Code UG Weekly Notes 3-27-02
Weekly Highlights for Week Ending 3/27/2002
*** Indicates item is appropriate for the HQ senior staff and may appear
on the OBPR Web site: http://spaceresearch.nasa.gov
GENERAL
MICROGRAVITY INTEGRATED PERFORMANCE CONFERENCE: Microgravity Research Program Office’s Dr. Vlasse participated in the Microgravity Integrated Performance Conference, held at the Johnson Space Center (JSC) 3/12-14/02. The Conference was the first major effort by the International Space Station (ISS) to discuss and summarize the latest information on the microgravity environment, covering both the Systems and Payloads efforts. In the steady-state regime (0.0-0.01 Hz), the comparison of measurements and analysis to the ISS requirements demonstrated that the requirements are met. In the vibratory regime (0.01-2 Hz), the active vibration isolation system (ARIS), appears to indicate that it will be able to meet the ISS requirements. The transient regime (thruster firings, dockings, etc.) will be handled by the use of the 30-day microgravity periods at Assembly Complete.
EDUCATION and OUTREACH
MARSHALL SPACE FLIGHT CENTER’S MICROGRAVITY RESEARCH MEDIA ACTIVITIES:
Ø INTERNATIONAL SPACE STATION: Paul Janesky, Flint Journal, Flint, Michigan, was provided information about students, teachers and communities in Michigan participating in the student biological samples experiments to International Space Station program.
Hasrzial al-Hasymi, Institute for Social and Environmental Studies, Jakarta, Indonesia, was provided information about science on board the International Space Station.
Ø Steve Johnson, WHNT-TV, Huntsville, AL, interviewed Carrie Olsen of the Payload Operations Center about progress of science operations and the first anniversary of operations of the Payload Operations Center; William Kirby of Teledyne Brown Engineering about payload planning support to Station, and Richard Grugel of the Biological and Physical Space Research Laboratory about Grugel’s materials science experiment and the Microgravity Science Glovebox facility planned for flight to the International Space Station in May.
Ø Karen Petersen, WAAY-TV, Huntsville, AL, interviewed Carrie Olsen of the Payload Operations Center about progress of science operations and the first anniversary of operations of the Payload Operations Center.
Ø Trina Tsouderous, People Magazine, interviewed Ron Porter of Marshall Center’s Microgravity Science and Applications Department, as well as Greg Jenkins and Michael Kerjes of the University of California – Irvine about their roles in the development and goals of the student biological samples microgravity experiments prepared in special educational workshops for flight to the International Space Station.
VIDEO CONFERENCE TO DEMONSTRATE MICROGRAVITY TO STUDENTS: At the request of Dennis Christopher, an educational specialist working at NASA GSFC and Dr. Robert Lipton from Pennsylvania State University, John McQuillen (GRC) and Dennis Stocker (GRC) conducted a ViTS for 30 students and their teacher from the Berks County Schools on Monday, March 18. The title for the conference was Microgravity and included a discussion of Newton’s Laws, demonstrations with the mini-drop tower and the water balloon video.
REDUCED GRAVITY STUDENT FLIGHT OPPORTUNITY PROGRAM: This year a student team from the University of Alabama at Birmingham’s (UAB) Department of Mechanical Engineering will use equipment designed by the NASA Glenn Microgravity Science Division (MSD) to support their KC-135 flight investigation titled "Electrostatic Charge Distribution On Particles." The students from UAB were accepted into the Reduced Gravity Student Flight Opportunity Program (RGSFOP), based on a proposal that illustrated both innovation and scientific merit. The UAB student’s research involves suspending charged particles (diameter ~1 mm) in an electric field and tracking their motion (translation and rotation). This experiment is the first to try and verify the existence of a non-uniform charge distribution. Microgravity is required to suspend the particles for protracted periods (10-20seconds). To aid the students in their research, NASA Glenn provided "freefloat" equipment, an electric field generator and particle dispersion device, along with other support equipment, for the student’s use. The equipment was originally designed as support equipment for the Fluid Physics Flight experiment, "Electrostatics of Granular Materials". Several NASA Glenn engineers and scientists also provided expertise and advice to aid the students in their design and integration of the NASA equipment. This is the second year in a row UAB has been selected. Last year’s flight team was featured on the cover of the ASME Mechanical Engineering Magazine. Their current flight dates are scheduled for 4/9-4/10. More info can be found at http://microgravityteam.tripod.com/ or by contacting Prof. Heng Ban (hban@uab.edu).
SHUTTLE FLIGHT PROGRAM
MRPO PARTICIPATION IN STS-107 MISSION INTEGRATED TRAINING SESSION #2 (MITS#2) AT THE JOHNSON SPACE CENTER: Microgravity Research Program Office (MRPO) employees participated in MITS#2 on 3/20/02 at the Johnson Space Center (JSC) in preparation for the STS-107 flight. The training session simulated a number of Flight Day 8 on-orbit activities for Code UG/UM-sponsored payloads. The final Mission Integrated Training Session (MITS#3) has not been officially scheduled, though it is expected to take place prior to one of the five scheduled Joint Integrated Simulations (JISs) for STS-107, where Code U payload representatives will interface indirectly with the JSC flight control team.
ISS FLIGHT PROGRAM
MICROGRAVITY RESEARCH PROGRAM OFFICE (MRPO) PAYLOAD OPERATIONS STATUS ON THE INTERNATIONAL SPACE STATION (ISS) UF1 STAGE: Successfully completed Week#14 (3/17-23/02) of Increment 4 UF1 Stage, and have entered into Week#15 (3/24-30/02). All MRPO payloads have completed their scheduled operations and will continue to conduct activities involving plant growth, crystal growth, and the cell preservation phase. The last attempt at troubleshooting the Physics of Colloids in Space (PCS) payload was unsuccessful.
Using a monitor and keyboard borrowed from the Human Research Facility (HRF) and an ISS pin/jumper kit to make electrical connections from the EXPPCS Avionics Section to these HRF equipment items, astronaut Carl Walz executed the EXPPCS recovery procedures on Wednesday, 3/20, but without success. The impediment that was encountered lay in getting the HRF monitor to display a signal, which may have been something in the setup of the monitor or it may be an indication that the EXPPCS CPU is not functioning, (one of the possible foreseen failure scenarios). The EXPPCS team is still reviewing video camcorder footage and still camera images of the procedure and final setup state, as well as electrical power draw profiles, to assess what happened. Possible next steps are building and launching an interconnection cable which will more fully ensure the connections between these equipment items, or de-orbiting the EXPPCS Avionics Section for inspection and repair. In spite of the negative results on the recovery to date of EXPPCS, the EXPPCS team expresses much gratitude to astronaut Carl Walz and the entire ISS program on the planning and execution of an intricate set of procedures for recovery of EXPPCS.
LOW TEMPERATURE FACILITY CAN USE ADAPTER FOR ATTACHING TO CARRIER: NASDA has accepted the rotated and offset standard FRAM (flight releasable attach mechanism) for LTMPF for the 2nd utilization flight. Ball Aerospace is finishing the center of gravity, mass, and volume study to provide to the ISS payload office’s attached payload team before the face-to-face meeting with NASDA in April.
SCIENCE HIGHLIGHTS
COMBUSTION SCIENCE:
AERODYNAMICS, UNSTEADY, KINETIC, AND HEAT LOSS EFFECTS ON THE DYNAMICS AND STRUCTURES OF WEAKLY-BURNING FLAMES IN MICROGRAVITY: The purpose of this experimental study, led by Prof. F. Egolfopoulos of University of Southern California, is to obtain quantitative information about the characteristics of weakly burning flames in microgravity to analyze near-limit phenomena. Recently, the validity of the static approach was further investigated using Digital Particle Image Velocimetry (DPIV). The obtained laminar flame speeds appear to be very close to the values obtained through the transition technique. By combining both techniques, laminar flame speeds of mixtures of methane and ethane with hydrogen, oxygen, nitrogen and helium were determined. More specifically, laminar flame speeds were determined by independently varying the equivalence ratio and flame temperature in order to decouple thermal and concentration effects. In addition to CH4 flames, additional experiments were conducted with lean C2H6 flames in which various amounts of H2 were added. Subsequently, those flames were diluted with He and N2 and the laminar flame speeds were measured at various flame temperatures. It is essential to vary the flame temperature independently of the equivalence ratio in order to decouple concentration and temperature effects. It was also found that under conditions of high O2-concentration and low flame-temperature, the GRI30 mechanism systematically over-predicts the experimentally determined laminar flame speeds. This region is of interest to near-limit flames, lean-burning in general, and to flame ignition. It was not possible at this time to identify the sources of discrepancy.
DETAILED STUDIES ON THE STRUCTURE AND DYNAMICS OF REACTING DUSTY FLOWS AT NORMAL AND MICROGRAVITY: This program, led by Prof. F. Egolfopoulos of USC, is designed to obtain quantitative information about the propagation, structure, and extinction of reacting dusty flows, and gain physical insight into controlling the physico-chemical mechanisms. In the area of flame ignition, the numerical study on strained non-premixed and premixed methane/air flames by hot inert particles is completed. The numerical model was augmented by introducing the capability of capturing turning-point behavior, typical at the states of ignition and extinction. Non-premixed ignition was studied by counterflowing heated air against a fuel stream consisting of methane and nitrogen. Results show that for ignition achieved by heated air, the ignition temperature has a non-monotonic behavior, i.e. for low methane concentrations it decreases with the methane concentration, making thus ignition easier, but at higher methane concentrations it is harder to ignite as more methane is added. For the particle ignition case, however, a monotonic behavior is observed, i.e. the more methane is present in the fuel stream the higher is the ignition particle injection number density or in other words it is harder to ignite. These results were explained based on the synergistic effect of the thermal structures of these reacting layers as well as on the kinetics of methane. In the area of combustible particles, an experimental investigation of the extinction states of gaseous flames of methane and propane seeded by 50-micron diameter, spherical glassy carbon combustible particles was initiated. So far only premixed flames were investigated in counterflow configuration, stabilizing a single flame below the gas stagnation plane (GSP) by injecting the combustible mixture and the particles from the bottom burner and air from the top burner. Initial results reveal that at relatively low strain rates particle ignition occurs and the exothermicity introduced to the gas phase makes the existing gaseous flame stronger. At relatively higher strain rates the particles do not ignite and act as inert cooling agents due to the reduced residence time of the particles in the flame region. However, the chemical coupling between the two phases are not yet fully understood and are still under investigation. It should also be noted here that the particle mass delivery rate also changes as the strain rate changes. Thus significance of variable particle mass delivery rate will be revealed when particle seeder is calibrated for the type of particle being used.
FLUID PHYSICS:
PHYSICAL OPTICS TREATMENT OF THE SHADOWGRAPH: Fluid Physics PI Prof. Cannell (University of California Santa Barbara) and his team present an analysis of the shadowgraph method of visualizing convective flows based on physical optics, treating the refractive-index perturbation caused by the flow as a transmission grating. Various patterns in thermal convection of an isotropic fluid as well as normal rolls in electroconvection of a nematic liquid crystal are considered. The results differ significantly from those of geometrical optics, showing that use of the shadowgraph as a quantitative tool for amplitude measurements should not, in general, be based on geometrical optics. Results are published in the following paper:
Steven P. Trainoff and David S. Cannell, "Physical optics treatment of the shadowgraph," Physics of Fluids Volume 14, Number 4 April 2002
THE PROPAGATION OF A SURFACTANT LADEN LIQUID PLUG IN A CAPILLARY TUBE: Fluid Physics PI Prof. Grotberg (University of Michigan) and his team have modeled the propagation of a surfactant-laden liquid plug along a liquid-lined airway after it has been instilled. The model is most applicable to the later doses of surfactant, as for the initial doses the gradients in surface tension are so large that Marangoni stresses cause the plug to rupture very quickly. The liquid plug propagates along the airway under the pressure drop imposed across it during breathing. Ahead of the plug is a precursor film and as it is pushed through the airway it leaves behind a trailing film, thus coating the airways with a layer of surfactant. Reopening occurs if and when the plug volume decreases to a point at which it ruptures. The results of the analysis are that, for a given plug Capillary Number, pressure drop increases with increasing surface elasticity but decreases with increasing liquid precursor film thickness. The trailing film thickness increases with pressure drop, but at a slower rate when surface elasticity is larger. This model is relevant to delivery of surfactants into the lung by direct instillation into the bronchial network as is done in surfactant replacement therapy and the use of surfactant solutions to carry other substances ~e.g., genetic material into the airways. These results were reported in the following paper:
S. L. Waters and J. B. Grotberg "The propagation of a surfactant laden liquid plug in a capillary tube," Physics of Fluids Volume 14, Number 2 February 2002
FUNDAMENTAL PHYSICS:
REALIZATION OF BOSE-EINSTEIN CONDENSATES IN LOWER DIMENSIONS: Bose-Einstein condensates of sodium atoms have been prepared in optical and magnetic traps in which the energy-level spacing in one or two dimensions exceeds the interaction energy between atoms. This realized condensates of lower dimensionality. In anisotropic traps, a primary indicator of crossing the transition temperature for Bose-Einstein condensation is a sudden change of the aspect ratio of the ballistically expanding cloud. The transition to lower dimensions is a smooth cross-over, but has similar indicators. In the 3D Thomas-Fermi limit the degree of anisotropy of a BEC is independent of the number N of atoms, whereas in 1D and 2D, the aspect ratio depends on N. This was used in our experiments as a distinctive feature of lower dimensionality.
In the MIT traps, the ratio of the highest to lowest frequency was about 100. Due to this extreme geometry the number of atoms at the cross-over to lower-dimensionality was rather large (> 105 in the 2D case) which provides a good starting point for the exploration of phenomena which only occur in one or two dimensions.
This work by PI Wolfgang ketterle’s group at MIT was published in the paper "Realization of Bose-Einstein Condensates in Lower Dimensions" by A. Görlitz, J.M. Vogels, A.E. Leanhardt, C. Raman, T.L. Gustavson, J.R. Abo-Shaeer, A.P. Chikkatur, S. Gupta, S. Inouye, T. Rosenband, and W. Ketterle, in Phys. Rev. Lett. 87, 130402 (2001).
***DUKE GROUP CLAIMS 1ST IN LASER-COOLED ATOMIC PHYSICS: The group led by PI John Thomas at Duke University is the first group to achieve degeneracy in fermionic atoms by all-optical methods. The importance of the new result is that they are able to trap a special two-state mixture of spin up and spin down 6Li fermions. This mixture is ideal for studies of mechanisms of superconductivity ranging from ordinary BCS (Bardeen, Cooper, Schrieffer who won the Noble Prize on superconductivity) pairing to the newly predicted resonance superfluidity which may yield the highest temperature superconductors ever studied (in units of the Fermi degeneracy temperature TF). A magnetic trap, as used for Bose condensation, cannot be used for these studies, since both states are repelled from the trap.
The figure left shows the experimental setup. 70W of CO2 laser power is focused to a diameter of about 50 microns, yielding an intensity of 1.9 MW/cm^2. Since the laser operates at a wavelength of 10.6 microns, the optical scattering rate (determined by the Larmor formula) is only 2 photons/hour, yielding an optical heating rate of only 16 picoKelvin/second. The focused beam yields a trap depth of 0.7 mK, more than adequate to trap atoms from our 6Li magneto-optical(MOT) trap, which produces temperatures of 150 microkelvin. After the CO2 laser trap is loaded, the optical beams of the MOT are extinguished, and the atoms remain trapped. At any later time, a short pulse of the probe beam yields a camera image, determining the number and temperature of the atoms
by time-of-flight.
This result sets the stage for studies of resonance superfluidity, which requires that we apply an 850 G field to tune the elastic scattering cross section into resonance. The installation of our high field magnets is in progress.
A paper describing these results is accepted for publication in Physical Review Letters.
MATERIALS SCIENCE:
CRYSTAL GROWTH OF ZnSe AND RELATED TERNARY COMPOUND SEMICONDUCTORS BY VAPOR TRANSPORT: A paper, entitled "Partial Pressure for In-Se from Optical Absorbance of the Vapor," by R. F. Brebrick (Marquette University) and Ching-Hua Su (MSFC) was accepted for publication in the Journal of Phase Equilibria. The optical absorbance of the vapor phase over various In-Se compositions and between 673 and 1418K has been measured to obtain the partial pressures of Se2 and In2Se. The information is needed to provide the optimum conditions for the vapor growth of In-doped ZnSe.
IN-SITU OBSERVATIONS OF STRUCTURAL TRANSFORMATIONS IN UNDERCOOLED LIQUIDS VIA ELECTROSTATIC LEVITATION: Members of the Marshall Space Flight Center (MSFC) Electrostatic Levitator (ESL) Facility team visited Argonne National Laboratory 3/4-16/02 to perform the first experiments in support of the MSFC Center Director’s Discretionary Fund Project. The data gathered provide new insight into materials by combining the unique processing capabilities of electrostatic levitation with the structural insight obtained using the 100 KeV X-ray source at the Advanced Photon Source of Argonne National Laboratory. Data from the beamline studies will help support Dr. Ken Kelton’s Science Concept Review for the Flight Definition Project, "Quasi-Crystalline Undercooled Alloys for Space Investigation." Successful ESL melt cycles were performed using quasi-crystalline forming alloys and selected demonstration/calibration materials on the high-energy beamline. Excellent patterns were obtained. The results represent the first-ever observations of structural transformations via beamline electrostatic levitation. Preliminary data analysis shows the formation of the icosahedral phase in the first recalescence of the quasi-crystalline forming samples. Data collection at Argonne will continue during the final week of March 2002.
UPCOMING EVENTS
Additional meetings and symposia can be found at: http://microgravity.grc.nasa.gov/ugml/ugmltext.htm
The MRPO Program Calendar can be found at:
http://webcal.msfc.nasa.gov/webevent.cgi?cmd=opencal&cal=cal85&
April 20-23, 2002, 2002 American Physical Society April Meeting
Albuquerque, NM http://www.aps.org/meet/APR02
April 22-25 2002 , 2002 Applied Computational Research Society Joint Meeting: Computational Micro And Nano Technology, International Conference on Computational Nano Science , Modeling & Simulation of Microsystems, San Juan Marriott Resort, San Juan, Puerto Rico http://www.cr.org
May 9-11, 2002, Fundamental Physics Investigator Workshop
Laguna Cliffs Marriott Resort, Dana Point, CA,
http://funphysics.jpl.nasa.gov/conference-02/index.html
