HR: 0800h
AN: P41A-0923    [Abstracts]
TI: Robotic Lunar Drilling Development for the Construction and Resource Utilization Explorer (CRUX) Project.
AU: * Zacny, K
EM: Zacny@HoneybeeRobotics.com
AF: Honeybee Robotics, 460 W34th Street, New York, NY 10001 United States
AU: Bartlett, P W
EM: Bartlett@HoneybeeRobotics.com
AF: Honeybee Robotics, 460 W34th Street, New York, NY 10001 United States
AU: Glaser, D
EM: Glaser@HoneybeeRobotics.com
AF: Honeybee Robotics, 460 W34th Street, New York, NY 10001 United States
AB: The Construction Resource Utilization eXplorer (CRUX) Project is a NASA funded R&D project intended to provide technology for the exploration of lunar and planetary surfaces and subsurfaces. CRUX will have ten instruments, six of which will require subsurface access. Central to the CRUX project is a low power, low mass, robotic drilling system capable of reaching, and delivering scientific instruments to, a target depth currently set at 2 m. Two drilling methods for lunar application have been investigated thus far. The first uses purely rotary drilling, and the second rotary-percussive drilling, similar to what was used by the Apollo astronauts. Both drilling methods utilize an auger for the removal of drilled cuttings. A breadboard drilling system able to function in rotary-drag and rotary-percussive modes was produced to develop and prove out the approach through testing. Spacecraft weight, power, soil properties, and environments are among the key design constraints. The drilling algorithm, rotation and penetration rates, drill bit designs, and auger designs are among the key design variables. The test results presented demonstrate the progress made in simulating the environment, designing an automated system to perform in it, and characterizing the performance of the system. During the initial phase of the research effort, drilling tests were performed in two different lunar soil simulants (FJS-1 and JSC-1, made in Japan and the USA respectively) that were prepared in the following manner. Each soil sample was first mixed with 10wt% distilled water, compacted to 2 g/cc using the Modified Proctor Test (ASTM D1557), and then frozen at 190K. Under these conditions, the soil became as hard as sandstone and served to simulate the water-rich soils that are theorized to exist in permanently shaded craters at the lunar poles. The high bulk density, high water concentration, and binding nature of the water within the regolith were all chosen to serve as a worst case to design towards in terms of drillability. The results from these drilling tests identified four areas that will be critical in the future design of a system that is optimized for low mass and low power consumption. These are 1.) The soil destruction mechanism used by the drill bit, 2.) The passage of cuttings from the bit into the auger flutes, 3.) The design of the auger, and 4.) the drilling algorithm used. With respect to the drill bit, it was found that, by changing the cutting elements from tungsten carbide (WC) to Polycrystalline Diamond Compacts (PDC), the drilling efficiency increased by 50%. Additionally, by streamlining the auger entry at the base of the bit to allow for the uninterrupted flow of cuttings from the bottom of the hole to the auger, conditions of auger jamming were removed and the total drilling power was also reduced. By changing the angle of the auger flutes and by increasing the rotational speed from 50 to 125 RPM, the power required to convey the cuttings upwards dropped by almost 80%. Note that a direct result of making the drill system more efficient is to reduce the heat input into the drilling formation, which, from the scientific standpoint of volatile retention, is crucial to support sensing the formation in its unaltered, in situ state.
DE: 0994 Instruments and techniques
DE: 5422 Ices
DE: 5462 Polar regions
DE: 5494 Instruments and techniques
DE: 6250 Moon (1221)
SC: Planetary Sciences [P]
MN: Fall Meeting 2005