MOL The Mission Operations Laboratory MOL The Mission Operations Laboratory NASA MSFC Engineering Directorate Huntsville, Alabama TIR Overview Charts August 28, 2012 Coarsening in Solid-Liquid Mixtures 2 (CSLM-2) Glenn A. Ferraro EO

MOL The Mission Operations Laboratory Page 2 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 Overview Science Objectives  The experiment will examine how dendrites form during solidification into an under cooled melt. These dendrites possess secondary and sometimes even ternary arms. While the tip radius and tip velocity of the dendrite are set by the growth conditions, the side branches behind the tip undergo a coarsening process under nearly isothermal conditions. This coarsening process sets the final arm thicknesses and distances between dendrite arms in the solidified structure, almost independent of the length-scale given by the dendrite tip. Since there is a close relationship between the size scale of the coarsened dendritic structure and the mechanical properties of the material, a greater understanding of this process will have important practical implications. Purpose  The objective is to study coarsening in solid-liquid mixtures at low volume fractions of solid. The topology and morphology of these dendritic mixtures will be determined using three-dimensional reconstructions and phase field simulations that employ these reconstructions as initial conditions will provide insights into the mechanisms of coarsening. These low volume fractions will enable the PD/PI team to examine coarsening of single or a few dendrites, something that is impossible on the ground. These studies will provide insights into the dynamics of morphological evolution of these systems and will point the way to the formulation of models of this technologically important coarsening process. Coarsening  Is a process in which particle-matrix interfacial area in a two-phase system decreases with time, thus reducing the energy of the system. Small particles dissolve and transport their mass by material diffusion due to a concentration gradient in the particle-matrix interface. Concentration depends upon particle curvature. Particles which are smaller than the average size have a concentration at the interface which is higher than that in the matrix, while particles which are larger have a lower concentration at the interface. Thus the large particles tend to grow at the expense of the small particles, the average particle size increases, and the total number of particles decreases with time.

MOL The Mission Operations Laboratory Page 3 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 Operations  Operations  The four main phases in CSLM-2 Operations are: Setup, Vacuum Draws, Sample Processing, and Stow. During the setup phase, the hardware is installed and configured and an ECR Program is performed. Next, the Vacuum Draws are performed to prepare the sample chamber. Four Vacuum Draws are performed in each Vacuum Draw Sequence, each lasting 8, 16, 6, and 23 hours, respectively*. A Vacuum Draw sequence is schedule prior to Sample Processing. Upon conclusion of each Vacuum Draw Sequence the samples are processed. At the end of the experiment, all hardware is stowed. SPU Processing timeVacuum DrawsData Transfer CSLM2-SPUx-PROCESS SPU 2 = 2/01:15:00 SPU 4 = 1/04:15:00 SPU 10 = 0/14:45:00 SPU 3 = 0/6:45:00 SPU 1 = 0/02:50:00 SPU 11 = 0/01:25:00 CSLM2-VAC-DRAW 1, 2, 3, or 4 Vac Draw 1 = 8 hours Vac Draw 2 = 16 hours* Vac Draw 3 = 6 hours Vac Draw 4 = 23 hours CSLM2-SPUx-DATA XFER SPU2 = 35 minutes SPU4 = 30 minutes SPU10 = 25 minutes SPU3 = 16 minutes SPU1 = 15 minutes SPU11 = 15 minutes *VAC DRAW 2 is not required for SPUs 1, 3, 10, and 11.

MOL The Mission Operations Laboratory Page 4 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 Operations Flowchart 1.ACTIVATE MSG AND LOAD SW 2.CONFIGURE MSG 3.INSTALL CSLM-2 ECU AND SPU 4.ACTIVATE CSLM-2 5.SECURE WV AND POWER DOWN MSG FACILITY 1.INITIATE SAMPLE HEATING 2.UNATTENDED DELAY 3.UNATTENDED SAMPLE PROCESSING 4.DATA TRANSFER 5.VERIFY TRANSFER AND EXCHANNGE SPU 6. UNATTENDED DOWNLINK 1.CONFIGURE MSG FACILITY 2.CHECK HUMIDIY LEVELS 3.OPEN VENT AND VACUUM VALVES 4.UNATTENDED VACUUM DRAWS (1-4) 5.TERMINATE VACUUM DRAW 6.PREP FOR NEXT DRAW (OR SAMPLE PROCESSING IF DRAWS ARE COMPLETE) 1.POWER DOWN MSG FACILITY 2.DISCONNECT CSLM-2 ECU 3.STOW ALL CSLM-2 HARDWARE 1. SETUP 2. VACUUM DRAWS (1-4) 3. SAMPLE PROCESSING 4. STOW CONTINUE UNTIL LAST SPU PROCSSED

MOL The Mission Operations Laboratory Page 5 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 Vacuum Draw Cycle  Sample Chamber Vacuum Draw 1 = 8 hours  Water line tubing vacuum draw = 30 minutes  Sample Chamber Vacuum Draw 2 = 16 hours  Water line tubing vacuum draw = 60 minutes  Sample Chamber Vacuum Draw 3 = 6 hours  Water line tubing vacuum draw = 60 minutes  Sample Chamber Vacuum Draw 4 = 23 hours -- These are all untended vacuum draws; crew will be scheduled to go back and forth to MSG to initiate each draw

MOL The Mission Operations Laboratory Page 6 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 Venting Cycles  Vacuum draw cycles are performed to evacuate the sample chamber in which the samples reside Water line tubing vacuum draw = 30 minutes  The tedious vacuum draw cycles and long vacuum draw times are required to remove any air within the sample chambers down to a molecular level. This reduces the amount of heat transfer from the sample holder to the exterior walls of the sample chamber resulting in a more stable science sample temperature  The longer processing time SPUs will have more extensive vacuum draw cycles. For example:  For the 2 day 1 hr 15 min and 1 day 4 hr 15 min processing times there will be four sample chamber vacuum draws of 8 hours, 16 hours, 6 hours, and 23 hrs  For the 2 hr 50 min, 1 hr 25 min, 6 hr 4 min, and 14 hr 45 min processing times there will be three sample chamber vacuum draws of 8, 6, and 24 hrs  There will be a water line tubing vacuum draw of either 30 or 60 minutes between each sample chamber vacuum draw

MOL The Mission Operations Laboratory Page 7 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 Hardware  Electronics Control Unit (ECU)  The Electronics Control Unit (ECU) contains both the Power Distribution System and the Data Acquisition and Control System. ECU software controls each experiment through a series of operating states. During these states, the status of selected parameters is displayed on an LCD screen. Crew procedures will periodically direct crew members to check LCD displays to verify humidity and other experiment parameters.  Power Two lever-lock toggle switches control experiment power and activate the experiment. A third lever-lock toggle switch controls experiment modes in the event of off-nominal conditions requiring the manual quench of the sample holder.  Temperature Control The primary function of the ECU is to control the heating of the lead-tin samples in the Sample Chamber. The ECU monitors and records sample temperatures. Software performs closed-loop control of the heater power based upon the sample temperature. Following the heat/soak cycle, the ECU software initiates the Quench mode.  Data The ECU contains a hard drive that records data during the experiment run. This data is transferred to the MSG Laptop Computer following the experiment run and is eventually downlinked to the ground.

MOL The Mission Operations Laboratory Page 8 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 Hardware (cont.)  Sample Processing Unit (SPU)  The Sample Processing Unit (SPU) houses the chamber where the lead-tin samples are contained and provides the Vacuum, Heating, and Quench systems needed for the experiment. The SPU is connected to the Electronics Control Unit (ECU) via an interconnect cable. After sample processing is complete, the SPU is removed and replaced by another SPU. Key components include the following:  Sample Chamber Large cylinder housing experiment samples. The Sample Chamber is evacuated prior to each experiment run. Following processing, it is returned to stowage.  SPU Comm Port Provides SPU identification to the ECU and receives solenoid valve power and control from the ECU.  Water Reservoir Contains the cooling water used to quench the samples at the end of sample processing. When water quench is required, a solenoid valve automatically opens, allowing air to pressurize the water in the reservoir. The burst disc in the reservoir opens and allows water flow into the spray nozzles and onto the Sample.  Air Cylinder When activated by experiment software, the Air Cylinder provides the pressure required to force water into the Sample Chamber for quenching.  Pressure Gauge Indicates pressure inside air cylinder

MOL The Mission Operations Laboratory Page 9 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 Hardware (cont.)  Base Plate  The plate between CSLM-2 experiment hardware and MSG Work Volume Floor.  Both the ECU and SPU mount to this 33 cm x 31.2 cm plate  Cables  Provide the power and data interface between CSLM-2 hardware and MSG.  ECU Power and ECU Data connects between the ECU and the back of the MSG Work Volume.  ECU Comm connects between the ECU and the SPU.

MOL The Mission Operations Laboratory Page 10 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 Hardware (cont.)  Vacuum Hose  Vacuum hose is used to evacuate the sample chamber via ISS VES prior to SPU processing.  Downlink Adapter  Shorting Cap Backshell used to modify a specific SPUs processing parameters  When connected to ECU J750, it triggers ground support mode in the ECU and allows for the transfer of files from the MLC into the ECU.

MOL The Mission Operations Laboratory Page 11 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 SAFETY CONTROLS  Mating/De-mating Connectors (check that power is OFF prior to mating/de-mating)  Excessive Moisture/Water in ISS Vacuum System (Power is OFF, water valve closed when vacuum shut-off valve and VES valve are open)  Excessive Moisture/Water in ISS Vacuum System (Check that MSG Vacuum vent valve is closed)  Wrist Straps  CSLM-2 Engineers and Technicians wore wrist straps at all times while hardware was being built, tested and handled to protect against damage from electrostatic discharge  It is likewise mandatory to continue to wear wrist straps while handling the hardware on Space Shuttle and Space Station

MOL The Mission Operations Laboratory Page 12 NASA MSFC Engineering Directorate Huntsville, Alabama CSLM-2 SAFETY CONTROLS (cont.)  Caution Boxes  As an extra precaution to keep the ISS vacuum system free of water, caution blocks have been included in the Crew Procedures  The blocks warn against connecting connector P935 on the SPU while the vacuum hose is connected  This will eliminate the possibility of the solenoid inadvertently triggering and releasing water into the ISS vacuum system  The caution boxes also remind the crew to have the SPU water valve closed while ISS vent valve and SPU vacuum valve are open