Cassini obtained its first high-resolution images of Methone on May 20, 2012. Methone is one of the smallest regular moons of Saturn, having a diameter of only about 3 kilometers. It was the first moon that Cassini discovered, very early in Cassini's mission at Saturn, in 2004.
I enthused about these Helene images the first time they came down from Cassini, and then forgot about them, and then was thrilled anew a couple of weeks ago when Daniel Macháček posted his version, processed from data published by the Cassini imaging team on April 1.
In the last few days as it's rounded periapsis in its current orbit of Saturn, Cassini has taken a lot of great photos of Saturn's moons. One series of photos was taken from pretty close to Janus, a moon about a third the diameter of Enceladus that orbits between the F and G rings. And among those, several were taken with the moon sitting in front of Saturn.
My notes on a two-part presentation by collaborators Jim Richardson and David Minton about the sizes of things in the Kuiper belt, a story they told by looking at Saturn's moons. How does that work? What connects Saturn's moons to the Kuiper belt is craters.
One of the more exciting talks last week was given by Antoine Lucas about his work with Oded Aharonson "denoising" Cassini radar images of Titan. Cassini's radar images are superior to the camera photos in revealing fine details and topography on Titan's surface, but they do suffer from a random noise component that makes the pictures look snowy. Antoine and Oded have developed a method for removing much of this noise.
One of the topics I found most exciting yesterday was a series of talks on Titan's climate. Bob West showed how Titan's detached haze has shifted with time. Zibi Turtle presented about how Titan's weather has changed with these seasonal changes. Jason Barnes followed up Zibi's talk -- which was based on Cassini camera images -- with a study of the same regions using data from Cassini's imaging spectrometer, trying to figure out what was going on with that brightening. Ralph Lorenz talked about rainfall rates on Titan. Jeff Moore asked: what if Titan hasn't always had a thick atmosphere?
Clearly, this is Saturn, and its rings, and if you look closer you can see a tiny circle, on top of the rings, which is Mimas, and two stars in the background. It should look weird to you that while the rings are bright, Mimas is a black dot. What is happening here? Nearly everything in this picture is lit by light that has not arrived directly from the Sun.
Evaporites form on planetary surfaces when dissolved chemical solids precipitate out of saturated solution as their liquid solvent evaporates and, until recently, were known to exist only on Earth and Mars. This article from the IAG Planetary Geomorphology Working Group describes the third planetary instance of evaporite, discovered on Saturn's moon Titan.
When I posted about the really cool Cassini SAR images of Enceladus a few weeks ago, I initially wrote that this was the first-ever SAR image of an icy moon other than Titan. Several people (some readers and two members of the Cassini science team!) corrected that statement: Cassini has performed SAR imaging of other icy moons (including Enceladus) before.
On the November 6, 2011 flyby of Enceladus -- the third such flyby in just a few weeks -- the Cassini mission elected to take a SAR swath instead of using the optical instruments for once. So here it is: the first-ever SAR swath on Enceladus. In fact, the only other places we've ever done SAR imaging are Earth, the Moon, Venus, Iapetus, and Titan.