Opportunity took this image with her Pancam in mid-January 2018 along the edge of the north fork in Perseverance Valley. The team named this intriguing textured and pitted outcrop ensemble Ojo del Muerto. It looked like San Miguel the first such rock the team imaged earlier in the month, and the team was starting to see a lot of them in this part of the valley. “We had seen in the previous remote sensing data was that these rocks appeared slightly different from the standard Shoemaker impact breccias,” said MER Project Scientist Matt Golombek. The rover is taking “a whole bunch” of images to see what these weird rocks are made of.
Meanwhile, JPL engineers prepared and executed a test of the Zero Degree Heater (ZDH) on the batteries, as Chief of MER Engineering Bill Nelson discussed in the September 2017 issue of The MER Update. Opportunity carries two 8-amp-hour lithium batteries, which she reenergizes with the solar power she produces. [During the rovers' prime missions, their solar arrays were able to produce around 900 watt-hours of energy per Martian day, or sol.]
While Opportunity's batteries have performed exceptionally well over the mission's lifetime, 14 years is – well, 14 years, and they are beginning to show some signs of aging. Though the rover has never once used the ZDH (amazing but true), it was designed specifically to warm the batteries. Since the Martian environment is so brutally cold, the theory for at long last deploying the ZDH is that warming the batteries during the recharge process may make the batteries both more effective and help them degrade slower.
The team wanted to be cautious before using the ZDH operationally and formulated a plan to test it. The first original test in this campaign was to turn on the heater briefly, manually as opposed to thermostatically, and in a controlled and recoverable setting, just in case of a fault. Opportunity executed the test in the morning of Sol 4964 (January 10, 2018), and from all appearances, it was successful.
During the second week of January, Opportunity spent several sols completing stereo, color panoramas, taking some targeted 13-filter images, and capturing some twilight images of the stone stripes the robot has been seeing in this part of Perseverance. Then she got her roving orders.
On Sol 4968 (January 14, 2018), the rover headed 6.97 meters (22.88 feet) farther into the north fork to try and reach some of the intriguingly textured rocks for closer investigation. She also imaged another of the intriguing textured outcrop rocks along the edge of the north fork, which the team named Ojo del Muerto. It looked like San Miguel and the team was starting to see a lot of them in this part of the valley. The next sol, the ‘bot took a day to recharge.
“We had seen in the previous remote sensing data was that these rocks appeared slightly different from the standard Shoemaker impact breccias,” said Golombek. “There were also some color differences to suggest they may be new and different rock types. The rock is very bumpy and has this lineated surface texture, which may be erosion caused by wind or sand or something else. But it doesn’t look the same as typical Shoemaker type rocks, so we’re taking a whole bunch of MIs to try and get some coverage to see what it is.”
And then, on Sol 4970 (January 16, 2018), the rover’s power portfolio began to really change as a series of dust gusters whipped up from Endeavour’s floor and whisked a good amount of accumulated dust from the rover’s solar arrays. “It’s not surprising,” said Arvidson. “The winds are supposed to be blowing up and out of this valley from the crater floor.”
The wind events sent the rover’s energy production up substantially. “We had a big jump on that sol,” confirmed Herman. “We went from a dust factor of about 0.68% to 0.76%, a jump of 0.08%. That is really a sizeable jump. Normally, with the dust cleaning events, it will just go up 0.01 or 0.02%, not 0.08%. The energy was 517 watt-hours,” said Herman.
The next sol, 4971, the rover’s dust factor improved by another 0.04% and on Sol 4972, it jumped another 0.02%, taking the dust factor up to 0.82% with power rising to 565 watt-hours. Then on Sol 4974, another cleaning event improved it by another 0.02%, taking the dust factor up to 0.84% and Opportunity’s power to 599 watt-hours. And as the month progressed, it would improve even more.
