A "special effects" photo of NASA's Mars Exploration Rover Spirit superimposed over "Husband Hill", one of the regions studied by the rover before its demise in 2009.
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.
In 2009, after five years of exploring Mars, NASA's Spirit rover hit an unexpected snag: a Red Planet sand trap.
After it cracked through a hard layer of topsoil, Spirit was doomed to spin its wheels with Mars sand up to its hubcaps. NASA engineers spent months trying to free the robot through remote maneuvering, but the Spirit rover was ultimately unable to escape, and it went silent in 2010.
Researchers are now working on new software that they say could help prevent other interplanetary explorers, such as NASA's car-size Mars rover Curiosity, from running into similar quagmires.
"There’s a lot of knowledge in civil engineering about how soils will react when subjected to heavy loads," MIT’s Karl Iagnemma, a principal research scientist in the department of mechanical engineering, said in a statement.
"When you take lightweight vehicles" — like rovers — "and granular soils of varying composition, it’s a very complex modeling process," Iagnemma added.
Iagnemma and colleagues say they have developed a video game-like model called Artemis to simulate and predict how a rover will move over a diversity of soil, which could help mission planners chart safer routes and maneuver out of tricky terrain.
The researchers refined the model with performance tests in a lab, which included rolling a spare wheel from Spirit's twin, the Mars rover Opportunity, over coarse and fine soil. The team also tested Artemis against real-world scenarios, steering rover-like robots in the Mojave Desert's Dumont Dunes.
Iagnemma hopes their model could help mission planners deal with unexpected challenging terrain, such as loose sand.
"Think about the difference between beach sand, which you can walk on and even play volleyball on, and cake flour," Iagnemma explained in a statement.
Artemis may even help the the mission planners for Curiosity, which landed on the Red Planet in August 2012 and is expected to traverse more challenging topography in the coming months and years.
"There are goals for taking the rover into places that are more difficult to travel, like dunes and steep slopes," Iagnemma said. "That time hasn't really been reached yet, so there’s a little time to get the model refined for Curiosity."
The research will be detailed in the Journal of Field Robotics.