Miniature 3D Multispectral Cameras for Space Science and Exploration: From Sample Analysis to Autonomous Robotics and Astronaut Health

MINIATURE 3D MULTISPECTRAL CAMERAS FOR SPACE SCIENCE AND EXPLORATION: FROM SAMPLE ANALYSIS TO AUTONOMOUS ROBOTICS AND ASTRONAUT HEALTH N. J. Murray1, A. M. Evagora1, E. C. M. Daly1, F. J. Abernethy2, J. I. Mortimer2 and S. J. Barber2. 1Dynamic Imaging Analytics, Milton Keynes, MK14 6GD, UK [email protected] 2School of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, UK. Figure 1: Prototype SamCam mounted to ProSPA SIS Eng. Model Introduction: We have developed innovative cameras for planetary science and exploration utilising lightfield (plenoptic) imaging technology: in addition to capturing the intensity of light, the incoming direction of the photons are also recorded. This is achieved by over-sampling the scene using patented sub-lens arrangements which yields various advantages: (1) the distance from the camera to the target scene can be accurately calculated, as well as the absolute positions of objects within the scene; (2) the camera produces a metrically calibrated and accurate 3D image from each exposure of a single sensor (i.e. not reliant upon Structure-from-Motion (SfM) or stereo camera pair) (3) camera is smaller, lighter and more rigid than a typical stereo-pair and less prone to occlusions and specular reflections; (4) faster optics promoting less motion blur and increased sensitivity; (5) increased depth-of-field removes the need for mechanical focusing stages; (6) sub-lenses can be provided with narrow-band filters to achieve all of the above advantages in combination with multispectral imaging; and (7) scalable to view scenes at a distance from mm to m scale, with a camera <250 grams and typically 78×54×38 mm in size. SamCam for ProSPA/PROSPECT: SamCam (Sample Camera) will image lunar regolith samples within ESA’s PROSPECT instrument [1] for lunar polar volatiles prospecting on Intuitive Machines IM-4 mission within NASA’s CLPS program. PROSPECT comprises the ProSEED drill and the sample analysis package ProSPA. ProSEED drills to a depth up to ~1 m then deploys two tools at the drill tip to collect regolith samples. One services other payloads; the second acquires a ~60 mm3 regolith core for ProSPA. After sampling, the drill is withdrawn and aligned to the ProSPA Solids Inlet System (SIS) shown in Fig.1. A piston discharges the sample directly into one of 25 Sample Ovens on a Carousel, which then rotates to place the sample under SamCam for imaging. SamCam Objectives: SamCam aims to (1) confirm delivery of sample into the oven, and show any regolith particle contamination on oven seals; (2) provide geologic context for the subsequent thermochemical, evolved gas and mass spectrometry analyses and enable estimation of sample density; (3) obtain images to enable estimation of the amount of sample within the oven with target error better than ±20%. Together with quantitative determination by mass spectrometry of released volatiles, this allows PROSPECT to determine the volatile content per unit volume of lunar regolith. Figure 2: SamCam and Sample Oven prototype (pen for scale) SamCam Design: SamCam illuminates the oven scene with four warm-white LEDs, supplemented by four further LEDs to increase intensity in the NIR (Fig.2). Reflected light from the oven and sample is collected by the Primary Lens and refocused onto a 3D plus camera cube through the Secondary Lens Array. Raw images comprise multiple sub-images that originate from sub-apertures of the Primary Lens. These subimages contain localized redundancy of scene information, as the sub-apertures are physically offset throughout the Primary Lens. Computer Vision techniques allow features to be matched and either triangulated to provide depth information (Fig.3), or warp images with projective distortion and superimpose to increase resolution, signal-to-noise, or generate an RGB or false color image (Fig.4). Figure. 3: Raw colorized SamCam images of sample oven empty (left) and containing anorthosite and JSC1A (right). The central image is panchromatic. Further panchromatic images in Row 1 Column 3 (R1C3), R2C1, R3C4, R4C2 enable 3D reconstruction of the scene and depth map Figure 4: Reconstruction of RGB image example Test Campaign and Results: We will present the latest results of using the SamCam Engineering Model to estimate sample volume and mass. The SamCam Flight Model will be developed by late 2025. The program has been de-risked through TRL raising activities funded by the UKSA [2], including breadboarding and extensive environmental testing the Eng. Model. Other Applications: The multispectral 3D image data cube can be further tailored to specific space applications These were demonstrated for the LUVMI-X Moon rover [3] through the Navigation Camera ‘NavCam’ and closely related Surface terrain Camera ‘SurfCam’, (Fig.5) and 3D/360 degree panoramic camera. Miniaturization of the latter allows for imaging down-borehole within an instrumented lunar drill [4]. The ability to track and predict the motion of an object in 3D space has wider applications from Guidance, Navigation and Control of vehicles in space to the optimization of robotic motion systems (e.g. control of robotic arm/manipulator). Such applications would be enhanced by rapid on-board image processing. We are therefore deploying our algorithms to embedded GPU, enabling rapid and autonomous range-finding [5]. Figure. 5: LUVMI-X Surface Camera Developments under UKSA Pathfinder and the ESA DRACO mission have produced similar cameras utilising hybrid VIS/SWIR imaging sensors that allow for similar 3D and multispectral data products in the range 400 to 1,700 nm. Whereas for our 6-channel DRACO cameras (Fig.6), the three SWIR channels are providing thermal data in the range 180°C to 600°C, Narrow Band Pass filter stock is available for probing water/ice absorption edges useful for lunar exploration. Figure. 6: DRACO 6-channel multispectral VIS/SWIR cameras Conclusion: SamCam is a compact and versatile 3D multispectral imager. A large depth of field has been achieved in a compact design with no moving parts and sample volume can be estimated to better than ±10%. The optical system can be readily tailored for many space and terrestrial applications requiring high precision quantitative 3D performance within a compact, low mass and rugged camera. Acknowledgments: PROSPECT is a project of and funded by ESA. Early development of SamCam was funded by the UK Space Agency References: [1] Barber, S. J. et. al. (2017) LPSC 2171 [2] https://www.gov.uk/government/case-studies/lightfield-photography. [3] Gancet. J. et. al. LUVMI-X 2021. [4] Barber, S. J. et. al. 2020 i-Drill [5] Daly, E. C. M. et al. (2023) SPIE 12571