In the two closest images one of the most spectacular geological thrust systems on the planet can be seen close to the terminator of the planet, just to the bottom right of the spacecraft’s antenna. The escarpment, called Beagle Rupes, is an example of one of Mercury’s many lobate scarps, tectonic features that probably formed as a result of the planet cooling and contracting, causing its surface to become wrinkled like a drying out apple.
Beagle Rupes was first seen by NASA’s Messenger mission during its initial flyby of the planet in January 2008. It is about 600 km in total length, and cuts through a distinctive elongated crater named Sveinsdóttir.
Beagle Rupes bounds a slab of Mercury’s crust that has been thrust westwards by at least 2 km over the adjacent terrain. The scarp curves back at each end more strongly than most other examples on Mercury.
In addition, many nearby impact basins have been flooded by volcanic lavas, making this a fascinating region for follow-up studies by BepiColombo.
The complexity of the topography is well displayed, with shadows accentuated close to the day-nightside boundary, providing a feeling for the heights and depths of the various features.
Members of the BepiColombo imaging team are already having a lively debate about the relative influences of volcanism and tectonism shaping this region.
“This is an incredible region for studying Mercury’s tectonic history,” says Valentina Galluzzi of Italy’s National Institute for Astrophysics (INAF). “The complex interplay between these escarpments shows us that as the planet cooled and contracted it caused the surface crust to slip and slide, creating a variety of curious features that we will follow up in more detail once in orbit.”
As BepiColombo moved farther from the planet it appears to nestle between the spacecraft’s antenna and body from the perspective seen in these images. A ‘farewell Mercury’ sequence of images was also taken from afar as BepiColombo receded from the planet; these will be downloaded tonight.