January 20th, 2013 by James Ayre
NASA’s Mars rover, Curiosity, is about to start drilling into the Red Planet for the first time, after discovering a treasure trove of what looks like water-created minerals.
Essentially it’s sedimentary rock that is “criss-crossed by mineral-filled veins,” that were very likely formed because the whole area was saturated with water.
The Mars Science Laboratory first noticed the rocky outcrop “on the wall of Gale Crater that was full of a crusty mix of cemented pebbles,” last September shortly after landing. “It matched signs of an alluvial-fan feature seen from orbit” and is providing some of the best evidence yet that there was once a very large amount of water flowing on the Martian surface.
“Now Curiosity has entered Yellowknife Bay, a terrain that exhibits all the signs of a different type of water presence. In fact this depression in the landscape seems to be entirely distinct from the earlier Gale Crater landing site only about 500 meters away.”
In Yellowknife Bay, the “sedimentary rocks (formed from the crushed remains of earlier rocks) are filled with fractures and veins of what might be hydrated calcium sulfate (bassinite or gypsum) – deposited when water soaked this area.”
The area “is literally shot through with these fractures,” says John Grotzinger, a geologist at the California Institute of Technology in Pasadena., Calif., and the mission’s chief scientist
The area also contains large numbers of ‘nodules’, of “deposited material, and also cross-bedded layering, and even a rather shiny pebble embedded in sandstone that’s provoked our human pattern recognition system into thinking there’s a martian ‘flower’ popping from the ground.”
I’m not sure why it was thought to look like a flower by some people, but the mineral was certainly very distinct looking in the landscape. And it does make the area seem even more attractive as a place to begin drilling.
During the next few weeks, Curiosity will be, first testing out its drill in order to clean it, and then it will begin drilling in the most interesting looking spots. The drill, attached to a 7-foot robotic arm, is coated in Teflon, so before any ‘sterile’ sample taking can be done it will need to be cleaned of possible contaminants by drilling into pretty much any uninteresting looking rock.
The drill is able to bore about 5 cm deep, which is considered deep enough to get well past crust of these rocks. It will be very interesting to see what it finds.
Hopefully this will provide much more insight into what the early environment of Mars was like.
Groundwater on Mars is also still a possibility, whether frozen or liquid. It would be very interesting to be able to dig down deep into the Martian sand and see what you could find. Lava tubes especially seem like an interesting place to explore, and caves with collapsed roofs. Unfortunately, Curiosity won’t be able to explore any of these, so that will have to wait.
Perhaps the most interesting place for future exploration, though (in my opinion), are the ice caps. There are some obvious technological difficulties to exploring such a region though.
“Both the northern polar cap (Planum Boreum) and the southern polar cap (Planum Australe) are believed to grow in thickness during the winter and partially sublime during the summer. Data obtained by the Mars Express satellite made it possible in 2004 to confirm that the southern polar cap has an average of 3 kilometres (1.9 mi) thick slab of ice with varying contents of frozen water, depending on its latitude; the polar cap is a mixture of 85% CO2 ice and 15% water ice. The second part comprises steep slopes known as ‘scarps’, made almost entirely of water ice, that fall away from the polar cap to the surrounding plains. The third part encompasses the vast permafrost fields that stretch for tens of kilometres away from the scarps. NASA scientists calculate that the volume of water ice in the south polar ice cap, if melted, would be sufficient to cover the entire planetary surface to a depth of 11 meters.”
“Results, published in 2009, of shallow radar measurements of the North Polar ice cap determined that the volume of water ice in the cap is 821,000 cubic kilometers (197,000 cubic miles). That’s equal to 30% of the Earth’s Greenland ice sheet or enough to cover the surface of Mars to a depth of 5.6 meters (dividing the ice cap volume by the surface area of Mars is how this number is found). The radar instrument is on board the Mars Reconnaissance Orbiter.”
Image Credits: NASA/JPL-Caltech/MSSS; Polar Ice via Wikimedia Commons
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