After ten years in service (when it wasn’t supposed to last longer than nine months), one would think that left for the Opportunity rover to do. And yet, Opportunity is still hard at work, thanks in no small part to its solar panels being their cleanest in years. In its latest research stint, NASA’s decade-old Mars Exploration Rover Opportunity is inspecting a section of crater-rim ridgeline chosen as a priority target due to evidence of a water-related mineral.
Orbital observations of the site by another NASA spacecraft – the Mars Reconnaissance Orbiter (MRO) – found a spectrum with the signature of aluminum bound to oxygen and hydrogen. Researchers regard that signature as a marker for a mineral called montmorillonite, which is in a class of clay minerals (called smectites) that forms when basalt is altered under wet and slightly acidic conditions. The exposure of it extends about 240 meters (800 feet) north to south on the western rim of Endeavour Crater.
The detection was made possible using the MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) combined with rover observations some 3 kms (2 miles) north on the crater’s western rim. Rocks exposed there contain evidence for an iron-bearing smectite – called nontronite – as well as for montmorillonite. That site yielded evidence for an ancient environment with water that would have been well-suited for use by microbes, evidence that could boost our understanding of what Mars looked like billions of years ago.
Opportunity reached the northern end of the montmorillonite-bearing exposure last month – a high point known as “Pillinger Point.” Opportunity’s international science team chose that informal name in honor of Colin Pillinger (1943-2014), the British principal investigator for the Beagle 2 project, which attempted to set a research lander on Mars a few weeks before Opportunity landed there in January of 2004.
Colin and his team were trying to get to Mars at the same time that we were, and in some ways they faced even greater challenges than we did. Our team has always had enormous respect for the energy and enthusiasm with which Colin Pillinger undertook the Beagle 2 mission. He will be missed.
Though selected as a science destination, Pillinger Point also offers a scenic vista from atop the western rim of Endeavour Crater, which is about 22 kms (14 miles) in diameter. The picture below shows a section of a color shot taken by Opportunity’s panoramic camera (Pancam) upon arrival. A full-size view of this picture can be seen by going to NASA’s Jet Propulsion Laboratory Mars Exploration Rovers webpage.
Initial measurements at this site with the element-identifying alpha particle X-ray spectrometer at the end of Opportunity’s arm indicate that bright-toned veins in the rock contain calcium sulfate. Scientists deduce this mineral was deposited as water moved through fractures on Endeavour’s rim. The rover found similar veins of calcium sulfate farther north along the rim while investigating there earlier last month.
As Opportunity investigated this site and other sites farther south along the rim, the rover had more energy than usual. This was due to the solar cells being in rare form, says Opportunity Project Manager John Callas of NASA’s Jet Propulsion Laboratory:
The solar panels have not been this clean since the first year of the mission. It’s amazing, when you consider that accumulation of dust on the solar panels was originally expected to cause the end of the mission in less than a year. Now it’s as if we’d been a ship out at sea for 10 years and just picked up new provisions at a port of call, topping off our supplies.
Both Opportunity and its rover twin, Spirit, benefited from sporadic dust-cleaning events in past years. However, on the ridge that Opportunity has been navigating since late 2013, winds have removed dust more steadily, day by day, than either rover has experienced elsewhere. The rover’s signs of aging – including a stiff shoulder joint and occasional losses of data – have not grown more troublesome in the past year, and no new symptoms have appeared.
It’s easy to forget that Opportunity is in the middle of a Martian winter right now. Because of the clean solar arrays, clear skies and favorable tilt, there is more energy for operations now than there was any time during the previous three Martian summers. Opportunity is now able to pull scientific all-nighters for three nights in a row — something she hasn’t had the energy to do in years.
During Opportunity’s first decade on Mars and the 2004-2010 career of Spirit, NASA’s Mars Exploration Rover Project yielded a range of findings about wet environmental conditions on ancient Mars – some very acidic, others milder and more conducive to supporting life. These findings have since been supplemented and confirmed by findings by the Curiosity Rover, which hopes to find plenty of clues as to the nature of possible life on Mars when it reaches Mount Sharp later this summer.