Volume XXII, Issue 63
November 5, 2015

Editor: Peter Chi
Co-Editor: Guan Le
Distribution Support: Sharon Uy, Todd King, Kevin Addison
Email: editor at


Table of Contents

1. Space Science Pioneer Robert Farquhar Dies at 83



Space Science Pioneer Robert Farquhar Dies at 83

From: Andrew Cheng (andrew.cheng at

Space science has lost a true pioneer and visionary in Robert Farquhar. Bob was an expert in planetary exploration and spacecraft mission design at NASA, the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and KinetX, Inc., in Tempe, Arizona. He died from complications following a respiratory illness at his home in Burke, Virginia on Sunday, October 18 at the age of 83. A 50-year veteran of deep space missions, he was active to the end.

At our last meeting, only weeks before, he was excited to tell me of his latest conquests, and he had a new mission idea he wanted me to see. He reminded me of his most recent exploit, as senior advisor for mission design and navigation for the Chang’e-2 mission, implemented by the China National Space Administration: Chang’e-2 left its lunar orbit, entered a halo orbit around the Earth–Sun L2 Lagrangian point, and then transferred into a flyby of the near-Earth asteroid 4179 Toutatis in December, 2012, accomplishing China’s first interplanetary mission. This was vintage Bob.

Bob Farquhar will be remembered as the inventor and developer of halo orbits, which occur around the Lagrangian points in the restricted three-body problem, concerning the orbits of a test mass (e.g., a spacecraft) in the gravitational fields of two large bodies orbiting each other, such as the Earth and the Sun. The halo orbits occur in the regions around the Lagrangian points (or libration points) where the gravitational attractions of the two large bodies nearly cancel each other. Bob developed the concept of halo orbits, the properties of trajectories near libration points, and applications of these trajectories for his PhD in astronautics, which he obtained from Stanford University in 1968 under John Breakwell.

The first mission to use a halo orbit was the International Sun-Earth Explorer/International Cometary Explorer (ISEE-3/ICE) mission, which was placed (as ISEE-3) in a halo orbit about the L1 Sun-Earth Lagrangian point on November 20, 1978 to investigate solar-terrestrial relationships and to study the outermost boundaries of the Earth’s magnetosphere, the solar wind near the Earth, and the bow shock wave that slows the solar wind upstream of Earth’s magnetosphere. As the mission’s flight director, Farquhar led the team that flew the spacecraft in its halo orbit.

But Bob’s true love was comets. He was deeply frustrated that the US would not have any spacecraft visit Comet Halley during its March, 1986 apparition in the inner solar system, although the European Space Agency, the Soviet Union (with France), and the Institute of Space and Astronautical Science of Japan all did mount missions to do so. Bob wanted to do the first comet mission, and with ISEE-3 he found a way to accomplish that. In 1982, ISEE-3 left its halo orbit around L1, performed a series of passages between the Earth and the L2 libration point and five lunar swingbys, became the International Comet Explorer, and finally intercepted comet Giacobini-Zinner on September, 1985, passing through the comet’s plasma tail.

And that’s how Bob enabled the U.S. to become the first nation to encounter a comet. His knowledge of halo orbits was key to calculating the successful mission design. But he was most proud that his mission got to a comet before the so-called Halley Armada could encounter Comet Halley in 1986. Bob always loved to say, that he was a sore loser, but he was an even worse winner.

Bob’s next challenge was to find a way to accomplish the first spacecraft visit to a near-Earth asteroid. These objects, Earth’s closest neighbors in the solar system, are remnant bodies from planet formation. It was necessary for this mission to be implemented at lower cost than any previous planetary mission. Bob realized that this mission could not only visit a Near-Earth asteroid, but it could actually perform an orbital study of Eros, one of the largest and most important near-Earth asteroids, instead of some more accessible, but smaller and less interesting, target that could be reached with a lower energy orbit. Bob found the Earth gravity assist trajectory for the mission that became the Near Earth Asteroid Rendezvous (NEAR) mission, which was the first launch of the NASA Discovery Program in January, 1996.

At APL from 1990-2007, Bob became the flight director for the NEAR mission (and I was the NEAR Project Scientist). NEAR (later renamed NEAR-Shoemaker) was the first spacecraft to orbit and perform an in-depth investigation of an asteroid, and then safely land on it in February 2001. Bob and I agreed from the outset that we were going to land the spacecraft on the asteroid. As it turned out, the critical gamma ray spectrometer measurements of Eros, that confirmed its primitive composition, were possible only after the landing. Indeed it can be said, of doing the NEAR mission with Bob, that ‘It was the best of times, it was the worst of times’.

Also while at APL, Bob helped lead the mission design for the Comet Nucleus Tour (CONTOUR) mission; the Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) mission to the planet Mercury; and the New Horizons mission to Pluto. CONTOUR would have realized Bob’s fondest hopes, by visiting three spectacularly interesting comets, but it was not to be. The day that CONTOUR failed, in August, 2002, sticks in my memory – it was the saddest I ever saw him.

Born in September 1932, Farquhar attended elementary and high school in Chicago. Bob served in the Army in Japan and in Korea during the Korean War. After the Korean ceasefire, Bob obtained his bachelor’s degree in aeronautical engineering from the University of Illinois in 1959. He received an engineering master’s degree from UCLA in 1961. In 1960, he joined NASA’s Marshall Space Flight Center in Huntsville, Alabama, where he participated in the design of the Saturn V launch vehicle. From 1961-1964, he worked at the Lockheed Missiles and Space Company in California, perfecting orbital dynamics and control of satellites while also assisting in the preparation of an Interplanetary Flight Handbook for NASA. He earned his Ph.D. from Stanford University in 1969 under John Breakwell. From 1969-1990, he worked at NASA’s Goddard Space Flight Center in Greenbelt, Maryland and at NASA Headquarters. He led studies of post-Apollo lunar exploration concepts and the lunar shuttle transportation system, and he held management positions for numerous satellite projects.

Bob won numerous honors and awards from the military, NASA, and space organizations and associations. Bob’s book, “Fifty Years on the Space Frontier: Halo Orbits, Comets, Asteroids, and More”, was voted the best book of 2015 by the International Academy of Astronautics. This book reveals a great secret: there are two plaques which he put on the NEAR spacecraft, knowing that it would land on asteroid Eros and repose there in eternal peace. These plaques commemorate two loves of his life, his first wife Bonnie and his current wife Irina. That was also Bob, a true romantic. There will never be another like him.

Andrew F. Cheng
The Johns Hopkins University Applied Physics Laboratory


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