International Planetary Probes Workshop (IPPW) June 218 Surface and Subsurface Sampling Drills for Life Detection on Ocean Worlds Fredrik Rehnmark Senior Systems Engineer Honeybee Robotics Exploration Technology Group (ETG) rehnmark@honeybeerobotics.com Image courtesy NASA
Contributors Honeybee Robotics JHU/APL Kris Zacny (PI) 1,2 Ralph Lorenz (Co-I) 1 Fredrik Rehnmark (Systems, Drilling) 1,2 Tighe Costa (Pneumatics, Drilling) 1,2 Zach Mank (Sample Manipulation) 1 Jameil Bailey (Avionics) 1 Joey Sparta (Pneumatics, Testing) 1 Paul Chow (Thermal Analysis) 2 Nick Traeden (Mechanical Support) 1 1. COLD (Concepts for Oceanworlds Life Detection) Technologies 2. SLUSH (Search for Life Using Submersible Heated) Drill SBIR 2
The Challenge The search for life beyond Earth is a search for similar or analogous environmental conditions, including abundant liquid water. Recent discoveries of water on ocean worlds including Titan and Europa have piqued interest in these destinations but liquid water is buried kilometers deep beneath an icy crust. State-of-the-art in ultra-deep drilling on Earth Kola Superdeep Borehole: 23 cm diameter, 12 km deep, 19 years (197-1989) Vostok Hole: 13.7-16.5 cm diameter, 4 km deep, 22 years (199-212) State-of-the-art in deep drilling on the Moon. Apollo Lunar Surface Drill: 2 cm diameter, 3 m deep, 1 cm/sec New planetary drilling methods are needed to reach subsurface water on ocean worlds. Drilling will take time and plenty of power. In the meantime, surface sampling at sites of scientific interest could take advantage of natural transport and preservation processes to collect early data more quickly and easily. 3
Planetary Excavation Methods Method Material Strength Sample Alteration Ease of Delivery Scooping Rasping, Abrading Sawing Coring Drilling Melting Loose, unconsolidated surface material Hard rock and ice Hard rock and ice Soft surface material Hard rock and ice Hard ice No heating Minimal heating, generates small particles Minimal heating, generates small particles Minimal heating, preserves stratigraphy Minimal heating, generates small particles Release of volatiles, possible chemical alteration Can be problematic with sticky material (e.g., Phoenix) and highly variegated particle size Max. Depth Power* ~1 cm W Cuttings scattered ~1 cm ~3 W Cuttings scattered ~1 cm ~1 W Removing core can be difficult Cuttings deposited around bit Liquid water or slush can be easily pumped ~1 cm ~1 W >1 m ~1 W - 1 kw >1 m ~1 kw Drilling is suitable for both surface and deep cryogenic sample acquisition with minimal risk of sample alteration. * note: estimates do not include power consumed by deployment system (e.g., robotic arm, etc.) 4
Extrapolation Based on Field Tests Arctic: water-ice and permafrost at 265K 13 Watt, 6 inch (15.2 cm), rotary-only ROP: 5 cm in 4 min = 7.5 m/hr Energy: 173 Whr/m Specific Energy: 1 kwhr/m^3 Extrapolate to 9K (ROP drop by 5%) 13 Watt, 6 inch (15.2 cm), rotary-only ROP: 5 cm in 2 min = 3.6 m/hr Energy: 32 Whr/m Specific Energy: 2 kwhr/m^3 Greenland: water-ice at 26K 14 Watt, 4 inch (1 cm), rotary-percussive ROP: 1 ft in 1 min = 18 m/hr Energy: 78 Whr/m Specific Energy: 1 kwhr/m^3 Extrapolate to 9K (ROP drop by 5%) 14 Watt, 4 inch (1 cm), rotary-percussive ROP: 6 inch in 1 min = 9 m/hr Energy: 156 Whr/m Specific Energy: 2 kwhr/m^3 116 days to reach 1 km depth! 46 days to reach 1 km depth! 5
Instrumented Drilling Testbed Drill Feed Stage Rotary Percussive Drill Freezer Feed-Thru Heated Probe Body (Non-Rotating) Go-Pro Camera Heated Bit (Rotating) Water Ice Sample 6
Heated Bits (6.2cm Dia) Full-face Peripheral Heating Central Heating Auger 7
Drilling Modes Comparison (24K) Drilling, Melting and Slushing (WOB controlled to 1N) Baselined with full-face bit in 24K water ice to compare power consumption. 18 AMNH Bit (Unheated Drilling), 24K Ice, 12-4-217 12 14 AMNH Bit (Slush Drill), 24K Ice, 12-4-217 12 25 AMNH Bit (Melt Probe), 24K Ice, 12-4-217 1 Depth (mm) 16 14 12 1 8 6 4 2 ROP: 2.4 mm/s Power: 82.7 W SE:.37 Whr/cc 5 1 15 2 25 3 Time (sec) 1 8 6 4 2 Speed (rpm) HBA_HOLE_DRILL_DEPTH HBA_MOTOR_VEL_AUG HBA_MOTOR_VEL_PERCUS Depth (mm) 12 1 AMNH Bit (SLUSH), 24K Ice, 12-4-217 1 8 6 4 2 Depth (mm) 14 12 1 8 6 8 ROP:.46 mm/s 6 HBA_HOLE_DRILL_DEPTH 4 HBA_MOTOR_VEL_PERCUS 6 5 2 SE:.93 Whr/cc 4 4 3 5 1 15 2 25 3 2 Time (sec) 2 1 5 1 15 2 25 3 Time (sec) Speed (rpm) Power: 465 W HBA_MOTOR_VEL_AUG 1 9 8 7 Power (W), Temp (K) HBA_HOLE_DRILL_DEPTH BIT POWER BIT TEMP PROBE POWER PROBE TEMP Depth (mm) 2 15 1 5 ROP:.5 mm/s Power: 6 W SE: 1.2 Whr/cc 5 1 15 2 25 3 35 4 Time (sec) 9 8 7 6 5 4 3 2 1 Power (W), Temp (K) Drill Depth Bit Power Bit Temp Probe Power Probe Temp Drilling Slushing Melting 8
Test Results (log scale Y-axis) Goal: Repeat test with each prototype bit and cryogenic simulants. Does not include chips transport and compaction 9
Theoretical Melting Speed* Minimum Power Required (kw) 1 1 1.1.1.1 Minimum Power Required vs. Melting Speed 6.2 cm Diameter, 1 m Long Melt Probe * Solution adapted from: 1) Aamot, H.W.C. (1967). Heat transfer and performance analysis of a thermal probe for glaciers. U.S. Army Cold Regions Research and Engineering Laboratory (IJ SA CRREL) Technical Report 194 and 2) Ulamec et al., (27), Access to glacial and subglacial environments in the Solar System by melting probe technology, Rev Environ Sci Biotechnol (27) 6:71 94. Melt Probe 24K Ice AMNH Bit Slush 12-4-17.1.1.1.1 1 1 Melting Speed (m/hr) Heated Drilling Unheated Drilling 7 K Ice Without Conductive Losses 12 K Ice Without Conductive Losses 18 K Ice Without Conductive Losses 24 K Ice Without Conductive Losses 7 K Ice With Conductive Losses 12 K Ice With Conductive Losses 18 K Ice With Conductive Losses 24 K Ice With Conductive Losses 24K Ice AMNH Bit Unheated 12-4-17 24K Ice AMNH Bit Melt Probe 12-4-17 1
Drilling in Cryogenic Simulants (77K) DRACO Bit in Water Ice at 77K 6 12 5 1 Depth [mm] 4 3 2 1 ROP: 1.89 mm/s Power: 59.6 W SE:.52 Whr/cc 8 6 4 2 Rate [RPM, BPM] Drill Depth Auger Vel Percussor Vel 5 1 15 2 25 Time [s] DRACO Bit in Ammonia Ice at 77K 6 12 5 1 LN2 bath Depth [mm] 4 3 2 1 ROP: 1.99 mm/s Power: 56.3 W SE:.47 Whr/cc 8 6 4 2 Rate [RPM, BPM] Drill Depth Auger Vel Percussor Vel 5 1 15 2 25 Time [s] DRACO Bit in Paraffin Wax at 77K 6 12 5 1 4.6 cm diameter bit Depth [mm] 4 3 2 1 ROP: 1.12 mm/s Power: 65.1 W SE:.96 Whr/cc 1 2 3 Time [s] 8 6 4 2 Rate [RPM, BPM] Drill Depth Auger Vel Percussor Vel 11
Conclusions Deep Drilling (Melting vs. Slushing vs. Unheated Drilling): Melt probe is at a disadvantage in cryogenic water ice due to enhanced thermal conductivity Energy required for unheated drilling is least but depth is limited by risk of ice melting and re-freezing around bit, causing it to get stuck For deep drilling, slushing avoids sticking and facilitates transport of cuttings away from drill bit however tether management is still a complication Surface Drilling (Cryogenic Material): Minimizing temperature rise of sample preserves volatiles and makes fines easier to transport Depending on the hardness and brittleness of the sample, rotaryonly mode may avoid cracking sample into large chunks that cannot be further reduced in size for easy transport 12
Future Work Combine drill with pneumatic transport and sample delivery subsystems for end-to-end testing of the entire sampling chain at 1K 13
Acknowledgements This work was funded by NASA s Concepts for Ocean worlds Life Detection Technology (COLDTech) program and by NASA s Small Business Innovative Research (SBIR) program. We owe our sincere thanks and appreciation to the COLDTech program director Ryan Stephan (NASA HQ) and the SBIR COTR Juergen Mueller (JPL/Caltech). 14
Questions Thank You!