(Nanowerk Spotlight) A new report, which reviews the history of nanotechnology R&D at NASA over the past 15 years, shows that NASA is the only U.S. federal agency to scale back investment in this area ("NASA's Relationship with Nanotechnology: Past, Present and Future Challenges"; pdf). The study, authored by a team from Rice University’s Baker Institute for Public Policy, argues that nanotechnology has the proven capability of revolutionizing most areas of technology that will be critical to NASA's future missions: "The agency needs a bolder plan for R&D to match the requirements of those missions and to recapture its place at the forefront of nanotechnology."
In a previous Nanowerk Spotlight we reported on an example of NASA's futuristic research efforts with regard to shape-shifting airplanes.
NASA computer animation intended to illustrate the concept of a morphing, or shape-changing, aircraft
NASA's Morphing program makes extensive use of nanotechnology, for instance by developing electroactive polymers to improve sensing and actuation. Researchers working in this area now have created a novel intrinsic unimorph carbon nanotube (CNT) polymer composite actuator.
Research on carbon-based nanomaterials as well as nanosensors has been one of the key focus areas of the NASA Ames Center for Nanotechnology. The center, established in 1996, was already churning out scientific papers (so far it has published over 350 nanotechnology related papers) by the time the National Nanotechnology Initiative (NNI) was created in 2001.
In 2003, a period of budget cuts started and, with decreased funding for research, NASA stopped work on many promising new technologies. The report notes that approximately 300 out of roughly 360 science programs were killed midstream.
From 2003 to 2010, while the total federal science research budget remained steady between $60 and $65 billion (in constant 2012 dollars), NASA's research appropriations decreased more than 75 percent, from $6.62 to $1.55 billion. Consequently, from 2004 to 2007, NASA reduced annual nanotechnology R&D expenditures from $47 million to $20 million. The report notes that the center at Ames rapidly downsized, from a peak of 60 researchers with an $18 million budget, to approximately 10 researchers and a $2 million budget funded largely by the U.S. Department of Defense.
In 2012, however, NASA is seeing an increase in nanotechnology-specific R&D, from $17 million in 2011 to $23 million in 2012, that was put toward developing next-generation nanomaterials and nanoscale systems (see NNI budget by agency).
It's not as if NASA doesn't have any ideas as to how nanotechnologies could be used to advance space technologies. In 2010, the agency drafted a 20-year Nanotechnology Roadmap (pdf) as part of its integrated Space Technology Roadmap. According to this document, nanotechnology can have a broad impact on NASA missions, with benefits principally in four areas:
Reduced Vehicle Mass
Replacement of conventional aerospace materials (composites and metals) with advanced composites derived from durable nanoporous matrixes and low density high strength and/or stiffness fibers can reduce aircraft and spacecraft component weight by one-third. Additional weight savings can be realized by replacing heavy copper wiring, which accounts for 4000 lb of weight on a Boeing 747 and about one-third of the weight of large satellites, with low density carbon nanotube wiring cables. Use of structural aerogel insulation in place of multilayer insulation (MLI) for cryotanks can eliminate the need for external foam insulation and the associated parasitic weight and production costs.
Improved Functionality and Durability
Nanoelectronic devices based upon graphene, carbon nanotubes, semiconductor nanowires, quantum dots/semiconductor nanocrystals and rods, are inherently more radiation and fault tolerant, have lower power requirements, higher speeds than conventional CMOS electronics. Integration of nanoelectronics and nanotechnology derived emission sources and detectors will lead to the development of advanced spectrometers and imagers that are one to two orders of magnitude lighter than conventional instrumentation, with twice the sensitivity and resolution and half the power requirements. Quantum structure enhanced solar cells will enable the development of flexible, radiation tolerant solar cells with >50% efficiencies. These could be incorporated into the exterior of habitats and rovers providing for integrated power sources at reduced systems weight.
Enhanced Power Generation and Storage and Propulsion
Nanotechnology affords the possibility of creating high surface area materials with inherently higher surface activities and reactivity that could significantly enhance the performance of batteries and fuel cells and improve the handling characteristics of propellants. Use of nanostructured metal catalysts in PEM fuel cells could increase their energy density by 50%. Use of nanoporous materials and nanocomposites could enable the development of new batteries that could operate over a wide temperature range, from -100 to 100°C, to provide surface power for rovers and EVA suits. Nanoscale metal based propellants could replace cryogenic propellants and hypergolics leading to simplified storage, transfer and handling and reduced launch pad and in-space operational requirements.
Improved Astronaut Health Management
Nanoporous materials with tailored pore size and shape and surface chemistries will lead to the development of more efficient systems for the removal of carbon dioxide and other impurities from breathing air and organic and metallic impurities from drinking water. Distributed, autonomous state and chemical species detectors could find use in air and water quality monitoring systems, and in astronaut health monitoring. Nanofluidics based devices will enable the development of real-time, minimally invasive medical diagnostic systems to monitor astronaut health and aid in diagnosing and treating illness. Electrospun nanofibers with demonstrated potential to support tissue engineering and regenerative medicine can expand and radically change astronaut health management methods. Boron nitride or carbide based nanocomposites could be used as part of a habitat or rover structure, providing radiation shielding and MMOD protection.
The NASA Nanotechnology roadmap is subdivided into four themes: Engineered Materials and Structures; Energy Generation, Storage and Distribution; Propulsion; and Electronics, Sensors and Devices.
Technology area breakdown structure for nanotechnology roadmap. (Source: NASA)
The document also identifies five "Grand Challenges" that would enable the development of nanotechnologies with the most impact on NASA Missions:
Development of scalable methods for the controlled synthesis (shape and morphology) and stabilization of nanopropellants
High surface area and reactivity (metallic and inorganic) nanoparticle co-reactants or gelling agents can be used to develop alternatives to cyrogenic fuels and hypergolics. Nanopropellants have the potential to be easier to handle and less toxic than conventional propellants, leading to simplified storage and transfer. A propellant comprised of nanoscale aluminum particle/ice slurry was demonstrated in tests by a team of researchers from Purdue and Penn State in a successful rocket launch. Technical issues that need to be addressed includes the development of passivation chemistries to control unwanted oxidation and the development of processing methods to tailor the shape, composition and morphology of these nanoparticles for controlled burning characteristics and methods to produce nanopropellants in large scales with good batch-to-batch consistency. NASA is currently partnering with other federal agencies in this area, but more work and investment is warranted.
Development of hierarchical systems integration tools across length scales (nano to micro)
High sensitivity and low power sensors (ppb to ppm level at µW - nW), high-speed (hundreds of GHz) electronics, and measurement enabling nanocomponents for miniature instruments are bound to interface with larger (micro, meso, and higher) systems to accomplish desired operation. System integration issues at that level can pose significant challenges and require the design of devices and processes that are suitable for both nano and microstructure fabrication schemes (chemical, thermal, and mechanical issues), structural integration techniques that are mechanically and thermally robust, and the development of efficient interconnects. In addition, a better understanding of factors that can degrade system performance, such as the effect of nano-micro-meso interfaces, packaging, and signal interference at component level, is needed along with effective mitigation strategies. NASA investments in meeting these challenges can be leveraged with those of other federal agencies to accelerate developments in this area and address NASA specific needs.
Development of integrated energy generation, scavenging and harvesting technologies
The use of quantum structures (dots and rods) to enhance absorption of solar energy and carbon nanotubes to improve charge transport and develop transparent electrodes will enable the development of flexible, radiation hard solar cells with greater than 50% efficiencies. Nanostructured electrode materials, self-assembled polymer electrolytes and nanocomposites will enable the development of new ultracapacitors with 5 times the energy density of today’s devices and new, lighter and safer lithium batteries. Incorporation of flexible, conformal photovoltaics and improved efficiency, lightweight, flexible batteries into EVA suits and habitats would lead to enhanced power and reduced mass and enable longer duration EVA sorties and missions. Developments needed in this area include functionalization chemistries to allow incorporation of carbon nanotubes into devices, reliable, repeatable large scale manufacturing methods, as well as approaches to enhance radiation tolerance and nanoengineered coatings to prevent dust accumulation. An increased NASA investment in this area can be leveraged against ongoing efforts at Energy Frontier Research Centers as well as the NNI Solar Energy Signature Initiative.
Development of nanostructured materials 50% lighter than conventional materials with equivalent or superior properties
Carbon nanotube derived high strength and modulus, low density carbon fibers and lightweight, high strength and durability nanoporous polymers and hybrid materials will enable the development of advanced composites that would reduce the weight of aircraft and spacecraft by up to 30%. Technical challenges that need to be addressed include the development of reliable, low cost manufacturing methods to produce nanotubes, fibers and nanocomposites in large quantities and systematic studies to understand damage progression, degradation and long-term durability of these advanced composites to enable their efficient use in future aerospace vehicles. This technology area would be well suited for an NNI Signature Initiative that could be led by NASA. Development of graphene based nanoelectronics. Graphene based nanoelectronics can enable the development of radiation hard, high-speed devices, flexible electronic circuits, and transparent electrical conductors (a superior replacement for indium-tin-oxide coatings) that would find broad applications in NASA missions in exploration, science and aeronautics. Technical challenges that need to be addressed include the development of reliable, reproducible, and controlled methods to produce graphene on a large scale, a clear understanding of graphene and dielectric interfaces, device physics, foundry-conducive processes to produce large scale electronic circuits, and heterogeneous system integration issues. A concerted collaborative development supported within NASA and by other Federal agencies, including efforts in the planned NNI Nanoelectronics Signature Initiative, can realistically make graphene electronics a system of choice for avionics, extreme environment applications, an integral part of “smart” skin material (EVA suits), and for future probes and planetary landers by 2028-2032.
The NASA roadmap document importantly also points out that, in addition to meeting NASA needs, nanotechnology can also address societal needs in clean energy, medicine and national security:
Advanced structural nanomaterials and nanoengineered coatings can be used to develop lightweight, more damage tolerant turbine blades for wind energy that are less susceptible to ice accretion and insect fouling. Advanced aerogel insulation can be used to improve the energy efficiency of homes. Nanotube electrical wiring can have a significant impact on reducing resistivity losses in electrical power transmission lines. Advanced photovoltaics, batteries and fuel cells can also meet needs for clean energy storage and generation. Nanoelectronics, sensors and actuators, and miniature instruments have wide use in many applications to meet other National needs. For example, nanosensors possess high sensitivity, low power and small size that can fit in a cellphone for extended coverage of sensing network for homeland security applications in detecting toxics and chemical threats. Such a cellphone sensor can be used in a clinic or at home for medical diagnosis and health monitoring at the point of care as well. First responders for natural disasters and other accidents can also use it to determine the cause of the problem and make a decision at the point to have a solution for the problem. Nanosensors can form a wired and/or wireless network that can be used to monitor the safety of a building or a stadium as well as for battlefield chemical profiling.