Hans Beat Wackernagel (1931–1992)

H. Beat Wackernagel, best known for his pioneering role in the development of US Space Command's ability to maintain a catalog of all manmade space objects, died in Colorado Springs on 2 August 1992. He is survived by his wife, the former Irene Chavez, two daughters and two sons.

Born in Basel, Switzerland on 31 August 1931, Beat received his PhD in astronomy, physics, and mathematics from the University of Basel in 1958. He entered the United States that same year, having been recruited by the US Air Force to assist in the development of a "space surveillance capability." Sputnik 1 had been launched on 4 October of the previous year, and the Air Force had now identified a military requirement for the surveillance of space and was assembling a new scientific and engineering team to design, develop, and operate a space tracking and surveillance system that could maintain current accurate orbital elements for the population of space objects expected to grow steadily with time.

The space surveillance team was assembled in the basement of a building of the Air Force Geophysics Research Laboratory at Hanscom Field, Massachusetts. They and their vacuum pumps were squeezed behind shipping and receiving. Despite the inhospitable environment, the team made rapid progress. Their first milestone was acquiring the technical means of space surveillance. It turned out out that the Smithsonian had just ordered a dozen Baken-Nunn satellite tracking cameras for scientific research. The Air Force just increased the order to 17 cameras and deployed its own allotment of five to provide global optical space surveillance. Beat was involved in reducing tracking data from the cameras, in modeling the geopotential needed to derive the perturbations on a satellite's orbit that cause it to depart from a Keplerian (osculating) ellipse, and in developing estimation-theoretic models needed to update preliminary, deterministice estimates of the orbital elements.

The space surveillance team recognized that optical data alone could not lead to accurate, near-real-time orbit determinations and mission assessment, because it provided no measurement of distance and because the reduction of tracks to topocentric right ascension and declination took too long. Radar was adapted to the problem by civilian laboratories and contractors under Air Force supervision, and within about two years of its inception, the space surveillance team had its disposal observations that consisted of time, azimuth, elevation (altitude to an astronomer), and range (sensor-to-satellite distance).

The new space surveillance program grew quickly and split into a research and development segment at Hanscom and an operations segment in Colorado Springs. Wackernagel chose to go with the operations segment and remained with it until his retirement in 1990, after 32 years of federal civil service, which was recognized by a letter from then President Bush on the occasion of his retirement. He and C.G. Hilton collaborated on Mathematical Foundation for Space Surveillance Center Astrodynamic Theory in their years together at Colorado Springs, where, after nearly 20 years, it is still the "bible of space surveillance applications." The fact that space surveillance adheres to the metric system is directly attributable to Beat. Although his Spacetrack Earth Model (STEM) for the geopotential has now been superseded, it was long the standard for classified military space tracking data.

In the later years of his career, Beat involved himself with the Global Positioning System and with its implications for space surveillance as well as for terrestrial navigation. He lectured on astronomy and astrodynamics and on the GPS and its applications at the University of Colorado in Colorado Springs. He was a pilot holding licenses for single and multi-engine aircraft, gliders, and hot air balloons, and was for many years, an official of the annual Colorado Springs Labor Day Weekend Balloon Contest.

Beat loved Colorado Springs and played an important role in its emergence as a center for space operations. He is remembered and missed by his many colleagues and fellow space enthusiasts. He was an emeritus member of AAS at the time of his death and had previously been a member of the Division on Dynamical Astronomy.

A note from the editor: We feel a good deal of sorrow and embarrassment that we only became aware of the death of fellow AAS member Beat Wackernagel nearly five years after the fact, and even then only because his colleague, Roger Mansfield, told us. The AAS will try to keep better track of its emeritus members in the future!