Tech Briefs

Microelectronic Repair Techniques for Wafer-Level Integration

Goddard Space Flight Center, Greenbelt, Maryland Wafer-level integration was employed to mount the microshutter array for the James Webb Space Telescope (JWST) and the detector-read-out hybrid for TIRS (Thermal Infrared Sensor). In the case of the JWST substrate, two conductors (polysilicon and aluminum) separated by a silicon oxide insulating layer were fabricated on a roughly 85-mm-square silicon wafer. The size of the substrate, the density and length of the conductive traces, and the requirement of zero shorts and zero opens on the finished device necessitated nearly impossible cleanroom requirements. Techniques were developed to repair the inevitable shorts and opens created during the wafer fabrication process. The wafers were repaired to zero shorts and zero opens without degradation of device performance.

Posted in: Electronics & Computers, Briefs

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Multi-Gigabit-Rate Radiation Hard Bus

Goddard Space Flight Center, Greenbelt, Maryland A concept was developed for a multi-gigabit-rate, radiation-hardened (RH) bus that would support open-system architecture and provide a cost-effective, high-speed interconnect. This concept is based on Advanced Science and Novel Technology Company’s SerDes system, which supports a variety of interfaces, and operates at frequencies from DC to more than 15 GHz. The design of the improved SerDes is based on the company’s proprietary library of RH cells and functional blocks using annular FETs (field-effect transistors) that are available in commercial CMOS (complementary metal-oxide-semiconductor) technologies. Bus architecture and preliminary SerDes circuit design have been accomplished during this phase. At the time of this reporting, the complete chip was to be designed and fabricated in the next phase.

Posted in: Electronics & Computers, Briefs

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Hovercraft Landing System

Ames Research Center, Moffett Field, California A concept for recovering reusable spacecraft or capsules, or reusable rocket boosters, has them land on an airbag-based, cushioned platform positioned on a highly maneuverable hovercraft. This landing method would have performance advantages over conventional approaches to reusability by placing most of the landing function on the hovercraft while maintaining the safety benefit of an open ocean landing away from populated areas; however, it would be similar to a dry landing as the spacecraft or booster would not enter the water.

Posted in: Mechanical Components, Briefs, TSP

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Novel Catalytic Reactor System for CO2 Reduction via Sabatier Process

Marshall Space Flight Center, Alabama A novel, short-contact-time Microlith Sabatier reactor system for CO2 reduction offers a significant advance in support of manned spaceflight. Compared to the current and prospective alternatives (including microchannels), the reactor is much smaller and lighter, more energy and resource efficient, and more durable. In the spacecraft cabin atmosphere revitalization system (ARS), the utilization of CO2 to produce life support consumables such as O2 and H2O, via the Sabatier process as part of the CO2 Reduction Assembly (CRA), is an important function. This innovation is an integrated, stand-alone system consisting of a Microlith-based CO2 methanation reactor, water separation and recovery system, and automatic control software for ground demonstration. The system efficiently achieves high CO2 conversion and high CH4 selectivity for optimum water generation. The apparatus is capable of operating at high throughput while maintaining targeted performance of close-to-equilibrium CO2 conversion. The specific mass and volume of the reactor are much lower compared to the state-of-the-art metrics. H2 and CO2 (reactants) enter the system, and their flow rates are automatically controlled. The catalyst within the reactor promotes the conversion of the reactants to H2O and CH4. Since the reaction is exothermic, a thermal management approach is implemented to maintain reactor operating temperature and to avoid catalyst deactivation. The product H2O is separated from the CH4 via a condenser and separator system to provide two single-phase product streams. This innovation utilizes a novel thermal management approach to enable self-sustained operation without additional power requirements. A full support system including mass flow controllers, valves, heat exchanger, and water condensation and separation system was developed. The reactor and system were integrated with a newly developed automatic control system that enables single pushbutton start and steady-state operation with minimal user interface. This work was performed by Christian Junaedi and Kyle Hawley of Precision Combustion, Inc. for Marshall Space Flight Center. For more information, contact Ronald C. Darty, Licensing Executive in the MSFC Technology Transfer Office, at Ronald.C.Darty@nasa.gov. Refer to MFS-33063-1.

Posted in: Mechanical Components, Briefs

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Technology for a Comet Sample Return Mission Version 2

Harpoon-based sample collectors with rectangular cross-sections are regarded as the best candidates. Goddard Space Flight Center, Greenbelt, Maryland A standoff sample collection system would be capable of quickly obtaining a sample from environments as varied as comets, asteroids, and permanently shadowed craters on the Moon from vehicles ranging from traditional planetary spacecraft to platforms such as hovering rotorcraft or balloons at Mars, Venus, or Titan. The depth of penetration for this harpoon-based hollow collector design was experimentally determined to be proportional to the momentum of the penetrator, in agreement with earlier work on the penetration of solid projectiles. A release mechanism for the internal, removable sample cartridge was tested, as was an automatic closure system for the sample canister and tether recovery approaches.

Posted in: Mechanical Components, Briefs, TSP

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Nitrous Oxide Ethane-Ethylene Engine

Marshall Space Flight Center, Alabama The Nitrous Oxide Ethylene-Ethane (NEE) engine uses nitrous oxide as an autogenously pressurizing oxidizer, and a mixture of ethane and ethylene is used in the same manner as fuel. Initially, the ethane and ethylene mixture has the same vapor pressure as the nitrous oxide. By using the autogenous pressurization capabilities of these propellants, instead of an additional pressurization system, greater system simplicity and reliability can be attained. The NEE can obtain a specific impulse of 320 s, making it the highest-performing, non-toxic, storable bipropellant rocket propulsion system in existence at the time of this reporting.

Posted in: Mechanical Components, Briefs

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Method for Improved Gun-Drilled Cold Plate Fabrication and Inspection

Lyndon B. Johnson Space Center, Houston, Texas A method was developed for obtaining proper fluid distribution through parallel gun-drilled passages and for being able to inspect the actual drilled passages to guarantee that the designed minimum wall thickness is not violated. This invention uses one feature that addresses both issues mentioned. By machining a “trough” in the center of the cold plate that intersects the gun-drilled passages where they meet in the center, the area where the two drilled passages intersect is removed and any mismatch is eliminated. This allows access for direct inspection of the drill wander. An integral cap, which incorporates orifice features to address the fluid distribution, is then inserted into this trough. This method can also work in a two-layer cold plate where every other fluid passage is for the alternating fluid layer.

Posted in: Mechanical Components, Briefs

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