During the next couple of sols, the rover conducted the in-depth analyses on the abraded surface spot with her MI and APXS, and then spent the rest of the week taking Panoramic Camera (Pancam) pictures of Knudsen Ridge that will be stitched together into one of the mission’s hallmark oversize panoramas.

Opportunity ground another millimeter into the target spot on Pvt. Potts again during the second week of January, and then brushed the target on Sol 4259 (January 16, 2016) to sweep away the grind tailings. The robot then conducted the usual MI and APXS "looks" inside the ground target and took more color Pancam images of Knudsen Ridge.

“It took a few sols to pull [the RAT] off, because of power limitations in the Martian winter, ”said Gale Paulsen, Senior Systems Engineer & Deputy Director at Honeybee Robotics and Spacecraft Mechanism Corporation, who oversees the RAT. Nevertheless, he reported: “The grind and brush went great and the RAT is still healthy.”

Having looked at and examined the chemical composition of the undisturbed surface, the brushed surface, and ground down surface of the Pvt. Potts outcrop, the rover’s study was complete. It wasn’t surprising to the scientists that there was no surprise in the data. “It looks like normal Shoemaker breccia material,” said Arvidson. Just like they expected and just like so many rocks Opportunity has found around craters.

The rover then bumped 5 centimeters (2 inches) on Sol 4262 (January 19, 2016) to position herself in front of Private John Collins, a patch of soil or coarse, dark grains. “It’s a really interesting, dark gray sand deposit, a couple centimeters wide, that is kind of running downhill,” said Arvidson. “It seems to be a little bit of an oddity, and we're just wondering what it's doing there.”

On Sol 4263 (January 20, 2016), Opportunity began several sols of MI and APXS investigations of the target. During the Martian winter, illumination for the MI is at a very low angle, so there's a lot of contrast and in that contrast the scientists noticed that Pvt. Collins has a little ridge in the middle, and an interesting, pitted texture on the surface. “We're not exactly what sure causes the pits, but it's just a pile of normal windblown dark basaltic sand, as seen from the spectra from Pancam and as seen from the APXS,” said Arvidson. “So there's nothing in the composition that's odd.”

Opportunity spent much of the third week of January and into the fourth week attending to routine engineering business, like adjusting her attitude [physical, not psychological], and taking more Pancam and Navigation Camera (Navcam) images, as she finished up her in-depth study of Pvt. Collins.

By the end of Sol 4267 (January 24, 2016), the robot field geologist’s work at this site was done. So, for the rover, was another year. [Technically, Opportunity wrapped her year in her sleep since the anniversary time of 8:54 p.m., PST, was 06:54 local Mars time and the rover normally wakes at 9 a.m. or later.] After a full sol’s work in the depths of winter on her anniversary though, the rover that loves to rove had effectively put a “bow” on her 12th Earth year of surface operations.

Mars, it must be noted, has “cooperated,” as the MER team is wont to say, except for that nasty, planet-circling dust storm in 2007 that nearly smothered Opportunity. Yet, Spirit and Opportunity turned out to be engineering marvels that have amazed the world, robot heroes that have and are taking Earthlings on the first overland expedition of Mars.

“It's been an adventure,” said Squyres. “Above all, it's testimony to the work that was done by the remarkable team that built Spirit and Opportunity so many years ago.”

Indeed. Still, Opportunity has roved for so long, has been “Little Miss Perfect” for so many years, so many miles, that she’s astonished even the members of even that “remarkable team” that built her and safely delivered her to the surface.

"While Opportunity is a bit worse for wear, I have to admit that once again our ability to understand the lifetime of our own designs is really poor,” said Manning. “With their rather constant temperature environment and with fewer moving parts, it makes some sense to me that the Voyager spacecraft would live for decades. It is harder for me to believe that a highly mechanical, solar powered Mars rover that must suffer rather impressive daily and yearly temperature extremes and dust storms would be capable of lasting more than a few years,” he said.

Of course, the engineers at JPL “work hard” to build spacecraft that are as reliable as possible, but without years of testing, they really don't know whether what they build is “reliable enough,” said Manning, currently the chief engineer for the Low-Density Supersonic Decelerator. And, MER had only three years to go from single power point presentation to Cape Canaveral. “One tiny goof in our rover design can make the difference between a 12-year lifetime and a one-month lifetime,” he noted. “Apparently, we goofed when we said that the rovers wouldn't last much longer than a few months. I guess you can say that was the right kind of goof."