Curiosity Has Hit a Martian Mineral Jackpot
As far as rocks on any planet go, this formation looks fascinating -- but these rocks are on Mars and they hold clues to TWO periods of water on the red planet.
As far as rocks on any planet go, this formation looks fascinating. But it's even more fascinating to know that this particular rocky outcrop was photographed on Mars by NASA's Curiosity rover and it holds further clues to the red planet's wet past and, potentially, Mars' habitable potential.
Currently studying the "Pahrump Hills" region at the base of Mount Sharp in the center of Gale Crater, this new view snapped by Curiosity on March 18 shows a work site Curiosity's mission scientists call "Garden City." This area is interesting as it shows two-tone mineral veins protruding from the surrounding rock.
The tough mineral veins were formed in Mars' ancient wet past and they are sticking out of the rock up to 6 centimeters (2.5 inches) high. This means that the veins formed within the rock and the softer surrounding bedrock has since eroded away.
When comparing the geology of this particular area with the rocks that Curiosity has analysed in lower sections of Mount Sharp, a story emerges Mars' ancient geological history.
"Some of (the mineral veins) look like ice-cream sandwiches: dark on both edges and white in the middle," said Linda Kah, Curiosity science-team member at the University of Tennessee, Knoxville, in a NASA Jet Propulsion Laboratory news release. "These materials tell us about secondary fluids that were transported through the region after the host rock formed."
Like previous rocks studied by Curiosity, the prominent veins at Garden City were formed when water flowed through cracks in bedrock, depositing minerals inside these fractures. The chemistry of the rock neighboring the fractures became altered and these tough veins formed. Previously, the robotic geologist has found other bright veins rich in calcium sulfate.
However, Garden City appears to be different from previous samples - the darker material in the veins suggest an early episode of water on Mars, whereas the brighter mineral deposits shows a later episode of water flow.
"At least two secondary fluids have left evidence here," added Kah. "We want to understand the chemistry of the different fluids that were here and the sequence of events. How have later fluids affected the host rock?"
Curiosity has been studying rocky configurations since landing on the Martian surface in 2012.
Over the past 6 months, the rover has been focused on Pahrump Hills, studying the layers of rock spanning an elevation of only 10 meters. Garden City is the highest point (so far) of this survey and there are very obvious changes in the mineral history over this small cross section.
"We investigated Pahrump Hills the way a field geologist would, looking over the whole outcrop first to choose the best samples to collect, and it paid off," said David Blake of NASA's Ames Research Center, Moffett Field, Calif., and principal investigator for Curiosity's Chemistry and Mineralogy (CheMin) instrument.
Geology is as much about the science of rocks as it is about looking back in time. Looking through the different layers of sedimentary rock reveal periods of when a region was covered in water. Likewise, different mineral layers reveal episodic water flow through cracks in rock, locking a chemical "tag" within those cracks. Curiosity is equipped with a complex suite of tools that analyse these layers, slowly building a picture of the geological history of Gale Crater.
This latest picture from Mars certainly looks like Curiosity has hit the geological jackpot; not only is there obvious signs of minerals that were formed in the presence of water in sedimentary rock (which was also formed through the presence of water), but the two-toned minerals are indicative of two distinctive wet periods. But what does it mean? For now, we'll need more data, but that's why Curiosity is hard at work, exploring the layers of Mount Sharp, slowly adding more detail to the rich history of water and organics on the red planet.
This March 18, 2015, view from the Mast Camera on NASA's Curiosity Mars rover shows a network of two-tone mineral veins at an area called "Garden City" on lower Mount Sharp.
Since NASA's Mars Science Laboratory (MSL) rover Curiosity landed on the red planet, each sol (a Martian "day") of the mission sees a flood of new photographs from Aeolis Palus -- the plain inside Gale Crater where Curiosity landed on Aug. 5. In September 2012, mission controllers sent the command for Curiosity to flip open the dust cap in front of the robotic arm-mounted Mars Hand Lens Imager (MAHLI). Until that point, the semi-transparent dust cap only allowed MAHLI to make out fuzzy shapes -- although it did a great job imaging Curiosity's "head" and it is also famous for capturing Curiosity's first color photograph. But since the true clarity of MAHLI has been unleashed, we've been treated to some of the most high-resolution views of the rover, Martian landscape and, most importantly, we've seen exactly what MAHLI was designed to do: Look closely at Mars rocks and dirt, assembling geological evidence of potential past habitability of Mars.
The Business End
Curiosity is armed with 17 cameras and MAHLI is designed to capture close-up photos of geological samples and formations as the rover explores. MAHLI was designed and built by Malin Space Science Systems and is analogous to a geologist's hand lens -- only a lot more sophisticated. Its high-resolution system can focus and magnify objects as small as 12.5 micrometers (that's smaller than the width of a human hair!). This photograph captured by the rover's Mastcam shows the MAHLI lens (with dust cap in place) in the center of the end of Curiosity's instrument-laden robotic arm.
To aid its studies, MAHLI is equipped with four LEDs to light up the imager's samples.
The first photograph to be returned from MAHLI without the dust cover in place was received on Sol 33 (Sept. 8) of Curiosity's mission. Shown here is a view of the ground immediately in front of the rover. Although this photo was a test, mission scientists were able to do a very preliminary study of the large "pebble" at the bottom of the picture: "Notice that the ground immediately around that pebble has less dust visible (more gravel exposed) than in other parts of the image. The presence of the pebble may have affected the wind in a way that preferentially removes dust from the surface around it," they wrote.
How Did Lincoln Help MAHLI?
On Sol 34 (Sept. 9), MAHLI was aimed at Curiosity's calibration target. This target is intended to color balance the instrument and provide a "standard" for mission scientists to refer to. The 1909 Lincoln penny was provided by MAHLI's principal investigatory Ken Edgett. Using a penny as a calibration target is a nod to geologists' tradition of placing a coin or some other object of known scale as a size reference in close-up photographs of rocks, says the MSL mission site.
Although MAHLI will be used to examine microscopic scales, it is showing its prowess at generating some spectacular high-definition views of the rover. Shown here is a mosaic of Curiosity's three left-side dusty wheels.
Hazard Avoidance Cameras
Hazard Avoidance Cameras, or Hazcams, have become "standard issue" for the last three rovers to land on Mars. Mounted on the front and back of rovers Opportunity, Spirit and Curiosity, these small cameras provide invaluable information about the terrain and potential hazards surrounding the rovers. These cameras are not scientific cameras -- they are engineering cameras. Shown here, MAHLI has imaged the four front Hazcams on Curiosity. Interestingly, it was these cameras who returned Curiosity's first dusty image after touch down in August.
Using the flexibility of the robotic arm, MAHLI was able to check the underside of Curiosity. As the camera can focus on objects from 0.8 inch (2.1 centimeters) to infinity, MAHLI has incredible versatility allowing mission controllers to focus on the very small features of Mars to checking the health of the rover to viewing the impressive vistas beyond.
In October 2012, the Internet was abuzz with speculation about a "mystery object" lying beneath the rover during digging operations at "Rocknest." Sadly, after studying the translucent object, mission scientists deduced that it wasn't anything native to the alien environment, it was actually a piece of plastic that had fallen from Curiosity. Yes, Curiosity is littering the red planet.
The MAHLI camera was very attentive while Curiosity dug trenches in the Mars soil at "Rocknest."
In early 2013, MAHLI snapped another curious photo. This time, after driving to a rocky outcrop at a location dubbed "Yellowknife," the camera picked out what appeared to be some kind of organic-looking object embedded in the rock. Nope, it's not a Mars "flower" -- more likely it's a concentration of minerals.
In what has become an iconic photo of Curiosity, MAHLI was commanded to capture dozens of high-resolution pictures of the rover. Like an "arms length" shot you may have in your Facebook profile, Curiosity did the same, composing a mosaic of pics taken with its outstretched robotic arm.
Curiosity Cleans Up!
The Mars rover isn't only a scientific superstar, it also has a talent for cleaning. This circular pattern on a Mars rock was brushed aside by Curiosity's Dust Removal Tool (DRT), helping the rover carry out analysis of the rock surface beneath the layer of dirt.