Robert Farquhar, Co-Investigator, APL
Is Stardust-NExT your first comet mission? If no, what other ones have you worked on?
My first involvement with spacecraft missions to comets came in 1972 when I participated in a Comet Study Group at NASA/Goddard. We proposed a mission called Cometary Explorer that would carry out flybys of two comets, Grigg-Skjellerup in 1977 and Giacobini-Zinner in 1979. Although this mission was endorsed by NASA's Comet and Asteroid Science Working Group, NASA was not able to fund it. We then proposed a slow-flyby (~ 7 km/sec) of comet Encke in 1980. This mission also failed to achieve project status. Between 1974 and 1980, I worked on several proposals for low-cost comet missions with no success. Then, in 1981, I became the NASA Program Manager for a fast-flyby mission to Halley's Comet. Unfortunately, this project was also terminated. NASA never seemed to have enough money to initiate a comet mission.
I then tried a different approach. Instead of trying to find funds for a new project, I decided to use a spacecraft that was already operating in a “halo orbit” around the Sun-Earth L1 libration point. This spacecraft was called the International Sun-Earth Explorer-3 (ISEE-3), and I was the Flight Director for this mission. In 1982 and 1983, ISEE-3 used five lunar gravity-assist maneuvers to send it to comet Giacobini-Zinner. After the final lunar swingby, ISEE-3 was renamed International Cometary Explorer (ICE). On September 11, 1985, ICE Intercepted comet GZ and flew through the comet’s tail, thus becoming the first successful mission to a comet.
In 2002, I was the Mission Director for the ill-fated Comet Nucleus Tour (CONTOUR) mission that planned to intercept three comets, Encke, Schwassmann-Wachmann-3, and d’Arrest. Unfortunately, a catastrophic solid rocket motor failure about 43 days after launch prevented CONTOUR from carrying out its mission.
What is the greatest highlight of your career to date?
I would say the ISEE-3/ICE mission or the Near-Earth Asteroid Rendezvous (NEAR) mission. NEAR was launched in 1996, and was inserted into a close orbit around the near-Earth asteroid 433 Eros on February 14, 2000. NEAR successfully landed on Eros on February 12, 2001. NEAR was the first spacecraft to orbit and land on an asteroid. Both of these accomplishments are historic spaceflight "firsts!"
How did you come up with the concept of reusing the Stardust spacecraft?
When I learned that the Stardust Project was planning to retarget the main spacecraft for an Earth return in 2009, I began to look for possible follow-on comet targets. From my viewpoint, the target that made the most sense was Tempel 1. I liked this target because we might be able to complete the science goals of the Deep Impact mission by observing the crater made by Deep Impact's copper probe. Working with my colleague, David Dunham, we quickly determined that the Stardust transfer to Tempel 1 was feasible.