Rosalind Franklin (ExoMars) 2028

MSSL leads the team providing the Panoramic Stereo Cameras for ESA's Rosalind Franklin (ExoMars) 2028 rover mission, and are also helping build the Enfys infrared instrument.

The Rosalind Franklin Rover is a joint mission between ESA and NASA. MSSL leads the PanCam team to provide the rover's scientific ‘eyes’, and are contributing to the complementary Enyfs infrared spectrometer. The Rosalind Franklin Rover is scheduled to launch in 2028 and arrive at Mars in 2030. It will drill up to 2m below the harsh Martian surface to search for signs of past, or even present, life.

PanCam includes two Wide Angle Cameras (WACs) and a High Resolution Camera (HRC). The WACs are spaced 50cm apart for better stereo vision than our human eyes, and each has an 11-position filter wheel for colour images and to provide geological and atmospheric science. The HRC will look closely at rocks to determine texture. Enfys will look at part of HRCs field of view, providing infrared spectra to help with mineral identification. Together, PanCam and Enfys help set the context, and help the mission team decide where to drill.

The Martian environment presents the main technological challenge facing PanCam. Because the instrument is mounted on the rover mast, it is exposed to fine dust which settles from the atmosphere and is exposed to a difficult thermal environment. On Mars, temperatures may fall as low as -120C depending on latitude and season, and there is, like on Earth, constant diurnal cycling during the 24 hour 37 minute ‘sol’, with warmer temperatures during the day and colder temperatures at night. Even near the equator, at the rover’s Oxia Planum landing site, the range is quite extreme: perhaps as "warm" as 0-10 °C during the day, but falling to -90 to -100 °C at night. The PanCam and Enfys teams need to ensure that electronics and mechanical parts maintain reliable operation throughout the 218 sol mission.

Like the rest of the rover, PanCam and Enfys have planetary protection challenges, for example ensuring that we do not contaminate the Martian surface, not only because we want to be good planetary neighbours, but also so we do not affect the results of the sensitive biological and chemical analyses to be performed on-board.
 

Rosalind Franklin 2028 Science Objectives

The overall goals of the Rosalind Franklin (ExoMars) 2028 rover are to search for signs of past and present life on Mars, and to characterise the water/geochemical environment as a function of depth in the shallow subsurface. 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:

1. 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.
2. To collect scientific samples from different sites, using a rover carrying a drill capable of reaching well into the subsurface and into surface rocky outcrops.
3. 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 subsurface (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 item 3 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 orbiters
5. Support rover track planning
6. Image the acquired sample

The PanCam science team has developed a detailed science traceability matrix which links the high level goals to instrument performance.

PanCam plays a key role as part of the lander payload in several ways associated with wide angle and high resolution imaging, as mentioned above. We now consider the hardware implementation and, in broad terms, how the instrument addresses the objectives. 

PanCam sets the geological and morphological context for the rest of the payload. Geological and red/green/blue filters provide a powerful camera system for planetary science.  A pair of Wide Angle Cameras (WACs) and a close-up High Resolution Camera (HRC) provide complementary imaging at different scales. PanCam with the other context instruments can view the lander top surface and verify mechanism deployments and potentially landing pad interaction with the regolith. In the current ExoMars design, PanCam is the only instrument which can remotely sense the geological context of the landing site, provide detailed 3D terrain models and measure the surface Bidirectional Reflectance Distribution Function (BRDF).

PanCam Design

The PanCam design for Mars includes the following major items (see Coates et al., Astrobiology, 2017):

(a) Wide Angle Camera (WAC) pair, for multi-spectral stereoscopic panoramic imaging, using a miniaturised filter wheel. The WAC camera units themselves are provided byThales Alenia Space, Switzerland, and the filter wheels and drives are produced by Mullard Space Science Laboratory, University College London (MSSL-UCL).

(b) High Resolution Camera (HRC) for high resolution colour images. The HRC hardware is produced by OHB, Munich and DLR Institute for Planetary Research, Berlin, Germany. 

(c) Pancam Interface Unit (PIU) and DC-DC converter to provide a single electronic interface. The PIU and DC-DC converter are provided by MSSL-UCL.

(d) PanCam Optical Bench (OB) to house PanCam and provide planetary and dust protection. The OB is provided by MSSL-UCL.

The PanCam mechanical design is illustrated below. The optical bench is located on a rover-supplied pan-tilt mechanism at the top of the rover mast, at a height of ~2m above the Martian surface. 

 

PanCam layout (Credit: MSSL)

The main characteristics of the WACs and HRC are shown in Table 1.

Table 1 - PanCam performance
	WACs (x2)	HRC
FoV (°)	38.3 (edge)	4.88
Pixels	1024x1024	1024x1024
Filter type	Multispectral	RGB
Filter type	Filter wheel	Bayer
Filter number	11 per ‘eye’	1
IFOV (µrad/pixel)	653	83
Pixel scale (2m)	1.31mm	0.17 mm
Focus	Fixed (1.0m-∞)	Mechanical autofocus (0.98m-∞)

 

Each of the WACs includes 11 filters comprising R,G and B colour bands, a geological filter set (optimised for use on Mars, especially water-rich mineral identification) and atmospheric filters to analyse the water and dust content in the Mars atmosphere. The filter wheel and WAC camera system is illustrated below.

 

Mechanical configuration of WAC filter wheel and cameras (C.Theobald/MDO, MSSL-UCL)

The HRC includes a Bayer filter to provide colour information. The optical path is housed within the optical bench structure and comprises a baffle and mirror arrangement, a focus mechanism and a detector with associated readout electronics, shown below.

 

HRC subsystems : a) exploded view and b) accommodated into an Optical Bench prototype (DLR/KT/MSSL)

The PIU is the main interface between the ExoMars rover and the PanCam subsystems, and uses an FPGA implementation. The final system component is the Optical Bench, which provides a planetary protection barrier to the external environment (including HEPA filters), as well as mechanical positioning of the PanCam components. A view of the Proto-Flight-Model is shown in below.

Proto-flight mode of PanCam (MSSL) 

In addition to the major four PanCam optical bench mounted components outlined above, three additional hardware components known as the ‘Small items’ are part of the PanCam design to improve the scientific return and provide useful engineering data, namely the PanCam calibration target (PCT), rover inspection mirror (RIM) and fiducial markers (FidMs), both provided by Aberystwyth University. 

 

PanCam arrangement on the rover (schematic). The Optical bench is at the top of the mast, the PCT is at the front of the rover, the FidMs on the top deck and the RIM near the front bogey of the rover.

The PanCam calibration target (PCT) is implemented using coloured glass elements similar to ‘stained glass’ with a shadow post for relief. The calibration target is located on the rover deck. The design accommodates the ISEM calibration target.

 

PanCam and ISEM Calibration Target (PCT) design – Aberystwyth University

Radiometric and geometric calibration is overseen by MSSL with involvement from Aberystwyth, Joanneum Research and DLR.  

In addition to the PanCam hardware components mentioned above, the ExoMars PanCam team includes a 3D vision team which provides key software and calibration support for the PanCam team.

Field Trials

A number of ExoMars-related field trials and tests have been performed in the last few years, including participation in recent Arctic Mars Analogue Svalbard Expeditions (AMASE) 2008-11, Iceland (2014-5), MURFI (2016, Utah), ExoFit (2019, Atacama). For these tests, a representative PanCam simulator was used, provided by Aberystwyth University. This simulator includes representative (though not the final) filter wavelengths from which spectral information may be used to study mineralogy. These campaigns have been used, in combination with teams from other ExoMars instruments, to develop working procedures representative of a mission to Mars, as well as to test instrument performance, develop calibration techniques and pursue scientific investigations of particular areas. These included e.g., the Bockfjord Volcanic Complex (BVC), and the Nordaustlandet/Palander Icecap.

The AUPE PanCam simulator at tests in a Hertfordshire, UK quarry and at the AMASE campaign, Svalbard

Other PanCam ground tests have included ‘blind’ geological identifications performed in the AU Mars analogue facility, tests in a quarry in Hertfordshire with the Astrium UK ‘Bridget’ prototype rover, tests as part of the SAFER campaign, tests in Iceland in 2013 and 2015, tests in Boulby mine and tests with the Raman team in Staffordshire, UK (2015).

PanCam Instrument Team

Name	Function		Location
Andrew Coates	PanCam PI (TC)		UCL-MSSL (UK)
Mary Carter	PanCam Project Manager		UCL-MSSL (UK)
Nicole Schmitz	PanCam Co-PI, HRC lead scientist		DLR-PF (D)
Jean-Luc Josset	PanCam Co-PI, WAC		Space Exploration Inst. (CH)
Matt Balme	PanCam deputy PI, science deputy		OU (UK)
Ernst Hauber	Science deputy		DLR-PF (D)
Gerhard Paar	Lead Co-I, 3D Vision		Joanneum Research (A)
Matt Gunn	Lead Co-I, instrument calibration scientist, radiometric correction software, AU Coordinator		Aberystwyth University (UK)
Tom Hunt	PanCam System Engineer		UCL-MSSL (UK)
Barry Whiteside	PanCam System Engineer		UCL-MSSL (UK)
Graham Willis	PanCam PA Manager		UCL-MSSL (UK)
Alex Rousseau	PanCam PP&CC Engineer		UCL-MSSL (UK)

PanCam Science Team

Solmaz Adeli, DLR-PF, Germany

Francesca Altieri, INAF, Italy

Steve Banham, Imperial College London, UK

Rob Barnes, Imperial College London, UK

Jean-Pierre Bibring, IAF, France

Eleni Bohacek, University of Leicester, UK

Tomaso Bontognali, SEI, Switzerland

John Bridges, University of Leicester, UK

Christy Caudill, University of Western Ontario, Canada

Valerie Ciarletti, LATMOS, France

Claire Cousins, University of St Andrews, UK

Ian Crawford, Birkbeck University of London, UK

James Darling, University of Portsmouth, UK

Joel Davis, Imperial College London, UK

Maria Cristina de Sanctis, INAF, Italy

Jean-Pierre de Vera, DLR-PF, Germany

Alberto Fairén, INTA, Spain

Elena Favaro, ESTEC, Netherlands

Peter Fawdon, Open University, UK

Bernard Foing, University of Leiden, Netherlands

Francois Forget, Université Paris 6, France

Yang Gao, Kings College London, UK

Matt Golombek, JPL, USA

John Grant, JPL, USA

Grindrod, NHM, UK

Sanjeev Gupta, Imperial College London, UK

Klaus Gwinner, DLR-PF, Germany

Harald Hiesinger, University of Münster, Germany

Beda Anton Hofmann, NHM Bern, Switzerland

Pat Irwin, University of Oxford, UK

Ralf Jaumann, Free University Berlin, Germany

Marie Josset, SEI, Switzerland

Christian Köberl, University of Vienna, Austria

Ariel Ladegaard, Aberystwyth University, UK

Laeticia Le Deit, LPG Nantes, France

Mark Leese, Open University, UK

Greg Michael, Free University Berlin, Germany

Helen Miles, Aberystwyth University, UK

Sara Motaghian, NHM, UK

Stefano Mottola, DLR-PF, Germany

Jürgen Oberst, DLR-PF, Germany

Gordon (‘Oz’) Osinski, University of Western Ontario, Canada

Tim Parker, JPL, USA

Adam Parkes-Bowen, University of Leicester, UK

Manish Patel, Open University, UK

Priya Patel, JPL, USA

Dirk Plettemeier, TU Dresden, Germany

Louisa Preston, UCL-MSSL, UK

Frank Preusker, DLR-PF, Germany

Cathy Quantin-Nataf, University of Lyon, France

Catherine Regan, University of West Virginia, USA

Peter Rueffer, TU Braunschwig, Germany

Frank Scholten, DLR-PF, Germany

Christian Schroeder, MPS, Germany

Caroline Smith, NHM, UK

Roger Stabbins, NHM, UK

Katrin Stephan, DLR-PF, Germany

Nick Thomas, University of Bern, Switzerland

Daniela Tirsch, DLR-PF, Germany

Livio Tornabene, University of Western Ontarion Canada

Roland Trautner, ESTEC, Netherlands

Sebastian Walter, Free University Berlin, Germany

Frances Westall, CNRS Orleans, France

Lyle Whyte, McGill University, Canada

Rebecca Williams, PSI, USA

Colin Wilson, ESTEC, Netherlands

Enfys

Enfys (meaning ‘rainbow’ in Welsh), will replace the Russian-built Infrared Spectrometer for ExoMars (ISEM), meaning the mission can recover its full scientific potential. Work will be led by Aberystwyth University with support from STFC RAL Space and Qioptiq Ltd as well as UCL.

Enfys will identify targets on the surface of Mars for sampling and analysis, building on the scientific discoveries of the Mars rover mission.

Enfys and the mission’s UCL-led camera system PanCam will work together to identify minerals that could harbour evidence for life to enable the rover to drill for samples to be analysed by other instruments on the rover.