An unusual round landform in the Athabasca region on Mars, as seen by the Mars Reconnaissance Orbiter. The round “island” is isolated, sitting in a “sea” of old smooth lava flows. How it formed isn’t known yet, but theories include that it was pushed up somehow by lava or ice that was melted by the lava. There are a lot of lava flows in this region, so the involvement of volcanism is a likely possibility. Another interesting Martian puzzle!
New HiRISE image from the Mars Reconnaissance Orbiter showing an amazing network of polygon fractures inside a crater. The fractures are thought to be caused by the cracking of ice-cemented soil (permafrost). They are also known as periglacial landforms, such as in the polar regions on Earth. They are common on Mars, even near the equator, where there are large amounts of subsurface ice.
Some of the most interesting features on the surface of Mars are its gullies, often found on crater walls or other slopes, first seen from orbit back in 2000. They resemble gullies on Earth created by water, but the origin of located on Mars have become the subject of much debate. These gullies appear to be actively forming today, and are not just some relic of past activity that took place millions of years ago. But on Mars, water can’t exist for long on the surface even if it is briny, so how are these gullies being created? New observations from the Mars Reconnaissance Orbiter (MRO) spacecraft suggest that dry ice (frozen carbon dioxide) may actually be responsible. The new findings have been published in the journal Icarus.
The possibility of an ancient Martian ocean is an enticing one, and there has been growing evidence that it did indeed exist (dubbed Oceanus Borealis), covering most of the northern hemisphere, and about a third of the planet, billions of years ago. Now, some new observations of boulders in what likely used to be the ocean bottom have given scientists additional clues as to what this ocean was like, it was announced this past Saturday (February 15, 2014).