Tree rings provide snapshots of Earth’s past climate and, although they formed in a very different way, patterns within this crater also reveal details of the Red Planet’s history. This feature could be mistaken for a tree stump with its concentric rings. It’s actually a stunning orbital view of an ice-rich impact crater on Mars.
The image was taken by the CaSSIS camera on board the ESA/Roscosmos ExoMars Trace Gas Orbiter (TGO) on 13 June 2021 in the vast plains of northern Acidalia Planitia, at northern latitudes on Mars.
The interior of the crater is filled with deposits that are likely rich in water ice. These deposits are thought to have been deposited during an earlier time in Mars’ history when the tilt of the planet’s axis of rotation allowed water ice deposits to form at lower latitudes than today. Just like on Earth, the tilt of Mars gives rise to the seasons, but unlike on Earth, its tilt has changed dramatically over long periods of time.
One of the notable features in the crater deposits is the presence of quasi-circular and polygonal fracture patterns. These features are likely the result of seasonal temperature changes that cause cycles of expansion and contraction of the ice-rich material, which ultimately leads to the development of fractures.
Understanding the history of water on Mars and whether this ever allowed life to flourish is at the heart of ESA’s ExoMars missions. TGO arrived at Mars in 2016 and began its full science mission in 2018.
As highlighted by the ESA it’s a statement, the spacecraft is not only returning spectacular images, but also providing the best ever inventory of the planet’s atmospheric gases, with a particular focus on gases that are geologically and biologically important, and mapping the planet’s surface in search of places rich in water.
It will also provide data relay services for the second ExoMars mission comprising the Rosalind Franklin rover and the Kazachok platform, when it arrives on Mars in 2023. The rover will explore a region of Mars once thought to harbor an ancient ocean, and look for signs of life underground.