NASA's Mars rover Curiosity used its robotic arm-mounted Mars Hand Lens Imager (MAHLI) to capture views of its wheels on Nov. 24, 2013, after 6 days of inactivity due to an electrical "soft short." Note the punctures and holes in the rover's aluminum wheels -- the material was designed to sustain such damage after 463 sols (days) roving the Red Planet's surface..
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.
It's hard being a robot exploring another world, as NASA's Mars Science Laboratory has proven this month.
On Nov. 17, mission managers of the six-wheeled rover Curiosity announced that they were troubleshooting a suspected "soft short" in the robot's electrical system. A soft short is a glitch where a small amount of power is leached through a material that's partially conductive.
Curiosity's electronics are built with this eventuality in mind, so mission engineers weren't overly alarmed. However, the resulting voltage drop from the rover's chassis and power bus was cause for concern and could have affected the mission's robustness against more soft shorts in the future.
But on Nov. 25, NASA Jet Propulsion Laboratory (JPL) scientists announced that Curiosity was back to science operations after a precautionary six-day suspension and its power supply was back to pre-Nov. 17 levels.
Engineers had traced the soft short to the rover's Multi-Mission Radioisotope Thermoelectric Generator -- the mission's power source that harnesses the heat generated by pellets of radioactive plutonium-238 and turns it into electricity.
"We made a list of potential causes, and then determined which we could cross off the list, one by one," said Rob Zimmerman, rover electrical engineer at JPL in Pasadena, Calif., in a news release.
The return to normal levels of power after the soft short is consistent with shorts experienced by other spacecraft that use radioisotope thermoelectric generators (RTGs) for power. The NASA Cassini Saturn orbiter, for example, has experienced soft shorts, all of which have been troubleshooted, returning power to normal levels.
One of the first signs that Curiosity was back hard at work after the short hiatus was the new raw imagery uploaded to the JPL archive. Curiosity's robotic arm-mounted Mars Hand Lens Imager (MAHLI) was even used to check out the rover's undercarriage, including its six 20-inch aircraft-grade aluminum wheels.
As reported by Discovery News in May, Curiosity's wheels are showing obvious signs of wear and tear -- now including a rather dramatic hole in the thin material between a left-hand wheel's tread (see photo, top). These points of damage may looks serious, but it's all part of Curiosity's design.
"The wear in the wheels is expected," Matt Heverly, lead rover driver for Curiosity, told Discovery News on May 22. "The 'skin' of the wheel is only 0.75mm thick and we expect dents, dings, and even a few holes due to the wheels interacting with the rocks."
Aside from firing up its awesome array of cameras once more, Curiosity also delivered powdered rock from drilling operations to its onboard chemistry laboratory over the weekend, the first time since it analyzed samples from "Cumberland" rock six months ago.
Analysis of these new samples has already begun and planetary scientists are expecting a bountiful array of data that will further reveal Mars' geological history and potential habitability.
Curiosity landed inside Gale Crater on Aug. 6, 2012, and is currently roving toward a 5.5 kilometer high rise, Aeolis Mons (or "Mount Sharp") in the center of the crater's plain, Aeolis Palus. Along the way, however, the rover is stopping at geologically interesting points to continue to unravel the Red Planet's mysterious past.