Todd J. Barber, Cassini lead propulsion engineer
Where to begin this column? Truly, there is an embarrassment of riches from Cassini over the last few weeks. I can't possibly give proper scientific justice to the latest findings within a few paragraphs, but hopefully these highlights will send everyone clicking away to the Cassini home page and latest news. In yet another first in planetary exploration, it appears that Cassini may have discovered the first ring around a moon. Saturn's second-largest moon, icy Rhea, appears to be encircled with ring material, though rings actually haven't been imaged directly yet! A lack of electrons (symmetrically) on either side of Rhea as spied by a magnetic-field imaging instrument, along with other instrument observations, led scientists to this shocking conclusion. This again demonstrates the power of a flagship mission, using a large suite of scientific instruments to cooperatively tease out nature's secrets. You just never know which instruments may contribute to the next big surprise in the outer solar system.
Another recent press release (I can barely keep up with them) is about the potential discovery of a subsurface ocean on Saturn's largest moon, Titan. This purported ocean likely contains ammonia along with liquid water. Is it me or does it seem that Titan becomes more Earth-like with every precious flyby? It's often been described as Earth's distant cousin in a deep freeze, but the similarities seem to be overtaking the differences in my count. Another press release gave me pause for thought as Earthly gasoline approaches record-high prices -- it appears that Titan's reserves of liquid hydrocarbons exceed Earth's by a factor of 100 or more! Talk about finding a gusher!
Finally, in this column admittedly focused on Saturnian satellites (just two of Saturn's five highest-level scientific objectives, the other three being the magnetic field, rings, and planet itself), it would be sinful not to mention a daring Enceladus flyby on Wednesday, March 12. Zipping along at about 15 kilometers (9 miles) per second, our robotic friend buzzed Enceladus a mere 50 kilometers (30 miles) above the surface. This is the closest Cassini has been to any solid body since bidding adieu to Earth on launch night, October 15, 1997. Even more compelling, Cassini's trajectory actually brought us within the icy plumes of Enceladus! I simply can't wait for a March 26th press conference about additional scientific results from this historically close encounter. From the engineering side, I'm also happy to report the spacecraft came through its rendezvous unscathed, ready for the next challenge. In fact, as I write this, Cassini is prying additional secrets from Titan during today's T42 close flyby. Even though in space, the word "up" is rather arbitrary, I still close "Onward and Upward, Cassini!"