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.
The Martian rover Opportunity has become famous for its amazing longevity, but it is not the only one; orbiting spacecraft also usually enjoy long lifespans, and today the Mars Reconnaissance Orbiter is celebrating its 10th year exploring Mars from above. It has helped to revolutionize our understanding of Mars and its complex geological history as well as, of course, sending back thousands of incredible high-res images of the Martian surface.
It has been a year now since the Dawn spacecraft first reached the dwarf planet Ceres in the main asteroid belt between Mars and Jupiter, and during that time has shown Ceres to be a unique and complex little world. At first glance, Ceres just seems to be a heavily battered place, covered in craters like the Moon or Mercury, but a closer look reveals something more interesting: a small rocky world with large fractures, unusual “bright spots” randomly dispersed across the surface and an odd conical “mountain” which sits in isolation with nothing else like it around. Dawn has already acquired an enormous amount of data about Ceres, but now, in its lowest possible orbit, will continue to do for some time to come.
As the data from New Horizons continues to come in, we are learning more about what an incredible little world Pluto really is, with tall mountains of rock-hard water ice, as well as glaciers and vast icy plains composed of nitrogen ice. In some ways, these features are visually reminiscent of similar ones on Earth, and now this week another cool discovery was revealed: methane snow on some of Pluto’s mountain peaks.
NASA’s Curiosity rover on Mars may have been stealing the spotlight in recent years, but the other rover, Opportunity, is still going strong after 12 long years. Opportunity has survived the harsh environment and various challenges for much longer than anyone anticipated, and now is taking on a new task: climbing slopes as steep as 30 degrees while searching for deposits of clay minerals which had already been detected by orbiting spacecraft. The region where Opportunity landed, Meridiani Planum, is mostly flat plains, but now on the rugged edge of the huge Endeavour crater, the rover is becoming something of a mountain climber.
This coming September, a new NASA spacecraft, OSIRIS-REx, will be heading toward an asteroid to collect samples which will later be brought back to Earth. This is the first time for such a sample return mission to an asteroid by a U.S. spacecraft, but there’s also another unique aspect to this mission – artists, and space enthusiasts in general, are being invited to submit some of their work to be included onboard the spacecraft.
One of the most surprising discoveries in recent years in the outer Solar System is that there are small moons which have oceans inside them. Jupiter’s moon Europa and Saturn’s moon Enceladus are now known to have global oceans of water beneath their icy crusts, and others are thought to as well, including Ganymede, Titan, and possibly others. These moons have a lot of ice and rock as well, and gravitational tugging and heating from the large gas giant planets helps maintain a deep layer of liquid water inside them, where otherwise they would most likely be frozen solid in the deep cold so far from the Sun. Now it seems that another moon also once had an ocean, although in this case it is thought to now be solid ice: Pluto’s largest moon, Charon.