Petra, a startup based in San Francisco, has developed a semi-automated thermal drilling robot called “Swifty” that can penetrate the toughest geological layers by grinding rock into powder.
Instead of using mechanical drill bits, the “Swifty” robot employs a hot drilling head with high pressure to remove rock layers without direct contact. In a recent test, Swifty excavated a tunnel measuring 45 to 152 cm wide by shattering all types of rock. The test included a 60 cm wide tunnel through 6 meters of Sioux quartzite, the hardest rock on Earth that can only be broken with explosives. The robot drilled at a speed of approximately 2.5 cm per minute.
Thanks to the combination of heat and high pressure, the drilling robot can penetrate hard rock layers. (Photo: Petra)
“Previously, there was no method capable of drilling through such hard rock. Petra’s achievement is due to Swifty’s thermal drilling method, which can effectively cut through rock layers without direct contact,” said Ian Wright, the Chief Technology Officer of Petra.
Petra’s robot utilizes machine vision, an artificial intelligence system that allows the robot to “see” and make decisions based on obstacles it encounters. While in operation, the robot breaks rock using a mixture of gases heated to over 1,000 degrees Celsius, turning the rock into smaller fragments. Once the rock layer is shattered, a powerful vacuum system removes the debris, clearing the path for the robot to continue drilling.
“Petra can drill through the hardest geological layers underground, allowing customers to install equipment in remote areas prone to wildfires and storms. Additionally, we can simplify urban projects by enabling engineers to navigate beneath the maze of existing infrastructure,” a representative from Petra shared.
Petra’s technology is inspired by experiments conducted by scientists at the Los Alamos National Laboratory in the 1960s. They designed a nuclear-powered tunneling machine capable of moving through the Earth’s crust or even the Moon’s surface. Although the rock-melting drill never became a reality, Petra learned from the project and conducted its first tests in an industrial area in Oakland, California, in 2018. The initial experiments used plasma, but engineers quickly transitioned to using gas and heat to make the equipment less cumbersome.
Petra’s Swifty robot aims to excavate through bedrock at a cost low enough to provide impetus for businesses to lay power lines, network cables, and various other conduits underground. According to Petra, Swifty’s thermal drill can reduce excavation costs through bedrock by 50 to 80%. The company is currently testing the thermal drilling method on various rock types, from granite to limestone, across regions from California to the Appalachian Mountains.
