Carnegie Mellon researchers are helping a NASA underwater robot probe Earth's deepest sinkhole — Zacatón. The bot's journey will take place in May, aided by Carnegie Mellon-designed navigation and mapping software.
According to Bill Stone, leader of the NASA-funded Deep Phreatic Thermal Explorer (DEPTHX) mission, the 2.5-meter bot maneuvered "phenomenally well" within the confines of a smaller sinkhole during recent tests in Mexico.
Carnegie Mellon-developed software allows robotic sub to operate autonomously — without tethers or any communication with humans above. This capability has never been demonstrated on other autonomous underwater bots but is essential to the success of the DEPTHX mission.
Nathaniel Fairfield, a Carnegie Mellon PhD student, adapted software so the sub can keep track of its position in three dimensions as it maps the sinkhole.
"The fact that [DEPTHX] ran untethered in a complicated, unexplored three-dimensional space is very impressive," said Stone, an engineer and expert cave diver who heads Stone Aerospace Inc. of Austin, Texas. "That's a fundamentally new capability never before demonstrated in autonomous underwater vehicles," he added.
La Pilita, the "test" sinkhole, is located not far from Zacatón in the Mexican state of Tamaulipas. Both were formed by the collapse of a limestone chamber, which occurred when nearby volcanic activity caused groundwater to become heated and acidic.
David Wettergreen, associate research professor at Carnegie Mellon's Robotics Institute, described the La Pilita as having the appearance of an ordinary small pond, about 30 meters across.
"You can swim across it in a minute, and it's warm, too," he said. "But the top is like the neck of a vase; as you get deeper, it widens until it's more than 100 meters across. It's a duck pond that is 115 meters [375 feet] deep."
But no one knows Zacatón's depth; human divers have descended to 282 meters without reaching bottom.
NASA has funded the mission to develop and test technologies that might someday be used to explore the oceans hidden under the icy crust of Europa, one of Jupiter's moons.