DRILLING%20AND%20EXCAVATING%20TECHNOLOGIES%20FOR%20THE%20MOON

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DRILLING AND EXCAVATING TECHNOLOGIES FOR THE MOON
Rutgers Symposium on Lunar Settlements 3-8 June
2007 Rutgers University

• Kris Zacny
• Honeybee Robotics, NY

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Drills.
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Drill Design Background Principles

• Auger
• Efficiency and throughput are functions of
• Pitch angle
• Number of flutes
• Flute width
• Auger diameter
• Coating/surface friction of auger
• Cutting Bit
• For rock destruction, efficiency depends on
• Number and placement of cutters
• Bit material
• Inner and Outer diameters of cutting kerf
• For proper cuttings removal, bit geometry must
• Sweep chips to the outside
• Include junk slots to facilitate cutting flow
• Tooth
• Design parameters

Drilling Efficiency Specific energy (SE) is a
property of a given drilling process that
quantifies efficiency where Power is
drilling power, ROP is Rate Of Penetration and
Area is the area of the coring kerf. Greater
efficiency (lower SE) implies that less energy is
wasted as heat, resulting in lower core
temperature rise. Efficient drilling also tends
to correlate with better penetration and bit life
performance.
Auger
Cutting Bit
Tooth
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Drill Design Background Principles

• Weight On Bit (WOB)
• Determines stress exerted on the rock
• Must be sufficient to overcome the compressive
  strength of the rock for efficient cutting
• WOB threshold UCS Area cutter
• Since the cutter area increases with wear, bit
  life is directly proportional to available WOB

• Low Temperature Drilling
• Concerns
• Material embrittlement (especially brazes)
• CTE mismatches
• Increase in compressive strength of target rocks
• (10-20 stronger at -100C than at room
  temperature

• RPM
• Is directly proportional to
• Drilling power
• Core temperature rise
• Auger throughput
• Is inversely proportional to
• Auger torque (chip removal torque)
• Cutting bit torque (to some extent)
• Also affects
• Cutting bit efficiency
• Bottom hole cleaning
• Cutting bit chatter (if RPM is too low)
• Bit vibration (if a harmonic of RPM is at a
  resonant frequency)

• Dry Drilling
• Concerns
• Auger required for cuttings removal
• Less efficient drilling (regrinding)
• Higher bit wear
• Reduced penetration rate
• Higher core temperature rise

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History of Lunar Drills

• Apollo Lunar Surface Drill (1971, 1972)
• 500 Watt, Battery Powered and Human Operated
• 2 m A15, 3.5 m A16, 3.5 m A17 depth
• A15 The drill stem was hard to remove from the
  hole. It was left in while the other tasks were
  completed. At the end of the second EVA it took
  both astronauts working at the limit of their
  combined strengths to pull up the drill stem. It
  was physically exhausting. Its removal took an
  extra 15 minutes of EVA time and cause a severe
  shoulder sprain in Scott.
• 3rd Law of Robotics A robot must protect its own
  existence..

http//www.hq.nasa.gov/alsj/tools/judy20.jpg

• Luna (16, 20, 24)
• Autonomous Drill (1st was Luna 16 1970)
• 5727 kg Platforms
• Depths of 35 cm, 25cm, 2 meters
• Luna 24 1976

http//www.zarya.info/Diaries/Luna/Luna16.htm
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Apollo 17 drill extraction

• Improvement in A15 drill included a jack for
  drill extractionsbut it didn't make the job
  effortless
• Apollo 17 diary
• Jack .literally falls forward on the handle with
  his left hand.
• Schmitt - "I was trying to get all of my weight
  on the handle, just to get it to move. "
• Jack pushes so hard on the handle that his toes
  come up about a foot off the ground.
• Schmitt - "I was putting every bit of weight and
  momentum into it that I could.
• Jack is now effectively doing pushups on the
  handle.Jack's heart rate peaks at about 135
  beats per minute.Gene's heart rate has been
  running over 130 beats, with excursions to 145.

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Movies

• Apollo 16 and 17

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Need testing in simulants and environment

• Practical Problems
• Compacted lunar regolith simulant has low
  permeability trapped gas as vacuum is created
  escapes and carries the particles with.
• Particles have adsorbed moisture which turns into
  vapor (sublimation) when pressure drops below 5
  torr
• Need capabilities for sample preparation inside
  vacuum chamber very difficult and expensive

Exterior Thermocouple
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Movie

• Sublimation during drilling
• Outgassing
• Outgassing and sublimation

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Drilling in vacuum
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Drilling Test Results in Lunar Simulant
Total Power Drilling Cuttings
Removal Drill Bit Auger
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Auger Power
Auger Power f (RPM, Auger design)
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Can We Re-use the simulant?

• Drilling reduces size of soil grains
• Drilling a used soil is at least 50 more
  difficult in terms of Specific Energy

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Automated Drills
Note images not to scale
RATRock Abrasion Tool
TGSS Touch Go Surface Sampler
Mini-Corer
GSFCMole
Sniffer Sampling and Gas Analyzer System
SATM Sample Acquisition Transfer Mechanism
DeepDrill
Inchworm DeepSubsurface Platform
TelescopingDrill
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10-meter class drills
Autonomous Assembly, Core Capture, Core
Transfer
Autonomous Drilling smart drill
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CRUX 10-m Drill

• Drilling Methods
• Rotary,
• Percussive,
• Rot.-Perc. (Apollo)
• Downhole Instruments
• LANL Neutron Probe (R. Elphic)
• Thermal Conductivity and Diffusivity
• Electric Properties
• Thermal Analyzer
• Down Hole Camera
• Drill Bits/Augers

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The Arctic Planetary Analog
History Challenges Automation Hardware
Software Down-hole Sensing Conclusion
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3.2m - Devon Island Record and a real hands off
test
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Lunar Excavators
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Conventional Excavators Bucket Wheel/Ladder
Demonstration Unit for ISRU
CSM/NORCAT
Johnson van Susante, SRR VIII
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Conventional Excavators
Lunar Excavation Demo
Lunar Polar Resource Extractor
Lunar Miner Hauler
Eagle Engineering Report 175, July 7, 1988.
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Pneumatic Excavator Jet Lift Method
1. Jet-Lift Dredging Uses the Venturi effect of
a concentrated high-speed stream of water to pull
the nearby water, together with bed material,
into a pipe.
2. Sublimation and Air blasts experiments Small
gas volumes found to lift sand/dust at Mars
pressures.
Pat. 4322897
3. Combine 1 and 2 for Lunar Mining Modify
jet-lift method to mine lunar regolith
4. Benefits Simple design, no moving parts,
robust, uses gas instead of electricity
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Movies

• Mining sand
• Mining lunar simulant

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Pneumatic Excavator

• NOFB Monopropellant
• High energy density 1400 kWh/kg
• Use spacecraft propellant reserves and bring
  additional supplies
• Used for power conversion and to generate gas
• Used as a hot gas generator

Details of Power Conversion
FireStar Engineering
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Experimental Details
Plunge mining
Transverse mining

• Tests details
• Pressure 1 torr or higher
• Material Sand and Lunar Simulant
• Investigated
• Nozzle Types
• Transverse and Plunge Mining
• Particle Segregation (sieving)
• deltaP, Flow Rates, Flow time
• Particle Velocities

Particle Segregation
Nozzle Types
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Preliminary results

• Initial results suggest that it is possible to
  mine 3000 kg of regolith with 1 kg of gas.
• At the oxygen extraction efficiency of 3
  (hydrogen reduction), this represents 90 kg of
  Oxygen.
• The ISRU goal is 10 000 kg of O2 per annum gt100
  kg of monopropellant
• The results will improve in a lower lunar gravity
  and vacuum, and with possible gas recycling
• Oxygen extraction efficiency may improve with a
  better particle segregation during mining (mine
  mostly smaller fraction)

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Multiple uses of pneumatic system
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Final Thoughts

• Human assisted drilling and excavation is not
  easy
• Robotic drilling and excavation will be even more
  difficult
• Extensive testing on earth will minimize risks,
  however, it will not eliminate them because
  testing under certain conditions is impossible or
  not practical
• Earthly drilling and excavation technologies
  might not be the best for the lunar environment.
  Need to develop new methods.