The Type IV (T-4) Tracking Telescope at Mule Peak

The Type IV (T-4) Tracking Telescope at Mule Peak. . The instrument seen here is one of the early tracking telescopes that supported operations at WSMR during the height of the Cold War. Designed by engineers at the Army's Ballistics Research Laboratory in Maryland using direct input from Clyde Tombaugh, the T-4 filmed missile and rocket test flights - some at an altitude of at least 100 miles and flying at speeds in excess of 3,000 miles per hour at intense magnification on a high-speed camera. The recordings would make apparent small and subtle visual details not captured electronically to inform analysts of rocket behavior and performance., The 10-ton instrument was the largest tracking telescope in the world at the time. It consisted of a 16-inch Newtonian telescope (using mirrors rather than lenses for magnification) mounted to a 90-mm antiaircraft gun and hydraulic-powered gun mount. Tombaugh sited the T-4 atop Mule Peak, high in the Sacramento Mountains, roughly 40 miles northeast of WSMR's launch facilities. Of that location, Tombaugh stated, "I do not expect to ever find a spot more ideal in regard to the requirements for steady seeing," adding that "the entire range can be seen from the launcher to fully 100 miles northward.", The T-4's high-speed, 35-mm motion picture camera ran through 16 frames of film per second. Along with the magnified image, the T-4's film also recorded the instrument's orientation (elevation and azimuth), and a high-precision timestamp that was synchronized with other instruments on the range. During a test flight, the T-4's operator, called a "tracker", viewed the target through a six-inch spotting scope and kept it in frame with a pair of control handles., The T-4 filmed V-2, Viking, Nike Ajax, Aerobee, and WAC Corporal rocket launches, among others, from Mule Peak from 1948 through the early 1970s. It remained at Mule Peak for 71 years until its removal and restoration in 2019., Captions , Left: The T-4 tracking telescope featured in a 1948 issue of Popular Science magazine. , Above: Oblique diagram of WSMR showing the T-4's vantage over the full 100-mile-long range from atop Mule Peak, 4,000 feet above the desert floor. , Right: The T-4 fell into disrepair when newer technologies replaced it. It was removed from Mule Peak and restored in 2019. , Above: A "tracker" controls the T-4 atop Mule Peak. Dust and heat diffraction were less pronounced from that altitude, improving the T-4's imagery. The metal building in the background is a retractable shelter that protected the instrument, which was added in 1962. , Courtesy of WSMR Cultural Resources Program