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NASA will land its next rover, Perseverance, on the surface of Mars in February 2021, and an engineer from the Curiosity rover pilot team just spoke about what the process looks like.
There is approximately a 22-minute signal delay between Earth and Mars, which means that piloting the spacecraft over unfamiliar terrain requires unique planning. Evan Hilgemann, a NASA engineer who was selected to be part of the engineering team that piloted the Curiosity rover, recently wrote a post on Medium about what the experience was like.
His goal in writing the post was not just to share his unique story, but also to give everyone who watched Perserverence drive across the red planet a little behind-the-scenes history.
The first thing Hilgemann points out about piloting the rover is that “Curiosity only receives information from Earth once a day and is alone the rest of the time. “So how can your team fly the rover if it only gets information once a day?
Piloting the rover
For starters, the rovers are covered in 3D cameras that allow an accurate image of their entire surroundings. With the sensors on board, the rover can perform many tasks autonomously, such as collecting and scanning rocks with its integrated laser or driving according to pre-planned patterns. However, the robot sometimes gets stuck and when that happens it usually holds its own until it receives further instructions from the green planet.
The person who takes the initiative as the driver of the vehicle at any time has the responsibility to keep the vehicle safe. Achieving this goal successfully means being able to see where you are going. The engineering team can develop a virtual image of the rover’s surroundings using navigation cameras and hazcams. Hazcams are on-board cameras that detect nearby hazards, such as rocks or ledges, and navigation cameras focus on the surroundings at a greater distance to map out the location.
As for sending the instructions to the rover once the engineers get a clear picture, the team has a few options. They can send information in blind driving mode. Hilgemann notes that “driving blind it is the simplest form of navigation available. In this mode, the mobile will follow the specific instructions given to it, but will not make any adjustments based on actual progress. “
Another method is “visual odometry”, which according to Hilgemann is the most widely used method. Basically this method involves the rover taking photos at regular intervals, roughly every meter, and then comparing the images with previous photos to see where it has moved and how the terrain has changed.
RELATED: NASA’S PERSEVERANCE ROVER TO HUNT X-RAY FOSSILS
Finally, the most advanced driving techniques are called “autonav”, in which the rover can only cover “100 feet in an hour. “This mode is like autonomous driving in vehicles. Using its hazcams and onboard navigation cameras, the rover can develop an image of its surroundings and autonomously trace safe paths. The composite image that the rover looks like the image below, with the different colors indicating safe (green) or dangerous (red) terrain.
The next steps of perseverance
Assuming all goes according to Perseverance’s plan in February, the rover will begin to be piloted by its crew using one of the three methods described by Hilgemann. However, there is a significant risk that the rover will not reach the surface. The drone descent and landing phase is by far the greatest chance for catastrophic mission failures.
One note Hilgemann adds about the new rover is that it is something of a speed demon compared to Curiosity. He adds that “the new rover will generally be able to drive at least twice as fast as Curiosity thanks to new dedicated computing resources and better algorithms. Perseverance’s navigation cameras are also in color and with a higher resolution” than Curiosity.
Perseverance is scheduled to land on Mars on February 18, 2021.
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