NASA is working on a nuclear-powered robot to explore Jupiter’s frozen moon Europa.
It is believed the moon is home to a subterranean ocean which may harbour microbial life.
Ice above the ocean is thought to be between 2 and 30 kilometres (1.2 and 18.6 miles) thick and researchers have proposed a tunnelling probe as the best way to penetrate the frosty shell and study its internal structure.
Several flybys of the solar system’s gas giant between 1995 and 2003 by NASA’s Galileo spacecraft alerted scientists to the presence of the water.
Researchers agree the best place to look is underneath the thick, planet-wide ice shell where water is in contact with a rocky core.
They believe this is where biochemical ingredients for life may exist.
But it remains a mystery as to what is the best way to explore this world and collect samples.
‘Estimates of the thickness of the ice shell range between 2 and 30 kilometers (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.
Dr Dombard and his colleagues presented a possible solution to this problem at the American Geophysical Union meeting in Washington, DC, this week.
Dr Dombard’s team believe a nuclear-powered tunnelling probe is the best option for this mission.
The group 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 bot would also evaluate the habitability of the ice shelf itself.
‘We didn’t worry about how our tunnelbot would make it to Europa or get deployed into the ice,’ Dr Dombard said.
‘We just assumed it could get there and we focused on how it would work during descent to the ocean.’
The bot would sample ice throughout the shell, water towards the core as well as water at the ice-water interface, and would look at the underside of the ice to search for microbial biofilms.
The bot would also have the capability of searching liquid water ‘lakes’ within the ice shell.
The researchers considered two designs for their bot: one powered by a small nuclear reactor, and the other powered by General Purpose Heat Source bricks—radioactive heat source modules designed for space missions.
Heat from both these sources could be used to melt the ice shell and communication with Earth would be made possible by a string of ‘repeaters’ connected to the bot by fibre optic cables.