Todd J. Barber, Cassini lead propulsion engineer
Please pardon my lack of columns for a few months—my work on the Mars Science Laboratory (MSL) has filled every available block of time for many weeks. As I write this, MSL just launched on its 8.5-month journey to the red planet—wish us luck with landing next summer! Through a myriad of MSL duties, I still continue working as Propulsion Lead Engineer on the Cassini mission to Saturn. In mid-September, I had the honor and privilege of interviewing Jean-Pierre Lebreton, the European Space Agency (ESA) Project Scientist and Mission Manager for the Huygens mission, just as he retired from a decades-long career with ESA. Though he will remain active in research, Dr. Lebreton’s departure from ESA is a noteworthy milestone, and I felt it was only appropriate to honor his many contributions to space science in general and Cassini-Huygens in particular at this time. I ended up taking two full pages of notes during our late-night (Pacific Time) phone conversation, so I’ve already planned to make this column a two-part celebration of Dr. Lebreton’s unique and celebrated career with ESA.
Jean-Pierre was born in France and always showed a strong affinity for mathematics, later focusing on physics. It was only much later that he “morphed” into a space scientist. He obtained his PhD in experimental plasma physics from the University of Orleans, studying plasma diagnostics. He told me he always enjoyed working with his hands (building, breaking, and repairing things), so this may well have led him to become an experimentalist. As a propulsion engineer, I very much enjoyed our “sidebar” conversation about his early work with ion engines, even though it would be many years until an ion engine actually flew in space. After obtaining his doctorate, Dr. Lebreton accepted a two-year post-doc position at ESTEC (the European Space Research and Technology Centre) in the Netherlands, a technology research and project management center not unlike JPL. He ended up with a long-term contract and stayed 33 years with ESTEC!
Dr. Lebreton’s first space job came quickly within ESTEC, serving as the instrument manager for an active plasma experiment that included both an electron and an ion gun on Spacelab I, which flew on the space shuttle. This first truly US/European science collaboration in the space shuttle program studied plasma beam interaction effects with Earth’s ionosphere, at around 260 kilometer altitude. Jean-Pierre was both the team manager and experiment manager from 1980-1984, honing his skills in international cooperation with not only the U.S. but with Japan as well. Columbia and its payload, Spacelab 1, launched in November, 1983 on the STS-9 mission, and Jean-Pierre’s indoctrination into the world of space science was complete. In fact, within a year, he was working on early prototypes of a Saturn orbiter and Titan probe mission that would eventually become Cassini-Huygens!
Between 1984 and 1988, Dr. Lebreton was a study scientist for joint NASA/ESA studies to build a Saturn orbiter and Titan probe. ESA decided its primary contribution would be the Titan probe, and the name “Huygens” was selected almost immediately. Interestingly enough, Jean-Pierre’s recollection was that the Swiss delegation (not the Dutch) suggested the probe be named after Christiaan Huygens, but the Dutch concurred wholeheartedly (not surprisingly). It took over a year for NASA to select the Cassini mission (along with CRAF—the Comet Rendezvous & Asteroid Flyby mission) for a new start. CRAF was eventually canceled, and Cassini weathered a few survival scares of its own during the early 1990’s. Dr. Lebreton became the Huygens project scientist in 1989, a job he did not relinquish until just a few months ago! During the study phase, he worked closely with Wes Huntress, his counterpart at NASA, as the Cassini mission design matured and evolved from a dream to a feasible mission. Then he started a 20-year-long working relationship with his long-term counterpart at NASA, Dennis Matson, the Cassini project scientist at JPL. The removal of three articulated elements on Cassini (the scan platform, spin table, and dedicated Huygens relay antenna) in the early 1990’s, a cost-saving measure, actually ended up helping out Huygens, since now Huygens probe relay required Cassini’s high gain antenna (HGA). This precluded simultaneous Huygens/Cassini data gathering at probe relay, but the benefit to Huygens was unmistakable, as it allowed a significant increase of the data volume. During this pre-launch period, in Dr. Lebreton’s words, the spacecraft development from 1989 through launch in 1997 was “pretty smooth” although there were a “few bumps,” and the “ESA/NASA collaboration was excellent.”
Just a few weeks before launch in 1997, Jean-Pierre was at a pre-launch press briefing at NASA Headquarters (in Washington, DC) and learned of an air conditioning issue on the launch pad—at that press conference itself! Essentially, an air flow rate ten times the desired value was experienced throughout the interior of the Huygens probe on the launch pad, and this damaged the foam insulation within Huygens, mere weeks from launch! This issue required major action, including removing the top of the Titan-IV rocket, disconnecting Huygens from Cassini, and disassembling and rebuilding Huygens. Amazingly, this all happened within the span of one week! A new launch date of October 13, 1997, was selected, one week after the initially scheduled launch date and coincidentally the same day as an earlier scheduled soccer match between Cassini orbiter team members (from the US and Europe) and Huygens probe team members (also from both sides of the pond). Launch ended up getting scrubbed on the 13th due to bad weather, but the soccer game couldn’t be moved, so this intended post-launch celebration turned into a pre-launch grudge match at the Cape (though a friendly one). Jean-Pierre recalls the game was rather lopsided (7-to-1 or 8-to-1), but he could not recall which team actually won the game.
Two days later, the Titan-IVB carrying Cassini-Huygens lit up the central Florida morning sky and set off on a grand adventure. Jean-Pierre recollects on the launch vehicle’s disappearance into a large, low cloud and the sinking feeling (at least for a few seconds) of a launch vehicle massive failure as the cloud was illuminated from within. Cassini-Huygens would not be denied, though—it burst through the cloud tops and commenced a mission of great promise and discovery. Jean-Pierre, thank you for getting us to the launch pad with the wonderful Huygens probe, and thank you for your time. I look forward to telling the rest of your story in next month’s column. In the meantime, I couldn’t help but flash back to memories of Cassini-Huygen’s glorious ascent as I watched our next Mars rover depart Earth last weekend. Godspeed both MSL and Cassini!