Laboratory drilling under Martian conditions yields unexpected results

Current plans to drill boreholes in the surface of Mars suppose that diamond drill bits will be used on drilling equipment developing drilling power of 100 W or less. Such drilling produces very fine cuttings. At Martian ambient pressure, it has been shown that quite small gas flows are capable of clearing these cuttings from the hole. For example, the release of 1 L of gas compressed to 50 torr is capable of removing 25 g of cuttings from a borehole 50 mm in diameter and at least 250 mm deep. Generating such volumes of gas by compressing the Martian atmosphere would not be difficult. Alternatively, the required volume of gas could be provided by the sublimation of ice trapped in the pore spaces of soil or rock in the Martian surface. Once heated by the friction of the drill bit, the ice transforms into vapor, and blows the cuttings out of the hole. Since the cuttings are, in effect, freeze‐dried, they do not choke the drill bit or hole, with the result that the drilling efficiency is much greater than under terrestrial pressures and temperatures.