1. Introduction

Gary Arnold Flandro (born March 30, 1934 in Salt Lake City, Utah)^[1] is an United States aerospace engineer who currently holds the Boling Chair of Excellence in Space Propulsion (Emeritus) at the University of Tennessee Space Institute. He is also the Vice President and Chief Engineer at Gloyer-Taylor Laboratories (GTL).

2. Life and Work

Flandro earned his B.S. in Mechanical Engineering from the University of Utah in 1957, his Master’s in Aeronautics from the California Institute of Technology in 1960 and his Ph.D. from Caltech in 1967. He has worked at UTSI and held the Boling Chair of Excellence in Space Propulsion since 1991. Flandro has written or co-written 95 conference papers, most recently traveling to Kyoto, Japan to present a paper titled “Understanding Oscillatory Behavior of Liquid Propellant Rockets and Jet Engine Thrust Augmentors," at the Seventh International Symposium on Special Topics in Chemical Propulsion. He has also written or co-authored 54 refereed papers, four books and two book chapters. He has been named a Fellow of the American Institute of Aeronautics and Astronautics on May 13, 2008.^[2]

Flandro is an 11th generation pupil of Euler. The lineage is: Euler, Lagrange, Fourier, Lejeune Dirichlet, Lipschitz, Klein, Lindemann, Hilb, Bar, Liepmann, Marble, Flandro.^[3]

Flandro’s work has supported decades of space flight and has led to successful missions to the outer planets. His research work with combustion instability in solid rocket motors has “practically solved a challenging issue that had plagued the field for many years,” said Vigor Yang Head, School of Aerospace Engineering Georgia Institute of Technology.^[2] Flandro has coauthored several textbooks including: "Basic Aerodynamics: Incompressible Flow" with Howard McMahon and Robert L. Roach of Georgia Tech, and "Combustion Instability in Solid Propellant Rockets" with Edward W. Price of Georgia Tech. It is in regular use in Flandro's short courses at UTSI.

3. Gas Giants

During the summer of 1964 at the NASA Jet Propulsion Laboratory (JPL), Flandro was assigned the task of studying techniques for exploring the outer planets of the solar system. In this study^[4] he discovered the rare alignment of the outer planets (Jupiter, Saturn, Uranus, and Neptune) and conceived the Planetary Grand Tour multi-planet mission utilizing the gravity-assist technique to reduce the mission duration from forty years to less than ten years. This work was exploited by NASA with the Voyager 1 and Voyager 2 missions, launched in 1977.^[1][5]

Flandro was recognized for this work first by the British Interplanetary Society (1970 M. N. Golovine Award), and later by NASA (1998 Exceptional Achievement Medal, with the citation: "for seminal contributions to the design and engineering of multi-outer-planet missions, including the Grand Tour opportunity for the epic Voyager explorations").^[6]

The ideas from this research have had major impact on subsequent solar system exploration; the Galileo (Jupiter satellite tour) mission and the Cassini (Saturn satellite tour) were made possible by the gravity assist method. Flandro (also in 1965) studied gravity assist trajectories to Pluto; these are the basis for the New Horizons mission launched in January 2006, which arrived at Pluto in 2015.