PanCam – the science ‘eye’ of the Rosalind Franklin Rover

^ PanCam mast being fitted to ExoMars Rover. Each PanCam is one of two electronic stereo cameras on Mars Exploration Rovers Spirit and Opportunity. It has a filter wheel assembly that enables it to view different wavelengths of light and the pair of PanCams are mounted beside two NavCams on the MER camera bar assembly.

The Martian environment

The environment of Mars presents the main technological challenges facing PanCam. Because the instrument is mounted on the rover mast, it is exposed to the fine dust which settles from the atmosphere and is exposed to a difficult thermal environment. Temperatures may fall as low as -120ºC, depending on latitude and season, and there is, like on Earth, constant diurnal cycling, with warmer temperatures during the day and colder temperatures at night. Even at the equator the range is quite extreme: perhaps as ‘warm’ as 0ºC during the day, but falling to -90ºC at night. The PanCam team need to ensure that electronics and mechanical parts maintain reliable operation throughout a lengthy mission.

Rover science objectives

The overall goals of the ExoMars 2020 rover are to search for signs of past and present life on Mars, and to characterise the water and geochemical environment as a function of depth in the shallow sub-surface. The key new aspect of the mission as a whole is the retrieval and analysis of samples from up to 2m under the oxidised surface of Mars. The strategy of the mission is:

• To land at, or to be able to reach, a location possessing high exobiological interest for past or present life signatures, i.e. the rover must have access to the appropriate geological environment. The selected landing site is Oxia Planum.
• To collect scientific samples from different locations, using a rover carrying a drill capable of reaching well into the sub-surface and into surface rocky outcrops.
• At each site, to conduct an integral set of measurements at multiple scales: beginning with a panoramic assessment of the geological environment, progressing to smaller-scale investigations on surface outcrops, and culminating with the collection of well-selected sub-surface (or surface) samples to be studied in the rover’s analytical laboratory.

PanCam science objectives

The PanCam instrument plays a key role in the mission by contributing to the third goal above. The main objectives of the ExoMars rover PanCam instrument are to:

1. Provide context information for the rover and its environment, including digital elevation models and their proper visualisation.
2. Geologically investigate and map the rover sites, including drilling locations.
3. Study the properties of the atmosphere and variable phenomena, including water and dust content of the atmosphere.
4. Locate the landing site and the rover position with respect to local references, by comparison and data fusion with data from orbiting satellites.
5. Support rover track planning.
6. Image samples are taken by the rover.

PanCam design

PanCam plays a key role as part of the lander payload in several ways associated with wide-angle and high-resolution imaging.

The PanCam design includes the following major items:

• A pair of wide-angle cameras, for multi-spectral stereoscopic panoramic imaging, using a miniaturised filter wheel
• A high resolution camera
• An electronic interface to the rover
• An optical bench, which houses the PanCam and provides protection from Martian dust.

PanCam sets the geological and morphological context for the rest of the payload. Geological and red, green or blue filters provide a powerful camera system for planetary science. The pair of wide-angle cameras (WACs) and a close-up high-resolution camera (HRC) provide complementary imaging at different scales. PanCam can view the lander top surface and verify the deployment of mechanisms on the rover. PanCam is the only instrument which can remotely sense the geological context of the landing site, providing detailed 3D terrain models.

The PanCam science team is international, with scientists from nine countries. Many of the parts that make up the PanCam have been developed at the MSSL, in the UK. Based in the hills of Surrey, MSSL is part of University College London, and has been involved in many space science missions.

PanCam has been delivered to Airbus, Stevenage for integration into the Rosalind Franklin rover. The rover will be launched on a Proton-M rocket from Baikonur, Kazakhstan, at the end of July 2020, arriving at Mars on 19 March 2021.

You can find out much more about the ExoMars mission via the European Space Agency website and educational resources will be available through www.esa.int/ESA