ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
260 particle retention. All of CHIMRA’s sample transfer surfaces are an annealed titanium alloy and hand  polished (using a fine grit) to have  a smooth surface finish. Both the 150-micron and 1- millimeter screens  were 0.05-mm thick and fabricated through a photo-ch emical etching process that was compatible with  titanium. This temperature compatibility removed a CTE mismatch between the screen and the titanium  sieve frame that would result in varying screen t autness across temperature. Sinusoidal vibration was  shown to be extremely efficient at motivating particles through chambers similar to CHIMRA as long as the vibration levels were above a floor of 1 G. For t he purpose of sorting sample at 150-micron size, it  was found that vibration levels of 6 G’s or larger in  any singular direction motivated sample through the  sieve at acceptable rates, however it is important to  note that there is an expone ntial relationship between  the sieve throughput by mass and the vibration environment applied. Additionally, having levels around 6G’s or greater in two directions motivates sample through a screen substantially better than vibration in only one direction.                              Figure 15. Development Test Unit Drag                                   Figure 16. Flight VM Drag    In addition to the specific design points discussed above, global statements fr om lessons learned during  the development testing planning and execution can be made. It is extremely important to conduct all tests where particle interactions between particles or surfaces are being studied in a relevant environment. An important detail to track is the moistu re content in the sample and the gas being used to  purge the test environment; in fact, because atmo spheric moisture can have a drastic effect on the  results, test chamber humidity should always be specifically measured and controlled, and sample should be baked out for 24 hours prior to test. A hole in the CHIMRA development test suite that became apparent late in the design was that consecutive ru ns of alternating relevant samples had never been  performed. In fact, these types of tests performed by another instrument on MSL suggest this condition generates the worst electrostatic charge. To allow electr ostatic charge to be realistically developed, it is  important that all test articles have a similar ground path as the flight unit or be electrostatically isolated to  simulate a worst case charge buildup. A final recommendation for similar test programs is to be mindful of how clever a designer gets in attempting to extrapolate results to form conclusions not explicitly tested  for. At the time of CHIMRA’s design, particle behav ior and interactions within a device such as CHIMRA  are far from being fully understood and therefore t he best way to guarantee a successful design is to  explicitly perform tests that mimic the fli ght application as closely as possible.       NASA/CP-2010-216272
261  

Figure 17. CHIMRA Installed on EM Turret     Conclusions 

At the time of writing this paper the qualification and flight CHIMRA mechanisms are being assembled.  The engineering model CHIMRA has been functionally te sted at ambient conditions and integrated at the  next higher level of assembly onto the Robotic Arm as pa rt of the Turret (Figure 17). At this integration  level, the dynamics of the CHIMRA when driven by th e vibration mechanism were recorded in all relevant  robotic arm positions. This test data will be leveraged when the engineering model turret is installed in a  pressure chamber on a non-flight robotic arm. In this chamber, the end-to-end sample processing  capability of CHIMRA will be te sted and verified. It is during this test that the true robustness of CHIMRA  as a sampling platform will be measured.   

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.   The design, fabrication and assembly of the CHI MRA subsystem would not have been possible without  the tremendous amount of dedication, hard work a nd sacrifice made over a two year period by the  CHIMRA team: Andrew Bingham, Dave Berdahl, Cambria Hanson, Joel Johnson, Robert Kovac, Kurt Knutson, Matt Orzewalla and James Wincentsen. A hear tfelt thanks goes to those who acted as mentors  to myself and my team, providing their own time to ensure the success of CHI MRA: Mark Balzer, Kevin  Burke, Randy Foehner, Louise Jandura, Joe Melko,  Dave Putnam, Lori Shiraishi, Jeff Umland and Chris  Voorhees.   References   1. Okon, Avi. “Mars Science Laboratory Drill.” Proceedings of the 40 th Aerospace Mechanisms  Symposium , (May 2010).  2. Jandura, Louise. “Mars Sci ence Laboratory Sample Acquisition,  Sample Processing and Handling:  Subsystem Design and Test Challenges.” Proceedings of the 40th Aerospace Mechanisms  Symposium , (May 2010).  3.   Czichos, H. 1978. Tribology: A systems approach to the science and technology of friction, lubrication  and wear . Amsterdam: Elsevier Scientific Publishing.  

   NASA/CP-2010-216272
263 Performance of Regolith Feed Systems for Analog Field Tests of In-Situ Resource  Utilization Oxygen Production Plan ts in Mauna Kea, Hawaii 

Ivan I. Townsend*, Robert P. Mueller**, James G. Mantov ani**, Kris A. Zacny*** and Jack Craft*** 

Abstract 

This paper focuses on practical aspects of mec hanical auger and pneumatic regolith conveying system  feeding In-Situ Resource Utilization Oxygen producti on plants. The subsystems of these feedstock  delivery systems include an enclosed auger device, pneumatic venturi educ ator, jet-lift regolith transfer,  innovative electro-cyclone gas-particl e separation/filtration systems, an d compressors capable of dealing  with hot hydrogen and/or methane gas re-circulating in the system. Lessons learned from terrestrial  laboratory, reduced gravity and field testing on Mauna Kea Volcan o in Hawaii during NASA lunar analog  field tests will be discussed and practical design tips will be presented. 

Introduction   In-Situ Resource Utilization (ISRU) means using local resour ces on extra-terrestria l bodies to support  human and robotic operations on the surface (Coo ke 2006, Caruso 2007, Sanders 2008). One method of  ISRU is the production of water from the metallic  oxides in the lunar regolith by the use of, for example, a carbothermal reaction or a hydrogen reduction process. Electrolysis of the water yields oxygen which can then be used for life support, consumables, and propulsion propellant. Large mass savings are possible in lunar architectures that use ISRU since a large fraction of required oxygen won’t have to be transported from the Earth to the moon. In order to make ISRU oxygen production a reality, critical subsystems have to be developed and tested much sooner then non-critical parts. One of th e critical systems is a  regolith feed system, whose task is to deliver highly abrasive lunar soil feedstock directly into the reactor. The system has to be highly reliable, dust-tolerant, and lightweight and must also be able to dispose of the spent regolith after the reaction process.   This paper will present le ssons learned from the  design, fabrication and field testing of both auger and pneumatic types of regolith feed systems for hydrogen reduction and carbothermal oxygen production plants that were operated on Mauna Kea Volcano in Hawaii during NASA lunar analog  field tests. The volcanic ash called Tephra, which                                                    * ASRC Aerospace, Kennedy Space Center, FL  ** NASA Kennedy Space Center, FL  *** Honeybee Robotics Spacecraft Mechanisms Corporation, New York, NY 

Proceedings of the 40th Aerospace Mechanisms Symposium, NASA Kennedy Space Center, May 12-14, 2010  Figure 1.  Depiction of the Pneumatic Regolith  Feed System for a Carbothermal O 2 Reactor. NASA/CP-2010-216272
265 The hot regolith that was ejected from the reactor had to heat the cold regolith in the input hopper prior to  introducing it into the reactor for the next batch of oxygen extraction. 

Figure 2: A small excavation rover known as CRATOS is poised to climb up the ramp to deliver  about 20 kg of tephra to the input hopper of the ROxygen I demonstration plant The ROxygen I  oxygen production plant was field tested in Nov 2008 on the Mauna Kea Volcano in Hawaii, and used an enclosed, inclined auger as the regolit h feed system in a parallel configuration.  

Regolith valves for hot regolith are highly specialized and few vendors are capable or willing to tackle this challenge. Gemco Valve Inc. was the only vendor that  was willing to design and manufacture the regolith  handling valve for the ISRU ROxygen I project (see Fig. 3). Lead times for regolith tolerant valves with  metal seals were a challenging aspect of this design. Valves that are designed for terrestrial regolith or  abrasive materials handling are not normally designed to operate in a vacuum or to provide a reliable  pressure seal. This application called for 20 psi (138 kPa) on one side and near perfect vacuum on the other. Valves that handle regolith tran sfer application do not typically have an acceptable leak rate. Since  hydrogen gas is being used in the reactor, the risk consequence of a leak of hydrogen in an oxygen test environment in Earth’s atmosphere wo uld be very high. On the moon, a leak would result in the loss of  valuable hydrogen gas. Some aerospace applications require regolith handling valves to be light weight and small diameter. However, regolith handling valves are not typically designed for applications requiring less than 3-inch (7.6-cm) diameter and can be bulky  and heavy. Regolith handling valves that operate at  temperatures above 800 degrees Celsius are not readily available when required to operate with a vacuum on one side and pressure on the other. Commer cially available valve actuators are bulky and not  aesthetically pleasing. Metallic seals have difficulty sealing, so an interference fit must be designed which  can cause high actuation torque values. Moreover, when the valve gets hot, the metals expand causing  an even higher operating torque due to an increas ed interference fit. The sharp regolith particles  contribute further to a degradation of the sealing surfaces.    NASA/CP-2010-216272
266  

Figure 3: Spherical Disc Valve from Gemco, In c. having a 5-cm diameter and metal seats. 

Figure 4: Hot Tephra (~1000 C) flowing out of Gemco, Inc valve attached to the   bottom of the ROxygen I Reactor. 

Results and Lessons Learned from the Nov 2008 field test   NASA held an ISRU field test in November 2008 on Mauna Kea, Hawaii  at a location called “Wahine”  Valley. The valley had the advantage that fine grained Te phra had been washed into the valley basin over  time, and there is sparse vegetation with a low orga nic content to the Tephra. In addition, transportation  required good packaging of all hardware, similar to  the requirements of space transportation and the  environment was extremely dusty which served to provide additional operational challenges.   The ROxygen I hardware was assembled and checked out on site. The testing showed that 10 kg of Tephra could be reliably transferred into the reactor in  470 seconds. Eventually it was determined that 8  kg was the optimal reaction mass and this mass of Tephra was transferred in 408 seconds with smooth  NASA/CP-2010-216272
268   Figure 5: Flight experiment in May 2008 to test the flow of regolith simulant inside a hopper under  reduced gravity conditions.  

Results for NU-LHT-2M Lunar Simulant Test ing at 1/6-g using the Hammer Technique  Testing showed that quicker taps with a hammer at approximately 1” amplitude and approximately 4 strikes per second enhanced flow better than slow hard strikes. This hammering technique took 15  parabolas to empty the B-Side hopper for a total time of 300 seconds at 1/6-g.   Results for NU-LHT-2M Lunar Simulant Testing at  1/6-g Using the Front-To-Back Shake Technique  Front to back vigorous shaking worked better than hammering. This shaking technique took 8 parabolas to empty the A-Side for a total time of 160 seconds.    Results for NU-LHT-2M Lunar Simulant Test ing at 1/6-g Using the Bounce Technique  Bouncing the entire assembly off the floor of the aircraft worked better than both hammering and shaking with an amplitude of approximately 2” and frequency of approximately 3 bounces per second.  A-Side took approximately 97 seconds on average to empty its contents. B-Side took approximately  69 seconds to empty its contents. Testing clearly showed that the bouncing technique was the best  flow enhancing technique for this simulant.   Results for JSC-1A Lunar Simulant at 1/6-g  Both Side A and Side B did not flow without employing flow enhancement techniques.   Results for OB-1 Lunar Simulant at 1/6-g Using the Hammer Technique  Side A would flow until the hopper was empty using the Hammer technique in approximately 245 seconds. Side B would flow until the hopper  was empty in approximately 133 seconds.   Results for OB-1 Lunar Simulant at 1/6- g Using the Side-To-Side Shake Technique  Side A would flow until the hopper was empty using the side-to-side shake technique in approximately  102 seconds. Side B would flow until the hopper was empty using the Side-To-Side technique in approximately 96 seconds on average. This simulant showed that it would not flow without using flow enhancement techniques and that the Side-To-Side S hake technique allowed the simulant to flow  more consistently and faster than the Hammer technique.  NASA/CP-2010-216272
270 only maintenance-free alternative fo r separating pneumatically  conveyed lunar regolith particles from the  convey gas. Crosby and Agui (Crosby 2008) recently studied the cyclonic f iltration of a dilute flow of lunar  regolith simulant particles (JSC-1AF) in reduced gr avity as a possible means of filtering air inside a  habitat. Our study differs from this previous work by  focusing on the pneumatic transport of a very dense  flow of lunar regolith simulant, and the use of a series array of cyclones to separate the dense dusty gas  flow.  

Results and Lessons Learned   The objective of the Carbothermal Re golith Feed System was to transfer 5 kg of Hawaiian Tephra from a  hopper capable of accepting regolith from an excavator and deposit the regolith into a receiving bin  similar in size and height to the Carbothermal Reduct ion System regolith receiving bin that was tested  during the integrated Carbotherma l Reduction System Field Test in Hawaii 2010. The Carbothermal  Regolith Feed System was designed to lift regolith approximately 2 meters and weigh approximately 52  kg without regolith. A composite hopper was used wi th a non-sealing lid. The pneumatic feed system for  the Carbothermal field test on Mauna Kea in Feb 2010 met all of the requirements and achieved a  cyclone particle separation efficiency of 99.7%. The pneumatic feed system delivers approximately 0.63  kg of Hawaiian Tephra per minute. Regolith delivery is  fairly linear taking approximately 8 minutes to  deliver 5 kg to the receiving bin. 

Figure 6: Results from a December 2009 test showing the measured Tephra mass transferred by  the Carbothermal Regolith Feed System as a function of time. 

NASA/CP-2010-216272
271   Figure 7: The Pneumatic Feed System “Proof of Concept” Demonstrator for the Carbothermal O2  Reactor which was developed by NASA KSC a nd Honeybee Robotics, and demonstrated on  Mauna Kea in February 2010. 

In the 1-g environment of earth, pneumatic convey ing utilizes a small amount  of compressed gas to  transport a large quantity of granular material. A carefully designed cyclone s eparator can mechanically  separate the mixture of gas and granular material in a highly efficient manner, including micron-sized  particles. When the solid particulates in the dusty gas  flow collide with each other and with container  walls, they can become charged triboelectrically. Th is effect can be utilized to enhance the particle  removal efficiency by applying an electric field to the dusty gas flow inside the cyclone to guide the charged particles towards the wall of the cyclone wh ere they slow down and agglomerate, which makes it  easier to collect the particles at the solids outlet port located at the bottom of the cyclone (Dietz 1982). This type of cyclone is called an electrocyclone.  A reduced gravity experiment was performed by JS C researchers in 1992 involving the pneumatic  transport of 150-micron-diameter glass beads using a venturi eductor to feed the glass beads into an air  flow. They found that choking velocity measurements for vertical particle flow against gravity was  noticeably lower at 1/6-g as  compared to 1-g (Sullivan 1992, 1994). A lower choking velocity may result in  less internal pipe erosion caused by abrasive lunar dust if the dust can be conveyed at a lower velocity. However, the disadvantage with lowering the gas flow rate is that since cyclone separators are designed to operate at a specific input flow rate, a lower flow rate can reduce the gas-solids separation efficiency. Another aspect of our study was to investigate the use of an electroc yclone as a means of maintaining a  level of high efficiency for particle removal even if the dusty gas flow velocity is lowered. A high particle  NASA/CP-2010-216272
272 removal efficiency at the receiving end of the pneumatic transfer process is necessary in order to be able  to recycle the convey gas for repeated use.     Figure 8: The exhaust from the cyclone separator in the foreground in the right figure was the  input for an electro-cyclone (left figure) positi oned behind it during the reduced gravity flight  pneumatic regolith transfer experiment conducted in August 2009. Reduced gravity flight  experiment in Aug 2009, and cyclone separator s for gas-solids filtration, including electrocyclone.   The three main objectives of the terrestrial and redu ced gravity flight (RGF) experiments were (1) to  demonstrate the feasibility of pneumatically transfer ring lunar regolith as a de nse, dusty gas to an ISRU  reactor, (2) to measure our system’s typical mass transf er rate for a given lunar regolith simulant that is  conveyed pneumatically against gravity as a dusty gas to a fixed vertical height under local gravity  conditions (1-g and 1/6-g), and (3) to determine the effi ciency of our series cycl one filtration system in  removing particles from the exhaust gas flow, includi ng the potential use of an electrocyclone to enhance  particle removal efficiency.     The configuration of the experiment is depicted below in  Figure 9, and the specific details are as follows:   • The experiment assembly in Figure 9 consists  of a polycarbonate secondary containment box  with a secondary High Efficiency Particulate Arresting (HEPA) filter, supply and discharge  containers for lunar regolith simulant, an eductor for pneumatic conveying, a convey pipe, two cyclone separators co nnected in series with HEPA filters on the exhaust of the final cyclone, air  pressure and flow rate meters, and dust particle counters connected to the dusty gas inlet and the clean gas outlet of the second cyclone. Optional is a high voltage power supply that allows the  second cyclone B to act as an electrocyclone if desired.   

• Two lunar regolith simulants, known as NU-LHT -2M and Tephra, were studied. One simulant at a  time was contained within the experiment assemb ly shown in Fig. 9. The NU-LHT-2M lunar  regolith simulant is based on the chemical comp osition of NASA averaged Apollo 16 regolith  samples. Tephra is a volcanic ash and cinder material from Mauna Kea, Hawaii.    Figure 9 is a schematic of the ex periment hardware contained within an aluminum framed housing, and  enclosed by sheets of transparent polycarbonate around the sides and by sheets of aluminum at the top  and at the base. The housing structure was designed to allow the pneumatic regolith transfer experiment  to fly in a safely contained manner onboard an aircraft which conducted a series of parabolic flight paths.  During each parabola, the RGF experiment was perfor med for 25 seconds under simulated lunar gravity  conditions after which time the air flow was shut off during a period of time in which the experiment  experienced variable gravity condition s including increased gravity. The use of HEPA filters ensured that  NASA/CP-2010-216272
273 particles larger than 0.3 micron would not exit in to the ambient atmosphere  outside of the pneumatic  conveyor system. The polycarbonate sheets allowed fo r the pneumatic regolith transfer to be visible  outside of the box, and also served as a secondary containment in case of dust leakage from the system.  A secondary HEPA filter was mounted on the secondary containment box to  prevent the filtered air from  pressurizing the box. Compressed dry air was used as the convey gas so that the exhaust gas from the cyclones did not have to be vented outside of the aircraft. 

Figure 9. Graphic of the reduced gravity (1/6-g) experiment hardware including a close-up view  (right-side graphic) of a series array of cyclones with the upper most having a HEPA filter  attached to its exhaust gas outlet. The same setup was also used for ground tests at 1-g. (1) Two  cyclone array using a mechanical cyclone (A) and an electrocyclone (B); (2) SS pipe; (3) Interface  panel for gas inlet and gauges; (4) Regolith supply container and venturi eductor; (5) HEPA filter  on the secondary containment box (7);  (6) Regolith discharge container representing an ISRU  reactor mockup;  and (7) Secondary containmen t box using aluminum frame and supports, and  polycarbonate sheets. Total mass of the flight rig including lunar regolith simulant: 195 kg. 

The regolith supply container (transpa rent acrylic) in Fig. 9 could be f illed with 16.5 kg of lunar regolith  simulant that was to be transferred to the regolith discharge container (also tr ansparent acrylic), which  served as a mockup of an ISRU reactor chamber. Height restrictions onboard the RGF aircraft limited the total transfer height to 1.5 m for conveying the luna r simulants from the bottom of the regolith supply  container to the inlet of the first cyclo ne located above the regolith discharge container.   The gas/solids mixer shown in Fig. 10 is a stainl ess steel venturi eductor. The eductor pulls granular  material out from the center of the bottom plate of the regolith supply container, and it is used to entrain  the lunar regolith simulant into the air flow and to co nvey the dusty gas along a stainless steel pipe to the  cyclone separators.  The cyclone body and air exhaust pipe of the two cyclones shown in Fig. 8 were fabricated from stainless  steel, and they were joined using a non-metallic cap to electrically insulate the exhaust pipe from the cyclone body when the cyclone (B) is operated as an electrocyclone. Except for the air exhaust pipe of  the electrocyclone, which is connected to the high voltage output cable of a high voltage DC power  NASA/CP-2010-216272