Student Experiential Learning Through Design and Development of a Subsurface Melting Head for NASA RASCAL-Special Edition Competition

The US National Aeronautics and Space Administration, the European Space Agency, and the China National Space Administration are expected to launch unmanned probes to Mars with the goal of exploring its surface for signs of ancient life and probe for valuable resources such as water. These water resources, in the form of ice, are found in sheets up to hundreds of meters thick and buried mere meters from the surface in some locations. Such deposits could sustain long-term manned missions providing them with fuel, water, and oxygen. The development of melting head intended to melt and extract subsurface ice is spurred on by the involvement of the University of the District of Columbia’s participation in the NASA RASC-AL Special Edition Challenge. This challenge requires the development of a sampling platform capable of boring through 0.5-0.8m of simulated Martian overburden, reaching an ice sample, and extracting up to 200L of liquid water from this sample. In the past, many teams have relied on passive melting or augering the ice to the surface and melting it in a collection vessel. The design the District of Columbia student team has developed will melt ice in situ and pump it back to the surface in liquid form. To assist with melting the ice and developing a substantial ice cavity, the ice would be melted until a volume substantial enough to fill a pump and plumbing was created and the system will subsequently recirculate this water to speed the convective heat transfer from the melting head to the water. Passive melting probe penetration is measured both analytically and experimentally and compared to the results of re-circulation tests. Both phases of testing demonstrated a clear benefit of the water recirculation, increasing the convective heat transfer of the cartridge heater and in the case of ice melting, substantially increasing the ice melt rate. The theoretical passive melting rate was not attained; while the predicted rate was 0.64mm/s, only an average rate of 0.177mm/s was attained. This was due to several factors, not the least of which is the relatively small amount of heat loss due to convection and radiation from the exposed melting head before it entered the ice. The ambient temperature of 22°C counteracted this loss somewhat until the melting head cooled to near freezing temperature. The results of these tests indicate that there is a substantial increase in melting speed using an active method of ice melting using water recirculation.