Abstract Critical fragments are a type of lunar soil in which the average diameter of the particles is equal to or larger than the coring hole diameter of the drill bit. It is difficult to transmit critical fragments out of the borehole. Therefore, the accumulation of critical fragments under the drill bit can cause drill jams, cutter wear, a low coring rate, and lead to other unsatisfactory conditions. These drilling faults result in sample mission failure. A method to identify critical fragment layers must be developed to resolve this problem. A method that identifies homogeneous soil, rocks, and critical fragments based on the impact power spectrum of the drill top is proposed in this study. Three classical simulant conditions were introduced. The impact response signal data from the top of the drill were obtained when encountering each of the three test specimens. Next, a time-frequency conversion was used to process the data to obtain the frequency response and power spectrum. Then, the theoretical and single impact data were compared to verify the accuracy of the method. The impact power spectrum was obtained while using test specimens at 2 Hz, 5 Hz, and 8 Hz. A comparison of different response data indicated that 8 Hz can be used as an impact frequency to identify the critical fragment layers. This research provides a reference for drilling fault conditions in upcoming lunar sample missions.
Highlights An identify simulant lunar soil method based on drill power spectrum is proposed. The power spectrum of critical fragment layers is compared with the two conditions. Homogeneous soil can absorb high frequency power more readily. 8 Hz can be used as the impact frequency to identify the critical fragment layers.
Lunar critical fragment layer simulant identification using an impact method
Acta Astronautica ; 173 ; 294-302
2020-04-06
9 pages
Article (Journal)
Electronic Resource
English
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