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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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RF Characterization of a Photocurable PEDOT:PSS:PEGDA Conductive Biomaterial for 3D-Printing Implantable Antennas

In this work, we demonstrate photocurable PEDOT:PSS:PEGDA biomaterial as a promising candidate for intracorporeal 3D printing. Intracorporeal 3D printing offers a less invasive method which offer flexibility to tailor the form factor of printed structures. Previous work has demonstrated the feasibility of a robotic probe to 3D-print biological tissues intracorporeally via a minor incision. This same probe could also 3D-print implantable antennas as long as a suitable conductive material is identified in terms of conductivity, biocompatibility, and ability to cure at room/body temperature for safety purposes. We assess the frequency-dependent conductivity of this biomaterial and explore the Radio-Frequency (RF) performance of resulting antennas operating in free-space and inside tissue-emulating phantoms. Results show that PEDOT:PSS biomaterial with 21% and 30% PEGDA content exhibit a conductivity of ~10 4 S/m up to 5 GHz, suitable for wireless implants. Comparing the two, 21% PEGDA content exhibits poorer curing abilities, while 30% PEGDA exhibits slightly lower conductivity. Measurements for 2.4 GHz free-space dipoles conducted in an anechoic chamber reveal only ~0.8 dB and ~1 dB lower gain for PEDOT:PSS:21%PEGDA and PEDOT:PSS:30%PEGDA biomaterial, respectively, as compared to their copper counterpart. For a 5 mm-deep implanted patch antenna, these two biomaterials exhibit 3.05 dB and 3.84 dB higher transmission loss than copper, respectively. If deemed necessary, this performance degradation can be overcome by increasing the overall antenna size since the printing process is now minimally invasive and miniaturization requirements can be relaxed.

3D-printing↗

Centennial Challenges Program Update: From Humanoids to 3D-Printing Houses on Mars, How the Public Can Advance Technologies for NASA and the Nation

The Centennial Challenges (CC) program, part of NASA's Space Technology Mission Directorate (STMD), was founded upon the principle that engaging the public at large was a very important part of garnering the true magnitude of grassroots American innovation and ingenuity. The program uses a focused problem-statement approach to obtain solutions and/or stimulate innovation in key NASA technology gaps by catalyzing sources outside of the traditional aerospace community. The CC program announced the first two challenge competitions in 2005 incentivizing the public to participate using a congressionally authorized prize purse. Since then, the program has developed and executed more than 18 competitions and has awarded over $9 million in prize money. The challenges have covered a variety of technology areas, including propulsion, robotics, communications and navigation, human health, science instrumentation, nanotech, materials and structures, and aerodynamics. Centennial Challenges' accomplishments from October 2016 to December 2017--including significant increases in the amount and diversity of participants; increase in prize purse awards; strong alignments with NASA missions; and partnerships with industry, academia, and other government agencies-are summarized in this paper. Technological advancements, communication strategies, and legal authority are also discussed. NASA is leading the government agencies in the area of prizes and competitions to push technologies, and the CC program is one powerful example of NASA's continuing commitment to technological advancement and innovation through non-traditional programs. Currently, the Agency has in place the proven infrastructure, policies, and people needed to enable the successful use of competition tools, including the ones used as part of the CC program.

Centennial Challenge Prize↗

From 3D Printing Lunar and Mars Habitats to Affordable Sustainable Housing on Earth

In 2015, the NASA Centennial Challenges program launched the 3D-Printed Habitat (3DPH) competition to develop housing solutions for extended-duration missions on planetary surfaces using advanced additive construction technology. The challenge was executed in three phases with increasing complexities and requirements. The main goal of the competition was to use of planetary indigenous materials and mission recyclables as feedstock for large-scale, autonomous 3D printers to construct a habitat on the Moon or Mars. Phase 1 challenged teams to develop state-of-the-art architecture concepts that took advantage of unique capabilities offered by 3D-printing. In Phase 2, teams autonomously 3D-printed structural components using terrestrial/space-based materials and recyclables. Phase 3 tasked competitors to fabricate sub-scale habitats using indigenous materials with or without mission-generated recyclables and ended in a head-to-head competition. The developments from this challenge are applicable both to the fulfillment of NASA’s Moon to Mars mission and to the creation of affordable and sustainable housing solutions on Earth. This paper will summarize the results of the four-year challenge and provide an overview of team achievements as a result of the competition. Results from the competition include humanitarian and business opportunities created/negotiated and the development of 3D-printed housing solutions for people such those in need of shelter in Austin, Texas and 3D-printing houses at the United Nations habitat headquarters in Nairobi, Keyna. The Phase 3: Level 5 winner, AI. SpaceFactory, is currently 3D-printing an ecofriendly house in New York called Terra, a full-size habitat design for Mars and available on Earth.

M C Roman↗

CubeSub

This presentation introduces and discusses the development of the CubeSub submersible concept, an Autonomous Underwater Vehicle (AUV) designed around the CubeSat satellite form factor. The presented work is part of the author's MSc thesis in Aerospace Engineering at the Royal Institute of Technology, Stockholm, Sweden, and was performed during an internship at the Mission Design Division of the NASA Ames Research Center, Moffett Field, CA. Still in the early stages of its development, the CubeSub is to become a submersible test-bed for technology qualified for underwater and space environments. With the long-term goal of exploring the underwater environments in outer space, such as the alleged subsurface ocean of Jupiter's moon Europa, a number of technology and operational procedures must be developed and matured. To assist in this, the CubeSub platform is introduced as a tool to allow engineers and scientists to easily test qualified technology underwater. A CubeSat is a class of miniaturized satellite built to a standardized size. The base size is 1U (U for unit), corresponding to a 100 x 100 x 113.5 cu mm cube. A 1U CubeSat can in other words easily be held in one hand. Stacking units give larger satellite sizes such as the also commonly used 1.5U, 2U and 3U. The CubeSat standard is in itself already well established and hundreds of CubeSats have to date been launched into space. Compatible technology is readily available and the know-how exists in the space industry, all of which makes it a firm ground to stand on for the CubeSub. The rationale behind using the CubeSat form factor is to make use of this pre-existing foundation, making the CubeSub easy to develop, modular and readily available. It will thereby aid in the process of maturing the concept of a fully space qualified submersible headed for outer space. As a further clarification, the CubeSub is itself not meant for outer space, but to facilitate development of such a vessel. Along with its uses as a testbed, the CubeSub also holds the potential to become a useful tool for exploration and experimentation here on Earth. A highly standardized system utilizing well-known hardware can reduce the cost and required work load for researchers wishing to perform experiments and exploration. Users could design sensors and experiments to comply with the already well established CubeSat standard, which are then carried by the CubeSub to the region of interest. This in turn means that the end users can focus more on formulating the experiment itself and less about how to get it where they want it. The CubeSub is designed to be built up by modules, which can be assembled in different configurations to fulfill different needs. Each module will be powered individually and intermodular communication will be wireless, removing the need for wiring. The inside of the cylindrical hull will be flooded with ambient water to enhance the interaction between payloads and surrounding environment. The overall torpedo-like shape is similar to that of a conventional AUV, slender and smooth. This is to make for a low drag, reduce the risk of snagging on surrounding objects and make it possible to deploy through an ice sheet via a narrow borehole or navigate in tight areas. To keep costs low and further accelerate development, rapid prototyping is utilized wherever possible. Full-scale prototypes are being constructed through 3D-printing and using COTS (Commercial Off-The-Shelf) components. 3D-printing is used both for the largest hull components and the relatively small and delicate propellers. Arduino boards are used for control and internal communication

AUV↗

Additive Manufacturing for Affordable Rocket Engines

Additive manufacturing (also known as 3D printing) technology has the potential to drastically reduce costs and lead times associated with the development of complex liquid rocket engine systems. NASA is using 3D printing to manufacture rocket engine components including augmented spark igniters, injectors, turbopumps, and valves. NASA is advancing the process to certify these components for flight. Success Story: MSFC has been developing rocket 3D-printing technology using the Selective Laser Melting (SLM) process. Over the last several years, NASA has built and tested several injectors and combustion chambers. Recently, MSFC has 3D printed an augmented spark igniter for potential use the RS-25 engines that will be used on the Space Launch System. The new design is expected to reduce the cost of the igniter by a factor of four. MSFC has also 3D printed and tested a liquid hydrogen turbopump for potential use on an Upper Stage Engine. Additive manufacturing of the turbopump resulted in a 45% part count reduction. To understanding how the 3D printed parts perform and to certify them for flight, MSFC built a breadboard liquid rocket engine using additive manufactured components including injectors, turbomachinery, and valves. The liquid rocket engine was tested seven times in 2016 using liquid oxygen and liquid hydrogen. In addition to exposing the hardware to harsh environments, engineers learned to design for the new manufacturing technique, taking advantage of its capabilities and gaining awareness of its limitations. Benefit: The 3D-printing technology promises reduced cost and schedule for rocket engines. Cost is a function of complexity, and the most complicated features provide the largest opportunities for cost reductions. This is especially true where brazes or welds can be eliminated. The drastic reduction in part count achievable with 3D printing creates a waterfall effect that reduces the number of processes and drawings, decreases the amount of touch labor required, and increases reliability. When certification is achieved, NASA missions will be able to realize these benefits.

West, Brian↗

Mechanical Tensile Testing of 3D-Printed Titanium 6Al-4V at Cryogenic Temperature Presentation

- Titanium 6Al-4V is a highly desired material for use in space cryogenics applications. - Structural applications with good strength-to-weight ratios - Thermal isolation applications - Titanium 6Al-4V components can be fabricated via 3D-Printing which can be very beneficial to cryogenic spaceflight components: - 3D-Printing allows parts to be made with geometries and features that are very difficult and sometimes impossible via traditional methods. - Mass savings of components - Increasing structural integrity of components - Increasing thermal isolation and/or conduction of components - Cost savings - Schedule savings

Bryan L James↗

CubeSub - A CubeSat Based Submersible Testbed for Space Technology

This report is a Master's Thesis in Aerospace Engineering, performed at the NASA Ames Research Center. It describes the development of the CubeSub, a submersible testbed compatible with the CubeSat form factor. The CubeSub will be used to mature technology and operational procedures to be used in space exploration, and possibly also as a tool for exploration of Earthly environments. CubeSats are carried as payloads, either containing technology to be tested or experiments and sensors for scientific use. The CubeSub is designed to be built up by modules, which can be assembled in different configurations to fulfill different needs. Each module is powered individually and intermodular communication is wireless, reducing the need for wiring. The inside of the hull is flooded with ambient water to simplify the interaction between payloads and surrounding environment. The overall shape is similar to that of a conventional AUV, slender and smooth. This is to make for a low drag, reduce the risk of snagging on surrounding objects and make it possible to deploy through an ice sheet via a narrow borehole. Rapid prototyping is utilized to a large extent, with full-scale prototypes being constructed through 3D-printing and with COTS (Commercial Off-The-Shelf) components. Arduino boards are used for control and internal communication. Modules required for basic operation have been designed, manufactured and tested. Each module is described with regards to its function, design and manufacturability. By performing tests in a pool it was found that the basic concept is sound and that future improvements include better controllability, course stability and waterproofing of electrical components. Further development is needed to make the CubeSub usable for its intended purposes. The largest gains are expected to be found by developing the software and improving controllability.

Europa↗

Relevant Environment Additive Construction Technology (REACT)

Project Overview This project is focused on developing technologies that enable construction of a Lunar Safe Haven type structure on the moon. A full scale architectural and structural design will be completed based on lunar conditions and Artemis mission needs. A scaled structure will be 3D printed in simulated lunar environments. Technical Approach Polymer bound regolith composite materials will be developed and characterized for lunar additive construction applications. A full scale architectural and structural design will be completed based on the latest scientific data on lunar environments including radiation, meteoroids, thermal conditions, reduced gravity, and moonquakes. The project will culminate with a demonstration of additive construction in simulated lunar vacuum, thermal, regolith, and UV conditions. Results/Summary Preliminary material specifications have been developed and an initial batch has been produced. A first iteration of the architectural and structural designs have been completed. Hardware for 3D printing in simulated lunar conditions is under development. Contributing Partners AI Space Factory – Winner of the NASA 3D Printed Habitat Centennial Challenge Infusion and Transition Plan On-surface construction of infrastructure is a critical capability of the sustainable phase of the Artemis Program and eventual sustainable human presence on Mars. It provides the ability to create protective shelters on-demand using local resources. The 3D-printing technology will achieve TRL 6 in 1g/vacuum tests with thermal/UV exposure in this project. CLPS missions will be pursued for infusion to demonstrate vertical construction with lunar regolith and conditions. Modeling and simulation will be used to define the pilot-scale shelter construction mission for long-term exposure on the lunar surface to validate the system for Artemis operational deployment.

Lunar Construction↗

Manufacturing of Thermoset Polyimide Composites by Laser Sintering

Selective Laser Sintering (SLS) is an additive manufacturing technique that builds 3D models layer by layer using a laser to selectively melt cross sections in powdered polymeric materials, following sequential slices of the computer-aided design (CAD) model. SLS generally uses thermoplastic polymeric powders such as polyamides. The resultant 3D-printed objects are often weaker in their strength compared to traditionally processed materials, due to their higher porosity. This paper described the process development of using melt-processable imide oligomers terminated with reactive 4-phenylethynylphthalic anhydride (4-PEPA) to conduct laser sintering (LS). The first successful 3D-printing of high temperature RTM370 thermoset polyimide carbon fiber composites were further post-cured to promote additional crosslinking for achieving higher temperature (T g = 370°C) capability. Another novel imide oligomer, RTM385-SLS, formulated with a complex melt viscosity [ƞ*] of ~104-105 poise is also suitable for LS. RTM385-SLS resin powder was mixed with 20-25% of hexagonal boron nitride (h-BN) and subjected to LS to print out “Green” specimens which could be further post-cured to afford a thermally conductive but electrically insulating composites with high T g of 385 °C. The cured composite specimens were then subjected to mechanical testing, thermal conductivity and porosity measurements as well as SEM characterization.

additive Manufacturing↗

Improved Mechanical Performance in FDM Cellular Frame Structures through Partial Incorporation of Faces

The utilization of lattice-type cellular architectures has seen a significant increase, owing to their predictable shape and the ability to fabricate templated porous materials through low-cost 3D-printing methods. Frames based on atomic lattice structures such as face-centered cubic (FCC), body-centered cubic (BCC), or simple cubic (SC) have been utilized. In FDM, the mechanical performance has been impeded by stress concentration at the nodes and melt-solidification interfaces arising from layer-by-layer deposition. Adding plates to the frames has resulted in improvements with a concurrent increase in weight and hot-pocket-induced dimensional impact in the closed cells formed. In this paper, we explore compressive performance from the partial addition of plates to the frames of a SC-BCC lattice. Compression testing of both single unit cells and 4 × 4 × 4 lattices in all three axial directions is conducted to examine stress transfer to the nearest neighbor and assess scale-up stress transfer. Our findings reveal that hybrid lattice structure unit cells exhibit significantly improved modulus in the range of 125% to 393%, specific modulus in the range of 13% to 120%, and energy absorption in the range of 17% to 395% over the open lattice. The scaled-up lattice modulus increased by 8% to 400%, specific modulus by 2% to 107%, and energy absorption by 37% to 553% over the lattice frame. Parameters that emerged as key to improved lightweighting.

FDM↗