Challenges and methods of drilling on the Moon and Mars

There are many reasons for penetrating below the surface of an extraterrestrial body. One of these reasons include obtaining core or powder samples that have been preserved and unaltered for millions of years. Another reason is to provide subsurface access for in-situ scientific instruments such as heat flow probes and neutron spectrometers. However, there are a number of challenges associated with penetrating extraterrestrial bodies. These include specific mission requirements (depth, size of a sample, acceptable level of contamination), mission constraints (mass, power, volume, communication delay) and environmental constraints (temperature, atmospheric pressure or vacuum, dust, geological uncertainty). Having such a large number of variables leads to diverse approaches. This paper specifically outlines challenges associated with drilling on the Moon or Mars. It also reports test results with rotary and rotary-percussive drilling methods and how these two different approaches compare in respect to power, energy and Weight on Bit. The results have shown that although heavier and more power hungry, a rotary-percussive drill can significantly increase the overall drilling efficiency and reduce WOB requirements when compared to a rotary drilling method.