Advancing Commercial Space

This novel innovation from Ames Research Center allows spacecraft to share rides with larger spacecraft which are headed to Geosynchronous Earth Orbit (GEO). The secondary spacecraft is dropped off Geosynchronous Transfer Orbit (GTO) at any time during the day or year and will subsequently enter lunar orbit, with no constraint on the lunar orbit inclination. The secondary spacecraft can be relatively small, riding as a secondary payload with a larger primary spacecraft. The secondary spacecraft is intended to be controllable (i.e., maneuverable).

NASA has developed a game changing deployable aeroshell concept for entry, descent and landing (EDL) of large science and exploration-class payloads.The Adaptable, Deployable Entry Placement Technology (ADEPT) concept is a mechanically deployable semi-rigid aeroshell entry system capable of achieving low ballistic coefficient during entry suitable for a variety of planetary or earth return missions. It leverages Ames expertise in Thermal Protection systems (TPS) material and entry system design, development and testing. The deployable decelerator systems offer a lighter-weight solution to current rigid, high ballistic coefficient aeroshells. The deployable feature of ADEPT allows each mission to utilize an entry system design that fits within existing launch vehicle systems and later transforms into a low ballistic coefficient configuration for EDL. Consisting of rigid ribs and a TPS, deployment can be done for inspection in Earth orbit by extending the ribs and stretching the TPS in between (in a method similar to an opening umbrella) and thereby reducing the mission risk.

NASA's Heatshield for Extreme Entry Environment Technology (HEEET) is a 3-D woven heatshield design made to efficiently reject extreme heating during space vehicle entry into a planetary atmosphere. HEEET is a system to protect probe or scientific payload. The technology presents a revolutionary approach to the designing and manufacturing of TPS materials. The woven TPS configuration, in both its material composition and architecture, can be adapted to cover a range of space vehicle and environment choices including vehicle entry velocity, vehicle entry flight path angle, initial time interval for vehicle deceleration, vehicle nose shape (e.g., blunt or wedge), initial entry pressure, heating rate (variable with time), cumulative heat load, time interval for heating, and relevant atmospheric characteristics, among other attributes.

This technology from NASA allows a graded-surface densification of Phenolic Impregnated Carbon Ablator (PICA). PICA was developed at NASA Ames Research Center in the 1980s for the forebody heatshield of the Stardust Return Capsule. With a low density (~0.27g/cm), coupled with efficient ablative capability at high heat fluxes, PICA became an enabling technology for the Stardust mission. At the time of the mission, PICA was a developmental material, with no previous flight heritage. For missions with high heat flux, a lower overall mass can be obtained if the Thermal Protection System (TPS) composition changes from a carbon-based ablator at the heated surface to an insulator near the inner surface. This new process delivers a graded surface-densification application to PICA allowing for optimized performance and TPS weight reduction. The desired surface densification is adaptable in terms of density of the applied surface treatment and depth of the surface treatment.

NASA has created a new approach to make a low density flexible ablative Thermal Protection Surface (TPS) material. The material is foldable and can be stowed in space for very long periods of time (years) without compromising deployability or performance. These flexible ablators offer an alternative to rigid TPS materials there by reducing design complexity associated with rigid TPS materials resulting in reduced TPS cost. The low density flexible ablator is unique in that the material retains its flexibility after charring. The charred material has similar flexibility and strength to the virgin material. This is in contrast too there flexible ablator concepts whereas stiffer chairs produced during heating.

NASA has developed a method for producing a flexible, fibrous ablator thermal protection material for use on space vehicles experiencing temperatures of 1000 F (550 C) or above upon atmospheric re-entry. The flexible ablator has controllable elastic modulus and controllable flexibility to withstand a wide range of heating rates comparable to rigid ablators, such as PICA and Avcoat. A phenolic resin and/or a silicone resin can be used. The elastic modulus of the resulting material is low, in a preferred range of about 200-5000 kPa, and can be controlled by choice of a curing temperature and/or a time interval length for curing.

NASA has filed a patent on a technology that creates a new class of phenolic and carbon fiber reinforced phenolic composites for thermal protection systems. The new materials have the advantage of being lightweight, strong, tough, yet heat resistant, and flexible. Their best characteristic is their remarkable capability to retain excellent mechanical strength at high temperatures. This provides better thermal protection for re-entry conditions with high heating rates. The materials incorporate thermoplastic polymer segments that are uniformly distributed throughout, and chemically bonded to the phenolic network. Phenolic resin polymers are a class of widely used thermosetting polymers. Their numerous advantages include excellent heat, radiation, corrosion/chemical resistances, and being flame retardant. They are low cost and have versatile processing/manufacturing methods.

NASA has a new innovation that represents an exciting leap forward in reusable thermal protection systems (TPS) technology. The Toughened Uni-Piece Fibrous Reinforced Oxidation-Resistant Composite (TUFROC) allows for much more affordable and sustainable operations involving Space Launch Services and other systems that utilize Earth re-entry vehicles. TUFROC has an exposed surface design and appropriate materials combination that will allow a space vehicle to survive both the mechanical stresses of the initial ascent and the extreme heating and stress of re-entry. It provides a thermal protection tile attachment system that is suitable for application to a space vehicle leading edge and for other uses in extreme heating environments (up to 3600 degree F., and possibly higher, for short time intervals).

NASA has developed a unique and robust multifunctional material called 3DMAT that meets both the structural and thermal performance needs for a lunar return mission and beyond. The 3DMAT Thermal Protection System (TPS) uses a game-changing woven technology tailored to the needs of the Orion Multi-Purpose Crew Vehicle (MPCV) compression pad in order to support the lunar return mission, EM-1, and beyond. Compression pads serve as the interface between the crew module and service module of the Orion MPCV. The compression pads must carry the structural loads generated during launch, space operations, and pyroshock separation of the two modules. They must also serve as an ablative TPS withstanding the high heating of Earth re-entry. 3DMAT leverages the NASAs investment in woven TPS to design, manufacture, test, and demonstrate a prototype material for the Orion compression pads that combines the weaving of quartz yarns with resin transfer molding.

This innovation focuses on an improved low density ablator with improved structural performance and high temperature capability. A new polymer system consisting of cyanate ester and phthalonitrile resins were used to create this carbon reinforced ablator. Cyanate ester resin is a thermoset resin which has high char stability, high decomposition temperature, low oxygen content, low moisture absorption and high glass transition temperature (400 degrees Celsius). Phthalonitrile resin is another type of thermoset resin which has very high char stability, and high decomposition temperature (480 degrees Celsius).

For the past three decades, phenolic impregnated carbon ablators (PICAs) have been the state of the art in ablative entry materials for heat shields for Mars and Earth sample return missions for entry conditions. Traditional rigid PICAs have very low density and highly efficient ablative capability to provide mass efficiency for these heating regimes. Non-rigid variants of PICA provide additional benefits beyond traditional rigid PICA, offering reduced density variants with increased strain to failure. However, all three materials require lengthy infusion processes involving complex equipment and infrastructure, yield toxic byproducts, and the rigid thermal protection system (TPS) produced requires complex and costly integration processes. NASA Ames has developed a family of materials called Materials Engineered for Re-entry using Innovative Needling Operations (MERINO), a flexible PICA material based on felting and fiber intermingling techniques that can create a blanket of thermal protection material to install onto spacecraft.

Many important physical problems in aero-sciences involve unsteady, separated flows. The ability to measure and compute these flows has been a persistent challenge. Unsteady aerodynamics leads to unsteady loads which ultimately decrease system performance and shortens the system lifetime. Currently, dynamic pressure transducers are used to study unsteady flow in wind tunnel tests, which are expensive and do not provide accurate integrated unsteady loads on a wind tunnel model. NASA Ames has developed a first-of-its-kind technology to use a system comprised of fast-response pressure-sensitive paint (PSP), high-speed cameras, and high-powered excitation sources to collect data on pressure fluctuations on vehicle models in wind tunnels. Unsteady Pressure-Sensitive Paint (uPSP) is an emerging optical technique used in wind tunnel testing to measure fluctuating unsteady surface pressures.

The NASA Glenn Research Center (GRC) has expertise in small spacecraft electric propulsion (SSEP). NASA's SSEP project is developing technologies critical to expanding spacecraft capabilities and enabling ambitious new missions into deep space. Advanced SSEP technologies are based on the use of exceptionally fuel-efficient electrostatic Hall effect thrusters with optimized magnetic shielding. Low-power, high-throughput SSEP dramatically increases the capabilities of small spacecraft, and advanced magnetic circuit designs result in game-changing thruster performance. These advances can maximize reliability while minimizing launch cost. Innovators at GRC have developed a suite of SSEP technologies. GRC seeks commercial partners to help satisfy NASA exploration and science mission requirements while improving U.S. competitiveness in the global electric propulsion market and catalyzing innovation related to SSEP technology.

Innovators at NASA's Glenn Research Center have developed new technologies that increase the operational lifetime of a Hall effect thruster (HET), which is used primarily on Earth-orbiting satellites and can also be used for deep-space robotic vehicles. The operational lifetime of HETs is determined by the amount of time the thruster can operate before the plasma within the channel damages the magnetic system. Prior to this innovation, the plasma would erode the ceramic chamber of the HET in just over a year of operation. Glenn's breakthrough technology prolongs this operational lifetime through two related innovations. The first is an innovative magnetic field configuration that provides magnetic shielding to eliminate interactions between the high energy xenon plasma produced by the HET and the ceramic chamber that contains it. The second is a means of replacing eroded discharge channel material via a channel wall replacement mechanism. By increasing the lifetime and efficiency of HETs, Glenn's technology will enable a new era of space propulsion.

Innovators at NASA's Glenn Research Center have developed a breakthrough in ion thruster technology. The Annular Ion Engine (AIE) features an annular discharge chamber with a set of annular ion optics, potentially configured with a centrally mounted neutralizer cathode assembly. Compared to current state-of-the-art, cylindrically shaped ion thrusters, the AIE includes two primary advantages: 1) it enables scaling of ion thruster technology to high power at specific impulse (Isp) desirable for near-term missions, and 2) it provides a substantial increase in both thrust density and thrust-to-power (F/P) ratio. With its additional increase in lifetime service and improvements in packaging, Glenn's AIE represents the next generation of electric propulsion systems that require higher power, F/P, and efficiency, such as Solar Electric Propulsion (SEP) vehicles that may transport humans to the moon and Mars.

Innovators at NASAs Glenn Research Center have developed a suite of small spacecraft electric propulsion (SSEP) technologies critical to enabling new, ambitious missions into deep space. Advanced SSEP technologies are based on the use of exceptionally fuel-efficient electrostatic Hall effect thrusters with optimized magnetic shielding, achieving massive reductions in propellant mass relative to traditional chemical propulsion systems. NASAs low-power, high-throughput SSEP technology dramatically increases the capabilities of small spacecraft while maximizing reliability and reducing launch costs. The Power Processing Unit (PPU) is available for licensing on its own, or as a component of NASAs SSEP technology suite, which is available to U.S. companies through a no-cost, non-exclusive license agreement and companion Space Act Agreement. Click the <i>LEW-TOPS-162: Small Spacecraft Electric Propulsion (SSEP) Technologies</i> link in the <i>Additional Information</i> section for details.

NASA's Glenn Research Center has developed non-contact, ultra-bright luminescence-based surface temperature mapping and sensing systems capable of operating in environments with extremely high thermal radiation. This is accomplished through the use of a unique chromium-doped gadolinium aluminate (Cr:GdAlO₃) temperature-sensing phosphor. This technology has been proven accurate up to 1300&deg;C - a dramatic increase when compared to current state-of-the-art, which has only been demonstrated up to 600&deg;C. In addition to providing breakthrough temperature measurement capability, this innovation is immune to electromagnetic interference, making it ideal for operation in harsh, high-temperature environments. Furthermore, its unprecedented ultra-bright intensity allows for accurate temperature measurements in the presence of high levels of background radiation.

Innovators at NASA Johnson Space Center have developed a coil-on-plug ignition system for integrated liquid oxygen (LOX)/liquid methane (LCH4) thermal-vacuum environment propulsion systems operating in a thermal vacuum environment. The innovation will help quell corona discharge issues and reduce overall mass. Corona discharge represents a local region surrounding a high-voltage conductor where air has undergone an electrical breakdown and become conductive due to ionization, allowing a charge to leak off the conductor and cause a possible malfunction. NASA worked with commercial vendors to modify off-the-shelf automotive coil-on-plug spark plug systems for use with LOX/LCH4 igniters. The coil-on-plug configuration eliminates the bulky standalone coil-pack and conventional high-voltage spark plug cable by combining the coil and the spark plug into a single component. The test campaign successfully proved that coil-on-plug technology can enable integrated LOX/methane propulsion systems in future spacecraft.

Innovators at NASA Johnson Space Center have developed an additively manufactured thermal protection system (AMTPS) comprised of two printable heat shield material formulations. These formulations are directly applied by 3-D printer or other robotic extrusion system, and bonded to a spacecraft to devise a heat shield suitable for atmospheric entry. This technology could significantly decrease heat shield or thermal protection system (TPS) fabrication cost and time. Current state of the art TPS manufacturing and application methods are expensive, labor-intensive, and complex. These drawbacks are primarily due to the amount of skilled, manual labor needed for form fitting and bonding individual TPS tiles across a spacecraft’s forebody – each tile comprised of differing thermal properties and layers – and includes filling the gaps in-between the tiles with an additional component formulation. This AMTPS technology can solve these challenges and may represent a game changing innovation in TPS manufacturing – away from convention-al labor-intensive, costly, long-schedule techniques and towards automa-tion. It reduces the complexity of TPS integration, and eases the produc-tion of large and specially contoured heat shields. Additionally, this tech-nology allows heat shields to be created as a single mold and prevents the need to treat the tile gaps of current heat shields, thus eliminating numerous potential failure points.

Innovators at NASA Johnson Space Center have developed a thin film sensor that measures temperatures up to 1200 F, and whose prototype successor may achieve measurements up to ~3000 F – which was the surface temperature of the Space Shuttle during its atmospheric reentry. The novel sensor design also quells the deleterious effects of thermal expansion mismatch between the thermal protection system (TPS) material comprised in the spacecraft’s outer shell, and the embedded thin film sensors’ component materials. Current methods that capture temperature data from the surface of a reentering spacecraft typically rely upon the use of low frequency thermocouples embedded in the spacecraft’s TPS and are limited to ~700 F. However, these thermocouples lack the high frequency response required for anything but low frequency temperature or heat flux. This novel thin-film temperature sensor, also embedded as an in-situ device in the through-thickness of a spacecraft’s TPS, is designed to solve these issues by capturing data at an extremely high frequency rate (>1MHz). This technology may prove extremely useful in a burgeoning commercial aerospace industry where the ability to measure temperature from the surface of a reentering spacecraft can be used to enhance performance and safety. The thin film temperature sensor may also have commercial applications in hypersonic aircraft, energy production, metallurgical blast furnaces, and other extreme high enthalpy environments.

NASA's Langley Research Center has developed a technology that is projected to extend the laminar flow area over supersonic flight configurations by delaying the transition of boundary layer flow from laminar to turbulent state. This controls laminar flow over airframe components including wings, empennage, engine nacelles, and the nose region of an aircraft fuselage. It can be used in combination with many of the existing techniques for passive and active laminar flow control, but is particularly well-suited for a supersonic natural laminar flow design by virtue of avoiding the space, weight, system complexity, and maintenance penalties associated with suction based laminar flow control.

Innovators at Langley Research Center (LaRC) have developed a design and method to improve efficiency in nuclear propulsion technology for long-distance space missions. The nuclear thermionic avalanche cell (NTAC) Augmented Nuclear Electric Propulsion and/or Nuclear Thermal Propulsion design surrounds the rocket chamber and reactor core with an NTAC and safely converts gamma ray radiation expelled during nuclear fission processes, which would otherwise be lost to radiation shielding, into electric power to support additional propulsion. Compared to current radiation-shielded propulsion systems, this design is more efficient and lower weight, enabling faster nuclear propulsion travel. This technology potentially has a wide range of applications including nuclear power generation applications on Earth, and for unmanned vehicles, and commercial space exploration.

The two main sub-scale, ground-based rocket aerodynamics testing techniques hot-fire testing and cold-flow testing pose a series of tradeoffs. Hot-fire testing is generally much more accurate, but is often burdensome, costly, and requires long lead times due to design work, infrastructure preparation, etc. Cold-flow testing is much less expensive and has a rapid turnaround time, but conventional simulants (e.g., nitrogen, steam) used in cold-flow testing yield less accurate results (i.e., results that are not sufficiently representative of test article performance). While researching methods to optimize such tradeoffs, engineers at NASAs Stennis Space Center discovered that ethane can be tuned to approximate rocket exhaust plumes generated by several common rocket propellants. This led NASA to develop the HYdrocarbon Propellants Enabling Reproduction of Flows in Rocket Engines (HYPERFIRE), a sub-scale, non-reacting flow test system. HYPERFIRE uses heated ethane to enable physical simulation of rocket engines powered by a broad range of propellants in an inexpensive, accurate, and simple fashion.

Standard cylindrical and second-throat diffusers allow supersonic gas flows to expand within their walls and pull a vacuum on any upstream void. However, the high-Mach-number shock reflections that occur in the center of the plume create substantial losses and result in an inefficient pumping process. Centerbody diffuser designs provide an improvement by reducing the maximum Mach number of the core flow, but also increase the number of oblique shocks in the system by introducing multiple turns into the system. A new type of spike diffuser recently developed by NASA Stennis Space Center is able to provide approximately double the pumping performance of second-throat diffusers via Pareto-efficient reduction of both core Mach number and flow deflection. This enables substantially lower vacuum pressures to be achieved for a given feed pressure/mass flow via the use of higher-expansion-ratio driving nozzles. Spike diffusers are also spatially compact, requiring only ~25% of the length of second-throat designs

NASA is developing a lightweight one-piece regeneratively-cooled thrust chamber assembly (TCA) for liquid rocket engines. Liquid rocket engines create thrust through the expansion of combusted propellants within the TCA. Standard manufacturing of TCAs involves individually building the injector, main combustion chamber and nozzle, and then bolting or welding the components together at the joints. However, potential seal failures in these complex joints can cause catastrophic explosions, as in the tragedy of the Space Shuttle Challenger. NASA researchers are eliminating complex joints by manufacturing a 1-piece TCA utilizing 3D printing and large-scale additive manufacturing technologies to directly deposit the nozzle onto the combustion chamber. And, by replacing a traditional solid metal jacket with a composite overwrap for support, the overall weight is reduced by over 40%. Developed under the Rapid Analysis and Manufacturing Propulsion Technology (RAMPT) project, NASA seeks public-private partnerships to develop specialized large-scale additive manufacturing vendors and accelerate reliable spaceflight hardware to the US supply chain.

In mono-propulsion systems, a propellant is flowed across a catalyst to promote a chemical reaction and generate thrust. Conventional catalyst manufacturing methods entail (a) coating the inner walls of the thruster nozzle with a catalyst (generally undesirable due to limited catalyst-propellant contact), or (b) inserting a metal or graphite foam coated with a catalyst material into the thruster chamber. Method (b), while superior in terms of thrust generation, also possesses several limitations. Metal/graphite foams are difficult and expensive to procure, stochastic/random in nature (e.g., possess high variability in terms of geometric and other properties), and must be jammed into the thruster chamber using a compression plunger during installation – a process that often leads to catalyst damage. A new manufacturing method that improves repeatability, thruster reactivity, and tailorability (e.g., mechanical, chemical, and fluid flow) while reducing cost and lead time is thus highly desirable. To address this need, NASA and EOS developed methods to additively manufacture (AM) ultra-fine lattice structure propulsion catalysts.

Low-cost, large-scale liquid rocket engines with regeneratively cooled nozzles will enable reliable and reduced-cost access to space. Coolant, contained under high pressure, circulates through a bank of channels within the nozzle to properly cool the nozzle walls to withstand high temperatures and prevent failure. It has been a challenge to affordably manufacture and close out the intricate nozzle channels. As such, NASA developed a robust and simplified additive manufacturing technology to build the nozzle liner outer jacket to close out the channels within and contain the high-pressure coolant. The new Laser Wire Direct Closeout (LWDC) capability reduces the time to fabricate the nozzle and allows for real-time inspection during the build. One variation enables a bimetallic part (copper/super-alloy, e.g.) to help optimize material where it is needed. The manufacturing process has been demonstrated on a series of different alloys. Hot-fire testing is complete&#8212the parts were exposed to extreme combustion chamber temperatures and pressure conditions for 1,000+ seconds. Micro-graph examination of the hot-fired test article has verified that the coolant channel closeout bonds are reliable and that there is very little deformation to the coolant channels. The picture above was taken during the hot-fire testing of a nozzle.

NASA’s Marshall Space Flight Center has developed a novel turbine blade design and manufacturing approach that provides a significant reduction in turbine blade resonant vibration. In particular this innovation addresses the unique resonance vibration challenges of conventionally machined turbine bladed-discs, or blisks. The design approach includes an internal blade tuned mass absorber structure that can be placed at optimal location where deflection is greatest. Additive manufacturing is used to make this unique structure. Prototypes have demonstrated a 50% reduction in resonant vibration. Importantly, the innovation also enables improved predictive modelling of the resonant behavior of new blisk designs because the tuned-mass absorber acts as a linear system. In contrast, modelling of conventional blade dampers is extremely complex and therefore requires an expensive iterative test program dedicated to validation of the damper design.

NASAs Marshall Research Center has developed a system for generating iodine vapor from solid iodine, for use as a propellant in a Hall or ion thruster propulsion system. Xenon has generally been the preferred propellant of choice for these spacecraft ion propulsion systems, but more recently iodine-based systems have gained significant attention due to comparable performance to xenon, and the system-level advantages of low storage pressure and higher storage density with more propellant per unit volume. However the solid iodine, in comparison to gaseous xenon, must be sublimated into a vapor for ionization, and a heat source must be used to increase the sublimation rate of the solid iodine to a level that is useful for propulsive purposes. The subject innovation is a spring-loaded mechanism to optimize the contact of the solid iodine with the heated structure in the zero-gravity environment of space.

NASA Marshall Space Flight Center and collaborators at Utah State University have developed a prototype for a highly efficient hybrid motor designed for spacecraft. This innovative motor addresses the need for both substantial propulsion during orbital maneuvers and precise control for attitude adjustments and stability. Hybrid motors offer a variety of advantages over traditional liquid and solid propulsion systems. Hybrid motor systems are significantly simpler than a liquid engine system, and offer safety gains and possible throttling capabilities compared to a solid rocket motor. However, the practical implementation of rapid throttling has presented significant challenges in the industry. The NASA motor tackles this hurdle by leveraging a digital valve technology, effectively reducing full-scale throttle time to one second or less and enabling the potential for rapid restart and short pulses of thrust. This hybrid motor technology holds promise for the future of space exploration and offers potential solutions for improved motors on low earth orbit spacecraft (commercial or government) as well as sounding rockets, missiles, and other systems.