The Prince Albert Radar Laboratory (PARL) was a radar research facility operated by the Defence Research Telecommunications Establishment (DRTE), part of the Canadian Defence Research Board. Its primary purpose was to test long-range radio propagation and radar techniques in the presence of the aurora borealis. This was part of a greater ABM effort being carried out in concert with the United States Air Force, and PARL operated along with two similar instruments at the Rome Air Development Centre and MIT Lincoln Laboratory. The site continues to operate today, used as a satellite downlink station known as the Prince Albert Satellite Station (PASS). The original study that led to PARL came about as the side effect of questions about the effects of the aurora on radar systems. There was some concern that the aurora could shield incoming reentry vehicles from observation until they were too low to be effectively attacked by the long range interceptor missiles then being designed (Nike Zeus). The United States Air Force sent a request to Peter Forsyth for further information. Forsyth had done extensive research on the aurora while earning his PhD at the University of Saskatchewan, Saskatoon, including the first observations using radar. Forsyth was invited to a meeting at Rome, the outcome eventually led to an agreement whereby two radars would be sent to Canada, one would be placed in Churchill, Manitoba where the aurora is often at its maximum, while another would be located a distance away at a lower "grazing angle" in order to compare the returns from two different locations. Finding a suitable location was not difficult; they wanted a site near Saskatoon so travel from the University would not be onerous, but one that would have line-of-sight visibility of Churchill. At first a site outside Dundurn was considered, but eventually Prince Albert was selected instead. This may have had a lot to do with Prince Albert being in the home riding of the Prime Minister, John Diefenbaker. After a visit to Millstone Hill Observatory, where the Lincoln Lab was developing what would become the BMEWS radar, a suitable lab for the Prince Albert site was selected. The Millstone Hill site used a prefab steel building, but a Canadian equivalent was selected in its place, and construction on the "silo" for the radar started while the buildings arrived and were assembled. The BMEWS radar operated on a frequency of 448 MHz