by Bob Sparrow
If you read this entire blog, I think you’ll find some pretty amazing stuff. I understand that most people aren’t that interested in astronomy or astrophysics, but I’ve been fascinated with space for a long time; in fact I was told by my teachers early on that I was just taking up space in school. At the time I didn’t understand what they meant – now I do! I recently finished the best-selling book, Astrophysics for People in a Hurry, by Neil DeGrasse Tyson and my brain still hurts from reading it, but the parts of it that I understood were mind-blowing! So watching what happened last week and learning details about the entire Cassini mission has been riveting for me.
Depending on your astronomical interests, you may have heard about Cassini’s Grand Finale, which took place last Friday. The $3.3 billion Cassini project was a joint effort between NASA, the European Space Agency and the Italian Space Agency (Don’t ask me why Italy is not part of the European Space Agency), to launch a satellite that would orbit Saturn and send back invaluable information about the ringed planet and its multiple moons. NASA’s Jet Propulsion Lab in Pasadena managed the mission. Saturn, as I’m sure you’re aware is about 764 times larger than earth.
Cassini, named after the Italian astronomer, Giovanni Cassini, who made extensive discoveries about Saturn, is a satellite, about 22’ x 13’ in size, that launched from Cape Canaveral in October 1997 and, after a little more than 6 ½ years to travel the approximate 1 billion miles, reached its Saturn orbit in June 2004. So for the last 13 years it’s been beaming home miraculous images and scientific data, revealing countless wonders of this planet, its rings and its 6o+ moons. The most interesting of Saturn’s moons are Titan, the only other body in our solar system that has liquid on its surface, and Enceladus the brightest shining body in our solar system which has geysers gushing up to the surface from hidden oceans beneath the surface.
And while there is more technology in our cell phones today than what went into space with Cassini in ’97, it did some pretty amazing stuff over the last 20 years. Part of its mission included the sending of a landing craft to the surface of Titan, Saturn’s largest moon. The landing craft was named, Huygens, after the Dutch astronomer Christiaan Huygens, who discovered Titan. Both Cassini and Huygens lived in the late 1600s. The information that this landing craft gave us about Titan’s similarity to Earth would amaze you.
So after 20 years of sending invaluable data back to Earth, Cassini, they say, simply ran out of fuel, but hey, they got 20 years to the gallon. It does beg the question, were they using regular or supreme? OK, I’ll tell you what fueled Cassini, but you have to promise not to tell anyone else. It was powered by three radioisotope thermoelectric generators, which use heat from the natural decay of about 73 pounds of plutonium-238 (in the form of plutonium dioxide – obviously!) to generate direct current electricity via thermo electrics. But even that doesn’t last forever, especially when you’re traveling for 20 years at an average speed of around 41,000 mile per hour!
The last hours of Cassini’s mission had it doing its final flyby of Titan, which gave it the gravitational nudge toward the surface of Saturn, where it maneuvered between the innermost rings before it finally disintegrates on its way to the surface of Saturn at around 4:55 PDT last Friday morning. The team planned this ending, as they didn’t want Cassini floating around in space with the possibility of running into something else, like one of Saturn’s many moons. The Cassini mission changed the course of planetary exploration, it was in a sense, a time machine as it has given us a portal to see the physical processes that likely shaped the development of our solar system, as well as planetary systems around other stars.
If you’re the least bit interested in this kind of stuff, a program I saw it on last Wednesday was on the NOVA channel called Death Dive to Saturn; it may be replayed over the next few weeks on some of the scientific channels. You can also go to the JPL site below to see more details and photos of the end of Cassini’s mission.
Total miles traveled by Cassini getting to and orbiting Saturn: 4.9 billion, without an oil change.