The electrical resistivity of monolayer graphene exhibit significant changes upon expose to different concentration of oxygen (O2) at room temperature. The monolayer graphene, grown by chemical vapor deposition with perfect uniformity within 1 cm × 1 cm will attach O2 molecules and enhance the hole conductivity, which will lead to a change of resistivity of graphene thin film. We quantified the change of resistivity of graphene versus different O2 concentration and the detection limit of the simple O2 sensor was 1.25% in volume ratio.

https://ir.nctu.edu.tw:443/bitstream/11536/15036/1/000298254200062.pdf

Oxygen sensors made by monolayer graphene under room temperature

The selection of spacecraft and space suit atmospheres for future human space exploration missions will play an important, if not critical, role in the ultimate safety, productivity, and cost of such missions. Internal atmosphere pressure and composition (particularly oxygen concentration) influence many aspects of spacecraft and space suit design, operation, and technology development. Optimal atmosphere solutions must be determined by iterative process involving research, design, development, testing, and systems analysis. A necessary first step in this process is the establishment of working bounds on the atmosphere design space.

/pdf/bounding-the-spacecraft-atmosphere-design-space-for-future-3g7zsvoxj3.pdf

Bounding the Spacecraft Atmosphere Design Space for Future Exploration Missions

There is provided a vessel storing cryogenic fluid having a passive thermodynamic venting system for effectively and reliably transferring heat in a reduced-gravity environment. The storage vessel has a storage tank for holding the cryogenic fluid under pressure. The storage vessel is compartmentalized using a screen trap so that the heat exchanger of the venting system extends through a compartment which includes only the liquid phase of the cryogenic fluid. A screen gallery, screen trap and vane assembly cooperate to separate the gas and the liquid phases of the cryogenic fluid. The thermodynamic venting system includes a throttle device for reducing the temperature of cryogenic fluid. A conduit in contact with heat exchange elements transfers heat from the liquid phase of the cryogenic fluid to a relief valve for venting the heat external of the storage tank.

Passive low gravity cryogenic storage vessel

Liquid Acquisition Devices for Advanced In-Space Cryogenic Propulsion Systems

Influential factors for liquid acquisition device screen selection for cryogenic propulsion systems

A program was conducted to provide the technology base for the SS/RCS flight tankage. Through a combination of analysis, subscale testing and computer predictions, a surface tension acquisition/expulsion system design was developed for the Orbiter RCS application. A full-scale tank system was fabricated and ground verification testing was conducted. Cleaning, inspection, fill and drain, and one-g expulsion performance were demonstrated. Results show that the fine-mesh screen, compartmented tank system provides the performance, flexibility, reusability, and other characteristics required by the pulsing, high flowrate RCS. It provides the required expulsion under widely differing high-g boost abort and reentry vectors oriented 119 deg apart and during on-orbit operation under omnidirectional low-g conditions.

Surface Tension Propellant Acquisition System Technology for Space Shuttle Reaction Control Tanks

An assessment of habitat pressure, oxygen fraction, and EVA suit design for space operations

In support of NASA’s Superfluid Helium On-Orbit Transfer (SHOOT) Flight Experiment, two pumping approaches are being evaluated. NASA-GSFC is conducting tests on the thermomechanical (TM) pump while NASA-ARC is sponsoring tests on a centrifugal pump at the NBS Cryogenic Laboratory. For either of these approaches, a common concern is the method that should be employed for fluid acquisition. While technology is available for design, fabrication, and operation of fluid acquisition systems with conventional fluids, performance with superfluid helium (SFHe) is uncertain. As a result, Martin Marietta joined with NASA to investigate the use of capillary acquisition systems. Assurance is needed that the devices will work with superfluid helium under an adverse 10−4g operational environment. Minus one-g outflow tests were conducted with SFHe in conjunction with the TM pump set-up in the Cryogenic Laboratories at GSFC. Both fine mesh screen and porous sponge systems were tested. A screen acquisition device was also tested with the low-NPSH centrifugal pump. Results to date show that the screen and sponge are capable of supplying SFHe to the TM pump inlet against a one-g head up to four cm which is more than sufficient for the SHOOT application. Results with the sponge are reproducible while those with the screen cannot always be repeated. Further tests to characterize these systems are required.

Acquisition System Testing with Superfluid Helium

Surface tension propellant acquisition system technology for Space Shuttle reaction control tanks

A surface tension propellant acquisition/expulsion configuration was selected for the Space Shuttle Reaction Control Subsystem tankage to supply gas-free propellant during the low- and high-g operational environment (.00001 to 3.0 g) plus the numerous omnidirectional intermittent (pulse) demands of each mission. Candidate concepts to meet these stringent requirements were identified; this was followed by analysis and design sensitivity evaluations. A trade study resulted in the selection of a compartmented tank with individual flow channels as the preferred concept. Details of the analysis and design are presented.

D. A. Fester

Papers

Surface Tension Propellant Acquisition System Technology for Space Shuttle Reaction Control Tanks

An assessment of habitat pressure, oxygen fraction, and EVA suit design for space operations

Acquisition System Testing with Superfluid Helium

Surface tension propellant acquisition system technology for Space Shuttle reaction control tanks

Space Shuttle Reaction Control Subsystem propellant acquisition