Maximising The Scientific Return of the ExoMars Enfys Spectrometer

Description

Invited for an oral presentation at the 19th United Kingdom Planetary Forum

Modern planetary science relies on instrumentation to gather data from which we can make inferences, plan activities, and discover new and exciting features beyond Earth. Enfys, an infrared reflectance spectrometer that will form part of the ExoMars 2028 Rosalind Franklin Rover (ERF), represents one of the first steps in the ERF’s science pathway. Ensuring that the data from Enfys is accurate, informative, and fully optimised is of utmost importance for characterising mineralogy and potential biosignatures. This work investigates how deconvolution can be applied to Enfys data to recover fine spectral features lost to instrument broadening, maximising the instrument’s scientific return.

Enfys measures the spectra of its target from a distance through non-destructive infrared reflectance spectroscopy. Sunlight reflected from the target enters Enfys’ optical window, passes through a beam splitter and a set of Linearly Variable Filters (LVFs), and finally reaches a photodiode. The design builds upon Aberystwyth’s expertise and heritage from the PanCam filter wheels [1-2], also part of the ERF. This approach is ideal for an astrobiology mission, as the sample remains undisturbed throughout the spectral acquisition process.

LVFs allow a higher signal-to-noise ratio but come with the drawback of a moderately broader and wavelength-dependent Point Spread Function (PSF). This broadening causes fine features in a spectrum, such as doublets or shoulders, to be smoothed out in the returned data. The smoothing is frequently referred to as a convolution of the sample with the PSF. If one knows the instrument function (inherent broadening), it is often possible to recover some of this lost, smoothed detail via deconvolution. Deconvolution is often
used in photography and astrophotography but has rarely seen implementation in the spectroscopy field. The Enfys deconvolution process utilises a custom variable-kernel Richardson-Lucy algorithm that has been developed by the author and accounts for the Wavelength-dependent PSF. This represents one of the first applications of wavelength-dependent deconvolution in planetary exploration spectroscopy. The ability to recover even a fraction more detail from the data returned by Enfys would effectively increase its spectral resolution and give the ERF science team extra diagnostic features for sample identification.

Presented will be a brief overview of Enfys, the methodology used to determine its instrument function, the data deconvolution process, and the resulting improvements in spectral feature retrieval.

[1] A. J. Coates et al., ‘The PanCam Instrument for the ExoMars Rover’, Astrobiology, vol. 17, no. 6–7, pp. 511–541, Jun. 2017, doi: 10.1089/ast.2016.1548.

[2] C. R. Cousins et al., ‘Astrobiological considerations for the selection of the
geological filters on the exoMars PanCam instrument’, Astrobiology, vol. 10, no. 9, pp. 933–951, Nov. 2010, doi: 10.1089/ast.2010.0517. .

Period	09 Jan 2026
Held at	University College London, United Kingdom of Great Britain and Northern Ireland