2006 Anniversary Edition
2006 Special Anniversary Edition
What is now the Alaska Satellite Facility (ASF), started out as a single-purpose imaging-radar receiving station conceived by a small working group formed by the National Aeronautics and Space Administration (NASA) in 1982.
Synthetic Aperture Radar (SAR) satellites, when they were introduced, provided a new and exciting tool to look at Earth. The United States pioneered the scientific use of these satellites with Seasat, but the satellite had only a short lifetime and the European Space Agency (ESA) had proposed to launch its own SAR satellite.
The RADARSAT-1 Antarctic Mapping Project (RAMP) was conceived in the early 1980’s by Stan Wilson, Bob Thomas, and Bill Townsend. The idea developed as part of negotiations over participation by NASA in the Canadian Space Agency’s (CSA) RADARSAT-1 project. Both Ed Langham at CSA and Shelby Tilford at NASA reacted favorably to the exciting concept, and two complete mappings of the Antarctic were included in the Memorandum of Understanding.
The Japanese Aerospace Exploration Agency (JAXA; formerly known as NASDA) successfully launched the Japanese Earth Resources Satellite (JERS-1, nicknamed FUYO) in late 1992 into a polar sun-synchronous, 44-day, repeat orbit that allowed image coverage of most of the Earth. The JERS-1 instrument package included an L-band, HH-polarized SAR, along with two optical instruments.
The first radar images that I ever saw were those in a publication that is, or should be, familiar to anyone associated with ASF - Seasat Views Oceans and Sea Ice with Synthetic Aperture Radar by Lee-Leung Fu and Ben Holt. I ordered a copy soon after its publication in February 1982 when I read that it contained images of ice island (tabular iceberg) T-3, sometimes known as Fletcher’s Ice Island.
A synthetic aperture radar (SAR) system transmits electromagnetic (EM) waves at a wavelength that can range from a few millimeters to tens of centimeters. The radar wave propagates through the atmosphere and interacts with the Earth’s surface.
The ability to derive quantitative estimates of fine-scale ice motion and deformation from pairs of Seasat SAR images provided the primary scientific basis for implementing ASF. Being able to identify the detailed opening and closing of leads and how the ice cover moved and deformed over short time intervals provided basic knowledge of air-sea-ice heat and momentum fluxes.