The disclosed embodiment is directed to systems in the art of space exploration for removing dust from human environments.
Lunar dust has posed a problem to NASA since the Apollo expedition. Unlike dust on earth, lunar dust is not subject to earthbound erosive forces like wind, which, over time, smooths the surfaces of dust particles. Lunar dust is jagged, sharp-edged, and extremely fine, and it does not pack down like it would in earth's gravity. And due to radiation, lunar dust is electrostatically charged. The charged dust can be seen floating above the moon's surface, a phenomenon known as Dusty Plasma.
Lunar dust particles attach readily to space suits, causing damage to suit material. Sub-micrometer and micrometer-sized particles invade seals, joints, and space-suit fabrics, and can remain airborne in a human habitat, causing respiration hazards. Challenges presented by lunar dust include damage from abrasion, the effects of dust's electrostatic charge on the suit system, and dust intrusion to the suit system.
Because astronauts breathe through the ventilation system in their space suits, lunar dust entering a space suit can be dangerous. Lunar dust accumulating on spacesuits is an additional problem. NASA has appealed to the scientific public to help mitigate these problems through innovations that filter lunar dust from an astronaut's breathing environment, as well as innovations that protect mating and venting of connectors and suit components by use of specialized dust covers.
The Exploration Extravehicular Mobility Unit (xEMU) is a NASA-developed personal spaceship worn by an astronaut during lunar exploration. The xEMU holds life-support systems that protect astronauts from the harsh environment of space, enclosing them in a sealed, Earth-like atmosphere. The xEMU prevents inhalation of dust or contamination of the suit's life-support system.
NASA identified particular venting components on the xEMU that must be protected from lunar dust: the Spacesuit Purge Valve (SPV); the Low-Flow Purge Valve (LFPV); the Positive-Pressure Relief Valve (PPRV) and the Rapid-Cycle Amine (RCA) bed, all of which flow outward; the Negative-Pressure Relief Valve (NPRV) which flows inward; and battery vents, which flow in both directions as the batteries ventilate. One skilled in the art understands that an RCA bed is also referred to as a pressure swing bed. These valves are sensitive to any added flow resistance during venting, so an innovation that changes air resistance as it expels or prohibits the entrance of lunar dust must accommodate this.
The SPV and the LFPV are operable by crew members during extravehicular activities (EVA).
A tortuous path is defined as a path having at least one twist, bend, or turn. A tortuous path may be defined proximate a pipe (or other type of flow conduit) of a flow control device. For example, a tortuous path can be provided about the inner or outer surface of a vent or conduit.
One skilled in the art understands that dust in various earthly and other planetary environments may be problematic in valves and the like. A valve cover designed for lunar dust may be applicable to Martian dust, for example. This application refers to lunar dust for the purpose of clarity.
A dust-mitigation device used in space exploration is a system for protecting the venting components of certain environments from the entry of lunar dust. The system enables ventilation while preventing dust from reaching sealing surfaces of a spacesuit's valves (SPVs) such as the Positive Pressure Relief Valve (PPRV) and the Low-Flow Purge Valve (LFPV). One iteration is designed for Exploration Extravehicular Mobility Unit (xEMU); another iteration is designed for the protection of the Negative Pressure Relief Valve (NPRV).
A combination of elements protects xEMU components from dust particles. To protect the LFPV, PPRV and NPRV components, vented purge-gas flows past a membrane valve (check valve), through a tortuous flow path, diverting most of the residual dust out of the dust covers. In some embodiments a fine screen filters lunar dust to protect the valves as cabin air flows into the spacesuit. In some embodiments a fine screen is a 35-micron screen.
In operation of the Rapid Cycle Amine Diverter Valve, gas flows out to space vacuum. The vacuum is used to exhaust collected CO2 from the RCA which employs a swing bed. One bed collects CO2 as spacesuit air passes through; the other vents, are pressure swing beds that collect CO2 to the vacuum of space. In order to reduce ullage remaining in the bed system it is important to reduce resistance presented to the exiting gas flow. To achieve this goal, in place of a check valve, Samarium Cobalt magnets are used to attract lunar dust.
In some embodiments a tortuous flow path begins in a direction that is substantially parallel to a vent cover central axis and is turned about the tortuous flow path until the direction of flow is substantially perpendicular to the vent cover central axis. This turning of the flow path mitigates a trajectory caused by flow that is substantially parallel to a vent cover central axis.
The check valve 116 prevents inflow (
A second iteration of the embodiment is depicted in
A cap 210 above a base 219 is affixed to a screen, which in some embodiments is a screen of approximately 35 microns 212. A check valve 216 moves within the cap 210 to seal against the base 219. The cap 210, base 219, check valve 216 and screen 212 are coaxial with a central axis 205. The cap 210 is a portion of a frusto-conical surface, also referred to as a frusto-conical surface portion, that influences the direction of flow. The base 219 is a portion of a conical surface that is offset from the frusto-conical surface portion that makes up the cap 210. One skilled in the art understands that an offset surface is substantially parallel to another surface. A tortuous flow path 214 winds from the ambient environment over an upper surface 222 of the base 219, under a surface 226 of the cap 210, through an opening 224, through a check valve 216 and through the screen 212. The check valve 216 prevents any inflowing dust through the tortuous path from reaching the screen 212 (
A third iteration of the embodiment, depicted in
An array of magnets 330 in the housing 328 provides a primary dust-mitigation device. Magnets 322 and 324 are a secondary dust mitigation device. One skilled in the art understands that the primary device and secondary device may either, or both, be included depending on which particle-cleaning method is chosen.
A conduit 312 is flared at an end. A cap 310 has a frusto-conical portion 320 that extends into the conduit 312 and both cap 310 and conduit 312 are coaxial about a central axis 305. A first annular magnet 324 is affixed proximal to the exit of the conduit 312. A second annular magnet 322 is affixed proximal to the circumference of the end cap 310. A housing 328 is affixed to the conduit 312 and houses an array of magnets 330. A tortuous flow path 314 proceeds along a conduit in a direction that may be said to be substantially parallel to the central axis 305, past the array of magnets 330, where it is directed by the conical portion 320, through the flare in the conduit 312 and passed the first annular magnet 324 and the second annular magnet 322. The tortuous flow path may be said to turn approximately 90° to flow in a direction that is substantially perpendicular to the central axis 305. One skilled in the art understands that lunar dust, being partially ferrous, is magnetic. Dust moving against the flow 314 may be trapped by the first annular magnet 324, second annular magnet 322 or finally by the array of magnets 330.
This configuration includes a tortuous path element, but with a smaller flow-path area due to the reduced mass flow of the intended environment. It also includes an inward-flow resistance protective element. In combination, these elements allow batteries to normally vent outward, and on occasion vent inward. As gas travels towards the vacuum of space it is directed to a substantially 90° turn along flow path 314 in an equal and planar manner. One skilled in the art understands that the intent is to negate any thrust that the astronaut may feel during RCA venting. The design is intended to act as a non-thrust port while minimizing any flow resistance to the exiting gas, while presenting a tortuous path to dust particles.
Number | Date | Country | |
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63314644 | Feb 2022 | US |