During the late 1950s, Bull conducted preliminary launch experiments at the CARDE (now known as Defence Research and Development Canada – Valcartier, or DRDC Valcartier) using guns as small as 76mm. These experiments soon caught the attention of the U.S. Army's Ballistic Research Laboratory as well as the U.S. Army's Chief of Army Research and Development, Lieutenant general Arthur Trudeau. At the time, aircraft engineers needed more information on the upper regions of the atmosphere in order to design better jet planes. However, launching rockets into the air to collect data was generally considered costly and inefficient. The U.S. military, in particular, was especially in need of a low-cost launch system that could cover altitudes that conventional aircraft and weather balloons couldn't reach to support the development of new supersonic aircraft and missile systems. By late 1960, CARDE and the Ballistic Research Laboratory (BRL) conducted several feasibility studies surrounding the structural integrity of small gun-launched probes. Around the same time, BRL developed a smooth-bore, 5-inch gun system at Aberdeen Proving Ground that successfully launched a probe to altitudes exceeding 220,000 feet.