The Mars Sample Return mission has the goal to drill, break off, and retain rock core samples. After some results gained from rock core mechanics testing, the realization that scoring teeth would cleanly break off the core after only a few millimeters of penetration, and noting that rocks are weak in tension, the idea was developed to use symmetric wedging teeth in compression to weaken and then break the core at the contact plane. This concept was developed as a response to the break-off and retention requirements.
The wedges wrap around the estimated average diameter of the core to get as many contact locations as possible, and are then pushed inward, radially, through the core towards one another. This starts a crack and begins to apply opposing forces inside the core to propagate the crack across the plane of contact.
The advantage is in the simplicity. Only two teeth are needed to break five varieties of Mars-like rock cores with limited penetration and reasonable forces. Its major advantage is that it does not require any length of rock to be attached to the parent in order to break the core at the desired location. Test data shows that some rocks break off on their own into segments or break off into discs. This idea would grab and retain a disc, push some discs upward and others out, or grab a segment, break it at the contact plane, and retain the portion inside of the device. It also does this with few moving parts in a simple, space-efficient design.
This discovery could be implemented into a coring drill bit to precisely break off and retain any size rock core.
This work was done by Megan Richardson and Justin Lin of Caltech for NASA’s Jet Propulsion Laboratory. NPO-47444
This Brief includes a Technical Support Package (TSP).
Method for Cleanly and Precisely Breaking Off a Rock Core Using a Radial Compressive Force
(reference NPO-47444) is currently available for download from the TSP library.
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Overview
The document is a technical support package from NASA's Jet Propulsion Laboratory (JPL) detailing a method for cleanly and precisely breaking off rock cores using a radial compressive force. This method is encapsulated in NASA Tech Brief NPO-47444 and is part of the Commercial Technology Program aimed at disseminating aerospace-related developments with broader technological, scientific, or commercial applications.
The primary focus of the document is on the design and implementation of a tool or method that applies a radial compressive force to rock cores, which is essential for various geological and planetary exploration tasks. The document outlines specific design requirements, including a necessary compressive force of 359 lbs (1597 Newtons) and a minimum stroke of 2.5 mm. Additionally, there is a desire to maximize the stroke to enhance the tool's retention capabilities during operation.
The document also includes a scored results summary, indicating that the radial distance required by each tooth of the tool is half the linear distance, which is crucial for understanding the mechanics of the tool's operation. This information is vital for engineers and researchers working on the development and refinement of the tool.
Future work is suggested, emphasizing the need to begin developing possible implementations for the method described. This indicates an ongoing commitment to advancing the technology and ensuring its practical application in relevant fields.
The document serves as a resource for those interested in the innovative technologies being developed at JPL, particularly in the context of rock core sampling and analysis, which is critical for planetary science and exploration missions. It also provides contact information for further inquiries, highlighting the collaborative nature of NASA's research initiatives.
Overall, this technical support package encapsulates a significant advancement in the methodology for rock core extraction, with implications for both scientific research and potential commercial applications. The information is intended for stakeholders in the aerospace sector and beyond, promoting the sharing of knowledge and technology developed under NASA's auspices.
