Perseverance mobility system - Summary reader's response draft 2

According to NASA’s webpage on rover wheels, the mobility system of the Perseverance rover stands out among Martian vehicles. The rover can travel at speeds of 4.2cm per second and consumes less than 200 watts. The mobility system consists of the driving and suspension suspension systems. The driving system consists of six wheels fitted with brushless DC motors, accompanied by extra steering motors in the front and rear legs (NASA, 2019). These wheels, measuring 52.5 cm in diameter, are crafted from an aluminium alloy with titanium spokes. The wheels have individually modified “EC 32 flat drive” motors (Maxon, 2020) and retrofitted cleats to enhance traction. The legs are constructed from titanium tubing, enabling the rover to traverse uneven Martian terrain, overcoming obstacles surpassing 40 cm in height (NASA, n.d). The suspension system, identified as the "rocker-bogie" system, is composed of three interconnected components: the differential, rocker, and bogie. These elements collaborate to receive 3-axis position information from the internal measurement unit (IMU) and efficiently distribute the rover's weight across its six wheels. This intricately designed system minimises tilt during traversal over uneven Martian terrain, thereby enhancing the rover's overall stability (NASA, n.d). Compared to the previous Martian rovers, the Perseverance rover’s mobility system exhibits remarkable improvements in speed and rate of ground covered, enhancing the ability of the rover to explore the geography of the area, and fulfil its mission objectives. 

The first enhancement over the previous rover in the Perseverance rover is the speed. According to NASA’s webpage on rover cameras, the navigational system consists of 2 navigation cameras (Navcams) and 6 hazard avoidance cameras (HazCams). The Navcams are located on the rover's mast and is primarily used to navigate the rover safely, while the HazCams are located at the front and rear of the rover's body, detecting hazards and obstacles as the rover moves. These cameras work together with the rover's 2 central processors to process and analyse images as the rover transverses along the rocky Martian terrain, avoiding hazards and obstacles as it moves (NASA, n.d). This allows Perseverance to make decisions on the fly, navigating through the rocky martian terrain autonomously. The previous Martian rovers Curiosity and Opportunity needed to stop and access its location after travelling every few seconds, causing them to travel at a speeds of 4cm per second and 1cm per second respectively. The faster movement has led to Perseverance reviewing more Martian terrain at a faster rate. According to NASA’s webpage on Mars rock samples, during Perseverance’s first 1000th Sol on mars, it managed to sample 23 locations while its predecessor Curiosity sampled only 11 locations in the same period (Abbey et al., 2020). 

Another way that the Perseverance has been enhanced over previous rovers is enhanced mobility. In a report on the Perseverance rapid transverse campaign (Rankin et al., 2023), Perseverance could achieve average speeds of 4.2 cm per second, covering 5km in 31 sols (Solar day), while the previous Martian rovers, opportunity and curiosity took 96 and 240 sols respectively to cover the same distance. 

Due to the enhanced mobility of the rover, it could cover a larger distance in a shorter period. This allowed scientists to analyze and review more Martian terrain, and get the rover to high-priority science targets at a faster rate.

Compared to the Curiosity Rover, the Perseverance's wheels could face faster damage due to its higher mileage covered at a faster rate. According to JPL's webpage on Premature Wear of the MSL Wheels (2017), Curiosity faced progressive damage to its wheels due to metal fatigue. The metal fatigue, caused by the repeated stress from driving over sharp rocks caused a weakened condition in the wheels, resulting in deformation and fractures. Although the width of the wheels on Perseverance are narrower, the wheels are thicker and have a bigger diameter as compared to Curiosity. Due to the faster rate of travel, Perseverance's wheels may experience a faster rate of metal fatigue, eventually crippling the rover, causing scientific experiments and exploration of Mars with the Perseverance rover to halt.

The increase of scientific sampling at high-priority science targets due to faster rate of ground covered as compared to the Curiosity rover, shows the enhanced ability of the rover to fulfil its mission objectives of exploring the Martian geography and finding scientific discoveries that could help with paving the way for human life on Mars. Although, the improvements of the rover could cause a faster rate of metal fatigue on the wheels, the enhanced rate of scientific discoveries on Mars could still fulfil the mission objectives faster than ever before. 

 

 

References

Abbey, W., Anderson, R., Beegle, L. W., Peters, G., Morookian, J. M., Biesiadecki, J., Carsten, J., Collins, C., Davis, K., Kinnett, R., Klein, D., Kuhn, S., Logan, C., Maimone, M., Melko, J., Okon, A., Reid, J., Robinson, M., Singer, J., … Vasavada, A. R. (2020). A look back, part II: The drilling campaign of the curiosity rover during the Mars Science Laboratory’s second and Third martian years. Icarus, 350, 113885. https://www.sciencedirect.com/science/article/pii/S0019103520302657?via%3Dihub

Maxon. (2020, July 7). maxon DC motors are heading to Mars onboard NASA's Perseverance rover. https://www.maxongroup.net.au/medias/sys_master/root/8843051204638/maxon-DC-motors-are-heading-to-Mars-onboard-NASA-s-Perseverance-rover.pdf

NASA. (2022, April 8). How Perseverance Drives on Mars https://mars.nasa.gov/resources/26660/how-perseverance-drives-on-mars/

NASA. (2017, September 26). Premature Wear of the MSL Wheels. https://llis.nasa.gov/lesson/22401

NASA. (n.d.). Curiosity’s and Perseverance’s wheels – NASA mars exploration. https://mars.nasa.gov/resources/24910/curiositys-and-perseverances-wheels/

NASA. (n.d.). Mars Rock samples. NASA Mars Exploration. https://mars.nasa.gov/mars-rock-samples/#23

NASA. (n.d.). Wheels. https://mars.nasa.gov/msl/spacecraft/rover/wheels/

NASA. (n.d.). Rover Brains. https://mars.nasa.gov/mars2020/spacecraft/rover/brains/

NASA. (n.d.). Rover Cameras . https://mars.nasa.gov/mars2020/spacecraft/rover/cameras/

NASA. (n.d.). The Rover’s wheels. https://mars.nasa.gov/mer/mission/rover/wheels-and-legs/

Rankin A., Sesto T., Hwang P., Justice H., Maimone M., Verma V., Graser E., "Perseverance Rapid Traverse Campaign," 2023 IEEE Aerospace Conference, 7 March 2023, 07 March 2023.