Curiosity marks two years of excavating the Martian surface with Mojave 2 sample
NASA has stated with increasing frequency that it is focused on exploration of Mars. Image Credit: NASA
This week marks two years since humanity first tapped into the Martian bedrock. Well, not a person per-se. NASA’s Mars Science Laboratory rover Curiosity was the instrument of this historic excavation, and two years later the mini Cooper-sized robotic geologist continues digging into the Red Planet’s history. NASA highlighted the progress that the rover has made toward furthering our understanding toward the forces that have shaped the flash-frozen world’s past.
In that historic first dig, Curiosity employed its onboard drill to make the smallest of incisions (about 2.5 inches deep) in the expanse of Gale Crater. The rover’s mission was to assess whether or not the crater once offered an environment hospitable for life as we understand it.
Since then, the one ton rover has been moving slowly but steadily towards Mount Sharp, the large mountain at the center of the crater. Curiosity arrived at Mount Sharp five months ago, where it has once again resumed drilling small holes in search of answers to questions regarding water (and perhaps life) in the Red Planet’s distant past.
This view from the Mars Hand Lens Imager (MAHLI) camera on the arm of NASA’s Curiosity Mars rover shows some of the outcome from a shallow-depth, mini-drill test to assess whether a rock target called “Mojave” is appropriate for full-depth drilling to collect a sample. Image and Caption Credit: NASA.
The rover analyzes the fine particulates created from the drill by channeling it into one of two instruments on board, Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM). These instruments use a range of tools, including several distinct spectrometers, to measure everything from water to oxygen to methane levels.
In Sept., Curiosity took its first samples from the base of Mount Sharp, in a region NASA calls Confidence Hills. Now at Pahrump Hills, Curiosity is probing a rock named Mojave 2. Yet, unlike all previous drillings, the rover’s Earth-bound handlers are experimenting with a new, low-impact drilling technique.
As the leader of the surface science and sampling campaign, John Michael, explains, “This was our first use of low-percussion drilling on Mars, designed to reduce the energy we impart to the rock. Curiosity’s drill is essentially a hammer and chisel, and this gives us a way not to hammer as hard.” This is significant because many of the target rocks near the mountain are brittle and finely layered, and more rigorous drilling techniques might corrupt samples. Drilling at Mojave, the original sample site, broke the rock.
An animated set of three images from NASA’s Curiosity rover shows the rover’s drill in action on Feb. 8, 2013, or Sol 182, Curiosity’s 182nd Martian day of operations. Image and Caption Credit: NASA.
A NASA press release expanded on the ability to manipulate the drill speed: “The rover’s drill has six percussion-level settings ranging nearly 20-fold in energy, from tapping gently to banging vigorously, all at 30 times per second. The drill monitors how rapidly or slowly it is penetrating the rock and autonomously adjusts its percussion level. At the four targets before Mojave 2 — including three before Curiosity reached Mount Sharp — sample-collection drilling began at level four and used an algorithm that tended to remain at that level. The new algorithm starts at level one, then shifts to a higher level only if drilling progress is too slow. The Mojave 2 rock is so soft, the drill reached its full depth of about 2.6 inches (6.5 centimeters) in 10 minutes using just levels one and two of percussion energy.”
Scientists were originally drawn to Mojave 2 because of distinct rice-sized particles protruding from the rocks, which they hypothesized may be salt deposits, which could be indications of an evaporated lake. Initial analytics have produced interesting results. According to David Vaniman, Deputy Principal Investigator for CheMin, “Our initial assessment of the newest sample indicates that it has much more jarosite [a sulfate mineral] than Confidence Hills.” The drill samples from Confidence Hills suggest a less acidic environment than Pahrump Hills. Yet, the source and geological timing of Mojave’s greater acidity is still a matter of speculation.
As Curiosity continues slowly probing the Martian landscape, we are reminded how quickly achievements of immense engineering and scientific effort become routine components of our exploration of the solar system. Mars’ Gale Crater is lined with the minute pockets of man’s robotic reach, which began only two years ago.
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Josh Tallis
Since 2011 Joshua Tallis has served as the manager for research and analysis at an intelligence and security services provider in Washington, DC. Josh has co-authored several articles in the Journal of Counterterrorism and Homeland Security International with colleagues from the defense community. Previous work experience includes internships at the U.S. Congress and the Foundation for Defense of Democracies. Josh is also a PhD student in International Relations at the University of St Andrews' Centre for the Study of Terrorism and Political Violence. He is a Summa Cum Laude, Phi Beta Kappa and Special Honors graduate of The George Washington University where he received a BA in Middle East Studies from the Elliott School of International Affairs.
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