Scientists at TU Dortmund University are generating high-accuracy 3D models of the terrain in Oxia Planum on Mars, ahead of the arrival of the ESA/Roscosmos ExoMars rover, Rosalind Franklin, in 2021. The Digital Terrain Models (DTMs) have a resolution of about 25 cm per pixel and will help scientists to understand the geography and geological characteristics of the region and to plan the path of the rover around the site.

The region shown in this animation covers a large portion of the 120 x 19 km landing ellipse, with the eroded crater in the flyover towards the edge of the ellipse. Closer to the centre, the terrain is relatively flat, which is more favourable for landing and operations.

The DTMs are based on high-resolution imagery from the HiRISE instrument on NASA’s Mars Reconnaissance Orbiter. HiRISE imagery has been widely applied to the classic stereo method of combining two images taken from slightly different angles to create a 3D picture of the landscape. However, conventional stereo techniques have limitations when applied to relatively homogeneous regions like the rover’s landing site. The team used an innovative technique called ‘Shape from Shading’ in which the intensity of reflected light in the image is translated into information on surface slopes. This slope data is integrated into the stereo imagery, giving an improved estimate of the 3D surface, achieving the best resolution possible in the reconstructed landscape, showing small-scale features like dune ripples and other rough surfaces.

Oxia Planum lies at the boundary where many channels emptied into the vast lowland plains. Observations from orbit show that the region exhibits layers of clay-rich minerals that were formed in wet conditions some four billion years ago, likely in a large body of standing water. The rover contains a suite of instruments, including a drill, to examine the site for signs of biosignatures.

The models were presented at the EPSC-DPS Joint Meeting 2019 in Geneva on Monday 16 September 2019.