249 Mars Science Laboratory CHIMRA: A Device for Processing   Powdered Martian Samples 

Daniel Sunshine * 

Abstract 

The CHIMRA is an extraterrestrial sample acquisi tion and processing device for the Mars Science  Laboratory that emphasizes robustness and adaptability through design configuration. This work reviews  the guidelines utilized to invent the initial CHIMRA a nd the strategy employed in advancing the design;  these principles will be discussed in relation to both the final CHIMRA design and similar future devices.  The computational synthesis necessary to mature  a boxed-in impact-generating mechanism will be  presented alongside a detailed mechanism description. Results from the development testing required to advance the design for a highly-loaded, long-life and high-speed bearing application will be presented. Lessons learned during the assembly and testing of th is subsystem as well as results and lessons from  the sample-handling development te st program will be reviewed. 

Introduction 

The CHIMRA (Collection and Handling for In situ  Martian Rock Analysis) is the sample processing device  for the Mars Science Laboratory (MSL). Scheduled to launch in the fall of 2011, MSL is the next step in  NASA’s search for evidence to determine if the red planet’s environment was, or still is, suitable for  microbial life. To accomplish this goal, MSL houses an advanced suite of scientific  instruments that will be  able to ascertain whether the local geological environment  contains the chemical bu ilding blocks of life. In  order to feed science samples directly to these instruments, MSL required a state-of-the-art Sample Acquisition / Sample Processing and Handling (SA/SPaH) subsystem able to collect, sort, and deliver acquired samples to instruments in the rover. Utiliz ing a five degree-of-freedom robotic arm (Figure 1) and  a rotary percussive drill that forms the backbone of a five instrument turret (Figure 2) the SA/SPaH subsystem is able to collect powered  rock from depths up to 50 millimeter s. This powdered rock is then  transferred to the CHIMRA (Figure 3) for processing.  Each of the requirements for an extraterrestrial sample processing device are individually simple,  however when combined together, they form a colle ction of interconnected and dual-purposed device  constraints. The sample processing device must both acquire scooped regolith as well as accommodate sample transfer from the drill. The collected regolith or drilled powder must be sorted and separated into either sub-1 millimeter or sub-1 50 micron particle size s, reduced to a portion size of 45-65 cubic  millimeters for sub-150 mi cron sample or 45-130 cubic millimeters for sub-1 millimeter sample and  delivered to the science instruments on the rove r. In addition to these science-driven sampling  requirements, a number of self-imposed design constr aints were created that are essential to any  extraterrestrial sample processing device. These a dditional design constraints increase the robustness  and adaptability of a remotely operated sample proce ssing system. The response to these multi-faceted  constraints is an innovative and functionally dense device: the CHIMRA.                                                      * Jet Propulsion Laboratory, California In stitute of Technology, Pasadena, CA 

Proceedings of the 40th Aerospace Mechanisms Symposium, NASA Kennedy Space Center, May 12-14, 2010   NASA/CP-2010-216272