Monday, September 24, 2018

The Mars Drilling Project

I was absolutely mesmerized by the discussion between Jim Gavin and Chris McKay on Planetary Radio's August 1st, 2018 episode. The discussion revolves around the discovery of liquid water 1.5km below the South Polar Ice Cap on Mars, in the Planum Australe region. You can listen to the episode here.

I have decided to take a stab at developing a drilling technique to reach the 1.5km depth on Mars. I plan to develop prototypes at home so I can continue to learn more about this engineering challenge. I think the best approach is to first build a full scale Curiosity/Mars 2020 rover (scaled-up Sawppy rover?) to use as a test bed, and take ideas from various portable drill rigs to design a rig that can be used to robotically drill on Mars.

Disclaimer: Please note that I am not representing my employer or college. For now this is a personal project.

PURPOSE

To investigate the feasibility and challenges posed by taking liquid water samples from 1500m under the Mars South Polar Ice Cap. 

REQUIREMENTS
  • Drill to a depth of 1500m
  • Reasonable diameter bore hole to meet science objectives (which have not been identified), 50mm to 150mm estimated
  • Bore portal stabilization
    • Apron / casing at portal to stabilize for possibly years of inserting / removing drilling/servicing equipment
  • Ice core sample retrieval and transfer to science instruments (which have not been identified)
  • Water sample retrieval and transfer to science instruments (which have not been identified)
  • Sample caching for future ice core retrieval and return to Earth on a follow up mission, ala Mars 2020

POTENTIAL STRATEGIES
  • On-site fabrication and repair options using 3d printed stainless steel, robotic arms and actuators, and 3D printing of useful non-mechanical items using local substrate
  • Remote sensing - conventional mast may not be the best approach
  • Small "service" rover to support the main rover
  • Small bore-bots that can drive up and down the bore to inspect the bore, remove broken cutters, drill through stones or cobbles that would destroy a cutter, remove chips and shavings, etc. 

KEY CONCEPTS

The concept of robotically fabricating repair parts and tools on site should be core to the concept of this mission. We should plan for these failures and make as many drilling system components as easy as possible to fabricate, disassemble, and assemble to give ourselves the best chance of recovery from a technical or mechanical challenge during drilling or sample retrieval operations.

Casing requirements need to be immediately investigated and discussed as the scope of the drilling hardware can't truly be defined without understanding the bore requirements. We need to understand if the bore will be self supporting and stable, if it will have a consistent enough straightness, and if the bore "quality" will be sufficient to get to these depths without casing.

Another very important concept to consider is that the the orbiter teams will be reviewing existing radar data and scheduling instrument time to find other subsurface bodies of water. The final landing site may not be Planum Australe, and therefore we can't rule out drilling through frozen soil. A robust design that can accommodate both ice and permafrost drilling should be assumed until other landing sites can be ruled out. A future scope statement will need to address this.

Atmospheric pressure on Mars, even at a depth of 1.5km in the south pole region (which is still 1.5km above the mean elevation), is below the triple point for pure water. This means when drilling
into pure water ice there is zero risk of generating liquid that can re-freeze; only vaporized water will result, but of course the vapor can still deposit on drilling equipment. That said, the liquid water at a depth of 1.5km is expected to be completely saturated with salts. For this reason it is very important to know the chemistry of the ice we will be drilling so we can adjust feed rates to prevent the accumulation of liquid water around the drilling equipment in the bore hole. Periodic sampling of the evacuated drillings will be necessary to determine the appropriate feedrate and drilling speed. Core analysis can be done more thoroughly and separately in an onboard laboratory, but a method for quickly categorizing the chemistry of shavings will be very important to keep from freezing a drill head in place. There is an option to keep this simple by exposing samples to heat and observing the results with an optical instrument. Everything in this paragraph cannot be replicated on earth without operating in a vacuum cold chamber, so "practice" feeds and speeds will need to be substantially lower than may be possible on Mars, but we may want to stay away from these Mars maximum speeds for power requirement reasons. 

NEXT STEPS
  • Build a full scale functional but "approximate" Curiosity rover
  • While rover fab is being accomplished, continue to narrow down drill rig requirements
  • Define the scope of the drilling requirements
  • Aggregate known data about Planum Australe and the polar ice. We need detailed information about any soil that may be present in the ice.
    • Note: this ice deposit is referred to as the South Pole Layered Deposit (SPLD).

Update 2/15/19: Follow up study about factors keeping the deep water liquid (proposes volcanic activity):

Please feel free to comment here. An open and vibrant discussion will be key to doing this project properly.

Sunday, September 23, 2018

Mars Drilling Project Links and Resources

Original ESA liquid water discovery announcement: 
Follow up study about factors keeping the deep water liquid (proposes volcanic activity):

Planum Australe information:

Future Orbital Research Activities:
  • Use SHARAD instrument on MRO to further investigate Planum Australe and look for areas where water may be closer to the surface.
  • Review MOLA Laser Altimiter data set to find flat locations which may indicate floating ice sheets and identify areas for radar investigation by MARSIS (Mars Express, deeper ranging) and SHARAD (MRO, shallow ranging but higher resolution).

Drilling on Mars:

Ice Drilling:
  • https://icedrill.org/
  • New technique for access-borehole drilling in shelf glaciers using lightweight drills, V. Zagorodnov, et al. Journal of Glaciology, 60/223/2014 pg. 935.
  • Drilling in the Permafrost, Kudyashov, B.B., CRC Press, 1991
    • I have listed the Kudyashov book in both the Ice Drilling and Permafrost sections because he does discuss ice drilling and glacial drilling. Although not discussed to the extent that permafrost is, he does provide quite a bit of information about others' research on the subject. I plan to collect those sources that he references and post them here as well.

Permafrost, Resources and Contacts:

Drill Rigs:

Rover Testbed Info:

Saturday, September 15, 2018

Quinn Morley Resume

Custom Design, Fabrication, Tooling, and Prototyping

webinquiries@quinnmorley.com

- Extensive design experience including modeling, sketching, drafting, and lofting
- Hands on forming experience: brakeform, rollform, hydroform, etc.
- Reverse engineering of complex surfaces using CMMs, laser trackers and optical scanners
- Extensive personal and professional 3D printing experience
- Classroom instruction experience in topics like compound angles and flat pattern development
- Associate of Technical Arts, Welding Technology; Honors Graduate, Dean's List
- Associate of Arts and Science, Specializing in Mathematics

EXPERIENCE

2008 - Present: Aerospace Fabrication, Puget Sound, WA
- Journey-level fabricator
- Formming, trimming, and assembling parts and components from drawings and datasets including parts mating to lofted surfaces with compound contour, and experimental / emergent parts.
- Frequent use of CATIA, including to help other employees: plotting contour lines and 1:1 contour sketches of lofted surfaces on high accuracy plotters; extracting datum dimensions and trim profiles; flat pattern development; and shop aid tooling development.
- Never hesitant to assist other employees in development of their modeling, math, and layout skills whenever possible.
- Design and fabrication of complex shop aid tooling, including 3D Printed shop aids.
- Layout practices using 5 axis CMM, Romer and Faro arms, laser trackers; as well as manual layout techniques using compound sine plates, height gauges, mouse scribes, etc.
- Machining of production parts and shop aids on CNC 3 and 5 axis milling machines
- Repair, rework and assembly of major components
- Plating and processing: setup, striking, stripping, plating and inspection of plated parts.
- Hand layup, tool prep, bagging and machining of Carbon Fiber composite components.
- Experience working with people from different backgrounds on different shifts, with a focus on cultivating personal relationships.

EDUCATION

Currently studying for Associate of Science, Engineering
- Use Engineering problem solving techniques to model scenarios and perform analysis with hand calculations, and with the aid of computer algebra systems such as MATLAB and Wolfram Mathematica.

Associate of Arts and Sciences, specializing in Mathematics
- Advanced Mathematics including: Algebra; Trigonometry; Differential, Integral, Vector and Multivariable Calculus; Linear Algebra, Discrete Mathematics, and Differential Equations; Basic Physics and Chemistry. Technical Writing, English Composition, Advanced Computing, Hand Drafting, Computer Aided Design, Technical Analysis Reports.

Associate of Technical Arts, Welding Technology
- Honor Graduate, Dean's List
- Precision layout and metal cutting, creating and interpreting Engineering Drawings, experience performing and inspecting welding operations on ferrous and non-ferrous metals (including Aluminum and Titanium). Familiar with metallurgy of welds, heat treatment and stress relief procedures of steel, aluminum and titanium alloys, micrograph inspection and non destructive testing.  Experience with setting machine parameters and proper equipment setup. Communications and Human Relations training with a focus on building successful professional relationships.

Attended trade-related supplemental instructional classes after work, focusing on:
- Mathematics, including trigonometry, shop problems and compound angles
- Metallurgy, properties of materials and heat treat
- Shop safety and machine shop practices
- Precision measuring
- Geometric Dimensioning and Tolerancing (GD&T)
- Composite Materials and Technology

Note: This is a generic resume with minimal identifying information. Please contact me at the email address above if you have any questions or would like a complete resume.

Saturday, September 1, 2018

Prusa Mk3 Hot Extruder Fix

This is a gcode only fix for the hot extruder motor problem afflicting the Prusa i3 MK2 and MK3 (and both s models). The extruder current setting is obviously ridiculously high. My machine has over 13,000 hours on it, and I saw no reason to suddenly up the current so high on a proven setup. Published on 7/29/19, date of post adjusted for archival purposes.

Just thinking about how bad the web forums have gotten with 3D Printing related advice fatigues my mind, so I won't be posting this there. 

Set current on Mk3/s in the custom gcode section of PrusaSlicer:

M912 E28   M910-M918 have been disabled, ref issue #1277
M907 E475

Set current on Mk2/s in the custom gcode section of PrusaSlicer:

M907 E475

Note: E475 is half-way between old firmware values and new firmware values. Tune as required


Below is some additional information about the change, when and where it was made, and there are plenty of reference links at the end of the post.


Firmware v 3.7.2 current setting, variants/1_75mm_MK3-EINSy10a-E3Dv6full.h   (Mk3s identical).

260 #define TMC2130_CURRENTS_H {16, 20, 35, 30}  // default holding currents for all axes
261 #define TMC2130_CURRENTS_R {16, 20, 35, 30}  // default running currents for all axes
262 #define TMC2130_UNLOAD_CURRENT_R 12 // lowe current for M600 to protect filament sensor 

Commit for this change:




Firmware v 3.7.2 current setting, variants/1_75mm_MK25S-RAMBo13a-E3Dv6full.h

(Same lines for all MK2, note which board you have).

274 // Motor Current setting for BIG RAMBo

#define DIGIPOT_MOTOR_CURRENT {135,135,135,135,135} // Values 0-255 (RAMBO 135 = ~0.75A, 185 = ~1A)
#define DIGIPOT_MOTOR_CURRENT_LOUD {135,135,135,135,135}

278 // Motor Current settings for RAMBo mini PWM value = MotorCurrentSetting * 255 / range

#if MOTHERBOARD == BOARD_RAMBO_MINI_1_0 || MOTHERBOARD == BOARD_RAMBO_MINI_1_3
#define MOTOR_CURRENT_PWM_RANGE 2000
#define DEFAULT_PWM_MOTOR_CURRENT  {270, 830, 450} // {XY,Z,E}
#define DEFAULT_PWM_MOTOR_CURRENT_LOUD  {540, 830, 500} // {XY,Z,E}
#define Z_SILENT 0
#define Z_HIGH_POWER 200
#endif

Reference:


https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/tmc2130-driver-infos-and-modifications/

https://github.com/prusa3d/Prusa-Firmware/commit/964d019dd18d269203b9124f6f07c21ce78428c6#diff-d1d79099d6fb1bd5281c9ea0deb5060c
https://github.com/prusa3d/Prusa-Firmware/issues/58#issuecomment-286121531
https://github.com/prusa3d/Prusa-Firmware/issues/1277
https://github.com/prusa3d/Prusa-Firmware/issues/765
https://github.com/prusa3d/Prusa-Firmware/issues/769