Imagine you are waiting to take a picture using a remote set-up. The object you are photographing is about 22 metres wide and is white against a sandy rocky background. But, it is travelling at somewhere between 100 and 200 metres per second (360-720 km/h) and it is 700 kilometres away. Oh, and your camera is also on the move, travelling at 12,240 km/h. Finally, did I mention that if you tell the camera to move, it won’t hear you for 12 minutes or so because it is more than 200 million kilometres away?
Seems an impossible task, but NASA has just done it. Scientists operating the High Resolution Imaging Science Experiment (HiRISE) camera on the Mars Reconnaissance Orbiter captured this image of the Mars 2020 spacecraft and the Perseverance rover under its parachute as it approached the surface of the Red Planet. The camera is normally used to perform very high resolution mapping of the Martian surface, but mission managers realised that the position of the Orbiter would be just right to try to get an image of the descending spacecraft. Having commanded the Orbiter to pitch up and roll hard to the left, Mars 2020 passed into its field of view and this image was captured.
The HiRISE instrument was also able to capture images of the Perseverance rover on the surface as well as the impact points for the parachute and backshell assembly and the rocket-powered ‘skycrane’ that finally lowered the rover to the surface at the end of an entry sequence referred to as “seven minutes of terror”.