First tests of a laser ice drill for the exploration of interplanetary ice and icy soils

The exploration of icy moons and other icy regions such as permanently shadowed lunar craters, Martian polar caps or comets is of great scientific interest, as they might offer life-friendly environmental conditions or can serve as resource deposits for human exploration. In contrast to conventional melting probes, this work presents a laser ice drill, which drills a 6.15 mm diameter hole in the ice and drives the resulting gases and non-volatile additives from the bottom of the hole to the surface for analysis purposes. To demonstrate the concept, various types of ice with dust fraction up to 96.6 wt% were drilled in a laboratory setup. The tests were carried out at vacuum pressures in the 100 Pa range and ambient temperature. The drilling depth was simultaneously tracked with a laser rangefinder, so that a depth assignment of the ejected substances was possible. During the drilling tests, melting speeds of up to 1.7 m/h at 12.7 W laser power were achieved in pure granular ice and 1 m/h at 19.7 W in clear ice. In dusty ice, however, even higher drilling speeds were achieved without increasing the laser power. The melting rates of all drilling experiments are simulated in good agreement with a thermal model.