Table of Contents

Background mission

Archiving global radar data

The RADARSAT-1 Background Mission has created an archive of uniform global SAR data using the satellite's multi-mode imaging capabilities.

Apart from commercializing the use of RADARSAT-1 SAR data and meeting specific user needs, the RADARSAT-1 Program has undertaken two important baseline missions. The first is the high-resolution satellite coverage of Antarctica two times during the mission (completed in October 1997 and December 2000). The second is the ongoing Background Mission, which, since 1996, has generated multiple data acquisitions of the Earth's surface using the various imaging modes of the spacecraft.

Beam modes are the RADARSAT advantage

Using the ScanSAR Wide beam with a 500-kilometre-wide imaging swath and 100-metre resolution, the world's continental mass, continental shelves, and polar caps were imaged in 1997 as part of the Background Mission.

A second coverage using the ScanSAR Narrow beam with a 300-kilometre-wide imaging swath and 50-metre resolution was done during different seasons from those of the first coverage. 

Creating continental mosaics

RADARSAT-1 was used to generate high-resolution mosaics of the continents as a snapshot in time of the area. Using the ScanSAR Narrow beam coverage, mosaics of Canada, the U.S., and Australia were produced.  A mosaic of Africa  was completed using the ScanSAR Wide and Narrow beams. These were acquired in relatively short time spans and can be used for studying terrestrial geology, geomorphology, vegetation, coastal features, wetlands, urbanization and ice dynamics.

In keeping with its ongoing mission, RADARSAT-1 acquired a stereo data set of the world's entire landmass. This stereo data set used a combination of Standard beams (7, 4 and 2) and the Wide 2 beam.

The first coverage of the stereo data sets was carried out with a very shallow incidence angle (47 degrees) RADARSAT-1 Standard 7 beam (S7). The second coverage used steeper beams (S2 and S4), although the Wide 2 beam was sometimes used to complete the coverage. Seasonal coherence was maintained where possible to ensure high-fidelity stereo pairs.

These mosaics were produced as a joint project between CSA and MDA Geospatial Services. Data were received by the Canada Centre for Remote Sensing and processed by MDA. The full-scale mosaics are available from MDA.

The Antarctica Mosaic

For a brief period in 1997, to capture images of Antarctica, RADARSAT-1 was rotated 180 degrees in yaw so the radar could image to the left of the satellite track instead of the right, which is its normal view. Images were acquired while the satellite was looking left and the result was a stereo pair that included left- and right-looking image pairs using Standard 4 beams.

No matter how small or how remote

In addition to imaging continental masses with various RADARSAT-1 beam modes, multiple Background Mission imaging campaigns from 1996 to 2001 have covered over 50 oceanic islands, from the Arctic to the sub-Arctic, mid-latitudes, and Antarctic regions. Because of their size and remoteness, these islands are often ignored in Global Earth System studies. RADARSAT, with its on-board recorder, various imaging modes, swath widths and resolution, offered a unique opportunity to acquire remote sensing data of the islands. Thus, the Background Mission provided an archive of multi-step imagery to observe seasonal changes on the islands.

The Background Mission has also acquired Fine beam images (10-metre resolution) of the world's major and capital cities from 1998, and over 170 cities have been imaged.

Disaster response efforts and research

Currently, the RADARSAT-1 extended Background Mission provides ongoing coverage of the Arctic Basin and the world's major deltas. The data will help in understanding the effects of global warming and other environmental phenomena.

Special coverage helps monitor natural disasters under the Canadian Space Agency's Disaster Watch program and the International Charter "Space and Major Disasters." In fact, the RADARSAT-1 image archives are regularly used as a reference because they show an area's state prior to the occurrence of a disaster.

RADARSAT-1's full view of Canada

This mosaic is the first complete view of Canada from space obtained by RADARSAT-1. Its 276 ScanSAR Narrow beam images were captured over a brief seven-day period in January 1999, producing a "snapshot" of the entire country. Because of darkness and cloud cover, satellites with optical and infrared sensors would take a very long time to capture such a vast territory. RADARSAT's synthetic aperture radar (SAR) sensor captures data through clouds, darkness, smoke and fog. In addition, its unique ScanSAR beams covers swaths 300 to 500 kilometres wide, distinguishing RADARSAT-1 from the other SAR satellites in operation.

The ability of RADARSAT-1 to capture seasonal overviews like this one, is especially useful for environmental change detection, regional-scale mapping, and ice and ocean monitoring.

Contact 

For more information, please contact:

Dr. Ahmed Mahmood
Manager, Missions
Executive Secretariat, International Charter "Space and Major Disasters"
Satellite Operations
Canadian Space Agency
6767 Route de l'Aéroport
Longueuil, Quebec  J3Y 8Y9
Telephone: 450-926-4432
Fax: 450-926-4433
E-mail: ahmed.mahmood@asc-csa.gc.ca