When the topic of ice on Mars comes up, the first thing that usually comes to mind are the polar ice caps which are prominent even in small telescopes. There is, however, ice elsewhere on the planet as well, such as beneath the surface in the mid-latitudes, covered by dust. Now, a new study has revealed the extent of these subsurface glaciers and the amount of frozen water they contain.
This is interesting, a recent HiRISE photo from the Mars Reconnaissance Orbiter spacecraft showing an oval pit or crater with an opening in the bottom (cropped here from one of the larger images) near Galaxias Chaos on Mars. The opening is also oval, and you can see some sand dunes on the bottom. How did it form? More images are available here.
Whether or not Mars once had an ocean has been a subject of much debate for many years. There is substantial evidence pointing toward the possibility, but no “smoking gun” yet. Now, a new discovery from scientists at the California Institute of Technology (Caltech) is fueling that debate again – an ancient delta that appears to have emptied into the hypothetical ocean in the northern hemisphere.
A “missing” Mars lander and its associated hardware from the 1970s may have finally been discovered in images taken by the Mars Reconnaissance Orbiter. The Soviet Mars 3 lander was the first successful landing on Mars by any spacecraft, but after transmitting for only 14.5 seconds after touchdown on December 2, 1971, it went silent and was never heard from again. Its exact landing site was unknown, but now may have finally been located after all these years.
The Curiosity rover has returned yet more images of Mount Sharp, and these are the best and highest-resolution ones yet. Taken by the 100-millimeter Mastcam camera, they show the layering of the mesas in the foothills in incredible detail. Also note the tiny speck in the centre of the white box in the middle of the image (magnified in the bottom corner of the image); that is a boulder about the same size as the rover, which is car-sized, giving a sense of scale. These mesas are huge, and they are dwarfed by the rest of the mountain itself! The images above and below have been enhanced to show the colours as they would appear if they were on Earth. Click on the images for larger versions.
The image below is an orbital view from Mars Reconnaissance Orbiter showing the same region of foothills. This is where Curiosity will be driving later on; the mesas and canyons will be seen up close providing views never seen before by a rover on Mars. There is also a channel cutting through the middle portion of the image, which is thought to be an ancient riverbed. Other similar channels and their alluvial deposits can be seen elsewhere in this region. Click on the image for larger version and then click to zoom in.
Plate tectonics are a geological phenomenon that, in our solar system, have long been thought to be unique to Earth. The Earth’s crust is broken into seven different major sections or “plates,” kind of like a cracked eggshell. These plates move around, slide against each other and even move above and below each other. Earthquakes are a common result of all of this activity.
Other planets and moons in our solar system haven’t shown evidence of this so far, even though some are volcanically active, like Jupiter’s moon Io for example (volcanic activity is possible without plate tectonics). Mars has huge shield volcanoes, but they are thought to have been extinct for millions or billions of years. A lack of crustal movement would explain why Mars’ volcanoes have tended to become so large, much bigger than any on Earth, since they remained in one spot and just kept growing instead of moving around.
But now a new report challenges this view of Mars, suggesting that it did once have active plate tectonics, but that the crust was divided into no more than two plates and that they moved much more slowly than those on Earth, due to Mars’ smaller size and cooling of its interior early in its history.
See Examiner.com for the full article.
A new “oblique view” image has been posted on the HiRISE website showing an area inside Gale crater, the landing spot of the Curiosity rover. The high-resolution image, taken by the Mars Reconnaissance Orbiter, shows a portion of Mount Sharp and the surrounding terrain of layers, canyons, buttes and sand dunes. The viewing angle is 45˚, similar to looking out the window of an airplane. Zoom into the image to see all of the amazing detail!
Although smaller than the Earth, Mars has been found to be a geologically very diverse place, often similar to our own planet but also sometimes quite different – a world that is both eerily familiar and uniquely alien.
Now, another new discovery has raised more questions about the planet’s past, and how similar geological processes have shaped the landscapes of both worlds.
Photographs taken by the Mars Reconnaissance Orbiter spacecraft of the Athabasca Valles region near the equator have revealed hundreds of odd spiral shapes on the surface. So far, 269 have been found, ranging up to about 30 metres (100 feet) across each, at Cerberus Palus specifically, an area where “plates” of material have fractured, rotated and drifted over time. On Earth, similar looking coils can be formed by “ice rafts” or slow-moving lava flows, either of which may also explain the platy, fractured appearance of the ground.
So how did these coils form? By fire or ice?
When pahoehoe lava flows on Earth slide past each other, moving at different speeds or in different directions, they can form twisted, coiled shapes similar to those seen on Mars.
According to Andrew Ryan, one of the authors of the new study published in the journal Science, “Everything that we have observed in Athabasca Valles can be formed by lava. Although you could attribute certain features to ice, the lava coils indicate that this is not the case. There are no known mechanisms to naturally produce spiral patterns in ice-rich environments on the scale and frequency observed in our study area.”
But not all scientists are convinced about the lava explanation. They contend that water ice could still account for the curious spirals – as explained by John Murray of the Department of Earth Sciences at the Open University in the UK:
“I think there are so many features here that it’s difficult to explain them other than [the theory] that this was essentially water that froze and has since sublimated away. Sublimation is when a solid turns directly into a gas. There is no lava that behaves in so many different ways.”
He adds, “You do get plates in lava, but on the scale of a few metres. Here you’re talking about things which are kilometres long, and the only way you can do that really is to have a liquid that’s extremely mobile and fluid – water or something like water. If you freeze the top of that, as in the Arctic, you do get ice floes that are several kilometres or more, which is what you get on Mars in this region. You never see anything like that in a lava flow.”
As with other Martian mysteries, the debate will probably continue for the forseeable future.
The paper is available here.
This article was first published on Examiner.com.
The Mars Reconnaissance Orbiter has taken incredible images of another giant dust devil, similar to one photographed in February, but much larger. This one, in Amazonis Planitia, is about 20 kilometres (12 miles) tall! That’s also a lot bigger than typical dust devils on Earth, more like the size of a terrestrial tornado.