NASA STTR Awards Focused on Advanced Thermal Protection Systems
This computer-generated art depicts Orion’s heat shield protecting the crew module as it enters the Earth’s atmosphere. (Credit: NASA)
by Douglas Messier
Managing Editor
As NASA is funding research into lighter and more capable thermal protection systems (TPSs) producing using additive manufacturing (3D printing) as it looks to land ever larger payloads on other worlds and return extraterrestrial soil samples to Earth.
The space agency recently selected four heat shield proposals from corporate-university partnerships for funding under its Small Business Technology Transfer (STTR) program. The phase 1 grants are worth up to $125,000 over 13 months.
Cornerstone Research Group of Ohio teamed with the University of Texas at Austin on a proposal that will develop a multi-layer TPS.
“Cornerstone Research Group Inc. (CRG) proposes to advance the state-of-the-art in space vehicle Thermal Protection Systems (TPS) through in-situ application and curing of a proprietary new resin technology called MG Resin, a family of thermoset formulations,” the company said.
“The resins are being explored with DARPA, MDA, NASA, and the Army for a range of applications including C/C hot structures, TPS, syntactic insulation, and elastomeric rocket motor insulation among others,” Cornerstone added.
NASA also selected a TPS proposal from Intelligent Optical Systems (IOS) of Torrance, Calif. and the University of Southern California in Los Angeles.
“IOS proposes to develop a modular system for in-situ bonding and curing of thermoset resin to the spacecraft structure to facilitate automated manufacturing of TPS. This system will be compatible with additive manufacturing techniques, high-temperature thermoset resins, and composite substrates currently in use and under development by NASA, SpaceX, and others,” IOS said in its proposal summary.
“Our system, combing in-line IR gelation of the resin extrudate and in-situ c-staging, will eliminate the need for large ovens or autoclaves. By leveraging advances in out of autoclave curing methods our system will enable curing of additively manufactured high temperature thermoset resin based TPS in-situ,” the summary stated.
NanoSonic of Pembroke, Virginia and Virginia Tech were also selected for a STTR award for an advanced heat shield system.
“NanoSonic and Virginia Tech will design and empirically optimize an innovative, commercially scalable additive manufacturing process integrating reactively deposited HybridSil polyimide nanocomposites for next-generation Thermal Protection Systems (TPS) employed on human rated spacecraft,” the proposal said.
“NanoSonic’s material technology and Virginia Tech’s additive manufacturing expertise will be synergistically combined to provide NASA with a pioneering additive manufacturing process and high temperature, high char yield material that drastically reduces the fabrication and installation cost of current TPS ensembles while also reducing seam density,” the document added.
Tethers Unlimited is partnering with Western Washington University on another selected proposal. The company said the Resin Additive Manufacturing Processed Thermal Protection Systems (RAMP TPS) would be cheaper and easier to produce as well as stronger than existing systems.
“RAMP TPS technology will enable cost-effective production of advanced thermal protection shields for a range of re-entry applications, including lunar exploration missions, Mars sampling missions, and asteroid sampling missions such as OSIRIS-Rex,” the company said.
“RAMP TPS could enable rapid, cost-effective production of thermal protection shields for ICBM re-entry bodies. It will also enable in-space production of large aerobrakes to support commercial ventures to obtain lunar resources such as water from the lunar poles and deliver it to propellant depots in LEO using aerobraking techniques,” Tethers Unlimited added.
Summaries of the STTR awards follow.
In-Space and Advanced Manufacturing SSTRs
In-Situ Application of Multi-Layer Thermal Protection System
Subtopic Title: In-situ Curing of Thermoset Resin Mixtures
Cornerstone Research Group, Inc.
Miamisburg, OH
The University of Texas at Austin
Austin, Texas
Principal Investigator
Richard Hreha
Estimated Technology Readiness Level (TRL)
Begin: 2
End: 3
Technical Abstract
Cornerstone Research Group Inc. (CRG) proposes to advance the state-of-the-art in space vehicle Thermal Protection Systems (TPS) through in-situ application and curing of a proprietary new resin technology called MG Resin, a family of thermoset formulations.
The resins are being explored with DARPA, MDA, NASA, and the Army for a range of applications including C/C hot structures, TPS, syntactic insulation, and elastomeric rocket motor insulation among others. The materials have demonstrated high char yield, low erosion, and good mechanical performance, and are compatible with a wide variety of fillers and substrates.
The overall material system is tunable to meet application, processing, and curing needs. Coupled with fillers, the resins allow a heat shield to be fabricated directly onto the vehicle and built up layer-by-layer for optimal performance to meet mission objectives.
Inner layers can be filled with microballoons for insulation, outer layers filled with chopped fiber for strength, and the surface carbonized for improved ablation resistance. The hybrid materials are suitable for automated processing and the combined value is quicker and lower cost production of TPS for space exploration vehicles.
Potential NASA Applications
Thermal Protection Systems (TPS)
- Aeroshells
- Hypersonics
Potential Non-NASA Applications
Foundry Refractory Materials
- Furnace liners
- Ladle liners
Fire Smoke and Toxicity Compliant Materials
Aircraft and marine interiors
Industrial Insulation
- Furnaces and boilers
- Reactors and piping
Duration: 13 months
A Modular In-Situ Curing Apparatus for Thermoset Resin Mixtures Applied as Thermal Protection
Subtopic Title: In-situ Curing of Thermoset Resin Mixtures Systems
Intelligent Optical Systems, Inc.
Torrance, Calif.
University of Southern California
Los Angeles, Calif.
Principal Investigator
Dr. Paul DiCarmine
Estimated Technology Readiness Level (TRL)
Begin: 2
End: 3
Technical Abstract
Future human extraterrestrial missions will require export and landing of countless payloads on the lunar and Martian surfaces. Such a quantity and rate of payload delivery will require cost-effective and rapid manufacturing of many large Thermal Protection Systems (TPS).
IOS proposes to develop a modular system for in-situ bonding and curing of thermoset resin to the spacecraft structure to facilitate automated manufacturing of TPS. This system will be compatible with additive manufacturing techniques, high-temperature thermoset resins, and composite substrates currently in use and under development by NASA, SpaceX, and others. Our system, combing in-line IR gelation of the resin extrudate and in-situ c-staging, will eliminate the need for large ovens or autoclaves.
By leveraging advances in out of autoclave curing methods our system will enable curing of additively manufactured high temperature thermoset resin based TPS in-situ. An infrared heat source mounted directly on the print head will rapidly gel the extrudate as it leaves the nozzle, enabling multi-layer printing. Upon completion of the printing process, a modular system of conductive heat blankets, conforming to the surface contours of the structure will control final cure of the thermoset.
The system will measure the temperature of the resin and provide feedback control and log thermal history during curing. In-line surface activation with a corona generator will ensure strong bonding to the underlying substrate and at layer interfaces.
Validation of the system will be performed by measuring the degree of cure of in-situ cured samples and measurement of bond strength. We anticipate in-situ cured samples to achieve a high degree of cure, char yield, glass transition temperature, and bond strength, comparable to traditionally cured resins. Target end points for Phase I work are deviation of no more than 10% between in-situ cured and control cured resins.
Potential NASA Applications
Potential applications for NASA include human missions to both the moon and Mars. Such missions will require TPS to protect both crew and cargo from heat during hypersonic flight. The advanced TPS production technology developed in this project will be applicable to the Human Exploration and Operations Mission Directorate’s (HEO) Orion spacecraft and commercial spaceflight. Further development of the technique will enable 3D printing and automated production of high temperature resilient parts and molds on Earth, the moon, and Mars.
Potential Non-NASA Applications
Commercial Space programs like SpaceX will benefit from advanced TPS manufacturing processes being developed by NASA. The proposed system will enable the parallelized and rapid production of heat shields required for interplanetary colonization. Additionally, this technology could enable commercial thermoset resin 3D printing technology and impact the advanced manufacturing market as a whole.
Duration: 13 months
Cure in Place Hybridsil Polyimide Materials for Next Generation Additively Manufactured TPS Heat Shields
Subtopic Title: In-situ Curing of Thermoset Resin Mixtures
NanoSonic, Inc.
Pembroke, VA
Virginia Tech
Blacksburg, VA
Principal Investigator
Vince Baranauskas
Estimated Technology Readiness Level (TRL)
Begin: 3
End: 5
Technical Abstract
Through the proposed NASA STTR, NanoSonic and Virginia Tech will design and empirically optimize an innovative, commercially scalable additive manufacturing process integrating reactively deposited HybridSil polyimide nanocomposites for next-generation Thermal Protection Systems (TPS) employed on human rated spacecraft.
NanoSonic’s material technology and Virginia Tech’s additive manufacturing expertise will be synergistically combined to provide NASA with a pioneering additive manufacturing process and high temperature, high char yield material that drastically reduces the fabrication and installation cost of current TPS ensembles while also reducing seam density.
The proposed additive manufacturing technology will be directly based on fused filament fabrication (FFF) and have near-term scalability within Virginia Tech’s large-scale automated additive manufacturing robotic assembly, which has 6 degrees of freedom and a current capability of generating MatEx produced structures on the order of ~8 x 8 x 8 feet.
The proposed additive manufacturing technique and materials will be molecularly engineered and iteratively developed to produce next-generation ablative heat shield components with equivalent utility as currently employed polymer infused carbon ablative tiles such as PICA and PICA-X.
The long-term value proposition to NASA and space industry market will be significantly reduced TPS installation cost, improved heat shield performance, and highly adaptable, seamless spacecraft integration.
Potential NASA Applications
NASA applications include integration within heat shield structures employed within current and future human rated spacecraft.
Potential Non-NASA Applications
Broand secondary non-NASA applications include use as low-cost additively manufactured high temperature insulative components and structures within aerospace, marine, and land vehicles within military and civilian platforms.
Duration: 13 months
Resin Additive Manufacturing Processed Thermal Protection Systems (RAMP TPS)
Subtopic Title: In-situ Curing of Thermoset Resin Mixtures
Tethers Unlimited, Inc.
Bothell, WA
Western Washington University
Bellingham, WA
Principal Investigator
Jesse Cushing
Estimated Technology Readiness Level (TRL) :
Begin: 2
End: 4
Technical Abstract
Tethers Unlimited, Inc. (TUI) and Western Washington University (WWU) propose to develop the “Resin Additive Manufacturing Processed Thermal Protection System” (RAMP TPS), an in-situ cured, additively manufactured, spacecraft heat shield material and process. RAMP TPS uses Direct Ink Writing (DIW) of an optimized benzoxazine resin-based compound, filled with carbon fibers, silica micro-balloons, cure accelerators, and viscosity modifiers.
Current TPS systems are expensive to produce, and they make various compromises in their heat shield performance properties. The RAMP TPS effort will leverage automation techniques borrowed from 3D printing, along with state of the art heat shield materials, while adding the ability to cure in-situ during robotic deposition.
RAMP TPS will offer superior mass-effectiveness through optimized material composition as well as graded low density printed core structures. While conventional TPS resins can require hours for an oven cure process,
WWU’s Benzoxazine formulation will use accelerator additives to chemically set within minutes of deposition using the heat supplied by TUI’s feedhead assembly. Initial heat shield performance characterization will be performed using density, strain at break, thermal conductivity, TGA measurements, and thermo-oxidative ablation testing with an oxy-acetylene torch.
This novel heat shield technology will have near term applications in lowering the cost of high-performance spacecraft production, as well as future applications within TUI’s in-space processes for automated production and servicing of re-entry vehicles.
Potential NASA Applications
RAMP TPS technology will enable cost-effective production of advanced thermal protection shields for a range of re-entry applications, including lunar exploration missions, Mars sampling missions, and asteroid sampling missions such as OSIRIS-Rex.
Potential Non-NASA Applications
RAMP TPS could enable rapid, cost-effective production of thermal protection shields for ICBM re-entry bodies. It will also enable in-space production of large aerobrakes to support commercial ventures to obtain lunar resources such as water from the lunar poles and deliver it to propellant depots in LEO using aerobraking techniques.
Duration: 13 months
