Todd J. Barber, Cassini lead propulsion engineer
It's been another busy week from the "flight deck" of Cassini, which is not surprising given the relentless barrage of sixteen-day orbits around Saturn. One thing I neglected to mention last week is that OTM-116 was the 100th maneuver executed by Cassini since launch nearly ten years ago! Such an auspicious occasion could not be glossed over, so the flight team decided to celebrate with a couple of cakes, punch, and the unveiling of a commemorative t-shirt design. Our navigation team did a superb job in their artistic layout, and they previewed a ten-year anniversary shirt design as well. Cassini did eighteen maneuvers in the nearly seven years between launch (October 15, 1997) and Saturn Orbit Insertion (SOI) on June 30, 2004. Since SOI, the spacecraft has obviously increased its maneuver frequency greatly! Even so, nearly one in three maneuvers in tour have been able to be canceled thanks to excellent navigation. That is the main reason we're celebrating Cassini's 100th maneuver of the mission with OTM-116! Since that time, OTM-117 was executed successfully as well, a large (8 meters per second) main-engine maneuver, setting up an exciting radio science Titan flyby (T33) on June 29, 2007.
Other than the ever-present schedule of maneuvers, this week offered the Cassini team (scientists and engineers alike) to reflect on the great accomplishments of the last three years in Saturnian orbit. To begin, Paul Hayne, an expert on interpreting the surface of Titan using VIMS (Visual and Infrared Mapping Spectrometer) data, visited JPL this week and presented his latest research to a packed house. As we've noted with every Titan encounter, this intriguing moon is not giving up its secrets easily. We now believe Titan is one of the most Earth-like worlds in our solar system, if in a perpetual deep freeze. The latest interpretation of VIMS results include the tentative identification of water ice and carbon dioxide frost on the Titan surface, while other key components remain unidentified. Following this very engaging lecture, the flight team was fortunate enough to view an encore performance from the Cassini Project Scientist, Dennis Matson, essentially an overview of the results from the last three years. What a wonderful experience it was to take an hour break from our spacecraft duties to reflect on the true bounty of scientific treasure from Cassini and Huygens! I think I was most captivated when Dennis said he expects to give this talk a year from now (at the end of the primary mission) with entirely new material! Clearly, many of Cassini's "finest hours" are still ahead of us!