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Research Containing: Space Flight

MOSFET dosimetry mission inside the ISS as part of the Matroshka-R experiment

by on 9 June 2015in Technology Development & Demonstration No comment

Radiation measurements of surface and deep organ doses were performed aboard the International Space Station, for the period of January 2006 to April 2007, using a MOSFET dosimetry system combined with the Matroshka-R spherical phantom. The averaged internal and surface dose rates are found to be 0.19 and 0.29 mGy d(-1), respectively. The levels of radiation dose to blood-forming organs (BFO) and to surface organs are compared with recommended safe limits. The maximum measured BFO dose has an average dose rate of 0.23 mGy d(-1) (84 mGy y(-1)), corresponding to 44 % of the recommended annual limit of 0.5 Sv, for a space radiation quality factor of 2.6. The annual surface dose is found to be higher at 126 mGy, corresponding to 16 % of the eye dose limit and to 11 % of the skin dose limit. Doses calculated using the Spenvis software showed deviations of up to 37 % from measurements.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/19933696

Microflow1, a sheathless fiber-optic flow cytometry biomedical platform: demonstration onboard the international space station

by on 9 June 2015in Technology Development & Demonstration No comment

A fiber-optic based flow cytometry platform was designed to build a portable and robust instrument for space applications. At the core of the Microflow1 is a unique fiber-optic flow cell fitted to a fluidic system and fiber coupled to the source and detection channels. A Microflow1 engineering unit was first tested and benchmarked against a commercial flow cytometer as a reference in a standard laboratory environment. Testing in parabolic flight campaigns was performed to establish Microflow1's performance in weightlessness, before operating the new platform on the International Space Station. Microflow1 had comparable performances to commercial systems, and operated remarkably and robustly in weightlessness (microgravity). Microflow1 supported immunophenotyping as well as microbead-based multiplexed cytokine assays in the space environment and independently of gravity levels. Results presented here provide evidence that this fiber-optic cytometer technology is inherently compatible with the space environment with negligible compromise to analytical performance.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/24339248

A Research Plan for Fire Prevention, Detection and Suppression in Crewed Exploration Systems

by on 9 June 2015in Technology Development & Demonstration No comment

Fire is a particularly critical danger in future extraterrestrial vehicles and habitats on long-range, long-duration missions since, unlike in most scenarios here on Earth, escape is not an option and the fire department will not be coming. In such vehicles and habitats, the first line defense lies in determining the ignitability and flammability of candidate materials under reduced and microgravity condition and at appropriate oxygen mole fractions and then using this information to help select materials to be used in these vehicles and habitats. If, despite our efforts to prevent a fire, one does occur, our next line of protection is fact and reliable detection of such occurrences (with minimum false positives) and definition of their location. After a fire and its location have been identified, we must have reliable means of extinguishing this fire as quickly as possible with as little impact to the mission and crew as possible. Finally, post-fire cleanup, toxicology of fire products and products of the interaction of the flame with the extinguishing, and virtual simulation training of the crew in fighting fires are also important areas which must be addressed by the research plan presented in this paper.

Related URLs:
http://dx.doi.org/10.2514/6.2005-341

ISS Acoustics Mission Support

by on 9 June 2015in Technology Development & Demonstration No comment

The ISS Acoustics Office provides space flight mission support on all acoustic-related issues and tasks. As part of this support, we define, develop, and implement requirements for a comprehensive noise mitigation program for space flight and the International Space Station. To ensure these requirements are complied with, we utilize on-orbit testing to define the environment, derive measures to safeguard the health, safety, and well being of flight crewmembers, and work on measures to reduce unacceptable levels. This program preserves crewmembers' hearing and provides for a safe, productive, and comfortable noise environment. This paper describes crew training with acoustic measurement devices, on-orbit testing, real-time remedial actions, the types of data produced, and examples of recommendations that are made to protect the crewmember's hearing.

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Microgravity flight characterization of the International Space Station active rack isolation system

by on 9 June 2015in Technology Development & Demonstration No comment

Space flight experiment test results of a Space Station Active Rack Isolation System (ARIS) are presented. The purpose of ARIS is to isolate microgravity sensitive science experiments mounted in Space Station racks from structural vibrations present on the large Space Station orbital structure. The overall objectives of the experiment were 1) to test and evaluate the ARIS design modifications made from 1997 to 2000 as a result of prototype flight testing performed on the Space Shuttle Atlantis, 2) to characterize isolation performance on the International Space Station, 3) to assess the impact that rack payload disturbances have on the microgravity environment, 4) to test alternative umbilicals designed to improve isolation performance, and 5) to gain on-orbit operational experience and validate procedures. The scope of the material presented is limited to microgravity performance issues, so only results related to the first four objectives are presented. Over a year of flight testing was completed, and ARIS consistently has performed extremely well such that station vibrations were isolated to levels well below the science requirement.

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Foam stability in microgravity

by on 9 June 2015in Physical Sciences No comment

Within the context of the ESA FOAM project, we have studied the stability of aqueous and non-aqueous foams both on Earth and in microgravity. Foams are dispersions of gas into liquid or solid. On Earth, the lifetime of a foam is limited by the free drainage. By drainage, we are referring to the irreversible flow of liquid through the foam (leading to the accumulation of liquid at the foam bottom, and to a global liquid content decreases within the foam). When the liquid films become thinner, they eventually break, and the foam collapses. In microgravity, this process is no more present and foams containing large amounts of liquid can be studied for longer time. While the difference between foaming and not-foaming solutions is clear, the case of slightly-foaming solutions is more complicated. On Earth, such mixtures are observed to produce unstable froth for a couple of seconds. However, these latter solutions may produce foam in microgravity. We have studied both configurations for different solutions composed of common surfactant, proteins, anti-foaming agents or silicon oil. Surprising results have been obtained, emphasizing the role played by gravity on the foam stabilization process.

Related URLs:
http://stacks.iop.org/1742-6596/327/i=1/a=012024

Ground‐Laboratory to In‐Space Atomic Oxygen Correlation for the PEACE Polymers

by on 9 June 2015in Physical Sciences No comment

The Materials International Space Station Experiment 2 (MISSE 2) Polymer Erosion and Contamination Experiment (PEACE) polymers were exposed to the environment of low Earth orbit (LEO) for 3.95 years from 2001 to 2005. There were forty‐one different PEACE polymers, which were flown on the exterior of the International Space Station (ISS) in order to determine their atomic oxygen erosion yields. In LEO, atomic oxygen is an environmental durability threat, particularly for long duration mission exposures. Although space flight experiments, such as the MISSE 2 PEACE experiment, are ideal for determining LEO environmental durability of spacecraft materials, ground‐laboratory testing is often relied upon for durability evaluation and prediction. Unfortunately, significant differences exist between LEO atomic oxygen exposure and atomic oxygen exposure in ground‐laboratory facilities. These differences include variations in species, energies, thermal exposures and radiation exposures, all of which may result in different reactions and erosion rates. In an effort to improve the accuracy of ground‐based durability testing, ground‐laboratory to in‐space atomic oxygen correlation experiments have been conducted. In these tests, the atomic oxygen erosion yields of the PEACE polymers were determined relative to Kapton H using a radio‐frequency (RF) plasma asher (operated on air). The asher erosion yields were compared to the MISSE 2 PEACE erosion yields to determine the correlation between erosion rates in the two environments. This paper provides a summary of the MISSE 2 PEACE experiment; it reviews the specific polymers tested as well as the techniques used to determine erosion yield in the asher, and it provides a correlation between the space and ground‐laboratory erosion yield values. Using the PEACE polymers’ asher to in‐space erosion yield ratios will allow more accurate in‐space materials performance predictions to be made based on plasma asher durability evaluation.

Related URLs:
http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.3076865

Spaceflight reduces vasoconstrictor responsiveness of skeletal muscle resistance arteries in mice

by on 9 June 2015in Physical Sciences No comment

Cardiovascular adaptations to microgravity undermine the physiological capacity to respond to orthostatic challenges upon return to terrestrial gravity. The purpose of the present study was to investigate the influence of spaceflight on vasoconstrictor and myogenic contractile properties of mouse gastrocnemius muscle resistance arteries. We hypothesized that vasoconstrictor responses acting through adrenergic receptors [norepinephrine (NE)], voltage-gated Ca2+ channels (KCl), and stretch-activated (myogenic) mechanisms would be diminished following spaceflight. Feed arteries were isolated from gastrocnemius muscles, cannulated on glass micropipettes, and physiologically pressurized for in vitro experimentation. Vasoconstrictor responses to intraluminal pressure changes (0–140 cmH2O), KCl (10–100 mM), and NE (10−9-10−4 M) were measured in spaceflown (SF; n = 11) and ground control (GC; n = 11) female C57BL/6 mice. Spaceflight reduced vasoconstrictor responses to KCl and NE; myogenic vasoconstriction was unaffected. The diminished vasoconstrictor responses were associated with lower ryanodine receptor-2 (RyR-2) and ryanodine receptor-3 (RyR-3) mRNA expression, with no difference in sarcoplasmic/endoplasmic Ca2+ ATPase 2 mRNA expression. Vessel wall thickness and maximal intraluminal diameter were unaffected by spaceflight. The data indicate a deficit in intracellular calcium release via RyR-2 and RyR-3 in smooth muscle cells as the mechanism of reduced contractile activity in skeletal muscle after spaceflight. Furthermore, the results suggest that impaired end-organ vasoconstrictor responsiveness of skeletal muscle resistance arteries contributes to lower peripheral vascular resistance and less tolerance of orthostatic stress in humans after spaceflight.

Related URLs:
http://jap.physiology.org/jap/113/9/1439.full.pdf
http://jap.physiology.org/content/jap/113/9/1439.full.pdf

Detecting accelerometric nonlinearities in the international space station

by on 9 June 2015in Physical Sciences No comment

The present work aims to study mechanical nonlinearities detected in the accelerometric records during a thermodiffusion experiment performed at the International Space Station, ISS. In that experiment the test cell was subjected to harmonic vibrations of different frequencies and amplitudes. Accelerometric data associated to the runs were downloaded from NASA PIMS website. Second order spectral analysis shows that the shaker modifies the normality of the data and introduces nonlinearities in the distribution of energy. High Order Spectral Analysis, HOSA, based on the bispectrum, bicoherence, trispectrum and tricoherence functions enabled us to study the kind of these nonlinearities. Additionally, a new method using the biphase and triphase histograms helps us to assess if quadratic and/or cubic phase coupling mechanisms are responsible for the anomalous nonlinear energy transfer detected. Finally, the RMS acceleration values are investigated to check if the vibratory limit requirements of the ISS are exceeded. This methodology is important not only in generic research of aerospace engineering but also in space sciences in order to help space researchers to characterize more globally their experiments. It is mentioned finally that HOSA techniques are not new, but never have been used in the analysis of accelerometric data coming from the ISS.

Related URLs:
http://www.sciencedirect.com/science/article/pii/S0094576514002240