Image courtesy of Tom George.
by Gunter Weller – Director, ASF, 1986-1993
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 question at NASA was whether to push for the launch of another U.S. SAR satellite or to work with the Europeans, making use of their data in return for launch and other help. NASA decided that it would be more cost-effective to build a receiving station rather than a new satellite. To get maximum area coverage and data downlink from these polar-orbiting satellites, the receiving station would have to be at high latitude. A multiple high-latitude receiving station network would ensure almost complete coverage of the polar regions. A report titled “Science Program for an Imaging Radar Receiving Station in Alaska” was written by a science working group in 1983.
In 1986 I was asked by Stan Wilson of NASA to explore the possibility of the Geophysical Institute (GI) hosting such a station. The GI had worked with NASA in the past therefore it seemed a good location, combining a high latitude on US soil with proven expertise and experience in both satellite tracking and geophysical research. At the time I was the chairman of the National Research Council’s Polar Research Board and Stan proposed that I become the director of the ASF. The person who would be essential for the success of the entire enterprise was John Miller, a senior engineer at the GI with considerable experience in the technical aspects of satellite tracking stations, including the Minitrack station and early ESRO (later ESA) tracking stations in Fairbanks. He agreed to become the Operations Manager. Professor Willy Weeks added scientific expertise as the Chief Scientist of the ASF.
A Memorandum of Agreement between NASA and the University of Alaska was drawn up and signed by the NASA Administrator and the President of the University. It stipulated that NASA would provide the equipment needed for the station and pay for its operating costs while the University would provide the necessary facilities, including housing the equipment and providing a suitable platform for the large satellite antenna, and it would also provide the staff to operate the facility. The University also insisted in being included in any research conducted with the satellite data so that it would not simply provide a service function for NASA.
Location, Location, Location
A site for the ASF had to be found and the obvious choice was to locate it in the Elvey Building, the home of the GI. Considerable modifications were needed for this. For a start, room had to be created for the location of the receiving and processing equipment and for the staff to operate this equipment. This was done by enclosing the patio that existed between the main tower of the Elvey Building and its annex. More importantly, where was the heavy 10-m diameter steerable receiving antenna to be located? After looking at various options it was decided that the roof of the seven-floor building would be ideal since it provided a good unobstructed horizon and station mask. Fortunately, the building was originally designed to have two more floors, which were deleted due to budget constraints, so the concrete core was strong enough to hold the antenna on top, after additional concrete was poured to provide a suitable platform. The construction work began in 1988 and was completed a year later. It was paid for completely by the University as agreed under the MOA.
In 1990, ASF was fully operational and awaited the launch of ERS-1. Due to limited data storage on the satellite, most of the data could only be received while the satellite was above the horizon as seen by a station. This was the reason to have several stations covering the polar region. Coverage of the region was a key objective of the ERS-1 program. ERS-1 was launched successfully in 1991 and the Japanese JERS-1 satellite in 1992. ASF began to receive and process massive amounts of data. One copy of the data was kept at ASF and another sent to either the European or Japanese satellite agencies.
ASF was also involved in the research made possible by the use of SAR data. Only approved researchers had access to the data and ASF submitted an omnibus proposal from University researchers called ALASKA (Arctic Lands and Shelves: Key Assessments) which was discussed and approved by ESA at several meetings in Frascati, Italy, and Noordwijk, Netherlands. The SAR data provided unique opportunities to examine sea ice and algorithms were developed with colleagues at JPL in Pasadena to track and quantify sea-ice movement. Geographical features, including volcanoes, glaciers, and other land forms were also studied.
Much has happened since the early days, but ASF has become an efficient and successful activity at the GI, and continues to provide excellent services to numerous researchers around the world.