What is the solar system moon with the densest atmosphere? Most space fans know that the answer is Titan. A few of you might know that Triton's is the next densest. But what's the third? Fourth? Do any other moons even have atmospheres? In fact, they do; and one such atmosphere has just been discovered.
Now that Cassini has returned to Saturn's equatorial plane, it has lots of opportunities to observe Saturn's moons. For about a week, Cassini has been taking regular sets of images of Iapetus, which I've assembled into an animation.
At last week's Lunar and Planetary Science Conference, the MESSENGER team held a press briefing to share results from the recent few months of incredibly low-altitude flight over Mercury's surface. The mission will last only about five weeks more.
Three talks on Tuesday at the Lunar and Planetary Science Conference concerned the first results from Dawn at Ceres. Chris Russell showed a map of "quads" with provisional names on Ceres, Andreas Nathues showed that Ceres' bright spot might be an area of plume-like activity, and Francesca Zambon showed color and temperature variations across the dwarf planet.
One presenter at the Lunar and Planetary Science Conference asked the audience not to blog about his talk because of the embargo policy of Science and Nature. I show how this results from an incorrect interpretation of those policies. TL;DR: media reports on conference presentations do not violate Science and Nature embargo policies. Let people Tweet!
Next week is the 46th Lunar and Planetary Science Conference (LPSC), and Emily Lakdawalla will be attending to tweet and blog about news from Rosetta; Curiosity; MESSENGER; GRAIL; Chang'e 3; Dawn; New Horizons; Cassini; and more.
A newly published paper confirms a subsurface ocean at Ganymede. An ocean there was already suspected from its magnetic field and predicted by geophysics; new Hubble data confirms it, and even says it is in the same place we thought it was before. Such consistency is rare enough in planetary science to be worth celebration.
Dawn has successfully entered orbit at Ceres, becoming the first mission to orbit a dwarf planet and the first to orbit two different bodies beyond Earth. I also have updates on Curiosity, Rosetta, Mars Express, Hayabusa2, the Chang'e program, InSIGHT, and OSIRIS-REx.
After several months of near-silence, ISRO's Mars Orbiter Mission has released on Facebook the first data product from its Methane Sensor For Mars. Don't get too excited about methane yet: there is no positive or negative detection. The news here is that the Methane Sensor for Mars is working, systematically gathering data. They also released several new photos of Mars.
NASA held a press briefing on the Dawn mission yesterday, sharing some new images and early interpretations of them. I see lots of things that intrigue me, and I'm looking forward to Dawn investigating them in more detail. I invite you to check out these photos yourself, and offer you some guidance on things to look for.
I've been resisting all urges to speculate on what kinds of geological features are present on Ceres, until now. Finally, Dawn has gotten close enough that the pictures it has returned show geology: bright spots, flat-floored craters, and enigmatic grooves.
Curiosity's second drilling campaign at the foot of Mount Sharp is complete. The rover spent about a month near Pink Cliffs, an area at the base of the Pahrump Hills outcrop, drilling and documenting a site named Mojave, where lighter-colored crystals were scattered through a very fine-grained rock.
Rosetta has closed to within 50 kilometers of Churyumov-Gerasimenko, on its way to a very close, 6-kilometer flyby of the comet tomorrow. To prepare for the flyby, Rosetta traveled much farther away, allowing it to snap these amazing photos of an increasingly active comet from a great distance.
At last! Cassini is orbiting in Saturn's ring plane again. I do enjoy the dramatic photographs of Saturn's open ring system that Cassini can get from an inclined orbit, and we won't be getting those again for another year. But with an orbit close to the ring plane, Cassini can repeatedly encounter Saturn's icy moons, and icy moon flybys are my favorite thing about the Cassini mission.
For the period of time before and after the Philae landing, Rosetta was able to orbit the comet close enough that it was in gravitationally bound orbits, circling the comet's center of gravity. As the comet's activity increases, the spacecraft has to spend most of its time farther away, performing occasional close flybys. The first of these is at 6 kilometers, on February 14.
Brief updates on four ongoing missions: JAXA's Akatsuki and Hayabusa2, and China's Chang'e 3 and Chang'e 5 test vehicle. JAXA has articulated the new science plan for Akatsuki. Hayabusa2's ion engines have checked out successfully. The Yutu rover is still alive on the Moon, and Chang'e 5 test vehicle has successfully tested crucial rendezvous operations in lunar orbit.
The Dawn mission released new images of Ceres yesterday, taken on February 4, when Dawn had approached to within 145,000 kilometers. More details are coming into view, and they're fascinating. For one thing, there's not just one white spot any more: there are several.
As I write this post, New Horizons is nearing the end of a weeklong optical navigation campaign. The last optical navigation images in the weeklong series will be taken tomorrow, but it will likely take two weeks or more for all the data to get to Earth. Two weeks! Why does it take so long?
The first results of the Rosetta mission are out in Science magazine. The publication of these papers means that the OSIRIS camera team has finally released a large quantity of closeup images of comet Churyumov-Gerasimenko, taken in August and September of last year. I explain most of them, with help from my notes from December's American Geophysical Union meeting.
Curiosity has spent the last two months completing a second circuit of the Pahrump Hills field site, gathering APXS and MAHLI data. The work has been hampered by the loss of the ChemCam focusing laser, but the team is developing a workaround. Over the holidays, the rover downlinked many Gigabits of image data. The rover is now preparing for a drilling campaign.
The landing of Huygens on Titan was a significant moment for planetary science and a great accomplishment for Europe. But the Huygens landing also stimulated the development of the international community of amateur image processors that does such great work with space images today. I was in the midst of it all at the European Space Operations Centre in Darmstadt.
A few recent newspaper articles provide some updates on the status of Japan's Venus mission, Akatsuki, and the service module of China's Chang'e 5 test vehicle, Xiaofei. In brief: Akatsuki still plans to attempt to enter orbit in December of this year, while Chang'e 5 T1 is headed to lunar orbit. Meanwhile, the Chang'e 3 mission has released an interesting image of M101, the Pinwheel Galaxy.