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How exactly does NASA guide its rover on the surface of Mars



NASA will land its next rover Persian on the surface of Mars in February 2021. An engineer on the Curiosity rover pilot team has just lifted the veil of this process.

There is approximately a 22-minute signal delay between Earth and Mars, which means that driving a spacecraft on unknown terrain requires some unique planning. NASA engineer Evan Hilgemann was selected as part of the team of engineers leading the Curiosity rover, and he recently wrote a “medium” article describing this experience.

His purpose of writing this article is not only to share his unique story, but also to provide some background knowledge for everyone watching Perserverence through the Red Planet.

Hilgemann’s first thing about driving a rover is,Curiosity receives information from the earth only once a day, and the rest of the time is determined by itself. “So, if the rover only gets information once a day, how will his team drive the rover?

Driving rover

For starters, the rover is covered by a 3D camera, which can accurately capture all surrounding environments. With the help of on-board sensors, the rover can complete a large number of tasks autonomously, such as using on-board lasers to pick and scan rocks or drive around in a pre-planned pattern. However, robots sometimes get stuck, and when this happens, they usually hold on tightly until they get more instructions from the green planet.

The person who takes the lead as the rover driver at any given time is responsible for ensuring the safety of the rover. Achieving this goal successfully means being able to see where you are going. The team of engineers can use navcam and hazcams to develop virtual images of the environment around the rover. Hazcam is a vehicle-mounted camera that can detect nearby hazards, such as rocks or ledges, while navcams focuses on the farther surrounding environment for location mapping.

NASA engineers introduce the feeling of driving a Mars rover
The layout of the rover camera on Hengxin. Source: NASA/JPL

As for once the engineer clearly sends instructions to the rover, the team can choose several methods. They can send information in blind driving mode.Hilgerman pointed out that “driving blindly It is the simplest form of navigation. In this mode, the rover will follow the specific instructions given, but will not make any adjustments based on the actual progress. “

Another method is the “visual ranging method”, which Hilgemann points out as the most commonly used method. The method essentially includes: the rover periodically takes an image about every meter, and then compares the image with previous images to see where it moves and changes in terrain.

Related: NASA’s Perseverance Roaming X-ray Fossils

Finally, the highest technology driving these technologies is called “automatic navigation”, in which the rover can only cover approximately “100 feet per hour. “This mode is like auto-driving vehicles. The rover uses its hazcam and navcams to display images of its surroundings and automatically draw a safe path. The composite image formed by the rover looks like the various types below the image. The colors indicate safe (green) or dangerous (red) terrain.

NASA engineers introduce the feeling of driving a Mars rover
Screenshot of NASA Autonav demo video. Source: NASA/JPL

The next step of perseverance

Assuming that everything goes according to the Perseverance Plan in February, the rover will begin to be driven by its occupants using one of the three methods described by Hilgerman. However, the rover will not be able to reach the ground, which is a great risk. So far, the landing and landing phase of the drone is the greatest chance of catastrophic failure in the mission.

Hilgemann’s addition to the new rover is that it is a speed demon compared to curiosity. He added: “Due to new dedicated computing resources and better algorithms, the new rover can usually be at least twice as fast as Curiosity. Perseverence’s navigation cameras are also higher in color and resolution.”

Perseverance is scheduled to land on Mars on February 18, 2021.




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