The Sample Handling System for the Mars Icebreaker Life Mission: from Dirt to Data
Concepts and Approaches for Mars Exploration (2012) 4186.pdf
The Sample Handling System For The Mars Icebreaker Life Mission: From Dirt To Data. A. Davé1,2, S. J. Thompson1,3, C. P. McKay1, C. R. Stoker1, K. Zacny4, G. Paulsen4, B. Mellerowicz4, B. Glass1, D. Willson1,5, R. Bonaccorsi1,6 1NASA Ames Research Center, Moffett Field CA 94035, 2Lockheed Martin IS&GS, 3Stinger Ghaf- farian Technologies, Inc., 4Honeybee Robotics, 5KISS Institute, 6SETI Institute
Summary: We describe a sample handling sys- cases were used in the tests, and design solutions to tem that can sample sticky ice-rich regolith augured up prevent jamming were created. (See jamming cases by the Icebreaker drill in a way consistent with plane- illustrated in Figure 3.) tary protection requirements.
Introduction: The Mars Icebreaker Life mission will drill to 1 meter depth in the ice-cemented ground near the Phoenix landing site. It will search for bio- marker evidence for life. Collecting samples from ice- rich soils on Mars in search for life presents two chal- lenges: protecting that icy soil from contamination from Earth and delivering icy sticky soil. Ice-rich sub- surface soils on Mars are considered a “special region” with respect to planetary protection and for this reason our drill and sampling system are separate and operate without contact. Clumpy, cohesive soil was observed at both the Phoenix and Viking 2 sites, possibly due to the presence of water and salts [1]. This type of soil clogged an instrument intake on Viking 2 [2], and similarly hindered sample delivery for the Phoenix mission [1]. For the Icebreaker mission, investigation of ice-rich ground is a priority, and it will most likely Figure 1. Sampling arm with Icebreaker drill in Mars be seen together with clumpy soil. A sampling arm chamber design is needed that can reliably deliver icy soil brought up by a drill to instruments on the lander deck.
Presented here is a sampling arm that meets the challenges of ice and contamination. Mars chamber tests fully demonstrated the sampling arm’s engineer- ing feasibility in a relevant end-to-end environment. The prototype was tested with the Icebreaker Drill and the SOLID life detection instrument, showing it is well integrated with collateral and ancillary systems, argua- Figure 2. The sampling arm collecting cuttings from bly reaching Technology Readiness Level 5. It was the Icebreaker drill while maintaining an air gap. operated in Mars polar temperature and pressure, re- trieving icy Martian soil simulant augured up by the drill and depositing it in the life detection instrument while meeting Planetary Protection requirements (see Figure 1). We have successfully demonstrated that the core of the Icebreaker payload can get from dirt to data. The arm’s success in the chamber tests proved
the feasibility of using an air gap to prevent forward Figure 3. Jamming cases were found to be A) when a contamination (The air gap is illustrated in Figure 2). single particle’s diameter matched the part clearance, or In addition, analysis of mechanical properties of B) when three particles together bridged the part clear- the Phoenix soil [3,4] in comparison with our attempts ance, effectively creating a keystone formation. C) to make cohesive soil simulant has brought to light Cases with even numbers of particles did not cause some principles that can be generally applied to future jamming. Mars sampling arm designs. Jamming and sticking Concepts and Approaches for Mars Exploration (2012) 4186.pdf
MMS sand is much coarser than the surface soils seen at the Phoenix site. (Particle size differences are shown in Figure 4.) “Phoenix soils appear to lack me- dium to large sand‐sized particles in a wide size range (200–1000 µm)… no such particle could be unambi- guously identified in any RAC or SSI images.” [3]. Our particle size analysis showed MMS sand was al- most entirely composed of 250 – 500 µm-sized grains. In future tests, MMS in its dust form mixed with water and perchlorate could be used as a more accurate sur- face soil analogue. Lastly, we have characterized the Icebreaker drill’s effect on soil, finding that its action may reduce the average particle diameter by nearly 100µm.
Figure 4. Comparison of MMS Sand particle sizes be- fore and after drilling, compared with Phoenix surface soils.
References: [1] Arvidson, R. E., et al. (2009), “Re- sults from the Mars Phoenix Lander Robotic Arm ex- periment,” J. Geophys. Res., 114, E00E02, doi:10.1029/2009JE003408. [2] Moore and Jakosky (1988), “Viking Landing Sites, Remote-Sensing Ob- servations, and Physical Properties of Martian Surface Materials,” ICARUS 81, 164-184. [3] Goetz, W., et al. (2010), “Microscopy analysis of soils at the Phoenix landing site, Mars: Classification of soil particles and description of their optical and magnetic properties,” J. Geophys. Res., 115, E00E99, doi:10.1029/2010JE003717. [4] Pike, W.T., et al. (2011), “Quantification of the dry history of the mar- tian soil inferred from in-situ microscopy,” Geophys. Res. Lett. 38, L24201, doi:10.1029/2011gl049896