Robert Allen Sparks, an x-ray crystallographer who contributed greatly to the use of computers in his field, died with his wife Nonie on 29 July 2001 in a traffic accident on State Route 6 near their home in Tillamook, Oregon. They were returning home after attending the annual American Crystallographic Association (ACA) meeting in Los Angeles.
Born on 16 August 1928 in Hollywood, California, Bob was a friendly, soft-spoken man, passionately interested in crystallographic methods, and liked and respected by all. He possessed an infectious enthusiasm for crystallography and great patience for anyone willing to learn it. Bob received his BS in 1950 and MS in 1953, both in chemistry, from UCLA.
While at UCLA, with Ken Trueblood, Bob was involved in the early computational stages of determining the chemical formula of vitamin B12. Under Trueblood’s direction, Bob, as a graduate student early in 1954, helped write the computer programs for the National Bureau of Standards SWAC computer that enabled calculation of electron-density maps for vitamin B12. This work, writing programs for binary-coded punch cards in assembly language, was highly significant in the days when computers were simply glorified adding machines.
In the early 1950s, the structure of vitamin B12 was the largest one of unknown chemical formula (93 nonhydrogen atoms) to be tackled. Trueblood, anxious to try out these computations on large structures, contacted Nobel laureate Dorothy Crowfoot Hodgkin at Oxford University. She sent experimental data and Bob, with Trueblood, Dick Prosen, and others, worked through many nights on the computer to produce B12 maps. They replaced, when necessary, the vacuum tubes in SWAC, which had a 20-minute mean time between failures. The structure of the hexacarboxylic acid, which established the ring structure of vitamin B12, was published by Hodgkin and others in Nature in 1955, and the air-dried and wet native B12 structures, which Bob worked on, were published in various publications during the period 1959 to 1962.
Bob received his PhD in 1958 from UCLA under the direction of Trueblood. Bob’s thesis was entitled “I. Refinement of Crystal Structures. II. The Structure of Anthracene and Naphthalene. III. The Structure of Postassium Chlorate.” He then became an NSF postdoctoral fellow at Oxford in Hodgkin’s laboratory, where he wrote a program to locate the 88 hydrogen atoms in the structure, a final confirmation of the chemical formula reported by Hodgkin and coworkers.
Bob cofounded Syntex Analytical Instruments in 1969 to develop computer-controlled x-ray diffractometers. That company, together with California Scientific Systems, which he cofounded in 1978, evolved into Bruker AXS, where Bob remained a driving force behind the development of more than 1000 diffractometers and charge-coupled device instruments for crystallography. He consistently strove to make the software easier to use and accessible to nonexperts, even as the instruments grew capable of solving larger and more complex structures. Several generations of instrument users consider him their mentor. While at Syntex, he also contributed to the development of computer-aided tomography scanners, and later to the development of the Imatron CT heart scanner widely used in hospitals today. A primary interest of his was the development of computer graphics programs to facilitate crystal structure determination and analysis; he presented a set of future plans for such work at the Los Angeles ACA meeting.
Bob’s work on crystal structure determination was combined with important contributions to the teaching of x-ray crystallography. He persuaded Trueblood to propose with him a national course for teaching crystallography. This proposal resulted in the annual ACA summer school in crystallography. Bob was codirector of the school for 10 years, from its inception in 1992, when it was held at the University of Pittsburgh, until it moved to its present location at the University of Georgia in Athens, where he actively taught during the summer of 2001 just before the ACA meeting in Los Angeles. The summer courses have been great successes; to date, about 407 students have attended. Bob also served as the treasurer of ACA from 1980 to 1985.
A symposium in his honor had been planned for the next ACA meeting in San Antonio, Texas. Bob had been informed of this honor and was delighted. The symposium will now be in San Antonio on 26 May 2002 as a memorial tribute to a man who has influenced and was admired by so many crystallographers.
