ExoMars 2022 Rover Rosalind Franklin

MSSL is leading the team providing the Panoramic Stereo Cameras for ESA's Exomars Rover Rosalind Franklin.

ExoMars is a joint endeavour between the European Space Agency and Russia's Roscomos agency, and consists of the 2016 Trace Gas Orbiter, and the 2022 Rosalind Franklin Rover. MSSL is leading the PanCam team to provide the rover's scientific ‘eyes’. The Rosalind Franklin Rover is scheduled to launch in September 2022 and arrive at Mars in June 2023. It will drill up to 2m below the harsh Martian surface to search for signs of past, or even present, life.

The Martian environment 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 -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 team need to ensure that electronics and mechanical parts maintain reliable operation throughout the 218 sol mission.

Like the rest of the rover, PanCam has 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.

YouTube Widget Placeholderhttps://www.youtube.com/watch?v=R9D6VGDqotIIntroduction to PanCam on the Rosalind Franklin rover, video (3 minutes) from UCL-MSSL (2021)

ExoMars 2022 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/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 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)
Craig Leff	PanCam Operations Lead, Data Archive manager		UCL-MSSL (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)
Guy Baister	WAC Project Manager		TAS-CH (CH)
Frank Trauthan	DLR HRC Operations		DLR-PF (D)
Carsten Henselowsky	PM for DLR contract with OHB		DLR-Bonn (D)
Elena Gubbini	OHB HRC Project Manager		OHB (D)
Harald Steininger	HRC PP&CC Engineer		OHB (D)
Sue Home	LFA (UKSA) representative

PanCam Science Team

The Instrument Science Team includes Andrew Coates (MSSL), Nicole Schmitz (DLR), Jean-Luc Josset (SEI), Matt Balme (OU), Ernst Hauber (DLR), Matt Gunn (AU) and Gerhard Paar (JR) from the instrument team above; plus the following team members:

Team Members	Institution
Solmaz Adeli	DLR (D)
Francesca Altieri	IAPS, INAF (I)
Elyse Allender	U. St Andrews (UK)
Matt Balme	Open University (UK)
Steve Banham	Imperial College (UK)
Rob Barnes	Imperial College (UK)
Jean Pierre Bibring	IAS, Orsay (F)
Eleni Bohacek	UCL (UK)
Tomaso Bontognali	Space Exploration Inst. (CH)
John Bridges	SRC, U. Leicester (UK)
Valerie Ciarletti	LATMOS (F)
Claire Cousins	U. St Andrews (UK)
Ian Crawford	Birkbeck U. London (UK)
James Darling	U. Portsmouth (UK)
Joel Davis	Natural History Museum (UK)
Jean-Pierre de Vera	DLR (D)
Ramy el-Maary	Khalifa U (UAE)
Nadezhda Evdokimova	IKI RAN (Ru)
Alberto Fairén	INTA (E)
Elena Favaro	OU (UK)
Peter Fawdon	OU (UK)
Anna Fedorova	IKI RAN (Ru)
Bernard Foing	ILEWG EuroMoonMars, Leiden/VU Amsterdam/CNRS (NL)
François Forget	CNRS (F)
Yang Gao	U. of Surrey (UK)
Stephan van Gasselt	FU-Berlin (D)
Matt Golombek	JPL (USA)
John Grant	Smithsonian Institution (USA)
Peter Grindrod	Natural History Museum (UK)
Sanjeev Gupta	Imperial College (UK)
Klaus Gwinner	DLR-PF (D)
Harald Hiesinger	U. Münster (D)
Beda Anton Hofmann	Naturhistorisches Museum, Bern (CH)
Pat Irwin	Oxford (UK)
Ralf Jaumann	FUB (D)
Geraint Jones	MSSL/UCL (UK)
Marie Josset	Space Exploration Institute (CH)
Christian Köberl	University of Vienna (A)
Ruslan Kuzmin	GEOKhI RAN (Ru)
Ariel Ladegaard	AU (UK)
Laetitia Le Deit	LPG Nantes, CNRS (F)
Mark Leese	Open University (UK)
Greg Michael	FUB (D)
Helen Miles	AU (UK)
Sara Motaghian	Natural History Museum (UK)
Stefano Mottola	DLR/IPF, Berlin (D)
Jürgen Oberst	DLR/IPF, Berlin (D)
Gordon Osinski	Univ. of Western Ontario (Ca)
Tim Parker	JPL (USA)
Manish Patel	Open University (UK)
Priya Patel	UCL-MSSL, UK
Dirk Plettemeier	Technische Universität Dresden (D)
Louisa Preston	Birkbeck U. London (UK)
Frank Preusker	DLR/IPF, Berlin (D)
Cathy Quantin-Nataf	U. Lyon (F)
Catherine Regan	UCL-MSSL, UK
Peter Rueffer	TUB (D)
Maria Cristina de Sanctis	IASF, INAF (I)
Frank Scholten	DLR (D)
Christian Schroeder	U. Stirling (UK)
Caroline Smith	Natural History Museum (UK)
Roger Stabbins	MSSL/UCL (UK)
Katrin Stephan	DLR (D)
Mitko Tanevski	Space Exploration Institute (CH)
Nick Thomas	Physikalisches Institut Bern (CH)
Roland Trautner	ESA/ESTEC (NL)
Frances Westall	CNRS (F)
Lyle Whyte	Dept. of Natural Resource Sciences, McGill University (Ca)
Rebecca Williams	PSI (USA)
Colin Wilson	Oxford (UK)