NASA’s Mars rovers strive to make groundbreaking scientific discoveries as they traverse the Martian landscape. At the same time, the crews operating the rovers are doing everything they can to protect them and the billions of dollars behind the mission. This balance of risk and reward drives decisions about where rovers go, the paths they take to get there, and the science they uncover.
Researchers at the School of Computing’s Robotics Institute (RI) have developed a novel approach to balancing the risks and scientific value of sending planet rovers into dangerous situations.
David Wettergreen, professor-researcher at the RI, and Alberto Candela, who obtained his doctorate. in robotics and is now a data scientist at NASA’s Jet Propulsion Laboratory, will present his work, “An Approach to Science and Risk-Aware Planetary Rover Exploration”, at the IEEE and RSJ International Conference on Robots and Intelligent Systems later this month in Kyoto, Japan.
“We looked at how to balance the risk associated with going to tough places against the value of what you might discover there,” said Wettergreen, who has worked on autonomous planetary exploration for decades at Carnegie University. Mellon. “This is the next step in autonomous navigation and producing more and better data to help scientists.”
For their approach, Wettergreen and Candela combined a model used to estimate scientific value with a model that estimates risk. Scientific value is estimated using the robot’s confidence in its interpretation of the mineral composition of rocks. If the robot thinks it has correctly identified the rocks without needing further measurements, it can choose to explore a new location. If the robot’s confidence is low, however, it may decide to continue studying the current area and improve its mineralogical model. Zoë, a rover that has been testing autonomy technologies for decades, used an earlier version of this model during experiments in 2019 in the Nevada desert.
The researchers determined the risk through a model that uses terrain topography and types of terrain composition materials to estimate how difficult it will be for the rover to reach a specific location. A steep hill with loose sand could doom a rover’s mission – a real concern on Mars. In 2004, NASA landed twin rovers, Spirit and Opportunity, on Mars. Spirit’s mission ended in 2009 when it got stuck in a sand dune and its wheels slipped when it tried to move. Opportunity pursued and worked until 2018.
Wettergreen and Candela tested their framework using real surface data from Mars. The pair sent a simulated rover rushing to Mars using this data, tracing different paths based on varying risks, and then evaluating the science gained from these missions.
“The rover did very well on its own,” Candela said, describing the simulated missions to Mars. “Even in high-risk simulations, there were still plenty of areas for the rover to explore, and we found that we were still making some interesting discoveries.”
This research builds on decades of IR work on autonomous planetary exploration. Papers dating back to the 1980s propose and demonstrate methods that would allow rovers to navigate the surfaces of other planets autonomously, and technology developed through this research has been used on recent Mars rovers.
Pioneering autonomous technology researchers at CMU have proposed Ambler, a six-legged autonomous robot that could prioritize its goals and chart its own course in places like Mars. The team tested the six-meter-tall robot in the early 1990s. Other rovers followed, including Ratler, Nomad and Hyperion – a rover designed to track the sun as it moves to recharge its batteries.
Zoë began her work in Harsh Environments in 2004 and traveled hundreds of miles through the Atacama Desert in Chile, an environment in many ways similar to Mars. In 2012, Zoë’s missions in the desert shifted to focus on autonomous exploration and decisions about where to go and what samples to collect. A year later, the rover autonomously decided to drill into the desert floor, and it discovered what turned out to be unusual and highly specialized microbes, demonstrating that automated science can lead to valuable discoveries.
Candela and Wettergreen hope to test their recent work on Zoë on an upcoming trip to the Utah desert. The couple also see their research making valuable contributions to future lunar exploration. Their approach could be used by scientists as a tool to study potential routes in advance and balance the risk of those routes with the science that could be gained. The approach could also help a generation of autonomous rovers sent to planet surfaces to conduct scientific experiments without the need for continued human involvement. The rover could assess risk and reward before charting its own course.
“Our goal is not to eliminate the scientists, not to eliminate the person from the investigation,” Wettergreen said. “Really, the goal is to allow a robotic system to be more productive for scientists. Our goal is to collect more and better data that scientists can use in their research.”
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Material provided by Carnegie Mellon University. Original written by Aaron Aupperlee. Note: Content may be edited for style and length.
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