NASA will land its next rover, Perseverance, on the surface of Mars in February 2021, and the engineer of the Curiosity rover pilot team has just discovered what the procedure is.
There is an approximately 22-minute signal delay between Earth and Mars, which means that piloting a vessel across unfamiliar terrain requires uniform planning. Evan Hilgemann, a NASA engineer selected to serve on the team of engineers who piloted the Curiosity rover, recently wrote a Medium post that opens up about what the experience was like.
His goal in writing the post was not only to share his unique story, but also to provide everyone watching Perserverence being transported across the red planet with a little background on what’s going on behind the scenes.
The first thing Hilgemann mentions about piloting a rover is that “Curiosity receives information from Earth only once a day, and the rest of the time it is independent. “So how does his team even pilot a rover if it only gets information once a day?
For starters, the rovers are covered with 3D cameras that allow an accurate picture of the entire environment. With sensors on board, the rover can perform a number of tasks on its own, such as capturing and scanning rocks with its built-in laser or driving pre-planned patterns. However, the robot sometimes gets stuck and when that happens, it usually holds on tight until it gets more instructions from the green planet.
The person who takes the lead as a rover driver at any time has a responsibility to keep the rover safe. Successfully achieving this goal means being able to see where you are going. A team of engineers is able to develop a virtual image of the rover environment using navcame and hazcame. Hazcams are cameras on a ship that spot hazards nearby, such as rocks or bumps, and occasionally focus on further location drawing environment.
As for sending the rover its instructions after the engineers get a clear picture, the team has several options. They can send information in blind mode. Hilgemann notes that “blind driving is the simplest form of navigation available. In this mode, the rover will follow certain instructions given to it, but will not make any adjustments based on actual progress. “
The second method is “Visual Odometry”, which Hilgemann notes is the most common method used. This method basically involves a rover that shoots at regular intervals, approximately every meter, then compares the images with previous images to see where it is moving and how the terrain has changed.
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Finally, the most modern driving technique is called “autonav”, in which the rover can only cover “100 feet per hour. “This mode is like self-driving in vehicles. Using its hazcame and navcame on board, the rover can develop an image of its surroundings and autonomously map safe paths. The composite image developed by the rover looks like the image below, with various colors indicating safe (green) or dangerous (red) terrain.
The next steps of perseverance
Assuming everything goes according to plan for the Perseverens in February, the rover will begin piloting its crew using one of the three methods Hilgemann described. However, there is a significant risk that the rover will not reach the surface. The landing and landing phase of the drone is arguably the greatest opportunity for catastrophic mission failure.
One note that Hilgemann adds about the new rover is that it is a kind of speed demon compared to Curiosity. He adds, “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 navigation cameras are also in color and higher resolution,” than Curiosity.
Perseverance will land on Mars on February 18, 2021.