Who has a smile bigger than it did ten years ago? This is a crater on the surface of Mars.

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

The first photo was taken in 2011 and the other in December of 2020, around the same season, and it shows some different changes. There are differences in color caused by different amounts of bright frost over a dark red ground, according to the HiRISE team.

You will also see that some features of the “blobby” may change shape due to the heat of the sun causing sublimation – when the solid directly turns into a gas, bypassing the liquid phase. This thermal erosion made the face ‘mouth’ larger, and the ‘nose’ – which had been composed of two circular depressions in 2011, is now larger and merging.

MRO is one of NASA’s oldest and longest-lived spacecraft. The mission began in 2005, arrived at Mars in 2006 and has been observing the planet Mars ever since. HiRISE is the most powerful camera ever sent to another planet, and it has provided a large number of incredibly detailed images of Mars features. They have been some of our favorites over the years Avalanches in progressAnd the Dark streams that may or may not be a salty substance seeping into the surface, Pictures from Our spacecraft and spacecraft are on the surface of MarsAnd the And many more.

But one of the main benefits of long-duration spacecraft is the ability to observe changes in what is observed. The HiRISE team has documented this ‘smiley face’ feature for more than a decade, which means we now have good comparisons alongside superficial changes, right before our eyes.

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

Check out more amazing Mars photos on the HiRISE website.