CASE STUDY
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Mars Perseverance Rover Case StudyPYTHON Image Sensors Add Vision
To Mars Perseverance EDL
Summary
Application

Location

Entry, Descent,Landing (EDL)
Camera SystemsMarsContracting
Agency/Customer
NASAFLIR® Systems

Deployment

Products Used

Mars 2020 Mission
Perseverance Rover

5x PYTHON 1300
1x PYTHON 5000

Overview“Seven Minutes of Terror.” The most challenging phase of the MARS Perseverance mission is the entry, descent, and landing(EDL) – a short and intense seven minutes when the spacecraft enters into the Martian atmosphere at 12,500 miles per hourand safely decelerates down to zero as it touches down on the surface. Perseverance completes this phase autonomously, andits success takes eleven minutes and twenty-two seconds to radio back to Earth.
The Mars Perseverance Rover includes a total of twenty-three cameras used in the engineering, EDL, and science camera
systems. EDLCAM systems aimed to capture EDL events in more detail than in previous missions. The camera system took
full-color video during the vehicle’s descent through Mars’ atmosphere to the surface. The images captured on the way down
help Perseverance’s mission planners select the rover’s initial drives. The EDLCAM system consists of a total of seven cameras:
Parachute Uplook Cameras (PUC), Descent-stage Downlook Camera (DDC), Rover Uplook Camera (RUC), Rover Downlook
Camera (RDC), and the LCAM. The LCAM was dedicated to providing critical image data to the Lander Vision System (LVS)
required for Terrain-Relative Navigation – an onboard computer analyzed the images to compare them with a map so that
Perseverance could autonomously choose the safest landing site relative to the rover’s position during the descent. It also
monitored the deployment of the parachute during the parachute descent phase of EDL.

Challenge

The critical challenge for the Mars 2020 Mission EDLCAM and LCAM systems was to improve knowledge of EDL and LVS
system performance using a video imaging system to capture key EDL events (including parachute deployment, skycrane
deployment, rover touchdown, and lander rocket plume dynamics) and using image capture to help autonomous TerrainRelative Navigation. The solution selection process comprised of qualification of commercial off the shelf (COTS) hardwareemphasizing cost and ease of system integration.
EDLCAM Cameras

Figure 1. Image acquired during Perseverance’s descent to Mars, using its Parachute Up-Look Camera A.
Image Credit: NASA and JPL-Caltech
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A vital requirement of the EDLCAM system was that it would not interfere with the flight system during EDL. The camera systemdesign could not compel changes to the flight hardware or software systems inherited from the Mars Science Library (MSL)
Curiosity rover. The camera systems’ minimum frame rate requirements were 30 frames per second (fps) to capture images ofthe parachute. The three PUC cameras were to start capturing images at a frame rate of 75 fps prior to parachute deployment
and drop the frame rate to 30 fps after thirty seconds until the backshell separation about ninety-eight seconds later. Each PUC
was expected to take approximately 5,190 images – a total of 15,750 for the system. The RDC camera system was to start
capturing images just before heatshield separation and continuing through touchdown on the surface of Mars. The RDC
captured images at 30 fps for approximately 260 seconds for a total of about 7,800 images. The RUC camera system was tostart capturing images just prior to the rover separating from the descent stage and continuing through rover touchdown on thesurface of Mars. The RUC captured data at 30 fps for approximately 140 seconds for a total of about 4,200 images.
LCAM Camera
The LCAM camera requirements include a field of view of 90◦ by 90◦, an array resolution of 1024 x 1024 pixels, and a globalshutter sensor. The camera system solution also needed to have a frame latency of less than 100 milliseconds between thecamera image trigger and the last pixel output of the image, a frame rate of up to 2 Hz, and an SNR of greater than 80:1 withapproximately one millisecond exposure time under the illumination conditions of the Mars environment.

Solution

Figure 2. PYTHON Family of CMOS Image Sensors

The Perseverance mission teams selected cameras from the FLIR Systems Chameleon®3 family of cameras for the EDL camera
systems. The solution chosen for the PUC, RUC, RDC, and LCAM camera systems includes sensors from the onsemi PYTHON
family of CMOS image sensors. The EDL engineers chose the PYTHON-based cameras from FLIR because of their global
shutter operation, small optical format, versatility, read-out speed (full frame rate, and quadratic speed increase reading out
smaller regions of interest). Within the Chameleon3 camera product family, the PYTHON-based cameras offered the highest
frame rates. The correlated double sampling (CDS) support in global shutter mode provides reduced noise to single-digit noise
performance and increased dynamic range to retain image detail in high-contrast situations. The PUC, RUC, and RDC camerasystems use PYTHON 1300 image sensors.
The LCAM uses a monochrome PYTHON 5000 global-shutter CMOS image sensor with a pixel array of 2592 by 2048 by 4.8µm pixels and on-chip 8-bit or 10-bit digitization with a frame rate capability of up to 100 frames per second. The LCAM systemsolution selected for Perseverance derived from successful deployment as the Vision Sensor System (VSS) camera on theNASA Goddard Space Flight Center (GSFC) Restore-L Mission and the P50 camera on the Naval Research Laboratory (NPL)
Robotic Servicing of Geosynchronous Satellites (RSGS) Mission that both used the onsemi PYTHON 5000 image sensor.

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Result
The next-generation imaging system of the Perseverance rover improved the operational capabilities of the Mars 2020 mission
by providing the first-ever color video of touchdown on the Martian surface. The EDLCAM video of crucial entry, descent, andlanding events successfully documented the mission systems’ performance. It will serve to instruct the design for EDL systems
in the future. Likewise, the success of the Lander Vision System LCAM to capture Martian surface images to assist TerrainRelative Navigation will facilitate more targeted landing capabilities for future missions to Mars. More than 1,300 images andvideo captured by these camera systems are available for viewing on the Mars 2020 mission Perseverance Rover website.

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