Written by Lucy Thompson, Senior Research Scientist, University of New Brunswick, Canada

Ground planning date: Friday, July 27, 2026

As the APXS uplink leader and strategic planner, I have the privilege of working with the rover engineers most days I am in operations. The APXS instrument measures the chemistry of rocks, unconsolidated materials and the atmosphere, and is located at the end of Curiosity’s robotic arm. This means that any target of interest we wish to analyze must be safe to deploy the arm, APXS and MAHLI (the foreground imager). Therefore, we rely on the rover’s engineers for evaluation and to sequence the arm movements to safely position ourselves on targets. Recently, our workspaces have been dusty with varying relief, but the rover engineers successfully found areas where they could graze and deploy APXS and MAHLI. This week was no exception, even though some of our workspaces didn’t seem ideal upon initial observation. The team managed to find rock targets of interest (x5), which the rover engineers were able to place the arm and brush safely so we could analyze them with APXS and MAHLI. This ensures that we acquire high-quality imagery and compositional data as we continue our climb up Mount Sharp, through rock layers of different hues and textures, tracking potential changes in the chemistry and environment of deposition and alteration.

The rover’s engineers are also responsible for safely piloting Curiosity to areas of interest identified by the science team. They must assess the terrain for potential hazards, such as large sturdy blocks that could damage the rover’s wheels, patches of sand/dirt where we could get stuck, and high slopes where the rover could slip. Despite unexpected wheel damage early in the mission and getting a little stuck in some dirt/sand just as we began climbing Mount Sharp, the engineers managed to successfully guide us over 23 miles (37 kilometers) of trail distance and over 4,400 feet (approximately 1.35 kilometers) of elevation gain. We recently asked to drive to specific locations to obtain images of what the team believes could be an erosional surface within the Mg sulfate/carbonate-bearing unit (see image accompanying this post). Of course, the engineers were able to accommodate our wishes, with the first stop crossed off on Monday’s plan and the trip being planned this weekend taking us to the next stop.

Rover engineers also ensure that our drilling activities are executed safely and successfully, and are responsible for sequencing the arm movement required to deliver drilled samples to our internal CheMin and SAM instruments. This required completely reconfiguring the way we drilled after an engine failed in 2016, with extensive behind-the-scenes work at JPL for nearly a year and a half before resuming. Since then, Curiosity has drilled more than 20 rock targets.

So, thanks to the rover engineers and all the engineers and scientists on the Curiosity team, we’ve had another full week of activities in Gale Crater. We continue to track the chemistry, textures, tone and sedimentary structures of the sulfate/carbonate unit as we climb Mount Sharp and get closer and closer to the Yardang unit with APXS, ChemCam, MAHLI and Mastcam. Curiosity also continues to monitor the local environment within Gale and the atmosphere in general.