Curiosity's Nevado Sajama postcard captures Mars on the eve of conjunction

by Clarence Oxford
Los Angeles CA (SPX) Jan 03, 2026

From its perch on a rugged ridge in Gale Crater, NASA's Curiosity rover has stitched together a holiday postcard that doubles as a science panorama, framing the Nevado Sajama drill site against a hazy Martian sky. The scene merges two Mastcam mosaics taken on Nov. 18, 2025 - late afternoon on sol 4722 and early morning on sol 4723 - then tinted in cool blues and warm golds to emphasize changing light, shadows, and atmospheric dust across the crater rim and distant buttes.

The ridge where Curiosity is parked belongs to the so-called boxwork unit, a landscape of resistant ribs and eroded hollows that the team has been dissecting with a focused drill campaign. In the foreground of the postcard, the rover sits atop one of these boxwork ridges overlooking Monte Grande, giving mission scientists a sweeping context view that ties the Nevado Sajama drill hole to nearby hollows, buttes, and fracture networks that record Gale's sedimentary history.

Earlier in the campaign, Curiosity's science team targeted the bedrock block dubbed "Nevado Sajama" as a prime candidate to understand why ridges stand proud while neighboring terrain is carved into depressions. During sols 4716 - 4722, the rover brushed the surface, collected Alpha Particle X-ray Spectrometer (APXS) and ChemCam measurements, and then drilled its 45th hole into the ridge, successfully acquiring a powdered sample for the internal laboratories.

CheMin, Curiosity's mineralogy lab, was given the first look at the Nevado Sajama sample, using X-ray diffraction to identify the crystalline phases that lock in clues to past water and diagenetic alteration. Those data set the stage for a follow-up run by the Sample Analysis at Mars (SAM) instrument, which performed an evolved gas analysis (EGA) experiment similar to a recent test in the nearby Monte Grande hollow to compare how fluids, cementation, and organics differ between ridge and hollow environments.

With extra power available in the planning cycle - a "power gift" - the team packed sols 4723 - 4730 with additional observations that complement the postcard's sweeping view. ChemCam fired its laser at seven nearby rock targets, while Mastcam, NAVCAM, and other cameras built up a massive 360-degree stereo mosaic of the boxwork region, capturing everything from hollow walls and buttes to dust-lifting events and cloud structure in Gale's increasingly dusty skies.

Throughout this intensive campaign, environmental monitoring continued alongside the geology, ensuring the postcard is anchored in a broader seasonal story. REMS and RAD tracked weather and radiation, Mastcam monitored dust opacity, and APXS even turned to the atmosphere itself, measuring argon and other components as the crater edged deeper into the Martian dusty season.

By late December, the mission entered a new operational phase as Earth and Mars approached solar conjunction, when the Sun moves between the two planets and blocks reliable communications. In sols 4750 - 4762, Curiosity wrapped up a pre-planned traverse between the "Valle de la Luna" hollow and the Nevado Sajama ridge, completing chemical and imaging transects of a ridge wall to document how textures, structures, and compositions evolve across the boxwork terrain.

Engineers then guided Curiosity back up onto a safe parking spot on the ridge, documenting the climb with a MARDI "sidewalk" video that tracks how the terrain flows beneath the wheels. Because arm activities with APXS and MAHLI were restricted in the final days before conjunction, the team leaned heavily on Mastcam and the hazard and navigation cameras to capture additional near-field targets and to keep watching for dust devils and other atmospheric changes that might affect rover health and future planning.

The postcard thus arrives as both a science product and a seasonal greeting from a rover preparing for several weeks of enforced quiet. While no new commands will be sent between Dec. 27 and Jan. 20 to avoid radio signals passing too close to the Sun, Curiosity will continue running a carefully uplinked conjunction plan that includes periodic environmental checks, atmospheric argon measurements, and passive monitoring of dust and sky conditions.

When contact resumes on the other side of the Sun, scientists will return to a uniquely well-documented site, armed with drill results from Nevado Sajama, stereo panoramas spanning hollows and ridges, and the context provided by this striking morning-and-afternoon postcard. Together, these data sets promise to sharpen understanding of how Gale's boxwork structures formed, why some layers resist erosion, and how Mars' climate and groundwater once interacted to sculpt this dramatic landscape.