A high-tech drill originally slated for use on Mars is heading for another cold, alien desert – Antarctica. Developed by a team of University of Glasgow engineers, the drill is on its way to the British Antarctic Survey (BAS) Skytrain Ice Rise research station, where it will be used to drill deep under the ice cap to help scientists gain a better understanding of Earth's climate history.
To develop even a vague idea of how the climate of the Earth has altered and the mechanisms that drive it, that means looking for evidence that doesn't just go back centuries or millennia, but whole geological epochs spanning tens of millions of years.
One of the ideal places to do this is Antarctica, which froze over some 15 million years ago. In one sense, the continent is a time capsule that has preserved evidence over a staggeringly long time. But in another, it's a dynamic record as the ice cap has moved, grown and shrunk, while the climate has warmed and cooled in cycles.
The hard part is getting at this evidence, which requires drilling through ice that can be over a mile thick to get to the bedrock. This is compounded by the fact that drilling through ice is different to drilling through rock, so collecting samples is a difficult problem, one now with a potential solution inspired by the Red Planet.
According to the Glasgow team, drilling on Mars presents its own challenges. Most drills work by pressing the bit down into the material in question, but the low gravity of Mars make this difficult – especially when the drill is stuck on the end of a relatively light and wobbly robotic arm.
The team's answer was the Percussive Rapid Access Isotope Drill (P-RAID). Instead of just spinning the drill bit, the P-RAID uses a hammering action watched over by an autonomous system. This allows the device to operate at the lowest possible weight-on-bit and the lowest possible torque.
The upshot of this is that the drill system is much smaller than conventional rigs and can fit inside the narrow boreholes used for taking ice core samples. After completing acclimation tests, the drill will be lowered to the bedrock under the icecap, where it will collect samples for return to Britain for analysis.
The hope is that by measuring the ratio of the various radioactive isotopes present, it will be possible to determine when and how often the ice has receded in the area. Not only do the isotopes provide dating evidence by their rate of radioactive decay, but exposure of the rock to sunlight affects their accumulation.
The team says that the drill has already visited Antarctica on previous occasions to test it in Mars-like conditions, but this is the first time it has been used for a geological experiment. The University of Glasgow research team consisting of Kevin Worrall and Ryan Timoney will leave this week for Antarctica, if the weather permits.
"We're hoping to get a sample of bedrock out from underneath the Antarctic ice sheet and return it to the UK for analysis," says Dr Patrick Harkness, who led the team of engineers. "When we do that we'll be able to determine how long it's been since that rock last saw the sun and that information will allow us to recreate the advance and withdrawal of the ice sheets, which gives us much greater information about the coming and going of ice ages. That could allow us to validate our climate models with much greater confidence and make better decisions about environmental matters here on Earth."
Source: University of Glasgow
