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 explained how the process is.
There is a signal delay of approximately 22 minutes between Earth and Mars, meaning that piloting the craft over unfamiliar terrain requires unique planning. Evan Hilgemann, a NASA engineer selected to join the team of engineers that piloted the Curiosity rover, recently wrote a Medium post explaining what the experience was like.
His goal in writing the post was not just to share his unique story, but to give anyone who sees Perserverence driving across the red planet a little bit of background on what goes on behind the scenes.
The first thing Hilgemann notes about piloting the robber is that “Curiosity only receives information from Earth once a day and is alone the rest of the time. So how does his team control the rover even if he only gets information once a day?
Control the robber
To begin with, the rovers are covered with 3D cameras that provide an accurate picture of their entire environment. With on-board sensors, the rover can perform a variety of tasks autonomously, such as picking up rocks and scanning with its built-in laser or driving around in pre-planned patterns. However, the robot sometimes gets stuck and when it does, it usually holds on tightly until it gets more instructions from the green planet.
The person who takes charge as the rover’s driver has the responsibility to keep the rover safe. To successfully achieve this goal means you can see where you are going. The team of engineers can develop a virtual image of the rover’s environment using navcams and hazcams. The hazcams are built-in cameras that detect nearby hazards such as rocks or ledges, and the navcams focus on the farther away environment for location plotting.
When it comes to steering the rover’s instructions 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 is the simplest form of navigation available. In this mode, the rover follows the specific instructions given to it, but makes no 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, about every meter, then comparing the images to previous photos to see where it has moved and how the terrain has changed.
RELATED: NASA’S PERSEVERANCE ROVER TO HUNT FOR FOSSILS WITH X-RAYS
Finally, the most advanced way of controlling the techniques is called ‘autonav’, in which the rover is only about ‘100 feet in an hour. “This mode is like self-driving in vehicles. Using the hazcams and navcams on board, the rover can develop an image of its surroundings and autonomously map out safe paths. The composite image that the rover develops is similar to the one below. with the different colors for safe (green) or dangerous (red) terrain.
The next steps of persistence
Assuming everything goes according to plan for Perseverance in February, the rover will be piloted by its crew using one of three methods Hilgemann describes. However, there is a significant risk that the rover will not reach the surface. The descent and landing phase of the drone is by far the greatest chance of catastrophic failure in the mission.
One comment that Hilgemann adds about the new rover is that it is a bit of a speed demon compared to Curiosity. He added, “The new rover will generally be able to travel 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 have a higher resolution” than Curiosity.
Perseverance will land on Mars on February 18, 2021.