After the Mars Science Laboratory, otherwise known as the Curiosity rover, dropped down the rabbit hole and safely landed on the surface of Mars there was much ado about the first images and hints at a watery past. Since then the rover has left the public eye but the rover has been no slouch, but has been poking, brushing, zapping, imaging and is now about to drill into the surface of Mars. The images alone are stunning but the chemistry data and other forms of analysis that this mobile laboratory can collect have been no less impressive even if they take much longer to collect, analyze and interpret. Some of the initial results are in and those results confirm that the Curiosity rover has landed in a wonderland that would stun even Alice. But while answers to some questions are coming into focus there are still puzzles here that could keep that grin on the Cheshire’s cats face.
For a blow-by-blow analysis and report of the latest results from data collected by Curiosity you must visit and read Emily Lakdawalla’s blog at Plantetary.org (http://www.planetary.org/blogs/emily-lakdawalla/2013/01151352-curiosity-sol157-glenelg-candy-store.html). In addition you can see my first post describing the mission of Curiosity and the initial pictures (Mars Curiosity Rover: A Geological History Detective). I will do my best to summarize a bit of what Curiosity has been up to with a lot of help from some great images from NASA and Mar’s fanatics who have further edited those images and add my own observations below. The images get better and better so be sure to scroll to the bottom is you don’t plan to look at all the images.
The Travels of Curiosity Since Its Landing:
The first big decision after landing was where would Curiosity go first. The main target, remember, is the huge 5km tall mountain in the center of the crater which is to the south on the picture below. Mission directors could have headed directly south but they decided to take a side trip to the east first to visit this are where you can see that there is a region where three different colored patterns of Mars surface come together. Satellite data suggested that the lighter color rock could be something more like bedrock than soils mixed with rock like where Curiosity landed. As we will see they were right and this area was MUCH more interesting than really anyone could have hoped it would be.
In the image above I want you to notice that there are many small round craters. This is probably important to remember because when you see surface images it is hard to visualize where they are but this area, like nearly everywhere on Mars, has been pummeled with meteorite falls and this has probably had a big effect on the history of the surface of Mars.
Below is a similar image but taken more recently at higher resolution. If you look carefully you can actually see the tracks left from the rover driving over the terrain. You can also see that there are definitely different surface textures. How these different types of surfaces came to exist seems to still be very much of a mystery.
Going Downhill:
You can’t see in the image above but generally the rover has been travelling downhill and so along the way it has been going down into successively lower units of rock. It is now at one of the lowest points (Yellowknife Bay) in the immediate area and so can now look up at where it has been. Below are some images of that trip.
Remarkably, there are rocks strewn all over the place on the hills where the rover landed. Below though, we see that as the rover begins to move down the hill it encounters areas where it can see that there are section of thin layers of rock that lie below the surface. The fact that small ledges can be seen suggests that the layers alternate between layers of harder and softer rock such that there has been differential amounts of erosion in the wind.
Below a “valley” of sorts appears. The light toned rocks are bare rock that we will see contain some really amazing features. What just amazed me and I still can’t explain it is how this lower elevation area is wiped nearly clean of rubble and is smooth rock and sand while the hills around are covered in many jagged rocks like rubble. You can see off in the distance that on the other side of this depressed area or valley that there are darker rocks which are area that are much like where the rover was standing while taking this picture.
Curiosity arrives at the junction of the different colored rocks from orbit in a place called “Glenelg”
Looking to the side and up the hill a bit we can now see the layers of rock in the panorama.
Above is right where the rover is today. It is getting ready to drill into this or a similar rock to take a closer look at the composition of them. But what we see here already is some of the clearest evidence of past water on Mars. The mudcrack-looking pattern is the result of veins in the rocks are actually the result of fractured rock that then has had the cracks filled with a light-toned material which has been identified by NASA as calcium sulfate. This is a form of rock that you would expect to be the result of precipitation from water percolating through the cracked rock. After the veins formed, apparently they were more resistant to erosion and so the rock has eroded leaving these raised veins forming this weird patter at the surface.
In the image above we again see these calcium sulfate veins in the rocks and we also see small round concretions which are also expected to be the result of precipitated minerals. The likely series of events here is that there were layers of sediments put down possibly by water or wind but that after they had solidified into rock that rock was fractured. It seems likely to me that this rock could have been fractured by meteorite impacts in the layers that at one time may have been meters or hundreds of meters stacked on top of these rocks. After the cracks formed water present and moving in these rock layers (like ground water on earth) precipitated out these veins and concretions. Later the rock above was eroded either by water or more likely wind revealing the features we see today.
Ok, now for some really awesome panoramic scenes which will help us get a better felling for the interior of this crater. You really have to click on these images to see them in their full glory.
The above image is a real head-scratcher for me. Where did the slabs of rock come from in the middle of this picture? They seem to be a continuation of layers of rocks that are found to the right of the picture but how did they erode so they are just sitting on top of these other layers without themselves eroding? Was this the result of a fast paced erosion process (even if very long ago) that resulted in sections of rock left behind? Clearly, processes which resulted in what we see today (veins of sulfates, conglomerate sedimentary rock, concretions, different layers of rock, etc..) are no longer in operation today since there is no water and there is not enough wind to provide a strong erosional force.
Below we have an image that helps you get a sense for how hilly the area is and where the rover came from to get to this point. Again, I can’t help but point out how smooth the area in the foreground is relative to the hills which have loose boulders and rocks on them. I really can’t figure that out.
The last picture below just provides some perspective of size because you can see the arm of the rover in the foreground and the wheels to each side. It also shows quite dramatically that there is a layer of rock sitting on top of the rock layer that the rover is on right now.
Naturalis Historia 