I’ve been busy lately, so I have not had much time to write, so here’s the latest on three different deep space probes!
First off, Hayabusa 2 made a successful flyby of the Earth on December 3, flying about 3,090 km above Hawaii at closest approach. The spacecraft was performing a gravity assist maneuver, and controllers now report the maneuver was performed flawlessly: Hayabusa 2 is right on target to encounter asteroid 162173 Ryugu in 2018. Hayabusa 2 is a follow-on to the original Hayabusa mission, which encountered serious difficulties but still managed to return samples from asteroid 25143 Itokawa. Hayabusa 2 builds on the lessons learned from that mission and should be able to return much larger samples, scheduled for 2018. It will also deploy a set of landers, both Japanese and European.
Earth from Hayabusa 2, just after the gravity assist. Summer has reached the South Pole.
Here’s a fantastic animation showing its flight:
The Mars Science Lander “Curiosity” is now well into its mission exploring Mount Sharp in the center of Gale Crater. Its latest object of interest is a field of sand dunes. The going will be difficult, and the team will be very cautious, since it was sand dunes that irretrievably mired MER-A “Spirit”. This is the rippled surface of “High Dune”, within a dune field named Bagnold Dunes.
The texture and particles are very intriguing, and Curiosity may learn a lot when it samples them. They’ve already used the wheels to help get a peek below the surface:
And still New Horizons returns data!
The probe is continuing its long, slow plod through the enormous data set that it collected at Pluto. Color data is now available for those high resolution images taken at closest approach, and it only looks wilder:
Click for the larger image. It’s really quite weird looking. The geology must involve some processes that simply don’t happen on Earth, although some of it looks distinctly familiar to our eyes.
Last but not least, Dawn!
Dawn has continued studying 1 Ceres, the closest of the dwarf planets, and there is new information on the mysterious lights in Occator Crater! Occator Crater has by far the brightest spots on Ceres, but the small world is sprinkled with bright spots. New spectrographic analysis is consistent with all of those spots being a salt called hexahydrite, which is a type of magnesium sulfate. Furthermore, all of the spots are associated with impact craters. This allows them to rule out ice volcanism. They believe the spots are salt left behind after water sublimated away following impacts which exposed a briny water layer just below Ceres’ crust. They aren’t yet suggesting that layer to be liquid, by the way. It could well be ice, which would rapidly boil away in the sunlight this close to the Sun. (Ceres is near the limit of our Sun’s golidlocks zone.) Occator Crater they think is brightest because of relative youth, and possibly also a more energetic impact digging deeper into this layer. It appears that the water may not have finished sublimating away from Occator Crater, as there is evidence of water vapor accumulating in the crater from both Dawn and also the Herschel Space Observatory.
Another team was analyzing for evidence of ammonia compounds on Ceres, and came up with a lot of evidence, locked up in clays. This is particularly interesting because surface ammonia is even more volatile than water; that Ceres has some suggests it formed further away from the Sun than its present position. Perhaps interactions with the giant planets pushed it in. Ceres is also unusually rich in water ice for a main belt asteroid, which would tend to suggest the same thing.
Here is a color-enhanced image of Ceres rotating. The enhanced colors help to pick out subtle differences but should not be interpreted as what the human eye would see.