°
| orbit_period      = 100.70 minutes
| apsis             = gee

| instrument_type   = radar

| programme         = [[RADARSAT Constellation|RADARSAT constellation]]
| previous_mission  = 
| next_mission      = [[Radarsat-2|RADARSAT-2]]
}}

'''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 [[Coordinated Universal Time|UTC]] on 4 November 1995,<ref>{{cite web|url=http://www.asc-csa.gc.ca/eng/satellites/radarsat1/|title=RADARSAT-1|date=11 September 2006 |access-date=20 October 2014}}</ref> from [[Vandenberg Space Force Base|Vandenberg Air Force Base]] in [[California]], into a [[Sun-synchronous orbit]] (dawn-dusk) above the [[Earth]] with an [[altitude]] of {{cvt|798|km}} and [[Orbital inclination|inclination]] of 98.60°.<ref name=characteristics/> Developed under the management of the [[Canadian Space Agency]] (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.<ref>{{cite web
 | last       = Jezek
 | first      = Kenneth
 | title      = 2006 Anniversary Edition – A Brief History of the RADARSAT-1 Antarctic Mapping Project
 | url        = https://asf.alaska.edu/notable/2006-anniversary-edition-a-brief-history-of-the-radarsat-1-antarctic-mapping-project/
 | work       = [[Alaska Satellite Facility]]
 | date = 18 April 2019
 | access-date  = 2023-01-15
}}</ref><ref>{{cite book
 | title      = Mapping Antarctica and Greenland with Shuttle Imaging Radar: A Report
 | pages      = 18
 | date       = September 1985
 | publisher  = [[California Institute of Technology]], [[Jet Propulsion Laboratory]]
}}</ref>

[[NASA]] provided the [[Delta II]] 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 ([[Quebec|Québec]], [[Ontario]], [[Saskatchewan]] and [[British Columbia]]) 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|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 was designed under the leadership of Dr. Peter Wood and built by Canadian Astronautics Limited (CAL) in Ottawa, to image the Earth at a single [[microwave]] frequency of 5.3&nbsp;GHz, in the [[C band (IEEE)|C band]] (wavelength of 5.6&nbsp;cm).<ref name=characteristics/> The SAR support structure was designed and manufactured by [[Northrop Grumman|Northrop Grumman Astro Aerospace]] and deployed to {{cvt|15|m}} 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 {{cvt|50|xx|50|km}} ({{cvt|2500|km2}}) with a resolution of {{cvt|10|m}}; Standard, which covered an area of {{cvt|100|xx|100|km}} ({{cvt|10000|km2}}) and had a resolution of {{cvt|30|m}}; and ScanSAR wide, which covered a {{cvt|500|xx|500|km}} ({{cvt|250000|km2}}) area with a resolution of {{cvt|100|m}}. RADARSAT-1 also had the unique ability to direct its beam at different angles.<ref name=characteristics/>

== Orbit ==
[[File:Radarsat 1 orbit trace.png|thumb|upright=1.0|left|Orbital trace of Radarsat-1]]

With an [[orbital period]] of 100.70 minutes, RADARSAT-1 circled the Earth 14 times a day.<ref name=characteristics/> 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 [[Interferometric synthetic aperture radar|interferometry]] 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,<ref name=characteristics/> 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]], it faces west, and when it ascends from the [[South Pole]], 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.<ref>{{cite press release|url=http://www.asc-csa.gc.ca/eng/media/news_releases/2010/1104.asp|title=Canadian satellite RADARSAT-1 celebrating 15 years of service to Canada and the world|access-date=2010-11-15|publisher=Canadian Space Agency|date=4 November 2010|url-status=dead|archive-url=https://web.archive.org/web/20101218235335/http://www.asc-csa.gc.ca/eng/media/news_releases/2010/1104.asp|archive-date=18 December 2010}}</ref> It outlived its planned five-year lifetime by a wide margin. [[Radarsat-2]] was launched on 14 December 2007 from [[Baikonur]], [[Kazakhstan]]<ref>{{cite news|url=https://www.cbc.ca/news/science/soyuz-rocket-lifts-canadian-radar-satellite-into-space-1.691231|title=Soyuz rocket lifts Canadian radar satellite into space|access-date=2007-12-14|publisher=CBC News|date=14 December 2007}}</ref>

RADARSAT-1 covered the [[Arctic]] 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|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 [[MacDonald, Dettwiler and Associates|MDA Geospatial Services Inc.]] concluded that RADARSAT-1 was no longer operational.<ref>{{cite press release|url=http://www.asc-csa.gc.ca/eng/media/news_releases/2013/0509.asp|title=RADARSAT-1: Seventeen Years of Technological Success|access-date=2013-05-30 |publisher=Canadian Space Agency|date=9 May 2013|url-status=dead|archive-url=https://web.archive.org/web/20130624011736/http://www.asc-csa.gc.ca/eng/media/news_releases/2013/0509.asp|archive-date=24 June 2013}}</ref>

== See also ==
{{Portal|Spaceflight}}
* [[RADARSAT-2]]
* [[RADARSAT Constellation]]

== References ==
{{Reflist}}

== External links ==
* [http://www.asc-csa.gc.ca/eng/satellites/radarsat1/ RADARSAT-1 from the CSA]

{{MDA Space Missions|state=autocollapse}}
{{Canadian Space Agency}}
{{Rest of the World Reconnaissance Satellites}}
{{Orbital launches in 1995}}

[[Category:Earth observation satellites of Canada]]
[[Category:Spacecraft launched in 1995]]
[[Category:Spacecraft launched by Delta II rockets]]
[[Category:Space synthetic aperture radar]]