Fluorinated Single Wall Nanotube/Polyethylene Composites for Multifunctional Radiation Protection

2002 ◽  
Vol 740 ◽  
Author(s):  
Merlyn X. Pulikkathara ◽  
Meisha L. Shofner ◽  
Richard T. Wilkins ◽  
Jesus G. Vera ◽  
Enrique V. Barrera ◽  
...  
Keyword(s):  
Radiation Protection ◽  
Space Mission ◽  
Low Earth Orbit ◽  
Proton Radiation ◽  
Freeform Fabrication ◽  
Nanotube Composites ◽  
Total Fluence ◽  
Hydrogen Exposure ◽  
The Stability ◽  
Single Wall Nanotubes

ABSTRACTFluorinated Single Wall Nanotubes (f-SWNTs) have been processed in polyethylene by an incipient wetting technique to achieve a well dispersed nanocomposite for radiation protection. In some cases, samples were further processed using the rapid prototyping method of extrusion freeform fabrication. Composites were exposed to 40 MeV proton radiation with a flux of about 1.7×107 protons/cm2/sec to a total fluence of 3×1010 protons/cm2.This exposure is consistent with a long-term space mission in low earth orbit. The samples were evaluated by means of Raman spectroscopy and thermogravimetric analysis (TGA). These results were compared to the unexposed composite and unfilled polymer samples. This study has focused on the stability of the nanotube composites when exposed to radiation and prior to hydrogen exposure. It was shown that the stability of the functional group is not constant with SWNTs produced by different processes and that radiation exposure is capable of defluorinating SWNTs in polyethylene.

Proton Irradiation Effects on Scandium Oxide/Gallium Nitride MOS Diodes

2001 ◽  
Vol 693 ◽  
Author(s):  
K. Allums ◽  
B. Luo ◽  
R. Mehandru ◽  
B. P. Gila ◽  
R. Dwivedi ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Proton Irradiation ◽  
Gate Dielectric ◽  
Schottky Diodes ◽  
Low Earth Orbit ◽  
Oxide Semiconductor ◽  
Breakdown Field ◽  
Proton Radiation ◽  
High Doses ◽  
The Stability

AbstractThe stability to proton radiation of GaN metal oxide semiconductor (MOS) diodes fabricated using the novel gate dielectric Sc2O3 was investigated. The MOS diodes were fabricated by depositing the dielectric with molecular beam epitaxy onto MOCVD-grown GaN on sapphire. The stability of GaN Schottky diodes was also investigated for comparison. Current-voltage (I-V) and capacitance-voltage (C-V), were employed to monitor any change in the electrical characteristics of the diodes. Preliminary testing indicates that the GaN-based diodes are in fact affected by proton irradiation, but only at fairly high doses. Doses equivalent to 10 years in low earth orbit, ~5x109cm-2, produce a decrease in the reverse breakdown field in both Schottky and MOS diodes. However, even after irradiation, the GaN MOS diodes showed twice the reverse breakdown voltage of non-irradiated Schottky diodes. Further, while the Schottky diodes showed reduced forward breakdown voltage, the MOS diodes showed no change in forward breakdown. These results suggest that the oxide/GaN interface is stable and is not being damaged by the radiation. The change in reverse breakdown is most likely due to generation of damage in the GaN resulting in the formation of shallow donors.

scholarly journals An advance in transfer line chilldown heat transfer of cryogenic propellants in microgravity using microfilm coating for enabling deep space exploration

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
J. N. Chung ◽  
Jun Dong ◽  
Hao Wang ◽  
S. R. Darr ◽  
J. W. Hartwig
Keyword(s):  
Space Exploration ◽  
Fluid Management ◽  
Microgravity Condition ◽  
Space Mission ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Deep Space ◽  
Deep Space Exploration ◽  
Quenching Efficiency ◽  
Proper Perspective

AbstractThe extension of human space exploration from a low earth orbit to a high earth orbit, then to Moon, Mars, and possibly asteroids is NASA’s biggest challenge for the new millennium. Integral to this mission is the effective, sufficient, and reliable supply of cryogenic propellant fluids. Therefore, highly energy-efficient thermal-fluid management breakthrough concepts to conserve and minimize the cryogen consumption have become the focus of research and development, especially for the deep space mission to mars. Here we introduce such a concept and demonstrate its feasibility in parabolic flights under a simulated space microgravity condition. We show that by coating the inner surface of a cryogenic propellant transfer pipe with low-thermal conductivity microfilms, the quenching efficiency can be increased up to 176% over that of the traditional bare-surface pipe for the thermal management process of chilling down the transfer pipe. To put this into proper perspective, the much higher efficiency translates into a 65% savings in propellant consumption.

scholarly journals A GA-SA Hybrid Planning Algorithm Combined with Improved Clustering for LEO Observation Satellite Missions

Algorithms ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 231
Author(s):  
Xiangyu Long ◽  
Shufan Wu ◽  
Xiaofeng Wu ◽  
Yixin Huang ◽  
Zhongcheng Mu
Keyword(s):  
Clustering Algorithm ◽  
Simulated Annealing Algorithm ◽  
Space Mission ◽  
Theory Model ◽  
Low Earth Orbit ◽  
Mission Planning ◽  
Experimental Simulation ◽  
Two Phase ◽  
Fitness Value ◽  
Planning Algorithm

This paper presents a space mission planning tool, which was developed for LEO (Low Earth Orbit) observation satellites. The tool is focused on a two-phase planning strategy with clustering preprocessing and mission planning, where an improved clustering algorithm is applied, and a hybrid algorithm that combines the genetic algorithm with the simulated annealing algorithm (GA–SA) is given and discussed. Experimental simulation studies demonstrate that the GA–SA algorithm with the improved clique partition algorithm based on the graph theory model exhibits higher fitness value and better optimization performance and reliability than the GA or SA algorithms alone.

One Variant of Manned Mission to Mars with a Nuclear Electric Propulsion

2011 ◽  
Vol 1 (2) ◽  
pp. 1-17 ◽  
Author(s):  
M. S. Konstantinov ◽  
H. W. Loeb ◽  
V. G. Petukhov ◽  
G. A. Popov
Keyword(s):  
Electric Propulsion ◽  
Space Mission ◽  
Optimization Criterion ◽  
Low Earth Orbit ◽  
Problem Definition ◽  
Specific Mass ◽  
Propulsion Systems ◽  
Propulsion Efficiency ◽  
Mass Minimization ◽  
Low Mass

In this paper, one possible way for implementing a manned mission to Mars is examined. Typical peculiarities of the mission are as follows: the nuclear electric propulsion; relatively low mass of the spacecraft at a low Earth orbit (200 tons) and the crew time in flight is high (900-1000 days). Space mission analysis of the chosen variant is performed. As an optimization criterion, the authors chose the fuel mass required for the flight. Under examined problem definition such mass minimization is equivalent to maximal final mass of the spacecraft and maximal permissible total mass of power and electric propulsion systems. The authors show that to implement the examined manned mission, it is necessary to create the nuclear electric power and electric propulsion systems with a specific mass lower than 12.5 kg/kW under propulsion efficiency of 0.8, specific mass of the system for propellant storage of 0.05 and manned spacecraft complex mass of 52.1 tons. Under propulsion efficiency of 0.7, specific mass of power-propulsion should be lower than 10.9 kg/kW.

Twinkle: a low-Earth orbit, visible and infrared observatory for exoplanet and solar system spectroscopy

2020 ◽  
Author(s):  
Billy Edwards ◽  
Marcell Tessenyi ◽  
Giovanna Tinetti ◽  
Giorgio Savini ◽  
Ian Stotesbury ◽  
...  
Keyword(s):  
Solar System ◽  
Thermal Environment ◽  
Space Mission ◽  
Low Earth Orbit ◽  
Atmospheric Composition ◽  
Orbital Parameters ◽  
Short Period ◽  
Wide Range ◽  
Solar System Objects ◽  
Scientific Potential

<p>The Twinkle Space Mission is a space-based observatory that has been conceived to measure the atmospheric composition of exoplanets, stars and solar system objects. The satellite is based on a high-heritage platform and will carry a 0.45 m telescope with a visible and infrared spectrograph providing simultaneous wavelength coverage from 0.5 - 4.5 μm. The spacecraft will be launched into a Sun-synchronous low-Earth polar orbit and will operate in this highly stable thermal environment for a baseline lifetime of seven years.</p> <p>Twinkle will have the capability to provide high-quality infrared spectroscopic characterisation of the atmospheres of hundreds of bright exoplanets, covering a wide range of planetary types. It will also be capable of providing phase curves for hot, short-period planets around bright stars targets and of providing ultra-precise photometric light curves to accurately constrain orbital parameters, including ephemerides and TTVs/TDVs present in multi-planet systems.</p> <p>Twinkle is available for researchers around the globe in two ways:</p> <p>1) joining its collaborative multi-year survey programme, which will observe hundreds of exoplanets and solar system objects; and</p> <p>2) accessing dedicated telescope time on the spacecraft, which they can schedule for any combination of science cases.</p> <p>I will present an overview of Twinkle’s capabilities and discuss some example exoplanet surveys to highlight the broad range of targets the mission could observe, demonstrating the huge scientific potential of the spacecraft.</p>

Twinkle: a low-Earth orbit, visible and infrared observatory for exoplanet and solar system spectroscopy

2020 ◽  
Author(s):  
Billy Edwards ◽  
Marcell Tessenyi ◽  
Giorgio Savini ◽  
Giovanna Tinetti ◽  
Ian Stotesbury ◽  
...  
Keyword(s):  
Solar System ◽  
Near Infrared ◽  
Surface Composition ◽  
Thermal Environment ◽  
Space Mission ◽  
Low Earth Orbit ◽  
Atmospheric Composition ◽  
Solar System Objects ◽  
Scientific Potential ◽  
Asteroids And Comets

<p>The Twinkle Space Mission is a space-based observatory that has been conceived to measure the atmospheric composition of exoplanets, stars and solar system objects. The satellite is based on a high-heritage platform and will carry a 0.45 m telescope with a visible and infrared spectrograph providing simultaneous wavelength coverage from 0.5 - 4.5 μm. The spacecraft will be launched into a Sun-synchronous low-Earth polar orbit and will operate in this highly stable thermal environment for a baseline lifetime of seven years.</p> <p>Twinkle’s rapid pointing and non-sidereal tracking capabilities will enable the observation of a diverse array of Solar System objects, including asteroids and comets. Twinkle aims to provide a visible and near-infrared spectroscopic population study of asteroids and comets to study their surface composition and monitor activity. Its wavelength coverage and position above the atmosphere will make it particularly well-suited for studying hydration features that are obscured by telluric lines from the ground as well as searching for other spectral signatures such as organics, silicates and CO<sub>2</sub>.</p> <p>Twinkle is available for researchers around the globe in two ways:</p> <p>1) joining its collaborative multi-year survey programme, which will observe hundreds of exoplanets and solar system objects; and</p> <p>2) accessing dedicated telescope time on the spacecraft, which they can schedule for any combination of science cases.</p> <p>I will present an overview of Twinkle’s capabilities and discuss the broad range of targets the mission could observe, demonstrating the huge scientific potential of the spacecraft.</p>

Fungal biomarkers are detectable in Martian rock-analogues after space exposure: implications for the search of life on Mars

2021 ◽  
pp. 1-14
Author(s):  
Claudia Pacelli ◽  
Alessia Cassaro ◽  
Mickael Baqué ◽  
Laura Selbmann ◽  
Laura Zucconi ◽  
...  
Keyword(s):  
Prebiotic Chemistry ◽  
Low Earth Orbit ◽  
Primary Target ◽  
Life On Mars ◽  
Organic Biomarkers ◽  
Target Molecules ◽  
Polymerase Chain ◽  
Fungal Biomarkers ◽  
The Stability

Abstract Mars is a primary target of astrobiological interest: its past environmental conditions may have been favourable to the emergence of a prebiotic chemistry and, potentially, biological activity. In situ exploration is currently underway at the Mars surface, and the subsurface (2 m depth) will be explored in the future ESA ExoMars mission. In this context, BIOlogy and Mars EXperiment was performed to evaluate the stability and detectability of organic biomarkers under space and Mars-like conditions. Our data suggested that some target molecules, namely melanin, azelaic acid and nucleic acids, can be detected even after 16 months exposure to Low Earth Orbit conditions by multidisciplinary approaches. We used the same techniques as onboard the ExoMars rover, as Raman and infrared spectroscopies and gas chromatograph-mass spectrometer, and polymerase chain reaction even if this is not planned for the imminent mission to Mars. These results should be taken into account for future Mars exploration.

scholarly journals Phase Separation in Porous Media Integrated Capillary Channels

2020 ◽  
Vol 32 (6) ◽  
pp. 1001-1018
Author(s):  
Kamal S. Bisht ◽  
Michael E. Dreyer
Keyword(s):  
Porous Media ◽  
Phase Separation ◽  
Life Support ◽  
Parabolic Flight ◽  
Rectangular Channel ◽  
Low Earth Orbit ◽  
Deep Space Exploration ◽  
Point Pressure ◽  
Pass Through ◽  
The Stability

Abstract Phase separation in space is critical for gas-free propellant supply, life support systems, refueling of spacecraft in low earth orbit (LEO), and for deep space exploration missions. In the absence of gravity, the stability of the liquid-gas interface depends on capillary forces. High liquid flow rates, sudden accelerations, and vibrational disturbances can cause the free surface of the liquid to collapse, which results in the ingestion of gas. Propellant tanks may have screen channel liquid acquisition devices (SCLADs) to position and maintain a gas-free propellant supply to the outlet. A saturated porous screen permits liquid to pass through but acts as a barrier to the gas. We investigated phase separation in porous media integrated capillary channels during parabolic flights (33rd DLR parabolic flight campaign in March 2019). An open side of a rectangular channel was covered with a dutch twill weave 200×1400. The liquid was ingested into the channel from its surroundings by establishing a differential pressure across the screen section. The gas-phase was blocked during the liquid withdrawal. We could show that the gas breakthrough occurs when the pressure difference across the screen exceeds the bubble point pressure. The experimental results showed good agreement with correlations from literature.

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