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At least 397 records · Page 22

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NASA NTRS1991

Utilization of common pressurized modules on the Space Station Freedom

During the preliminary design review of Space Station Freedom elements and subsystems, it was shown that reductions of cost, weight, and on-orbit integration and verification would be necessary in order to meet program constraints, particularly nominal Orbiter payload launch capability. At that time, the Baseline station consisted of four resource nodes and two 44 ft modules. In this study, the viability of a common module which maintains crew and payload accommodation is assessed. The size, transportation, and orientation of modules and the accommodation of system racks and user experiments are considered and compared to baseline. Based on available weight estimates, a module pattern consisting of six 28 ft. common elements with three radial and two end ports is shown to be nearly optimal. Advantageous characteristics include a reduction in assembly flights, dual egress from all elements, logical functional allocation, no adverse impacts to international partners, favorable airlock, cupola, ACRV (Assured Crew Return Vehicle), and logistics module accommodation, and desirable flight attitude and control characteristics.

Gould, Marston J.↗

NASA NTRS1991

A Knowledge-Based Approach to Configuration Layout, Justification, and Documentation

The design, development, and implementation of a prototype expert system which could aid designers and system engineers in the placement of racks aboard modules on the Space Station Freedom are described. This type of problem is relevant to any program with multiple constraints and requirements demanding solutions which minimize usage of limited resources. This process is generally performed by a single, highly experienced engineer who integrates all the diverse mission requirements and limitations, and develops an overall technical solution which meets program and system requirements with minimal cost, weight, volume, power, etc. This system architect performs an intellectual integration process in which the underlying design rationale is often not fully documented. This is a situation which lends itself to an expert system solution for enhanced consistency, thoroughness, documentation, and change assessment capabilities.

Craig, F. G.↗

NASA NTRS1991

Goodard Space Flight Center/Wallops Flight Facility airborne geoscience support capability

Goddard Space Flight Center's Wallops Facility (GSFC/WFF), operates six aircraft which are used as airborne geoscience platforms. The aircraft complement consists of two UH-1B helicopters, one twin engine Skyvan, one twin jet T-39, and two four engine turboprop aircraft (P-3 and Electra) offering the research community a wide range of payload, altitude, speed, and range capabilities. WFF's support to a principal investigator include mission planning of all supporting elements, installation of equipment on the aircraft, fabrication of brackets, and adapters as required to adapt payloads to the aircraft, and planning of mission profiles to meet science objectives. The flight regime includes local, regional, and global missions. The WFF aircraft serve scientists at GSFC, other NASA centers, other government agencies, and universities. The WFF mode of operation features the walk on method of conducting research projects. The principal investigator requests aircraft support by letter to WFF and after approval is granted, works with the assigned mission manager to plan all phases of project support. The instrumentation is installed in WFF electronics racks, mounted on the aircraft, the missions are flown, and the equipment is removed when the scientific objectives are met. The principal investigator reimburses WFF for each flight hours, any overtime and travel expenses generated by the project, and for other mission-related expenses such as aircraft support services required at deployment bases.

Navarro, Roger L.↗

NASA NTRS1990

Paving the way for space gardens

The Ecological Life Support System, a plant growth experiment now in its third year of closed chamber production at the NASA Kennedy Space Center, is discussed. Possible spin-off applications of hydrophonics experiments are noted. It is projected that long-term goals will include the integration of this garden system into the process of waste recycling for fertilization, air refreshment, and potable water recovery in a closed environment. The Biomass Production Chamber, a two-story bubble-shape steel biosphere modified from a Mercury/Gemini program attitude chamber provides a usable volume of 7.3 m x 3.6 m in diameter containing growing racks, piping for nutrient solutions, specialized lighting and sensors that provide information to the computers controlling the chamber and its functions. Computer programs provide highly sensitive monitoring and regulation of the system. Crops successfully harvested to date include dwarf wheat, lettuce, and soybeans.

Phillips, Patricia↗

NASA NTRS1990

Coherent lightwave communications; Proceedings of the Meeting, Boston, MA, Sept. 7, 8, 1989

Various papers on coherent lightwave communications are presented. Individual topics addressed include: overview of coherent light wave communications, frequency stabilization techniques for coherent lightwave systems, characterization of laser diode intensity noise at microwave frequencies with high sensitivity, FP and DFB semiconductor lasers with arbitrary external optical feedback, birefringence-controlled phase-shifter, polarization diversity and scrambling techniques for coherent systems, polarization control scheme for coherent optical systems, simulation of IF filtering effects on the performance of coherent optical receivers. Also discussed are: performance of optical DPSK receivers in the presence of optical channel noise, optical heterodyne communications with polarization modulation, coherent fiber optical subcarrier multiplexed system, engineered rack-mounted coherent transmission system, technology aspects of a coherent optical MAN, broadband exchange by coherent multicarrier switching, generalized temporal CDMA for optical communications. Overviews are given of recent progress at individual companies.

Sunak, Harish R. D.↗

NASA NTRS1991

A preview of a microgravity laser light scattering instrument

The development of a versatile, miniature, modular light scattering instrument to be used in microgravity is described. The instrument will measure microscopic particles in the size range of thirty angstroms to above three microns. This modular instrument permits several configurations, each optimized for a particular experiment. In particular, a multiangle instrument will probably be mounted in a rack in the Space Shuttle and on the Space Station. It is possible that a Space Shuttle glove-box and a lap-top computer containing a correlator card can be used to perform a number of experiments and to demonstrate the technology needed for more elaborate investigations.

Meyer, W. V.↗

NASA NTRS1990

Salad Machine - A vegetable production unit for long duration space missions

A review of NASA CELSS development specific to vegetable cultivation during space missions is presented in terms of enhancing the quality of life for space crews. A cultivation unit is being developed to permit the production of 600 grams of edible salad vegetables per week, thereby allowing one salad per crew member three times weekly. Plant-growth requirements are set forth for the specific vegetables, and environmental subsystems are listed. Several preprototype systems are discussed, and one particular integrated-systems design concept is presented in detail with views of the proposed rack configuration. The Salad Machine is developed exclusively from CELSS-derived technology, and the major challenge is the mitigation of the effects of plant-growth requirements on other space-mission facility operations.

Kliss, M.↗

NASA NTRS1991

Emergency egress requirements for Space Station Freedom

An objective was to determine if the pressurized elements and hatchways of the Space Station Freedom support the emergency egress of crewmembers during operation of the station at the stage of Permanently Manned Capacity. Emergency egress was defined as the exit from a pressurized element when an event occurs which makes that element uninhabitable. The possible egress paths for four emergency scenarios considered were: (1) accident occurs in a module and crewmembers translate to the attached node; (2) accident occurs at a node and crewmembers translate through it to the safe node; (3) accident occurs at a module close to a node and crewmembers are not able to translate through the affected area; and (4) accident occurs at a node and crewmembers cannot translate through it. The structural design of the pressurized elements and the hatches studied is adequate for the emergence egress translation requirement. The current location of a few racks may cause some obstruction for egress to the orbiter. The egress time required in the worst situation is estimated to be about 3 mins. There is a chance of getting crewmembers trapped in a module in case of a severe accident. Aids are needed for emergency egress translation.

Ray, Paul S.↗

NASA NTRS1991

NASA Goddard Space Flight Center Robotic Processing System Program Automation Systems, volume 2

Topics related to robot operated materials processing in space (RoMPS) are presented in view graph form. Some of the areas covered include: (1) mission requirements; (2) automation management system; (3) Space Transportation System (STS) Hitchhicker Payload; (4) Spacecraft Command Language (SCL) scripts; (5) SCL software components; (6) RoMPS EasyLab Command & Variable summary for rack stations and annealer module; (7) support electronics assembly; (8) SCL uplink packet definition; (9) SC-4 EasyLab System Memory Map; (10) Servo Axis Control Logic Suppliers; and (11) annealing oven control subsystem.

Dobbs, M. E.↗

NASA NTRS1992

Microgravity nucleation and particle coagulation experiments support

Modifications to the nucleation apparatus suggested by our first microgravity flight campaign are complete. These included a complete 'repackaging' of the equipment into three racks along with an improved vapor spout shutter mechanism and additional thermocouples for gas temperature measurements. The 'repackaged' apparatus was used in two KC-135 campaigns: one during the week of June 3, 1991 consisting of two flights with Mg and two with Zn, and another series consisting of three flights with Zn during the week of September 23, 1991. Our effort then was focused on the analysis of these data, including further development of the mathematical models to generate the values of temperature and supersaturation at the observed points of nucleation. The efforts to apply Hale's Scaled Nucleation Theory to our experimental data have met with only limited success, most likely due to still inadequate temperature field determination. Work on the development of a preliminary particle collector system designed to capture particles from the region of nucleation and condensation, as well as from other parts of the chamber, are discussed.

Lilleleht, L. U.↗

NASA NTRS1992

Studies on penetration of antibiotic in bacterial cells in space conditions (7-IML-1)

The Cytos 2 experiment was performed aboard Salyut 7 in order to test the antibiotic sensitivity of bacteria cultivated in vitro in space. An increase of the Minimal Inhibitory Concentration (MIC) in the inflight cultures (i.e., an increase of the antibiotic resistance) was observed. Complementary studies of the ultrastructure showed a thickening of the cell envelope. In order to confirm the results of the Cytos 2 experiment, we performed the ANTIBIO experiment during the D1 mission to try to differentiate, by means of the 1 g centrifuge in the Biorack, between the biological effects of cosmic rays and those caused by microgravity conditions. The originality of this experiment was in the fact that it was designed to test the antibiotic sensitivity of bacteria cultivated in vitro during the orbital phase of the flight. The results show an increase in resistance to Colistin in in-flight bacteria. The MIC is practically double in the in-flight cultures. A cell count of living bacteria in the cultures containing the different Colistin concentrations showed a significant difference between the cultures developed during space flight and the ground based cultures. The comparison between the 1 g and 0 g in-flight cultures show similar behavior for the two sets. Nevertheless, a small difference between the two sets of ground based control cultures was noted. The cultures developed on the ground centrifuge (1.4 g) present a slight decrease in comparison with the cultures developed in the static rack (1 g). In order to approach the mechanisms of the increase of antibiotic resistance on bacteria cultivated in vitro in space, we have proposed the study on penetration of antibiotics in bacterial cells in space conditions. This experiment was selected for the International Microgravity Laboratory 1 (IML-1) mission.

Tixador, R.↗

NASA NTRS1992

CRYOSTAT (18-IML-1)

The CRYOSTAT is an autonomously working rack mounted equipment. It provides two thermostat chambers, independently controlled by a processor via on/off switching of the current through peltier elements. The temperature profiles of the freezer and stabilizer are subdivided in a common number of steps, each one with a preprogrammable temperature gradient or at constant temperature. Core parameters can be reprogrammed by crew interaction in case of rescheduling the CRYOSTAT operation time due to changed mission requirements or contingency. Actions of the CRYOSTAT (e.g., opening the slide), the steps, actual temperature of the thermostat chambers, experiment time, and the housekeeping data are recorded on a built-in RAM and a tape. In each thermostat chamber, a specific sample container can be inserted which consists of a transparent Plexiglas block accommodating seven crystallization experiments.

Source record↗

NASA NTRS1991

Space Station Freedom

Information is given in viewgraph form on Space Station Freedom. Topics covered include future evolution, man-tended capability, permanently manned capability, standard payload rack dimensions, the Crystals by Vapor Transport Experiment (CVTE), commercial space projects interfaces, and pricing policy.

Keyes, Gilbert↗

NASA NTRS1992

Alternative methods to model frictional contact surfaces using NASTRAN

Elongated (slotted) holes have been used extensively for the integration of equipment into Spacelab racks. In the past, this type of interface has been modeled assuming that there is not slippage between contact surfaces, or that there is no load transfer in the direction of the slot. Since the contact surfaces are bolted together, the contact friction provides a load path determined by the normal applied force (bolt preload) and the coefficient of friction. Three alternate methods that utilize spring elements, externally applied couples, and stress dependent elements are examined to model the contacted surfaces. Results of these methods are compared with results obtained from methods that use GAP elements and rigid elements.

Hoang, Joseph↗

NASA NTRS1992

Coupled loads analysis for Space Shuttle payloads

Described here is a method for determining the transient response of, and the resultant loads in, a system exposed to predicted external forces. In this case, the system consists of four racks mounted on the inside of a space station resource node module (SSRNMO) which is mounted in the payload bay of the space shuttle. The predicted external forces are forcing functions which envelope worst case forces applied to the shuttle during liftoff and landing. This analysis, called a coupled loads analysis, is used to couple the payload and shuttle models together, determine the transient response of the system, and then recover payload loads, payload accelerations, and payload to shuttle interface forces.

Eldridge, J.↗

NASA NTRS1992

NASDA's activities on vibration isolation technology

The National Space Development Agency's (NASDA) activities in providing various vibration isolation technologies for the Space Station Mission are covered in viewgraph form. Technologies covered include an active vibration isolation system for extra sensitive missions in the low frequency range, a passive damping system consisting of a damping rack for the reduction of resonance amplification, and an isolator for vibration isolation from low frequencies. Information is given in viewgraph form on the active vibration isolation concept, voice coil type electromagnetic suspension, a profile of an active vibration isolation system, a three degree of freedom ground experiment, and acceleration feedback.

Source record↗

NASA NTRS1992

Soil texture and granulometry at the surface of Mars

The microtexture of the near-surface Martian soil was sensed with three diagnostic parameters: (1) the albedo A at normal incidence and phase angle 5 degrees, which relates to the composition of the top surface exposed layer; (2) the polarization parameter b characterizes the texture of the top surface layer in terms of grain size; and (3) the thermal inertia parameter I which refers to the soil compaction through the first few decimeters below the top surface sensed by polarimetry, in terms of size for the pieces making a granular regolith. Parameter b was derived from instrument VPM on board the Soviet spacecraft MARS-5, inertial I is from IRTM on the American Viking, and albedo A from both. The polarimetric scans racked strips covering two contrasted regions, the dark hued Mare Erythraeum, and the adjacent bright orange Thaumasia. Erythraem is characterized everywhere by a same type of terrain, despite the large geomorphological diversity of the surface. There is an ubiquitous coating or mantling with small dark grains, of both albedo 12.7 percent and particle size 10 to 20 microns, above a subsurface dislocation in pieces around 300 to 600 microns. A simple model is with sand-size particles completely coated with 15 micron dark grains.

Dollfus, A.↗

NASA NTRS1992

Integration mockup and process material management system

Work to define and develop a full scale Space Station Freedom (SSF) mockup with the flexibility to evolve into future designs, to validate techniques for maintenance and logistics and verify human task allocations and support trade studies is described. This work began in early 1985 and ended in August, 1991. The mockups are presently being used at MSFC in Building 4755 as a technology and design testbed, as well as for public display. Micro Craft also began work on the Process Material Management System (PMMS) under this contract. The PMMS simulator was a sealed enclosure for testing to identify liquids, gaseous, particulate samples, and specimen including, urine, waste water, condensate, hazardous gases, surrogate gasses, liquids, and solids. The SSF would require many trade studies to validate techniques for maintenance and logistics and verify system task allocations; it was necessary to develop a full scale mockup which would be representative of current SSF design with the ease of changing those designs as the SSF design evolved and changed. The tasks defined for Micro Craft were to provide the personnel, services, tools, and materials for the SSF mockup which would consist of four modules, nodes, interior components, and part task mockups of MSFC responsible engineering systems. This included the Engineering Control and Life Support Systems (ECLSS) testbed. For the initial study, the mockups were low fidelity, soft mockups of graphics art bottle, and other low cost materials, which evolved into higher fidelity mockups as the R&D design evolved, by modifying or rebuilding, an important cost saving factor in the design process. We designed, fabricated, and maintained the full size mockup shells and support stands. The shells consisted of cylinders, end cones, rings, longerons, docking ports, crew airlocks, and windows. The ECLSS required a heavier cylinder to support the ECLSS systems test program. Details of this activity will be covered. Support stands were designed and built for each module to sufficiently move and rotate each module. Secondary structures such as floors, ceilings, bulkheads, standoffs, racks, etc. were developed and built.

Verble, Adas James, Jr.↗