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.
Category Archives: Mars Reconnaissance Orbiter
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).
The question of whether there could still be liquid water somewhere on Mars today is one of the most debated in planetary science, and now there is new evidence that there just might be. The findings were announced today, February 10, 2014, by scientists from the Mars Reconnaissance Orbiter mission.
The new results have to do with features on the Martian surface called “recurring slope lineae” (RSL), which are dark, narrow streaks on some slopes which flow downhill and can reoccur in the same locations over and over again. They tend to form during periods of warmer temperatures and look like small rivulets of water running downhill, but is that what they really are?
“We still don’t have a smoking gun for existence of water in RSL, although we’re not sure how this process would take place without water,” said Lujendra Ojha, a graduate student at the Georgia Institute of Technology in Atlanta. He is the lead author of two new reports about the unusual flows.
In order to try and determine if these streaks are indeed water-related, Ojha and colleague James Wray examined RSLs at 13 known locations using images from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter.
While not yet finding the spectral signature of water or salts, they did find them for ferric and ferrous iron-bearing minerals. The minerals are more abundant in the slope streaks and so thought to be left over from whatever process created the streaks. Two possible explanations are related to these, and both involve water: an increase in the more-oxidized (ferric) component of the minerals, or an overall darkening due to moisture, just like you see with wet sand or dirt. It is also possible that fine dust is being removed from the surface, which could involve either a wet process or a dry one.
According to Ojha, “Just like the RSL themselves, the strength of the spectral signatures varies according to the seasons. They’re stronger when it’s warmer and less significant when it’s colder.”
As to why water itself wasn’t detected yet, the spectral observations might easily miss them since the dark flows are much narrower than the area of ground sampled by CRISM.
The most likely explanation for the RSLs according to scientists though is still near-surface briny water or ice, which, during warmer periods, could leak out at the top of slopes and remain liquid long enough in the cold and thin atmosphere to flow down the slopes.
“The flow of water, even briny water, anywhere on Mars today would be a major discovery, impacting our understanding of present climate change on Mars and possibly indicating potential habitats for life near the surface on modern Mars,” said Richard Zurek, Mars Reconnaissance Orbiter Project Scientist at NASA’s Jet Propulsion Laboratory in Pasadena.
This article was first published on Examiner.com.
This is an interesting new image from the HiRISE camera on the Mars Reconnaissance Orbiter, first posted on Beautiful Mars on Tumblr. What caused the unusual patterning on this mound? It’s reminiscent of polygonal terrain created by the freezing/thawing of subsurface ice, but whether that is the same explanation here isn’t known. All of the thousands of images taken so far by MRO can be seen here.
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.