It obeys voice commands and can carry 400 pounds of equipment over rugged terrain for 24 hours—but it sounds like a lawn mower, and US Marines worried that it could get them killed. The Marine Corps has shelved the Legged Squad Support System "robotic mule" developed by Google's Boston Dynamics and the Pentagon's DARPA research arm because its gas-powered engine was just too noisy, reports the BBC. "As Marines were using it, there was the challenge of seeing the potential possibility because of the limitations of the robot itself," Kyle Olson, a spokesman for the Marines' Warfighting Lab, tells Military.com. "They took it as it was: a loud robot that's going to give away their position."
The BBC notes that because of noise concerns about "BigDog," researchers created the quieter, electric-powered "Spot"—but it could only carry 40 pounds and didn't have the same autonomous capabilities as the bigger robot. Around $42 million was spent on the project over the last couple of years, and Olson tells Military.com that it wasn't a waste of money. "We tend to play with things that are fanciful and strange," he says. "Learning from it was a big part, and we're still learning." NBC News reports that the Warfighting Lab describes the mothballed robot as a "waypoint along a path of discovery and development," and the Marine Corps still believes in the "necessity of autonomous, unmanned, and robotic capabilities." (Boston Dynamics' Atlas robot has the walking ability of a drunk human.)