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.
A robotic detective of sorts is being dispatched to Mars to try to crack a long-standing mystery of why a planet that seems to have once been Earth’s twin, with oceans, rivers, rain and snow, ended up a cold desert.
"We know for a fact that it used to be very different. Mars used to have a wet climate ... but over billions of years that changed," said astronomer Michelle Thaller, with NASA's Goddard Space Flight Center in Greenbelt, Md.
Scientists believe the climate change happened because Mars lost its magnetic shield, leaving the planet vulnerable to solar and cosmic radiation. Over time, the ionizing rays took apart what was believed to have been a thick, protective atmosphere which kept Mars warm and wet.
NASA's Curiosity rover and other probes have given scientists a glimpse of ancient Mars by analyzing its rocks. The new scout, called MAVEN, will study what remains of Mars' atmosphere to learn about processes that are going on today.
"We'll get a window on what is happening now so we can try and look backward at the evidence locked in the rocks and put the whole story together about Martian history and how it came to be such a challenging environment," said Pan Conrad, a deputy principal scientist on the Curiosity mission.
MAVEN, an acronym for Mars Atmosphere and Volatile Evolution Mission, is designed to spend at least on year circling Mars, focusing not on the planet’s surface but on the thin layer of gases that remains in its skies.
Scientists want to know how cosmic rays and high-energy particles from the sun, which blast out into space during solar flares and powerful storms, peel away Mars’ atmosphere and how often the damage occurs.
One of MAVEN's three science instruments is a near-copy of one of Curiosity's gas analyzers, allowing the spacecraft to inhale the atmosphere and reveal its chemical composition.
The information should help scientists home in on the time in Mars’ history when conditions were most suitable for life.
"If live arose on Mars it probably did so early, within about 500 million years," of its formation, Conrad said.
A view of the dry ground immediately in front of the Curiosity Mars rover. Image credit: NASA/JPL-Caltech/Malin Space Sc
Earth had some key advantages that allowed it to keep its magnetic field and evolve into a mecca for life.
First, Earth is larger. Mars' diameter is about half the length of Earth's and it has just 10 percent Earth’s mass.
Being smaller meant Mars lost some of its inner heat faster than Earth, a process that may have directly or indirectly led to the disappearance of Mars' magnetic field some 4 billion years ago.
Mars also does not have a large moon like Earth's. Scientists believe the moon helped shield Earth from the heavy bombardment of asteroids and comets that pummeled the inner planets 3.8 billion to 4.1 billion years ago. Being closer to Jupiter also may have forced Mars to bear a greater share of the incoming asteroid strikes.
Those impacts may have been sufficient to warm Mars' surface and shut down convection in its core, another possible explanation for loss of the planet's magnetic field.
"Without that protection, the atmosphere moved away and then there was no way to moderate the conditions so that Mars could stay warm enough to have a surface that looks more like Earth’s," Conrad said.
MAVEN is slated for launch aboard an Atlas 5 rocket at 1:28 p.m. EST on Monday from Cape Canaveral Air Force Station in Florida. The journey to Mars will take 10 months.