The New Horizons mission has revolutionized our understanding of Pluto and its moons, after conducting the first-ever flyby last summer. These mysterious worlds were finally seen up close, and this new view created as many, if not more, new questions as it answered old ones. While the flyby may be long over now, the spacecraft itself is still in excellent health and continues to plunge deeper into the Kuiper Belt at the outer fringes of the Solar System. Scientists have been eager for New Horizons to continue exploring this region farther out past Pluto, and now a proposal has been formally submitted to NASA to do just that. This extended mission will conduct a flyby of at least one more Kuiper Belt Object (KBO) and last until 2021.
This image shows the stars Alpha Centauri A and Alpha Centauri B just above the edge of the cloud tops in Saturn’s atmosphere, as seen by the Cassini spacecraft. The two stars are part of the Alpha Centauri triple star system, which is the closest star system to our Solar System, but is still almost 30,000 times farther away from us than Saturn is.
The Cassini spacecraft has been orbiting Saturn for many years now, studying the massive planet and its moons in unprecedented detail. Now, Cassini might be able to help shed light on another Solar System mystery: the possible existence of a ninth planet in the outer Solar System far past Pluto, or “Planet Nine” as it has been dubbed. There is also a new report, based on old data, that the Huygens lander observed methane ground fog as it descended to the surface of Saturn’s moon Titan in 2005.
Almost, but not quite… the Opportunity rover is now driving to another area on the hillside where it is currently located, after attempting to reach a difficult rock target. The rover wasn’t quite able to get close enough to the target to conduct further studies, after driving on the steepest slope ever encountered by any rover so far, on Knudsen Ridge.
This image from the Curiosity rover on sol 1294 shows some very delicate rock formations on Naukluft Plateau, shaped by blowing Martian sand. The thin atmosphere and lower gravity also help in the formation of such spindly protrusions. Similar ones have also been seen before by the rover.
A beautiful image of Saturn’s moon Enceladus with its active water vapour geysers, taken by the Cassini spacecraft. The left side of the moon is lit by the Sun and the right side is illuminated by light reflected from Saturn, or “Saturnshine.” The geysers, over 100 known, originate from a subsurface global ocean and are known to contain water vapour, ice particles, salts and organics. The water vapour reaches the surface through cracks in the outer icy crust.
Another odd but beautiful image of Mars, showing a cone-shaped hill with sand dunes wrapping around it. The formation is in the Ganges Chasma region, and the image was taken by the HiRISE camera on the Mars Reconnaissance Orbiter. Mars has a lot of diverse geology, and this is another good example of that. Original images are here.
As has been discussed extensively now, New Horizons has revealed Pluto to be a place unlike any other in the Solar System, with vast plains and glaciers of nitrogen ice, tall mountains of solid water ice capped with methane snow, layers of haze in its atmosphere, and perhaps an ocean of water below the surface. Now, there is additional evidence that Pluto once had rivers and lakes of liquid nitrogen on its surface, during times when the atmosphere was thicker than it is now. Just when you think Pluto can’t get any more bizarre, it does.
Pluto is a tiny world in the outer fringes of the Solar System; for many decades it was only a mere speck of light in even the best telescopes, with only vague hints of surface features. Then, in July 2015, the New Horizons spacecraft flew past Pluto, the first time ever that humanity would get to see this mysterious place up close – and it did not disappoint. An enormous amount of data has continued to be sent back by New Horizons since the flyby, and now five new papers have been published which provide an in-depth overview of the findings so far about Pluto and its moons. Pluto is an active world, with its own unique geology different from anywhere else in the Solar System.
Ceres is the king of the asteroid belt, being the largest object in that region of the Solar System, and the Dawn spacecraft has shown it to be a very interesting world. While it is relatively small, classified as a dwarf planet, and very cold being so far from the Sun, there are hints that it has been surprisingly geologically active in the past and perhaps still is. Superficially it resembles the Moon or Mercury, gray and covered in craters. But there are also canyons, hazes, and unusual bright spots. Those spots have become a focus of much interest for scientists, and now new studies indicate that they appear to change in brightness from day to night, and may be evidence of ongoing activity inside Ceres.