9 Big Discoveries by Curiosity for its 9th Landiversary

Dr. Tanya Harrison
9 min readAug 5, 2021

Nervous Mars scientists around the world watched with bated breath as the behemoth Curiosity rover began its descent toward the surface of the Red Planet, known as the “Seven Minutes of Terror.”

We’d never sent something this size to land on Mars. We’d never used anything like the Skycrane to land on another world.

This was an audacious mission, and we all knew it.

Thankfully for all of us—and probably for the continued future of NASA’s Mars Exploration Program in general—the Skycrane system worked flawlessly, and Curiosity touched down at its permanent home in Gale Crater on August 5, 2012.

Curiosity rover under dusty skies on Mars.
Happy landiversary, Curiosity! Image credit: NASA/JPL-Caltech/MSSS

Gale Crater was chosen as the landing site for the rover based on satellite data suggesting the crater may have contained a lake around 3.5 billion years ago. While the water is long gone, its disappearance left behind a plethora of clays, sulfates, and other sedimentary rocks, all containing clues as to the martian environment when the lake was in existence. Curiosity’s mission goal was to look for signs of “habitability”—key things life as we know it would need to survive. Nine [Earth] years into its mission, it has revealed many important insights into the history of Mars. In celebration of its ninth landiversary, here are nine key discoveries from the rover so far:

1. Gale was definitely a lake!

From orbit, many signs pointed to Gale having been a lake in the ancient martian past. It has what appear to be water-carved channels running down its walls to the crater floor. At its centre is a towering mountain over 5 kilometres tall, the bottom chunk of which contains many water-bearing (“hydrated”) minerals. And…well, craters are giant holes in the ground, which is topographically conducive to making a lake. But thanks to chemical analyses by instruments aboard Curiosity such as its rock-zapping laser ChemCam and Alpha Particle X-ray Spectrometer (APSX), we have confirmation on the ground that the rocks inside Gale interacted with water. Not only that: The water was neutral to slightly alkaline pH, which is a good happy medium for life. This is in contrast to what we saw with the Opportunity rover on the other side of Mars at Meridiani Planum, where acidic groundwater flowed through the rocks

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Dr. Tanya Harrison

Professional Martian who's worked on rocks and robots on the Red Planet on multiple NASA Mars missions