Category Archives: Saturn
The end is near. On September 15, 2017, NASA’s Cassini spacecraft will end its mission as well as its very existence with a plunge into the atmosphere of the very planet it has been orbiting since June 2004. It’s a maneuver intended to protect the pristine environments of Saturn’s icy moons, some of which harbor hidden reserves of liquid water, from potential impact contamination by an incapacitated spacecraft at some distant time in the future. But even though the reasons are noble, there’s no doubt that the final flight of Cassini and its inevitable loss will be a sad event for all those — myself very much included — who have followed along on its journey of discovery all these years. (Literally my first feature post here was a picture from Cassini.)
The video above, released today by NASA, is a poignant look both back at Cassini’s voyages and ahead at its Grand Finale, the last and most daring part of its mission at Saturn. These last few months will be bittersweet for Cassini fans, as every week will bring us closer to the end but also new and breathtaking views of Saturn…up to and including one last “family portrait” of the planet, its beautiful rings, and family of amazing moons.
Must be dusty in here, there’s something in my eye…
The end phase of the mission begins April 22. Follow along with the Grand Finale here.
At the north pole of Saturn’s largest moon Titan lie the largest (and only known) bodies of surface liquid in the Solar System outside of Earth. But on Titan, where temperatures are regularly around negative 300ºF, the liquid isn’t water but rather methane and ethane: compounds which are found as gases here on Earth. Titan’s seas and lakes are exotic environments that scientists are only just starting to understand, and even with radar imaging by NASA’s Cassini spacecraft there’s a lot we just don’t know about them. But one thing some researchers have managed to figure out using simulated Titan environments in the lab is that these lakes may sometimes fizz with bubbles of nitrogen—potentially explaining some of the mysteries of Cassini’s observations.
“Thanks to this work on nitrogen’s solubility, we’re now confident that bubbles could indeed form in the seas, and in fact may be more abundant than we’d expected,” said Jason Hofgartner of JPL, who serves as a co-investigator on Cassini’s radar team and was a co-author of the study.
Read the news straight from NASA here: Experiments Show Titan Lakes May Fizz with Nitrogen
Saturn’s “yin-yang” moon Iapetus (pronounced eye-AH-pe-tus) is seen in this image, a color composite made from raw images acquired by Cassini’s narrow-angle camera on March 11, 2017.
The color difference on Iapetus is due to a fine coating of dark material that falls onto its leading hemisphere, sent its way by the distant moon Phoebe traveling within the recently-discovered giant diffuse ring. This dark coating of dust causes that half of Iapetus’ surface to warm up ever-so-slightly-more than the other, making the underlying water ice evaporate and redeposit on the other side. This in turn reinforces the cycle…a positive feedback loop.
I know I said in my previous post that the Solar System is not a vortex (and it’s not) but that doesn’t mean there are no vortexes in the Solar System—in fact, thanks to the churning atmospheres of the gas giants, it’s full of them! And that’s no better demonstrated than at the poles of Saturn, where giant hurricane-like storms spin away year after year, powered by atmospheric convection and the rapid rotation of the planet.
I’ve often posted about the vortex at the north pole of Saturn—and yes it’s quite impressive—but there’s also a similar feature at Saturn’s south pole as well, albeit a bit more subtle and much less turbulent. The image above is a color view, made from raw data acquired in red, green, blue, and polarized light by NASA’s Cassini spacecraft on July 15, 2008. That was a just over a year before Saturn’s spring equinox and the planet’s south pole was moving into shadow, but still had enough illumination for Cassini to capture some images.
Check out a more direct view down into the vortex below: