Curiosity (Mars Science Laboratory)

Curiosity is an 899 kg field laboratory, and in 2012 there was no proven way to put that much mass on the Martian surface. Airbags had worked three times, for Pathfinder in 1997 and for Spirit and Opportunity in 2004, but a bouncing ball big enough to hold Curiosity was not buildable. So the Mars Science Laboratory project invented the sky crane. The spacecraft met the atmosphere at about 5,900 m/s and flew a guided, lifting entry, throwing off tungsten ballast to shift its centre of mass and firing thrusters to steer. A 16 m parachute opened at roughly 11 km, the heat shield fell away, and about 1.6 km up the backshell was cut loose and eight throttleable rockets took over. Twenty metres above the ground, with about twelve seconds left, the descent stage paid the rover out on three nylon bridles and an umbilical, held 0.75 m/s until the wheels took the weight, severed the cords and flew off to crash at least 150 m clear. From cruise-stage separation to bridle cut the vehicle passed through six configurations and fired 76 pyrotechnic devices, every one of them on its own schedule. The whole thing took about seven minutes. The one-way light time that day was 13.8 minutes, so by the moment Earth heard that entry had begun, Curiosity had already been on the ground, or in pieces, for close to seven minutes. NASA's own pre-landing publicity called that stretch the seven minutes of terror, and the phrase escaped into the language. It worked. Touchdown came at about 05:17 UTC on 6 August 2012.

The mission was not sent to look for life. It was sent to ask whether Gale crater had ever been a place where life could have lived, and it answered inside seven months. Rather than head straight for the mountain, the team turned east to a shallow depression called Yellowknife Bay, where the rover found fine-grained mudstone instead of the basalt sand it had been driving over. On sol 182 the drill cut its first hole, into a slab named John Klein after an MSL deputy project manager who had died in 2011. NASA's dates for it differ by a day depending on time zone: 8 February 2013 Pacific, 9 February UTC. CheMin, the X-ray diffractometer, found the sample was at least a fifth clay minerals, which principal investigator David Blake reported as at least 20 percent. Those clays form in water of near-neutral pH and low salinity. SAM found sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon, and its principal investigator Paul Mahaffy pointed out that the pairings included sulfates and sulfides, a usable chemical energy source. NASA announced the result on 12 March 2013. Michael Meyer, lead scientist for the Mars Exploration Program, said that whether Mars could have supported a habitable environment was the fundamental question of the mission, and that from what was then known the answer was yes. Project scientist John Grotzinger called it a very ancient but strangely new grey Mars. The prime mission was 687 Earth days. The headline was in hand on day 218.

The wheels are the mission's visible scar. Each is 50 cm across, milled out of a single block of aluminium, with a skin about 0.75 mm thick spanning the gaps between the zigzag treads, called grousers, which stand 7.5 mm proud of the skin and sit 15 degrees apart around the rim. That thinness was deliberate mass-saving, and Mars punished it. The first large puncture appears in imagery on sol 411, in late 2013; by sol 463 a long rip had opened. Two separate mechanisms were at work. On hard bedrock the skin flexes and fatigues until it fractures near the chevron tips. Separately, cemented, wind-sharpened rocks that will not move punch straight through when the rocker-bogie suspension drives a wheel down onto them. JPL responded by driving shorter and more deliberately, reversing where reversing reduced the downward force, choosing routes across sand identified from orbital spectra, and eventually uploading software that lets each wheel turn at its own rate so a wheel hanging over a rock is not dragged across it. When two grousers snapped on the left middle wheel in early 2017, NASA said Earth testing put a wheel at about 60 percent of its useful life once three of its grousers had gone, and that it did not expect this to affect operations. It did not. Nine years after that, the blog for sols 4982 to 4987, dated 23 August 2026 and still the mission's latest post when this page was rechecked on 3 September, notes only that the left front wheel was perched on a small rock, enough of a slip risk that the team dropped the dust-removal brush from the plan, though MAHLI and APXS still worked two bedrock targets. The wheels have now carried the rover 38 km.

Methane is the argument that will not close. SAM's Tunable Laser Spectrometer has reported a background of roughly 0.4 to 0.5 parts per billion by volume in Gale crater, with occasional spikes, the largest about 21 ppbv in June 2019, dropping back under 1 ppbv within days. ESA's Trace Gas Orbiter, a far more sensitive instrument sampling the column at around 5 km up, has reported none at all. Three families of explanation have been offered. In 2021 NASA published a timing argument from John Moores of York University: TLS samples mostly at night, when the Martian boundary layer is still and any seepage pools near the ground, whereas the orbiter sees a churned daytime column, and Paul Mahaffy reported that two daytime measurements came back near zero as Moores had predicted. In 2024 a NASA Goddard group led by Alexander Pavlov proposed that methane sits sealed beneath brittle salt crusts that crack under temperature swings, or under the weight of a passing rover. Then in April 2025, Sebastien Viscardy, David Catling and Kevin Zahnle published a reanalysis arguing that the instrument's foreoptics chamber holds methane three to four orders of magnitude above the levels reported from the sample cell, that housekeeping pressure data show unexplained gas exchange, and that leaks of less than 0.1 percent of the foreoptics methane would reproduce every reported detection. They also object to the retrieval method, which averages three spectral lines separately rather than fitting the triplet. They proposed a specific two-night experiment to settle it. As of August 2026 no published rebuttal from the SAM team had appeared. Nothing here is resolved.

What Curiosity is actually doing in August 2026 is climbing. Since 2014 it has been working its way up Aeolis Mons, the 5 km mound at the centre of the crater. The IAU approved that name on 16 May 2012; NASA has called it Mount Sharp ever since, informally, for the Caltech geologist Robert P. Sharp. The traverse file read on 3 September 2026 puts the rover 1,002 m above where it landed, and NASA marked that kilometre of elevation gain on 26 August 2026. Most of 2025 and early 2026 went into the boxwork terrain, a field of 1 to 2 m ridges that look from orbit like spiderwebs and that formed when groundwater ran through fractures and left minerals behind, implying, as Rice University's Tina Seeger put it, that the groundwater table had to be pretty high, and that habitable conditions lasted later than orbital data had suggested. In April 2026 a drilled rock named Atacama lifted clean out of the ground stuck on the drill sleeve, which NASA said had never happened before, and took until 1 May to shake off. In June the rover photographed a valley floored with 4 to 8 cm polygons that project scientist Ashwin Vasavada said took the team's breath away. Meanwhile the plutonium keeps decaying. The MMRTG's stated design goal was to hold up power for a minimum of 14 years, and Curiosity passed 14 years on 6 August 2026. It is still driving, still drilling, and still going uphill.