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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

A water blown urethane insulation for use in cryogenic environments

Thermal Protection Systems (TPS) of NASA's Space Shuttle External Tank include polyurethane and polyisocyanurate modified polyurethane foam insulations. These insulations, currently foamed with CFC 11 blowing agent, serve to maintain cryogenic propellant quality, maintain the external tank structural temperature limits, and minimize the formation of ice and frost that could potentially damage the ceramic insulation on the space shuttle orbiter. During flight the external tank insulations are exposed to mechanical, thermal and acoustical stresses. TPS must pass cryogenic flexure and substrate adhesion tests at -253 C, aerothermal and radiant heating tests at fluxes up to approximately 14 kilowatts per square meter, and thermal conductivity tests at cryogenic and elevated temperatures. Due to environmental concerns, the polyurethane insulation industry and the External Tank Project are tasked with replacing CFC 11. The flight qualification of foam insulations employing HCFC 141b as a foaming agent is currently in progress; HCFC 141b blown insulations are scheduled for production implementation in 1995. Realizing that the second generation HCFC blowing agents are an interim solution, the evaluation of third generation blowing agents with zero ozone depletion potential is underway. NASA's TPS Materials Research Laboratory is evaluating third generation blowing agents in cryogenic insulations for the External Tank; one option being investigated is the use of water as a foaming agent. A dimensionally stable insulation with low friability, good adhesion to cryogenic substrates, and acceptable thermal conductivity has been developed with low viscosity materials that are easily processed in molding applications. The development criteria, statistical experimental approach, and resulting foam properties will be presented.

Blevins, Elana↗
NASA NTRS2008

Immune Function Changes during a Spaceflight-Analog Undersea Mission

There is ample evidence to suggest that space flight leads to immune system dysregulation. This may be a result of microgravity, confinement, physiological stress, radiation, environment or other mission-associated factors. It is attractive to utilize ground-based spaceflight analogs as appropriate to investigate this phenomenon. For spaceflight-associated immune dysregulation (SAID), the authors believe the most appropriate analogs might be NEEMO (short duration, Shuttle analog), Antarctic winter-over (long-duration, ISS analog) and the Haughton Mars Project in the Canadian Arctic (intermediate-duration). Each of these analogs replicate isolation, mission-associated stress, disrupted circadian rhythms, and other aspects of flight thought to contribute to SAID. To validate NEEMO as a flight analog with respect to SAID, a pilot study was conducted during the NEEMO-12 and 13 missions during 2007. Assays were performed that assessed immune status, physiological stress and latent viral reactivation. Blood and saliva samples were collected at pre-, mid-, and post-mission timepoints.

Crucian, Brian↗
NASA NTRS1999

Assessment of Localized Deformations in Sand Using X-Ray Computed Tomography

The internal fabric and localized deformation patterns of triaxial sand specimens were investigated using Computed Tomography (CT). Three displacement-controlled, conventional, drained axisymmetric (triaxial) experiments were conducted on dry Ottawa sand specimens at very low effective confining stresses (0.05, 0.52, and 1.30 kPa) in a microgravity environment aboard the Space Shuttle during the NASA STS-79 mission. CT scanning was p'erformed on these flight specimens, as well as on an uncompressed specimen and a specimen tested in a terrestrial laboratory at 1.30 kPa effective confining stress. CT demonstrated high accuracy in detecting specimen inhomogeneity and localization patterns. Formation of deformation patterns is dependent on the effective confining stress and gravity. Multiple symmetrical radial shear bands were observed in the specimens tested in a microgravity environment. In the axial direction, two major conical surfaces were developed. Nonsymmetrical spatial deformation was observed in the 1-G specimen. Analysis tools were developed to quantify the spatial density change. Void ratio variation within and outside the shear bands was calculated and discussed.

Alshibli, Khalid A↗
NASA NTRS1994

Head-Down Suspension Alters Stress-Responsiveness and Feedback Efficacy of 9a-Fludrocortisone in Rats

9a-Fludrocortisone (9aFF) has been used to decrease orthostatic hypotension in astronauts whorl they return to earth after space flight. An earth-based model for weightlessness in space is head-down posture in man and rats. In these studies male rats were suspended head-down or not for 7 days and treated 14 and 2 hours prior to ether stress in the AM with 9aFF (20 micrograms i.u.) at -14 and -2 h or at -2 h with steroid and at -14 h with oil; controls were treated 2x with oil. Rats were decapitated 10 min after ether and ACTH and corticosterone (B) were measured. Both ACTH and B responses were greater in suspended than control rats under all three steroid conditions, and the percentage inhibition of ACTH by 9aFF was similar. Basal activity in the HPA over the 7 d suspension period was probably not elevated since adrenal and thymus weights did not differ in the ambulatory and head down groups. We conclude that headdown suspension facilitates acute stress-induced activity in the HPA axis, but that HPA axis sensitivity to corticosteroid feedback does not change.

Horsley, C. J.↗
NASA NTRSDate not supplied

Fracture Mechanics Testing of Titanium 6AL-4V in LMP-103S Propellant

Propellant tank safe-life analysis is a spacecraft propulsion subsystem Launch Range processing requirement. The material property inputs for the safe-life analysis include the stress intensity factor for environment-assisted cracking (KEAC). The KEAC for titanium alloy Ti 6Al-4V in LMP-103S propellant was determined experimentally using an innovative test method following ASTM E1681, Standard Test Method for Determining Threshold Stress Intensity Factor for Environment-Assisted Cracking of Metallic Materials. This effort was a collaboration between NASA Goddard Space Flight Center and NASA Kennedy Space Center to expose the test specimens in the propellant, while loaded in the test fixtures, for 1000- hour (42 days) at 50°C. Two test rounds have been completed to date; 1) testing mechanically loaded specimens but without propellant and 2) testing mechanically loaded specimens wetted with LMP-103S propellant. The dry test was to evaluate the crack growth without exposure to the LMP-103S propellant, and further assess the un-wetted stress intensity factor for the full 1000-hour duration. The second round of testing included the propellant soak for the requisite 1000- hour at 50°C. Current results show that the threshold intensity factor for environment-assisted cracking (exposed to LMP103S) is 22.5 ksi√in for the bulk material and 36. 2 ksi√in for the weld material. A generic ‘candidate’ tank geometry and material thickness is developed for a damage tolerance of known surface cracks below the nondestructive inspection technique detection limit. Evaluations with and without the use of a threshold intensity factor for environment-assisted cracking is performed for the required 4x propellant tank service life using the software tool NASGRO. SP2024_00239

Green propulsion↗
NASA NTRS2014

Ground Testing of the EMCS Seed Cassette for Biocompatibility with the Cellular Slime Mold, Dictyostelium Discoideum

The European Modular Cultivation System, EMCS, was developed by ESA for plant experiments. To expand the use of flight verified hardware for various model organisms, we performed ground experiments to determine whether ARC EMCS Seed Cassettes could be adapted for use with cellular slime mold for future space flight experiments. Dictyostelium is a cellular slime mold that can exist both as a single-celled independent organism and as a part of a multicellular colony which functions as a unit (pseudoplasmodium). Under certain stress conditions, individual amoebae will aggregate to form multicellular structures. Developmental pathways are very similar to those found in Eukaryotic organisms, making this a uniquely interesting organism for use in genetic studies. Dictyostelium has been used as a genetic model organism for prior space flight experiments. Due to the formation of spores that are resistant to unfavorable conditions such as desiccation, Dictyostelium is also a good candidate for use in the EMCS Seed Cassettes. The growth substratum in the cassettes is a gridded polyether sulfone (PES) membrane. A blotter beneath the PES membranes contains dried growth medium. The goals of this study were to (1) verify that Dictyostelium are capable of normal growth and development on PES membranes, (2) develop a method for dehydration of Dictyostelium spores with successful recovery and development after rehydration, and (3) successful mock rehydration experiments in cassettes. Our results show normal developmental progression in two strains of Dictyostelium discoideum on PES membranes with a bacterial food source. We have successfully performed a mock rehydration of spores with developmental progression from aggregation to slug formation, and production of morphologically normal spores within 9 days of rehydration. Our results indicate that experiments on the ISS using the slime mold, Dictyostelium discoideum could potentially be performed in the flight verified hardware of the EMCS ARC Seed Cassettes.

biocompatibility↗
NASA NTRS2011

Mount Protects Thin-Walled Glass or Ceramic Tubes from Large Thermal and Vibration Loads

The design allows for the low-stress mounting of fragile objects, like thin walled glass, by using particular ways of compensating, isolating, or releasing the coefficient of thermal expansion (CTE) differences between the mounted object and the mount itself. This mount profile is lower than true full kinematic mounting. Also, this approach enables accurate positioning of the component for electrical and optical interfaces. It avoids the higher and unpredictable stress issues that often result from potting the object. The mount has been built and tested to space-flight specifications, and has been used for fiber-optic, optical, and electrical interfaces for a spaceflight mission. This mount design is often metal and is slightly larger than the object to be mounted. The objects are optical or optical/electrical, and optical and/or electrical interfaces are required from the top and bottom. This requires the mount to be open at both ends, and for the object s position to be controlled. Thin inside inserts at the top and bottom contact the housing at defined lips, or edges, and hold the fragile object in the mount. The inserts can be customized to mimic the outer surface of the object, which further reduces stress. The inserts have the opposite CTE of the housing material, partially compensating for the CTE difference that causes thermal stress. A spring washer is inserted at one end to compensate for more CTE difference and to hold the object against the location edge of the mount for any optical position requirements. The spring also ensures that any fiber-optic or optic interface, which often requires some pressure to ensure a good interface, does not overstress the fragile object. The insert thickness, material, and spring washer size can be traded against each other to optimize the mount and stresses for various thermal and vibration load ranges and other mounting requirements. The alternate design uses two separate, unique features to reduce stress and hold the object. A release agent is applied to the inside surface of the mount just before the binding potting material is injected in the mount. This prevents the potting material from bonding to the mount, and thus prevents stress from being applied, at very low temperatures, to the fragile object being mounted. The potting material mixing and curing is temperature- and humidity-controlled. The mount has radial grooves cut in it that the potting material fills, thus controlling the vertical position of the mounted object. The design can easily be used for long and thin objects, short and wide objects, and any shape in between. The design s advantages are amplified for long and thin fragile objects. The general testing range was 45 to +45 C, but multiple mounts were successfully tested down to 60 and up to 50 C and the design can be adjusted for larger ranges.

Amato, Michael↗
NASA NTRS2007

Analysis of Chromosomal Aberrations in the Blood Lymphocytes of Astronauts after Space Flight

It is a NASA requirement that biodosimetry analysis be performed on all US astronauts who participate in long duration missions of 3 months or more onboard the International Space Station. Cytogenetic analysis of blood lymphocytes is the most sensitive and reliable biodosimetry method available at present, especially if chromosome damage is assessed before as well as after space flight. Results provide a direct measurement of space radiation damage in vivo that takes into account individual radiosensitivity and considers the influence of microgravity and other stress conditions. We present data obtained from all twenty-five of the crewmembers who have participated in the biodosimetry program so far. The yield of chromosome exchanges, measured using fluorescence in situ hybridization (FISH) technique with chromosome painting probes, increased after space flight for all these individuals. In vivo dose was derived from frequencies of chromosome exchanges using preflight calibration curves of in vitro exposed cells from the same individual, and RBE was compared with individually measured physically absorbed dose and projected organ dose equivalents. Biodosimetry estimates using samples collected within a few weeks of return from space lie within the range expected from physical dosimetry. For some of these individuals chromosome aberrations were assessed again several months after their respective missions and a temporal decline in stable exchanges was observed in some cases, suggesting that translocations are unstable with time after whole body exposure to space radiation. This may indicate complications with the use of translocations for retrospective dose reconstruction. Data from one crewmember who has participated in two separate long duration space missions and has been followed up for over 10 years provides limited data on the effect of repeat flights and shows a possible adaptive response to space radiation exposure.

George, K.↗
NASA NTRS2008

Building a GPS Receiver for Space Lessons Learned

Over the past 4 years the Component Systems and Hardware branch at NASA GSFC has pursued an inhouse effort to build a unique space-flight GPS receiver. This effort has resulted in the Navigator GPS receiver. Navigator's first flight opportunity will come with the STS-125 HST-SM4 mission in August 2008. This paper covers the overall hardware design for the receiver and the difficulties encountered during the transition from the breadboard design to the final flight hardware design. Among the different lessons learned, the paper stresses the importance of selecting and verifying parts that are appropriate for space applications, as well as what happens when these parts are not accurately characterized by their datasheets. Additionally, the paper discusses what analysis needs to be performed when deciding system frequencies and filters. The presentation also covers how to prepare for thermal vacuum testing, and problems that may arise during vibration testing. It also contains what criteria should be considered when determining which portions of a design to create in-house, and which portions to license from a third party. Finally, the paper shows techniques which have proven to be extraordinarily helpful in debugging and analysis.

Sirotzky, Steve↗
NASA NTRS1999

The Effect of Skeletal Unloading on Bone Formation: Role of IGF-I

The best documented change in bone during space flight is the near cessation of bone formation. Space flight leads to a decrease in osteoblast number and activity, likely the result of altered differentiation of osteoblast precursors. The net result of these space flight induced changes is weaker bone. To understand the mechanism for these changes poses a challenge. Space flight studies must overcome enormous technical problems, and are necessarily limited in size and frequency. Therefore, ground based models have been developed to evaluate the effects of skeletal unloading. The hindlimb elevation (tail suspension) model simulates space flight better than other models because it reproduces the fluid shifts seen in space travel, is reversible, and is well tolerated by the animals with minimal evidence of stress as indicated by continued weight gain and normal levels and circadian rhythms of corticosterone. This is the model we have used for our experiments. Skeletal unloading by the hindlimb elevation method simulates a number of features of space flight in that bone formation, mineralization, and maturation are inhibited, osteoblast number is decreased, serum and skeletal osteocalcin levels fall, the ash content of bone decreases, and bone strength diminishes. We and others have shown that when osteoblasts or osteoprogenitor cells from the bones of the unloaded limbs are cultured in vitro they proliferate and differentiate more slowly, suggesting that skeletal unloading causes a persistent change in cell function which can be assessed in vitro. In contrast to the unweighted bones of the hindlimbs, no significant change in bone mass or bone formation is observed in the humeri, mandible, and cervical vertebrae during hindlimb elevation. The lack of effect of hindlimb elevation on bones like the humeri, mandible, and cervical vertebrae which are not unloaded by this procedure suggests that local factors rather than systemic effects dominate the response of bone to skeletal unloading. We have focussed on the role of IGF- 1 as the local factor mediating the effects of skeletal unloading on bone formation. IGF-I is produced by bone cells and chondrocytes; these cells have receptors for IGF-I, and respond to IGF-I with an increase in proliferation and function (e.g. collagen, and glycosaminoglycan production, respectively). IGF-I production by bone is under hormonal control, principally by GH and PTH, and IGF-I is thought to mediate some if not all of the effects of GH and PTH on bone growth. Thus, systemic changes in hormones such as GH and PTH may still have effects which vary from bone to bone depending on the loading history.

Bikle, D. D.↗
NASA NTRS1980

Evaluation of the stress corrosion cracking resistance of several high strength low alloy steels

The stress corrosion cracking resistance was studied for high strength alloy steels 4130, 4340, for H-11 at selected strength levels, and for D6AC and HY140 at a single strength. Round tensile and C-ring type specimens were stressed up to 100 percent of their yield strengths and exposed to alternate immersion in salt water, salt spray, the atmosphere at Marshall Space Flight Center, and the seacoast at Kennedy Space Center. Under the test conditions, 4130 and 4340 steels heat treated to a tensile strength of 1240 MPa (180 ksi), H-11 and D6AC heat treated to a tensile strength of 1450 MPa (210 ksi), and HY140 (1020 MPa, 148 ksi) are resistant to stress corrosion cracking because failures were not encountered at stress levels up to 75 percent of their yield strengths. A maximum exposure period of one month for alternate immersion in salt water or salt spray and three months for seacoast is indicated for alloy steel to avoid false indications of stress corrosion cracking because of failure resulting from severe pitting.

Humphries, T. S.↗
NASA NTRS1975

Effect of thermal profile on cyclic flaw growth in aluminum

Surface flawed and single edge notch tension specimens of 2219-T851 and -T87 aluminum were tested to determine static fracture characteristics and base line (constant amplitude, constant temperature) cyclic flaw growth behavior. Subsequent testing was then conducted in which flawed specimens were subjected to a thermal profile in which the applied stress was varied simultaneously with the temperature. The profile used represents a simplified space shuttle orbiter load/temperature flight cycle. Test temperatures included the range from 144K (-200 F) up to 450K (350 F). The measured flaw growth rates obtained from the thermal profile tests were then compared with rates predicted by assuming linear cumulative damage of base line rates.

Engstrom, W. L.↗
NASA NTRS1975

Research study on multi-KW DC distribution system

Power distribution system noise and transient stress on switchgear in large space vehicle power systems were investigated in terms of the effect of flight designs of long power distribution cables on load interface EMI requirements. A fifty meter cable pair was simulated to study interactions between the cable, load, and power source terminations. Power system noise characteristics were evaluated based on current spacecraft data, interface hardware filter designs, and power cable parameters. Parametric approaches were defined for evaluating switching transients at various distribution voltage levels. It is concluded that the state-of-the-art semiconductor switches represent a viable approach toward the implementation of power system design with distribution voltages of 120 VDC or less. The interface definition and design for the bus control unit was updated to be consistent with the established requirements.

Berkery, E. A.↗
NASA NTRS1975

User's instructions for the whole-body algorithms

The design of an algorithm that provides for the simulation of long and short term biological stresses is reported. The physiological responses of models representing circulatory, respiratory, cardiovascular, and thermoregulatory systems during space flight simulation are described.

Grounds, D. J.↗
NASA NTRS1999

Quantifying Void Ratio Variation in Sand using Computed Tomography

A series of displacement-controlled, conventional, drained axisymmetric (triaxial) experiments were conducted on dry Ottawa sand specimens at very low effective confining stresses in a microgravity environment aboard the Space Shuttle during the NASA STS-89 mission. Post-flight analysis included studying the internal fabric and failure patterns of these specimens using Computed Tomography (CT). The CT scans of three specimens subjected to different compression levels (uncompressed specimen, a specimen compressed to 3.3% nominal axial strain (epsilon(sub a)), and a specimen compressed to 25% epsilon(sub a)) are presented to investigate the evolution of instability patterns and to quantify void ratio variation. The progress of failure is described and discussed. Also, specimens' densities were calibrated using standard ASTM procedures and void ratio spatial variation was calculated and represented by contour maps and histograms. The CT technique demonstrated good ability to detect specimen inhomogeneities, localization patterns, and quantifying void ratio variation within sand specimens.

Alshibli, Khalid A.↗
NASA NTRS2016

Absolute Navigation Performance of the Orion Exploration Fight Test 1

Launched in December 2014 atop a Delta IV Heavy from the Kennedy Space Center, the Orion vehicle's Exploration Flight Test-1 (EFT-1) successfully completed the objective to stress the system by placing the un-crewed vehicle on a high-energy parabolic trajectory replicating conditions similar to those that would be experienced when returning from an asteroid or a lunar mission. Unique challenges associated with designing the navigation system for EFT-1 are presented with an emphasis on how redundancy and robustness influenced the architecture. Two Inertial Measurement Units (IMUs), one GPS receiver and three barometric altimeters (BALTs) comprise the navigation sensor suite. The sensor data is multiplexed using conventional integration techniques and the state estimate is refined by the GPS pseudorange and deltarange measurements in an Extended Kalman Filter (EKF) that employs UDU factorization. The performance of the navigation system during flight is presented to substantiate the design.

Zanetti, Renato↗
NASA NTRS1979

Space flight research relevant to health, physical education, and recreation: With particular reference to Skylab's life science experiments

Data collected in the Skylab program relating to physiological stresses is presented. Included are routine blood measures used in clinical medicine as research type endocrine analyses to investigate the metabolic/endocrine responses to weightlessness. The daily routine of physical exercise, coupled with appropriate dietary intake, sleep, work, and recreation periods were considered essential in maintaining the crew's health and well being.

Vanhuss, W. D.↗