Todd J. Barber, Cassini lead propulsion engineer
Engineering enjoyed a stroke of good fortune early in the month as well. As we prepared for a thrilling Titan-50 flyby on Feb. 7, our approach maneuver, OTM-181, was canceled. Often times skipping approach maneuvers incurs a small but justifiable propellant cost, but this time all the stars aligned in our favor. We actually saved about 1.2 meters per second (2.7 mph) in delta-V by canceling this maneuver, with no deleterious impacts to T50 science! Turning to the trusty old rocket equation, which I’ve joked I must use at least once per day as a propulsion engineer to get paid, I calculate this saved us about 1.0 kg (2.2 pounds) of propellant. That’s a good day in the world of engineering! OTM-182, a small clean-up maneuver (2.1 seconds on the main engine) following T50 went off without a hitch as well.
Speaking of the T50 flyby, this low altitude buzz of the solar system’s second-largest moon went swimmingly. We use Titan to shape future orbits with its large gravity field, yet another example of the wonderfully powerful technique of gravity assist. Of course, the low altitudes required for orbit modification thrill Cassini scientists as well, particularly when “sniffing” the atmosphere. To that end, our Ion and Neutral Mass Spectrometer (INMS) instrument was prime for this flyby, but a “ride along” was provided for radar as well. INMS was investigating a magnetospheric boundary region in Titan’s mid-Southern hemisphere, while radar executed both inbound and outbound altimetry along with imaging data for the mountains southwest of Tsegihi. Not to be outdone, our infrared and ultraviolet instruments also investigated atmospheric temperatures, minor hydrocarbon species, new gases, nitriles, cloud mapping, nitrogen and monatomic hydrogen emissions, scattering of haze aerosols — you name it! To me this sounds like a year of AP Chemistry squeezed into one brief flyby, but no one “crams” for a scientific test like Cassini, pulling all-nighters with ease, all without an ounce of caffeine. Even when our robotic emissary requires the same of her flight team on Earth, we are only too happy to oblige (with copious quantities of coffee, of course).