ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
xii     3:15  BREAK    3:30  SESSION VI I – A POTPOURRI  OF POSTERS   Bill Purdy, Session Chair   Purdy Engineering, Poolesville, MD  

• Nickel- Titanium Alloys: Corrosion “Proof” Alloys for Space Bearing, Components and Mechanism  Applications   Christopher DellaCorte, NASA Glenn Research Center, Cleveland, OH  

• Gossamer Technology to De- Orbit LEO Non -Propulsion- Fitted Satellites   Christian Dupuy, Centre National D'Etudes Spatiales, Toulouse, France;  O. Le Couls, EADS  Astrium , Saint Médard en Jalles, France  

• Preliminary Assessment of Seals for Dust Mitigation of Mechanical Components for Lunar  Surface Systems   Irebert Delgado, NASA Glenn Research Center, Cleveland, OH; Michael Handschuh, Ohio State University, Columbus, OH  

• Development of the Tri- ATHL ETE Lunar Vehicle Prototype   Matt Heverly, Jaret Matthews, Matt Frost & Chris McQuin, Jet Propulsion Laboratory, Pasadena, CA 

• An Approach to Designing Passive Self -Leveling Landing Gear with Application to the Lunar  Lander   Troy Rippere & Gloria Wiens, University of Florida, Gainesville, FL  

• Design and Manufacture of a Highly Reliable, Miniaturized and Low- Mass Shutter Mechanism   Markus Manhart,  T. Zeh, G. Preißler  & A. Hurni, Kayser -Threde GmbH, Munich, Germany; G.  Peter, I. Walter & J. Helbert, Deutsches Zentrum für Luft - und Raumfahrt (DLR), Berlin, Germany ;  K. Multhaup & H. Hiesinger, Institut für Planetologie, Westfaelische Wilhelms -Universitaet,  Muenster, Germany  

• Miniaturized Single- Shot Valve and its Application to the ExoMars Pasteur Paylo ad  Pierre Muller, Hartmut Henkel & Sabine Klinkner, von Hoerner & Sulger GmbH, Schwetzingen, Germany  

• MoS 2-Filled PEEK Composite as a Self -Lubricating Material for Aerospace Applications   Geraldine Theiler & Thomas Gradt, BAM Federal Institute for Materials  Research & Testing,  Berlin, Germany  

• Evolution of the IBDM Structural Latch Development into a Generic Simplified Design   Kristiaan De Vriendt, Helder Dittmer & Davy Vrancken, Verhaert Space, Kruibeke, Belgium; Peter  Urmston & Oscar Gracia, ESA/ESTeC, Noor dwijk, The Netherlands  

• Development of the Upgraded DC Brush Gear Motor for Spacebus Platforms   Robert Berning III, Moog, Inc., Chatsworth, CA; Olivier Viout, Thales Alenia Space, Cannes la  Bocca Cedex, France  

6:30- 9:30 LUAU & DISPLAYS  – Hilton pool deck and display area   Invited component suppliers display current products and provide tutorials. Live music and food on the beach!
xiii   FRIDAY, 14 MAY 20 10 

7:30  Friday Presenters’ Breakfast  

8:30  SESSION VII I – INSTRUMENTS   Scott Strickland, Session Chair   The Boeing Company, Cocoa Beach, FL  

• (Poster paper) Static Load Distribution in Ball Bearings   Mario Ricci, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, São Paulo State,  Brazil  

• BESST:  A Miniature, Modular Radiometer   Robert Warden, William G ood & Erik Baldwin -Stevens, Ball Aerospace & Technologies, Boulder,  CO 

• Development of an Actuator for Ambient to Cryo Application   Karen Menzel & Hans Jürgen Jung, EADS Astrium Gm bH, Friedrichshafen, Germany; Jörg  Schmidt, PHYTRON -Elektronik GmbH, Gröbenze ll, Germany  

• Development and Acceptance Testing of the Dual Wheel Mechanism for the Tunable Filter Imager Cryogenic Instrument on the JWST    Martin Leckie & Zakir Ahmad, COM DEV, Ltd., Cambridge, Ontario, Canada    10:00  BREAK  

10:15   SESSION IX  – SMALL SESSION ON SMALL SATELLITES  Gloria Wiens, Session Chair   University of Florida, Gainesville, FL  

• Xatcobeo: Small Mechanisms for CubeSat Satellites – Antenna and Solar Array Deployment   Jose Miguel Encinas Plaza, Javier Barandiarán Mancheño, Cesar Martínez Fernández & Fany  Sarmiento Ares, Instituto Nacional de Tecnica Aeroespacial (INTA), Madrid, Spain; Jose Antonio Vilán Vilán, Fernando Aguado Agelet & Miguel López Estévez, University of Vigo, Lagoas Marcosende, Spain  

• Concept, Design, and Prototyping of XSAS: A High Power Extendable Solar Array for CubeSat Applications   Patrick Senatore, Andrew Klesh, Thomas Zurbuchen, Darren McKague & James Cutler,  University of Michigan, Ann Arbor, MI  

• Development of a Solar Array Drive Assembly for CubeSat   Mike Passaretti & Ron Hayes, Honeybee Robotics Spacecraft Mechanisms Corporation, New  York, NY 

11:45  SPECIAL PRESENTATION   NASA Kennedy Space Center Overview  

12:15  TECHNICAL SESSIONS CONCLUSION   Stu Loewenthal, General Chairman, Lockheed Martin Space Systems, Sunnyv ale, CA   • Herzl Award Presentation   • Closing Remarks  

12:30 LUNCH    1:30- 4:00 FACILITY TOUR at KSC or Shuttle launch
xiv   SYMPOSIUM ORGANIZING COMMITTEE 

Alan C. Littlefield, Host Chair NASA KSC   Robert P. Mueller, Co -Host Chair NASA KSC  

Stuart H. Loewenthal, General Chairman, Lockheed Martin   Edward A. Boesiger, Operations Chairman, Lockheed Martin  

Steven W. Baumann, NASA GRC   Carlton L. Foster, NASA MSFC   Claef F. Hakun, NASA GSFC  Christopher P. Hansen, NASA JSC   Wayne Jermstad, NASA JSC   Edward C.  Litty, JPL   Gérard Migliorero, ESA/ESTeC   Fred G. Martwick, NASA ARC   Donald H. McQueen, Jr., NASA MSFC   Wilfredo Morales, NASA GRC   Fred B. Oswald, NASA GRC   Minh Phan, NASA GSFC   Donald R. Sevilla, JPL   Mark F. Turner, NASA ARC   Robin Tutterow, NASA LaRC   James E. Wells, NASA LaRC  

SYMPOSIUM ADVISORY COMMITTEE 

Ronald E. Mancini, NASA ARC (ret)   Stewart C. Meyers, NASA GSFC (ret)   William C. Schneider, NASA JSC (ret)
1 Mars Science Laboratory Drill 

Avi B. Okon¹ 

Abstract   The Drill for the Mars Science Laboratory mission is a rotary-percussive sample acquisition device with an  emphasis on toughness and robustness to handl e the harsh environment on Mars. The unique  challenges associated with autonomous drilling from a mobile robot are addressed. A highly compressed development schedule dictated a modular design archit ecture that satisfies the functional and load  requirements while allowing independent development and testing of the Drill subassemblies. The Drill consists of four actuated mechanisms: a spindle that rotates the bit, a chuck that releases and engages bits, a novel voice-coil-based percussion mechanism that hammers the bit, and a linear translation mechanism. The Drill has three passive mechanisms: a replaceable bit assembly that acquires and collects sample, a contact sensor / stabilizer mechanism, and, lastly a flex harness service loop. This paper describes the various mechanisms that makeup t he Drill and discusses the solutions to their unique  design and development challenges. 

Introduction 

The Mars Science Laboratory (MSL), scheduled to launch in the fall of 2011, is part of a long-term effort  of robotic exploration of Mars that will assess whet her Mars ever was, or is still today, an environment  able to support microbial life. The MSL rover featur es the most advanced robotic Sample Acquisition,  Sample Processing and Handling [1] (SA/SPaH) subsystem ever sent to  another planet (see Figures 1a  and 1b). The major elements of the SA/SPaH subsystem are a Robotic Arm (RA) with a tool and instrument laden turret. The tools are: a sample acqu isition Drill, scooping, si eving and portioning device  called CHIMRA [2], and the Dust Removal Tool (DRT). The instruments are the APXS and MAHLI.         

Figure 1. (a) MSL Rover   (b) SA/SPaH Turret   The primary sample acquisition element of SA/SPaH is  the Drill (see Figure 2)  which collects powdered  samples from various rock types (from clays to massive basalts) at depths up to 50 mm below the  surface. The Drill then transfers  the powdered sample to a proces sing device, the CHIMRA, which  subsequently delivers sieved and apportioned samples to the science instruments housed in the belly of                                                                ¹ 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    CHIMRA MAHLI   APXS  Drill DRT   NASA/CP-2010-216272
2 the rover. A typical sample acquisition operation with the Drill is described as follows. The Drill is placed in  contact with the target rock by the SA/SPaH RA. A telemetry switch indicates contact has been made.  The Drill is then preloaded onto the ta rget by the RA for increased stab ility, reducing the likelihood of  shifting during the operation. The Drill acquires the sample by rotating and hammering while maintaining  a desired weight on the bit. Upon the completion of sample acquisition, t he Drill retracts from the hole to a  stow configuration and is disengaged from the rock by the RA. Lastly, through a combination of gravity  manipulations by the RA and vibration environment generated by the Drill pe rcussion mechanism, the  sample is transferred from the Drill to  the CHIMRA for further preparation.  

Figure 2. Engineering Model MSL Drill, Bit Assembly in Foreground  (some of the turret brackets are attached to the housing and a ground adapter is chucked) 

Drill System Development 

Though the primary design objective of  the Drill is the reliable acquisition of samples from rocks of various  strength and composition, many as pects of the design (especially its mass and volume) were driven not  by its primary function, but from the dreadful things that could happen while on the surface of Mars. What follows are some of the device’s more pertinent design drivers.   Live long and drill – that’s a requirement!

The Drill is designed to provide 81 samples for the science payload on MSL. To meet the strict cross  contamination requirement across the sampling system, the Drill must also provide samples for dilution  cleaning: the acquisition of a pre-sample for the sole purpose of flushing the residual of the previous sample from the entire sample path. This, in effe ct, doubles the drilling depth requirement. Since drilling  on Mars is inherently a dry process,  a rotary percussive drill was implemented after development testing  showed that it produced significantly less bit wear th an a rotary drag bit type (especially on rock with high  compressive strength). Even still, in order to show margin to the life requirement, the Drill has the ability to replace a worn bit with a fresh one during the mission.  Additionally, since sample flows solely within the  bit, the ability to jettison a clogged bi t adds another level of robustness.   Two spare bit assemblies, housed in their own bit box assemblies, are mounted to the front panel of the  rover. A clever bit exchange method, which uses thr ee active elements of the Drill (translation, rotation  NASA/CP-2010-216272
5      (a) Drill Bit Assembly (DBA) (b) Drill Chuck Mechanism (DCM)  Figure 3 a-b.  Depictions of the Drill Sub-Assemblies  (c) Drill Spindle Mechanism (DSM) (d) Drill Percussion Mechanism (DPM)  Ball Screw Mechanism with Integral Force Sens or Drill Aft Housing and Linear Bearing System  (e) Drill Translation Mechanism (DTM)  (f) Drill Contact Sensor  / Stabilizer (DCSS)  (Bottom View)  (g) Drill Service Loop – round wire harness hidden   (Top View) 

Figure 3 c-g.  Depictions of the Drill Sub-Assemblies (cont.) 

Development and Design of the Drill Mechanisms 

Drill Bit Assembly   The Drill Bit Assembly (DBA) is a passive device which is rotated and hammered in order to cut rock (i.e.  science targets) and collect the cuttings (powder) in  a sample chamber until ready for transfer to the  CHIMRA. The DBA (Figure 4a) consists of a 5/8-in  (~16-mm) commercial hammer drill bit whose shank  has been turned down and machined with deep flutes designed for aggressive cutting removal. Surrounding the shank of the bit is a thick walled maraging steel collection tube allowing the powdered  NASA/CP-2010-216272
7 between the bit and spindle shaft to permit the following functions: the transmission of the hammer blow  directly onto the bit, the mating of a fresh bit, and rele ase of the bit both in free space and under load.     Drill Chuck Mechanism

The Drill Chuck Mechanism (D CM), also residing within the Chu ck / Spindle Sub-assembly (Figure 5),  enables the Drill to release worn bits and take hold of fresh ones stored on the rover front panel. The design driver not only included the requirement to su rvive the worst-case load scenario but also to  release the bit while subjected to it. The DCM is a dirt tolerant ball lock device that consists of eight stainless steel balls that are pushed out radially by a rotary cam. The cam is actuated via a drivetrain consisting of an electrically-commutated gearmotor with  a power-off brake, a single spur gear stage and a  harmonic drive. This mechanism underwent substantia l high fidelity development testing with a prototype  12-ball chuck mechanism (DDT-8). The objectives were to:   1. Verify cam mechanism tolerance to airborne dust  particles and self-generated rock particles, and  demonstrate the effectiv eness of its seals.  2. Measure the torque requirement to release unde r the worst-case load scenario with and without  the presence of various types of rock particulate.    3. Estimate the coefficient of friction at the ba ll interfaces to more accurately evaluate the peak  contact stress.  

Figure 5. Chuck / Spindle Subassembly with Bit Assembly   (inset: EM Unit Ready for Spindle Thermal Dyno Test)    The mechanism demonstrated 4X life operation, fully l oaded, with the ball cavities filled with both fine and  coarse Martian regolith simulant with sufficient to rque margin (Figure 6a). Even corundum particles  introduced were crushed easily. However, the coefficient of friction estimated from the test results showed  that the contact stresses on the cam was above the material allowable. This was verified upon disassembly and inspection of the cam where local surface deformation was found. Additionally, there  were tracks where the Lub-Lock 4306 dry lubricant was worn away (Figure 6b). The analysis also showed  that the highest stress was on the sloped portion of the cam profile. To lower the contact stress the cam  surface curvature was reduced by decreasing the numbe r of balls from twelve to eight. However, the  analysis still showed that this was insufficient, so a conforming curvature shape was also implemented on  Spindle Actuator  Spindle Geartrain  Spindle Torque CouplingChuck Geartrain  Chuck CamChuck Actuator NASA/CP-2010-216272
9 The hammer head has three tabs that engage the retraction hardstop. The flexure body has these  features: a splice cavity where the harness is con nected to the voice coil magnetic wire, a permanent  magnet assembly which activates a bank of reed switch sensors, and three flexure suspended DU  bearing segments. An inverted DU bearing is bonded to  the end of the voice coil bobbin providing an aft  support bearing surface which rides along the inner su rface of the voice coil magnetic field outer pole  piece. The aft bearing ensures that only dedicated we ar components are in contact. DU bearings were  selected for their high wear life and low service temp erature; the latter reduces the required heater power  for the cold operation of this mechanism. Beryllium Copper was selected for the bobbin material.   Within the hammer assembly there is the main spring of the mechanism which provides two functions: (1)  it stores the work done by the voice coil on the upstroke for delivery on the downstroke and (2) it captures the rebound energy from previous impa ct for use on the next impact. The voice coil actuator simply needs  to recoup the energy lost during the impact (causing rock fracturing) and internal mechanism losses. One technical challenge discovered on the prototype percussion mechanism was spring surge of the main spring. The original springs were failing prematurely due to the proximity of th e spring’s natural frequency  with the operating frequency. This was solved by changing the spring material to one with a lower shear  modulus, lower density and high fatigue strength. The new spring allowed a large amount of stored energy while maintaining an appropriately large s eparation between the operating frequency and its  natural frequency.   Inside the main spring, the voice coil harness is routed within a unique helical cable guide assembly whose helix direction is opposite of the main spring. Inspired by a telephone handset cord, the design controls the location of the harness, provides signi ficant stroke while minimizing wire strain, and has a  very low spring rate. To avoid contact with the main sp ring, the inner diameter of the cable guide helix is  control by a split, fingered mandrel integrated into the moving hammer head and stationary side of the  cable guide assembly. The outer diameter of the main  spring is controlled by the inner surface of the  flexure housing. During assembly of the mechanism, the clearances were verified to ensure there will  always be a gap between the two components.   

Figure 7. Drill Percussion Mechanism   Another challenge were eddy currents due to the electrically conductive voice coil bobbin material moving  quickly through a magnetic field. This manifested it self as a velocity dependent loss force (i.e., viscous  damping) that had to be eliminated for efficient operation. The solution implemented was to cut axial slots in the bobbin in the area that was exposed to the magnetic field. The slots were then filled with nonHammer Assembly  Helical Cable Guide Main Spring  Anvil AssemblyDPM Housing  Voice Coil  Magnetic Field  Assembly Hammer Head NASA/CP-2010-216272
11   Figure 8. Actual versus predicted hammer position, velocity and back-emf voltage 

A misunderstanding occurred during the specification of the voice coil driver when the term “tri-state” was used to describe the desired function during the coast period. This resulted in back-emf voltage induced  current during the coast period which effectively dynamically braked the voice coil – dissipating kinetic energy (bad) in the form of joule he at (worse). By the time the probl em was discovered, the firmware on  the driver could not be changed without a major co st and schedule impact. Fortunately, a work-around  was discovered: by commanding a low voltage to retract the hammer (instead of zero), the desired effect could be achieved.    Lessons learned : (1) What can appear to be clear communication across disciplines can often be  quite nebulous. For example: one expression or word can have different meanings depending on the individual’s interpretation. Exhaustive interact ion (and often repetition – especially in high  stress situations) with diagrams and simplistic ex planations are the surest bet for success. (2)  Sometime external project constraints can yield serendipitous outcomes as was the case with the voltage-drive method.   Lastly, mounted to the DPM housing is a series of si x normally open reed switch sensors which provide  coarse hammer position telemetry. The small reed switches are robust to large dynamic environments and were easily integrated into the existing rover avionics. The switches are activated by a magnet  mounted to the hammer assembly. The activation region s of the adjacent switches overlap providing up  to 12 position states. Figure 9 shows reed switch performance across the mechanism range of motion.  These sensors provide the only direct telemetry of the hammer motion and thus are useful for operational diagnostics. These sensors are not used for feedback control. Additionally, dr illing various rock types  during the development test program has shown a correlation between max hammer motion and rock strength. If this carries over to t he flight Drill, these sensors may also provide interesting science data  about the composition of the Martian rock.  

Figure 9. Reed switch data across the DPM stroke  0123456 ‐2 02468 1 0 1 2 1 4 1 6 1 8 2 0Reed Switch  Closed Hammer Position (mm)Retact Extend NASA/CP-2010-216272
13  

Figure 10. Translation Tube with Rollers and Thermal Hardware    (inset: an aft housing ready for dimensional inspection)    

Figure 11. Ball Screw Mechanism with Integral Force Sensor    Figure 12 shows the DTM undergoing two of its qualificat ion tests. One test demonstrates margin against  the maximum axial and side loads expected during sample  acquisition. The other is a characterization of  the retraction force generation capability of the DTM; the device is shown lifting 10,012 N at -70°C.   Gimbal Assembly  Force Sensor  DTM Actuator Ball nut  The hard rollers pairs on  either side are installed  with gaps to aft housing Self-preloaded soft rollers  are in contact with aft  housing axial rib  Ball Screw NASA/CP-2010-216272
15 requirement with positive margin. Lastly, integrated onto the housings of the DCSS forward joints are four  alignment posts that enable the Drill to dock with the bit box. 

Figure 13.  (a) Drill Contact Sensor / Stabilizer Assem bly at full articulation (inset: Return Spring)  (b) Compressed DCSS Coupler w/o Cover (inset: Coupler Piston with Seals)     Conclusion 

At the time of writing this paper the Qualification Model and Flight Model Drill mechanism subassemblies are being tested across the qualification operating temperature range (-70°C to +70°C for most components, colder for the DPM, DCSS and DBA). T he Engineering Model (EM) Drill assembly has been  functionally tested at ambient conditions and integrated at the next hi gher level of assembly – onto the  Robotic Arm as part of the Turret. There it was subjected to a sub-system level test to characterize the self-generated dyna mic environment used for sample flow with in the Drill and CHIMRA. Over the next few  months, the EM Drill will be mounted to another ma nipulator to undergo abbreviated drilling and sample  transfer testing at low pressure.       Acknowledgements 

The work described in this paper was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National  Aeronautics and Space Administration.   Developing the Drill and producing it for flight is an enormous undertaking that relies on personal  dedication and sacrifice. This author has been blessed with a fantastic team of hardware engineers who  have worked tirelessly for years to reach this poin t:  Kyle Brown (Chuck, Spindle and Bit), Ian Cady  (Percussion), Matt Haberland (Contact Sensor / Stabiliz er), Kerry Klein (Translation Mechanism), Kristo  Kriechbaum (Percussion), Justin Lin (Chuck, Spindle and Bit) and Paul McGrath (Translation Mechanism). Jack Aldrich, Mark Balzer, Richard Barela, John Bousman, Kevin Burke, Louise Jandura, Mike Johnson, Brett Kennedy, David Levine, Joe Melko, Suparna Mukherjee, Matt Orzewalla, Frank Ramirez, Dave Putnam, Don Sevilla, Lori Shiraishi, Jeff Umland, Robert Uyeda, Max Von Der Heydt and  Chris Voorhees have also cont ributed to the Drill development.        Bit Box Alignment Post (4X) Debris reservoir between seals Spline features act  as verniers for fine  preload adjustment  NASA/CP-2010-216272
16 References 

1. Jandura, Louise. “Mars Scienc e Laboratory Sample Acquisition, Sample Processing and Handling:  Subsystem Design and Test Challenges.” Proceedings of the 40th Aerospace Mechanisms  Symposium , (May 2010).  2. Sunshine, Dan. “Mar s Science Laboratory CHIMRA: A Devi ce for Processing Powdered Martian  Samples.” Proceedings of the 40th Aerosp ace Mechanisms Symposium, (May 2010).  3. Myrick, Thomas, Davis, Kiel and Wilson, Jack “Rock Abrasion Tool.” Proceedings of the 37th  Aerospace Mechanisms Symposium , (May 2004). 

   NASA/CP-2010-216272