The “Happy Face Crater” on Mars has changed before our eyes

Who has an even bigger smile than ten years ago? This awkward crater on Mars.

These two images were taken by the HiRISE (High Resolution Imaging Science Experiment) camera aboard the Mars Reconnaissance Orbiter and show how the surface of Mars changes over time – in this case, due to thermal erosion.

The first of these images was taken in 2011 and the other in December 2020, around the same season, and shows a few different changes. According to the HiRISE team, there are color variations due to different amounts of glossy frost on a darker red background.

You will also see that some of the “blobby” features have changed shape due to the heat from the sun causing sublimation – when a solid turns directly into a gas, bypassing the liquid phase. This thermal erosion enlarged the “mouth” of the face, and the “nose” – which consisted of two circular depressions in 2011, has now enlarged and merged.

MRO is one of NASA’s oldest and most durable spacecraft. The mission was launched in 2005, arrived on Mars in 2006, and has been monitoring Mars ever since. HiRISE is the most powerful camera ever sent to another planet, and it has provided a plethora of incredibly detailed images of the features of Mars. Some of our favorites over the years have been ongoing avalanches, dark flows that may or may not be brackish material seeping into the surface, images of our own spacecraft and rovers on the surface of Mars, and many others.

But one of the main advantages of long-lived spacecraft is being able to monitor changes in what is observed. The HiRISE team have been documenting this ‘smiley face’ feature for over a decade, which means we now have good side-by-side comparisons of surface changes, right in front of our eyes.

“Measuring these changes throughout the Martian year helps scientists understand the annual deposition and removal of polar frost, and monitoring these sites over long periods of time helps us understand climate trends over time. term on the red planet, ”wrote HiRISE co-investigator Ross Beyer.

Check out more amazing images of Mars on the HiRISE website.