The MARSIS instrument on Mars Express was originally designed to study the internal structure of Mars. As a result, it was designed for use at the typical distance between the spacecraft and the planet’s surface – more than 250 km.
But it recently received
a major software upgrade that allows it to be used at much closer distances and which could help to shed light on the mysterious origin of the moon Phobos.
“During this flyby, we used MARSIS to study Phobos from as close as 83 km,” says Andrea Cicchetti from the MARSIS team at
INAF. “Getting closer allows us to study its structure in more detail and identify important features we would never have been able to see from further away. In future, we are confident we could use MARSIS from closer than 40 km. The orbit of Mars Express has been fine-tuned to get us as close to Phobos as possible during a handful of flybys between 2023 and 2025, which will give us great opportunities to try.”