Operation Moonwatch in Australia

Abstract

When the United States decided to launch a satellite during the International Geophysical Year, it also needed to develop a network of tracking stations to monitor the satellite in orbit. The Smithsonian Astrophysical Observatory (SAO) developed an optical tracking network using Baker-Nunn telescope cameras to photograph the satellite against the fixed star background, enabling a precise determination of its orbit. These optical tracking cameras had a very narrow field of view. Calculations suggested that the first satellite would have a visual magnitude just at the limit of naked-eye visibility. Therefore, it would be a challenge for them to initially locate their high-altitude target.Anticipating this problem, Dr Fred L. Whipple, Director of the SAO, conceived a unique solution – recruiting a worldwide cadre of volunteer observers, particularly amateur astronomers, who would scan the skies at dawn and dusk reporting any satellite sightings to the SAO. These sightings would provide approximate locations for the Baker-Nunn observatories to begin their precision tracking. This global volunteer program, known as Operation Moonwatch, can be considered the first ‘citizen science’ project of the Space Age. Despite initial scepticism about this aspect of the optical tracking program, Moonwatch volunteers around the world made significant contributions to early satellite tracking.Operation Moonwatch groups in Australia made important contributions to this satellite tracking program, including several satellite spotting ‘firsts’. This paper will outline the Moonwatch program's history in Australia, focusing on the initial groups established to participate in the International Geophysical Year. It will look at their operations and the challenges they faced as volunteer organisations with limited funding, as well as their significant successes in satellite tracking and participation in the SAO's special observing programs.