A nuclear-powered tunnelling robot could one day be deployed on Europa to help search for signs of microbial life.
Jupiter’s moon Europa has an icy surface that is thought to cover a liquid ocean, which is in contact with a rocky core. This environment contains the biochemical ingredients for life but accessing it to collect samples remains a major challenge.
“Estimates of the thickness of the ice shell range between 2 and 30km [1.2 and 18.6 miles] and is a major barrier any lander will have to overcome in order to access areas we think have a chance of holding biosignatures representative of life on Europa,” said Andrew Dombard, associate professor of earth and environmental sciences at the University of Illinois at Chicago.
At a recent meeting of the American Geophysical Union in Washington, D.C., Dombard and his colleagues proposed a solution in the form of a nuclear-powered tunnelling probe.
Dombard and D’Arcy Meyer-Dombard, associate professor of earth and environmental sciences at UIC, are part of a group of scientists on the NASA Glenn Research COMPASS team, a multidisciplinary group of scientists and engineers tasked with designing technology and solutions for space exploration and science missions.
The group is said to have performed a concept study for a nuclear-powered “tunnelbot” that can penetrate the ice shell and reach the top of Europa’s ocean while carrying devices and instruments that can be used to search for signs of life or extinct life. The tunnelbot would also evaluate the habitability of the ice shelf.
“We didn’t worry about how our tunnelbot would make it to Europa or get deployed into the ice,” Dombard said. “We just assumed it could get there and we focused on how it would work during descent to the ocean.”
The tunnelling robot would sample ice throughout the shell, as well as water at the ice-water interface, and would look at the underside of the ice to search for microbial biofilms. The tunnelbot would also have the capability of searching liquid water “lakes” within the ice shell.
The researchers are said to have considered two designs for their bot: one powered by a small nuclear reactor, and the other powered by General Purpose Heat Source bricks, which are radioactive heat source modules designed for space missions. Heat from both these sources could be used to melt the ice shell. Communications would be provided by a string of repeaters connected to the tunnelbot by fibre optic cables.
The tunnelling robot proposal by Dombard et al has been predicated by evidence gathered by NASA’s Galileo spacecraft, which made several flybys of Europa between 1995 and 2003 and presented data that pointed to evidence of a liquid ocean beneath Europa’s icy surface.
Kathleen Craft from the Applied Physics Laboratory at Johns Hopkins University and COMPASS team leads Steven Oleson and J. Michael Newman of the NASA Glenn Research Center also worked on the concept study.