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Review
. 2020;216(8):137.
doi: 10.1007/s11214-020-00765-9. Epub 2020 Nov 24.

The Mars 2020 Engineering Cameras and Microphone on the Perseverance Rover: A Next-Generation Imaging System for Mars Exploration

J N Maki  1 , D Gruel  1 , C McKinney  1 , M A Ravine  2 , M Morales  1 , D Lee  1 , R Willson  1 , D Copley-Woods  1 , M Valvo  1 , T Goodsall  1 , J McGuire  1 , R G Sellar  1 , J A Schaffner  2 , M A Caplinger  2 , J M Shamah  2 , A E Johnson  1 , H Ansari  1 , K Singh  1 , T Litwin  1 , R Deen  1 , A Culver  1 , N Ruoff  1 , D Petrizzo  1 , D Kessler  1 , C Basset  1 , T Estlin  1 , F Alibay  1 , A Nelessen  1 , S Algermissen  1
Affiliations
Review

The Mars 2020 Engineering Cameras and Microphone on the Perseverance Rover: A Next-Generation Imaging System for Mars Exploration

J N Maki et al. Space Sci Rev. 2020.

Abstract

The Mars 2020 Perseverance rover is equipped with a next-generation engineering camera imaging system that represents an upgrade over previous Mars rover missions. These upgrades will improve the operational capabilities of the rover with an emphasis on drive planning, robotic arm operation, instrument operations, sample caching activities, and documentation of key events during entry, descent, and landing (EDL). There are a total of 16 cameras in the Perseverance engineering imaging system, including 9 cameras for surface operations and 7 cameras for EDL documentation. There are 3 types of cameras designed for surface operations: Navigation cameras (Navcams, quantity 2), Hazard Avoidance Cameras (Hazcams, quantity 6), and Cachecam (quantity 1). The Navcams will acquire color stereo images of the surface with a 96 ∘ × 73 ∘ field of view at 0.33 mrad/pixel. The Hazcams will acquire color stereo images of the surface with a 136 ∘ × 102 ∘ at 0.46 mrad/pixel. The Cachecam, a new camera type, will acquire images of Martian material inside the sample tubes during caching operations at a spatial scale of 12.5 microns/pixel. There are 5 types of EDL documentation cameras: The Parachute Uplook Cameras (PUCs, quantity 3), the Descent stage Downlook Camera (DDC, quantity 1), the Rover Uplook Camera (RUC, quantity 1), the Rover Descent Camera (RDC, quantity 1), and the Lander Vision System (LVS) Camera (LCAM, quantity 1). The PUCs are mounted on the parachute support structure and will acquire video of the parachute deployment event as part of a system to characterize parachute performance. The DDC is attached to the descent stage and pointed downward, it will characterize vehicle dynamics by capturing video of the rover as it descends from the skycrane. The rover-mounted RUC, attached to the rover and looking upward, will capture similar video of the skycrane from the vantage point of the rover and will also acquire video of the descent stage flyaway event. The RDC, attached to the rover and looking downward, will document plume dynamics by imaging the Martian surface before, during, and after rover touchdown. The LCAM, mounted to the bottom of the rover chassis and pointed downward, will acquire 90 ∘ × 90 ∘ FOV images during the parachute descent phase of EDL as input to an onboard map localization by the Lander Vision System (LVS). The rover also carries a microphone, mounted externally on the rover chassis, to capture acoustic signatures during and after EDL. The Perseverance rover launched from Earth on July 30th, 2020, and touchdown on Mars is scheduled for February 18th, 2021.

Keywords: Cameras; Mars; Planetary exploration; Remote sensing; Rovers; Space exploration.

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Figures

Fig. 1
Fig. 1
MSL Navcam mosaic. The mosaic as shown above covers a total field of approximately 90∘×70∘, and required portions of 6 individual Navcam images (∼2.75 images wide by ∼1.75 images high) to cover the field. The Perseverance Navcams will cover the same field of view in a single image. Reducing the image-to-image overlap in a mosaic improves the quality of a mosaic by reducing the number of seams. The reduction in overlap also reduces downlinked data volume by eliminating the redundant data in the overlap regions
Fig. 2
Fig. 2
Individual image coverage efficiency of images within a 10×1, 360-degree mosaic with spacing factor α=0.8. The total cumulative mosaic coverage efficiency is shown in Fig. 3
Fig. 3
Fig. 3
Mosaic coverage efficiency for an MSL 10×1 Navcam 360∘ mosaic, plotted as a function of the number of images (horizontal formula image, α=0.8, m=10). The variable m represents the number of images required for a full 360∘ mosaic
Fig. 4
Fig. 4
Mosaic coverage efficiency for a Perseverance 5×1 Navcam 360∘ Navcam mosaic, plotted as a function of the number of images (horizontal formula image, α=0.8, m=5). The variable m represents the number of images required for a full 360∘ mosaic
Fig. 5
Fig. 5
The MCE for several camera types, plotted as a function of azimuth. For coverage less than 360∘, a wider FOV camera will have a higher mosaic coverage efficiency than a camera with a smaller FOV. The variable m represents the number of images in a full 360∘ mosaic
Fig. 6
Fig. 6
Drive direction imaging with the MSL Navcams (greyscale, 0.8 milliradians/pixel) and the left Mastcam (color, ∼0.2mrad/pixel, inset in top image, and bottom image). The Perseverance Navcams have a pixel scale of ∼0.3mrad/pixel
Fig. 7
Fig. 7
Distinguishing two types of Martian material against metallic surfaces is challenging when using only luminance information (left), while the same assessment is relatively straightforward with 3-channel color (right). This image is from the MSL Mastcam (Malin et al. 2017). All of the Perseverance engineering cameras are color cameras
Fig. 8
Fig. 8
Location, approximate boresight location and direction, and notional image examples for the EDLCAMs
Fig. 9
Fig. 9
EDLCAM recording sequence, showing the approximate coverage of the data acquisition phases of the EDLCAM system. The acquisition frame rates of the cameras are listed in frames per second (fps), and the acquisition durations are listed on the bottom. The PUC frame rate listed in the yellow box is 75 fps
Fig. 10
Fig. 10
LCAM images are used by LVS to match features against a basemap. These feature matches are sent to an Extended Kalman Filter (EKF) that estimates the vehicle position. The vehicle attitude is propagated by an Inertial Measurement Unit (IMU). For details on the LVS see Johnson et al. . Figure from Johnson et al.
Fig. 11
Fig. 11
A CMV-20000 detector undergoing prototype testing in 2014 at JPL. The active imaging area is 32.77mm×24.58mm
Fig. 12
Fig. 12
Perseverance camera electronics block diagram
Fig. 13
Fig. 13
Flight Hazcam cameras
Fig. 14
Fig. 14
Perseverance Front Hazcams. L=left, R=right, A=RCE-A, B=RCE-B. Also shown are the Left/Right Navcams
Fig. 15
Fig. 15
Perseverance Rear Hazcams
Fig. 16
Fig. 16
Flight Navcam cameras
Fig. 17
Fig. 17
Closeup view of the Navcams mounted on the Remote Sensing Mast (RSM), a pan/tilt mast that points the cameras to targets of interest. The Navcams have a 42.4 cm stereo baseline. Also shown in the picture are the Mastcam-Z cameras (Bell et al. , this issue) located between the Navcams, and the SuperCam (Wiens et al. , this issue), located above the Navcams
Fig. 18
Fig. 18
Flight Cachecam camera assembly, including the lens, illuminator, and camera body. This photo shows the view looking directly into the Cachecam entrance aperture
Fig. 19
Fig. 19
The Perseverance Vision Assessment Station, which includes the Cachecam camera and cylindrical baffle. Sample tubes are presented to the camera by a Sample Handling Assembly (SHA), a small robot arm that brings sample tubes into the baffle from the bottom (the SHA is not shown in this picture). The illuminator assembly contains 3 LEDs that shine down onto the sample tube from the top. The camera looks down into the tube and acquires images of the top of the material within the tube
Fig. 20
Fig. 20
Location of the Cachecam within the Adaptive Caching Assembly (ACA), looking upwards from below the rover chassis. A portion of the Front Hazcam cover mechanism spring assembly can be seen in the upper right of the image
Fig. 21
Fig. 21
Schematic representation of the 10 available ECAM readout modes: a) full-scale (1×1, upper left), b) half-scale (2×2, upper right), c) quarter-scale (lower left), and d) 1/8th scale (lower right). In modes 0 through 8, all image tiles returned from the cameras are nominally 1280×960 pixels in size. In mode 9 the image tiles are 640×480 pixels in size. In the above figure the 1×1 and 2×2 tiles are shown aligned on even multiples of 1280×960 for simplicity. In actuality the location of tiles can be located anywhere on the sensor as long as the entire tile is inside the larger source image and the starting locations are even multiples of 8
Fig. 22
Fig. 22
EDLCAM flight hardware
Fig. 23
Fig. 23
Location of the DDC on the descent stage
Fig. 24
Fig. 24
Location of the RUC on the rover
Fig. 25
Fig. 25
Location of the RDC on the rover
Fig. 26
Fig. 26
The EDLCAM microphone (left, with bracket) and digitizer assembly (right). The microphone is approximately 42mm×40×19mm and weighs 52 grams. The digitizer assembly is approximately 56 mm in diameter and weighs approximately 50 grams
Fig. 27
Fig. 27
Location of the EDLCAM microphone on the Perseverance Rover. The microphone is located on the port side (Y-axis, rover coordinate frame) of the rover body, above the middle wheel
Fig. 28
Fig. 28
EDLCAM functional block diagram
Fig. 29
Fig. 29
The LCAM flight unit, just prior to delivery to ATLO
Fig. 30
Fig. 30
Location of the LCAM on the rover
Fig. 31
Fig. 31
The Mars 2020 web-based image viewing and data search tool
Fig. 32
Fig. 32
Instrument-level thermal vacuum testing of the Perseverance Hazcams
Fig. 33
Fig. 33
Results of stereo processing on a pair of 20 Megapixel prototype Navcam images in the JPL Marsyard. The higher pixel scale of the M2020 Navcams (compared to MSL) allows denser stereo maps at the same camera-to-object distance. The space between XYZ contours in the above figure is 10 cm. The red contour lines represent distance in the X direction of the local site coordinate frame and the green contours represent the distance in Y. The purple contours represent the distance in Z (height)
Fig. 34
Fig. 34
Examples of Navcam outdoor solar image testing, conducted with a flight-like Navcam. The left image was acquired in quarter-scale (4×4) mode, and the image on the right was acquired in full-scale (1×1) mode. The image on the right is cropped to show detail
Fig. 35
Fig. 35
Front Left Hazcam Image. Note the top of the image is obscured by a sun visor. During operations the sun visor region of the image will not typically be returned
Fig. 36
Fig. 36
Rear Hazcam image
Fig. 37
Fig. 37
Navcam image acquired during System Thermal Vacuum testing
Fig. 38
Fig. 38
Flight Cachecam image acquired during ATLO testing. The remove-before-flight cover shown in this image has a diameter of approximately 46.4 mm. The spatial scale of this image is approximately 12.5 microns/pixel (the cover is not exactly at the best focus distance)
Fig. 39
Fig. 39
EDLCAM testing. Indoor mortar firing test (left), outdoor mortar firing test (center), and simulated parachute image testing (right)
Fig. 40
Fig. 40
An MTF test image taken with the LCAM flight unit in the MSSS Cleanroom. This image was acquired unsummed and over the full format of the detector
Fig. 41
Fig. 41
LCAM image of the ceiling in the JPL Spacecraft Assembly Facility (SAF) taken after integration with the flight rover. This image was acquired in the flight mode (2×2 summed with windowing to give a 1024×1024 pixel format)
Fig. 42
Fig. 42
Notional Navcam operations sequence for a rover “drive direction” planning panorama, acquiring nine Navcam images of varying pixel scale. The background image for this figure (and Fig. 43) is from an MSL Mastcam panorama (Malin et al. 2017)
Fig. 43
Fig. 43
Notional Navcam 360∘ survey panorama, comprised of a 5×1 quarter-scale portion (images 1 through 5, shown in red), and a full-scale 360∘ inset panorama (16×1 full-scale tiles, shown in green)
See this image and copyright information in PMC

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