The robot spent the third and part of the fourth week of January taking color images of light toned bedrock and more of the textured and streaked rocks. She also worked in an APXS argon measurement for the mission-long study on Sol 4974 (January 20, 2018).

Opportunity homed in on a textured rock the team named Jornada del Muerto, which, again, looked like the San Miguel outcrop rocks. Although the research on these distinctive new rocks had just begun, the scientists were beginning to refer to identify them as San Miguel class. On Sol 4975 (January 21, 2018), the rover bumped for 1.32 meters (4.35 feet) to put Jornada del Muerto in reach of her IDD or robotic arm so she could examine it up close.

The robot field geologist then examined the rock using the routine science protocol, taking the MI pictures needed for a mosaic of the target spot on Sol 4977 (January 23, 2018), and then placing her APXS on the target.

Opportunity continued her work on Jornada del Muerto during the final week of the month. On Sols 4984 and 4985 (January 30, 31, 2018), she took more MI's and APXS integrations after off-setting the instruments just a skosh from the previous target spot on the rock to look at it again. The rover was also slated to take more color Pancam images of the margins and areas around the north fork and of her immediate surroundings.

The winds continued to whisk dust from the rover’s arrays as January wound down. Opportunity, with 45.09 kilometers (28.02 miles) on her odometer, was producing as much as 644 watt-hours of power, with a dust factor of 0.839. The Tau improved to around 0.423. “We did drive and get a better tilt towards the north where the Sun is this time of year,” said Herman. “Changing our tilt to more than 9 degrees really helped, especially because the sky is so clear so having direct sunlight was really useful.”

At the same time, Perseverance Valley is proving to be “complicated,” Arvidson said. “There are things that are becoming clear and we’re still puzzling about other things. For example, we’ve talked about wind etching of the rocks, the wind blowing up hill and these little wind tails in the rocks. What’s also becoming clear is that there’s a lot of regolith in the troughs and it is slowly marching downhill, down the valley, and is building up against the uphill sides of outcrops. In addition, it’s being shaped during its downhill march into stone stripes. Whether the stone stripes are due to wind, mass movement, or freezing and thawing of water in some previous epoch remains to be seen, but they are a surprising, unique morphology we haven’t seen anywhere else.”

At the halfway mark in the trek through Perseverance, neither rover nor science team members have seen a glimpse of Matijevic Formation, the oldest Martian terrain, and they are still doing the research to determine what carved the valley billions of year ago. But the research Opportunity is doing now is scientifically significant and will add to the story of water at Endeavour billions of years ago. “It points out that Perseverance Valley has unique features, in its overall shape, in the amount of regolith piling against the uphill sides of outcrops, and in terms of turning the regolith morphologically on the surface into these stone stripes,” said Arvidson.

In coming sols, Opportunity will continue working her way down the valley, said Golombek. “We’re not in any super rush here and we want to do it right.”

Opportunity and the team are powered up and ready to rove and rock.

“Our rover is now 14, which is 98 years in dog years, so I am always amazed about what she is still capable of doing,” said Bellutta. “In the short term, I am looking forward to completing the drive through the north fork. From HiRISE images, it looks quite challenging and interesting. In the long term, I think I want to see Endeavour from the bottom. I want to look back at the Valley and all the tracks we left. But among all things, I'm looking forward to year 16 and 17...and 18...”