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Tiny Probes Hold Big Promise for Future NASA Missions

Video of a probe-shaped test article that is a nearly-perfect match to the TVA flight article, tested in the IHF (Interactive Heating Facility) arc jet at a constant condition, matching the anticipated flight total heat load on the probe. After the flight, we will subject another test article with time-profiled heating to simulate the conditions determined from the actual flight trajectory reconstruction. This will be the first time we will have arc jet tested and flight tested the exact same geometry and materials.


This picture shows the entry probe and the metal outer shell. The metal shell allows the probe to be connected with the supply ship and also facilitates the probe to be released during break-up of the supply spacecraft during reentry. Credits: NASA

Sometimes to find the best solution to a big problem, you have to start small.

A team of NASA engineers has been working on a new type of Thermal Protection System (TPS) for spacecraft that would improve upon the status quo.

Having seen success in the laboratory with these new materials, the next step is to test in space.

The Conformal Ablative Thermal Protection System, or CA-TPS, will be installed on a small probe flight article provided by Terminal Velocity Aerospace (TVA) and launched on Orbital ATK’s seventh contracted commercial resupply services mission for NASA to the International Space Station on April 18.

TVA’s RED Data2 probe, only slightly larger than a soccer ball, is an unmanned exploratory spacecraft designed to transmit information about its environment.


The three probes shown in the above picture will reentry during the supply spacecraft break-up and collect data. The probe on the left has conformal TPS, the probe in the middle is Orion’s Avcoat TPS and the probe on the right is made of Shuttle Tile. Credits: NASA

“The purpose of the flight test is to gather supply vehicle break up data and at the same time demonstrate performance of the conformal ablative thermal protection system as the probe—encapsulated with TPS—enters Earth’s atmosphere,” explained Ethiraj Venkatapathy, project manager for Thermal Protection System Materials with NASA’s Space Technology Mission Directorate’s (STMD) Game Changing Development (GCD) program. “Thermal protection is a vital element that safeguards a spacecraft from burning up during entry.”

“Data obtained from flight tests like this one with TVA and NASA, combined with testing at different atmospheric compositions, allows us to build design tools with higher confidence for entry into other planetary atmospheres such as Venus, Mars or Titan,” he continued. “Partnering with a small business to get flight data for a developmental material is a very inexpensive way of achieving multiple goals.”

The TPS Venkatapathy and his team are designing uses newly emerging materials called conformal PICA (C-PICA) and conformal SIRCA (C-SIRCA), short for Phenolic Impregnated Carbon Ablator and Silicone Impregnated Reusable Ceramic Ablator, respectively.

The probe is essentially a hard aeroshell covered with the TPS and outfitted with sensors called thermocouples. To measure temperature during atmospheric entry, the thermocouples are embedded within the heat shield’s C-PICA and the back shell’s C-SIRCA to capture data for understanding how the materials behave in an actual entry environment.

With funding through STMD/GCD, NASA’s Ames Research Center led the work providing conformal ablative materials and TPS instrumentation installed on Terminal Velocity’s probes. Terminal Velocity is also working with NASA’s Johnson Space Center with funding from STMD’s Small Business Innovation Research program for miniaturizing and improving the data acquisition and transmission system as well as providing support for ISS flight certification.

Through the ISS Exploration Flight Project Initiative, Johnson certified three TVA probes for flight. One probe uses the conformal ablative materials, another has the Orion heat-shield material and the third probe uses shuttle tile material for reference. TVA delivered the assembled probes to the Cargo Mission Contract group for this flight.

After Orbital ATK’s resupply services launch arrives at the ISS, the probes will remain on the cargo ship awaiting their opportunity to go to work. Projected to be released from the ISS in June, once the cargo ship reenters Earth’s atmosphere and breaks up, the probes will deploy and then begin capturing data through the thermocouples embedded in the TPS.

“The probes are designed to be released from the metallic shell and once they are released, they start to get heated. The thermal response data are collected from the various locations where thermocouples are embedded within the TPS,” explains Robin Beck, technical lead for the conformal TPS development. “The probe includes an antenna that allows it to communicate with an Iridium satellite. As the probe descends into the atmosphere and slows to the speed of sound, the data are collected and stored, then transmitted to the Iridium satellite above, which in turn transmits the data to researchers on the ground.”

Once the flight test’s data are collected, TVA’s probe is allowed to fall into the ocean and is not recovered; however, these tiny spacecraft will contribute in a very big way to ensure the predictive models developed based on testing in ground facilities are valid and applicable in space.

“There are known and unknown risks, but both NASA and TVA are motivated to be successful as the benefits also translate to the larger community that wants to have on-demand access to space,” says Venkatapathy. “This technology has the potential to lower the cost of access to space for small payloads while making it attractive for universities and the non-aerospace community who may be novices to flight testing—a challenge in and of itself and not risk free.”

Because there is no backup for a spacecraft’s TPS, it is critical to understand and develop prediction capabilities that allow safe, robust entry system design. A successful flight test at this scale will increase confidence in the conformal ablator and allow mission planners to consider C-PICA and C-SIRCA for use in future programs such as New Frontiers or Orion.

For more information about NASA’s Game Changing Development program, visit:

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Ancient Art of Weaving Ready to Head to Mars and Beyond

Steve Jurczyk, NASA Associate Administrator for Space TechnologyEugene Tu, Director, NASA Ames Research CenterTBD Lockheed Martin Ray Harries, President, BRMMark Harries, BRMLeon Bryn, BRM TBD Congressional Members and staffBally Ribbon Mills invented and established new weaving capability to support NASA’s need to enable robotic science missions to Venus and Saturn. The new loom that is about to start weaveing 2.1” thick, 3-D, dual layer weave at 24” width is one of a kind, unique capability. Credits: NASA

Ethiraj Venkatapathy, project manager and chief technologist for the Entry Systems and Technologies Division at Ames, holds a compression pad made from 3-D woven material that will be used on the Orion spacecraft as a thermal protection system and shock absorber. Credits: NASA/David Bowman

Weaving processes created millennia ago are part of the most cutting-edge technology on NASA’s Orion spaceship that may one day shield humans from heat as they ride all the way to Mars and back.

That same technology is finding a home on Earth as well, enabling thicker, denser composite materials for race cars, among other applications.

It started with a connection problem: there are points across Orion’s heat shield surface that must link the crew capsule to its service module and, ultimately, the rocket. “At these points, you have to use a very strong, robust material,” explains materials engineer Jay Feldman, technical lead for the 3-D Multifunctional Ablative Thermal Protection System (3D-MAT) at NASA’s Ames Research Center.

But great insulators are often not particularly strong.

Luckily, Feldman and other engineers at Ames were already working with partners at weaving company Bally Ribbon Mills on next-generation heat-shielding material. Together, they were developing a three-dimensional quartz-fiber composite, woven using classic shuttle looms upgraded for the modern era.

NASA, Lockheed Martin, and Bally Ribbon Mills representatives tour the Bally Ribbon Mills facility in Pennsylvania. Credits: NASA/David Bowman

NASA, Lockheed Martin, and Bally Ribbon Mills representatives tour the Bally Ribbon Mills facility in Pennsylvania.
Credits: NASA/David Bowman

Three-dimensional woven composites offered big advantages over layered 2-D woven composites used in previous spacecraft. “When you have fibers going in all three directions, it’s very, very strong,” explains Feldman. “And we can also tailor the composition so it has relatively low thermal conductivity.”

An Old Art
Bally Ribbon Mills, in Bally, Pennsylvania was a natural partner for the project. A leading U.S. manufacturer of two and three-dimensional textiles, the company’s client list includes the U.S. Air Force, Formula One racing teams and biomedical companies.

The firm’s expertise extends back to 1923, when the family-owned company started out weaving silk hat bands. Three generations later the company had evolved into a high-tech custom engineering firm, explains Mark Harries, part of the fourth generation of his family to run the textile company.

“That’s when we really found our niche,” Harries says.

NASA Associate Administrator Stephen Jurczyk explains ADEPT to a member of the local media.

NASA Associate Administrator Stephen Jurczyk explains ADEPT to a member of the local media.
Credits: NASA/David Bowman

The NASA partnership, and the resulting material, have generated a lot of excitement at the space agency, prompting a January 2015 visit to the mill by then-NASA Administrator Charles Bolden, who declared: “From this day on, the path to Mars goes through Bally, Pennsylvania.”

For Orion, the threads are made of quartz, which is an excellent insulator and also capable of transmitting electrical signals.

Bally Ribbon Mills had to design new equipment to meet NASA’s needs: a thicker textile and, to improve compression strength, the same number of fibers going in all three directions.

The final product “is like a brick,” says senior textile engineer Curt Wilkinson.

Elegant Design
But the design is truly elegant, says Ethiraj Venkatapathy, project manager and chief technologist for the Entry Systems and Technologies Division at Ames. “The material can be a structure, it can be a thermal protection system, it can be a shock absorber, and it can carry loads,” he says, a contrast to designs that tend to focus on just one discipline.

Already the designers of Orion are looking at other spots where the 3D-MAT material may be incorporated. And outside NASA, government agencies and aerospace companies have expressed interest.

The work for NASA has also increased the product line the company offers in more frequently used materials, like carbon fiber, to its long-standing clients, including Formula One car manufacturers.

“It increases the size of the parts they can make,” Wilkinson says, which “gives them more opportunities for different locations in the car.”

Yet underneath the high-tech add-ons, the core of the process is the same type of shuttle looms the company used for silk in the 1920s. It’s an evolution that has kept nearly 300 jobs in central Pennsylvania, where most of the other textile mills have long gone out of business.

“We incorporate modern electronic components, and we also build and incorporate our own take-up systems, but the loom itself is extremely old,” Wilkinson says. “Using the same age-old steps of weaving, we’re now weaving material that’s going to go to Mars.”

Bally Ribbon Mills’ latest work with NASA is on the heatshield for extreme entry environment technology (HEEET) project for the agency’s Game Changing Development program. The HEEET project aims to develop the technology the agency needs for a heatshield to protect science payloads upon entry into Saturn or Venus that encounter extreme conditions. Bally took 18 months to design, develop and assemble the world’s most unique loom for weaving materials for the HEEET project. There is no other loom in the world that can weave 3-D, multi-layer materials to meet specifications for a heatshield that can withstand heating conditions much more extreme than those encountered by NASA’s Mars Science Laboratory Curiosity rover mission in 2012.

NASA has a long history of transferring technology to the private sector. Each year, the agency’s Spinoff publication profiles about 50 NASA technologies that have transformed into commercial products and services, demonstrating the wider benefits of America’s investment in its space program. Spinoff is a publication of the Technology Transfer Program in NASA’s Space Technology Mission Directorate.

To learn more about this NASA spinoff, read the original article from Spinoff 2017.

For more information on how NASA is bringing its technology down to Earth, visit:

Naomi Seck
Goddard Space Flight Center

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First 3D woven composite for NASA thermal protection systems

3D Woven Quartz

3D woven quartz preform helps to boost performance in the compression pads, part of the thermal protection system (TPS) for the Orion spacecraft. Source: NASA


NASA’s Orion Multipurpose Crew Vehicle has been designed to transport a crew of six to and from deep space, including an asteroid (≈2025) and Mars (≈2030). It comprises two modules: the Crew Module (or Command Module, CM), built by Lockheed Martin (see Sara Black’s article on its composite heat shield) and the Service Module (SM) built by Airbus Defense and Space for the European Space Agency (ESA).

In Dec. 2014, the Orion first flight test vehicle, EFT-1, was successfully launched on a Delta IV heavy rocket, reached an altitude of 5,793 km above earth, achieved speeds of 20,000 mph, and withstood temperatures over 2,200°C during reentry. However, the heat demands of this mission were much lower than what Orion will see when it goes further out, for example, to Mars.

Need for Better Compression Pads

Many lessons were learned during that test, including the need for improved ablative materials for the compression pads which enable attachment of Orion’s CM and SM. These pads — six total used on the EFT-1 spacecraft, redesigned now to total four for future Orion models — measure roughly 280 mm in diameter and 76 mm thick, and must resist launch & ascent loads and pyro-shock (explosive bolts) during CM/SM separation, as well as meet reentry demands for high-temperature resistance and ablation.

Orion's Compression Pads

Orion’s compression pads enable attachment of the Crew and Service Modules (left) and must resist structural loads during launch and ascent, as well as pyro-shock during CM/SM separation. Explosive bolt and CF/phenolic compression pad (center). Six compression pads were evenly spaced around the Orion CM’s blunt body heat shield for EFT-1 (right). Source: Jay Feldman, NASA Ames.

Ablative materials are solid substances which undergo a series of physicochemical transformations to control heat transfer. In other words, they keep underlying structures cool by managing energy as the materials are consumed through melting, vaporization, oxidation, sublimation and spallation. Ablative materials are a key part of a spacecraft’s thermal protection system (TPS), and are commonly made from fiber-reinforced composites. The compression pads discussed here are an important part of the overall TPS design for Orion. (NASA describes Orion’s composite ablative heat shield here.)



The carbon fiber/phenolic compression pads on the EFT-1, however, were expected to fail due to poor interlaminar strength unless a steel insert was added to handle some of the structural loads. The insert, which surrounds the explosive bolt, has significantly higher thermal conductivity than the composite, creating a thermal “short” in the TPS.

3D Solution

As a leader in NASA’s heat shield materials research and development, Jay Feldman had already been pursuing an internal R&D program exploring 3D woven fabrics for TPS solutions for subcontractor Analytical Mechanics Associates, Inc. (AMA, Hampton, VA, US) at NASA Ames Research Center (Mountain View, CA, US). Feldman led the project “3D Multifunctional Ablative TPS (3D-MAT) for Orion Compression Pad” which began in 2012. The goal was to overcome the traditional interlaminar weakness of 2D laminates and also eliminate the need for metal inserts to receive the bolts.

NASA Ames’ 3D-MAT program trialed different fiber and resin combinations before selecting 3D woven quartz and cyanate ester Source: Jay Feldman and NASA Ames.

NASA Ames’ 3D-MAT program trialed different fiber and resin combinations before selecting 3D woven quartz and cyanate ester Source: Jay Feldman and NASA Ames.

A variety of fiber and resin combinations were trialed, with the compression pads’ structural and thermal requirements driving final selection:

  • 3D orthogonal weave enabled high fiber volume (57%) for structural robustness;
  • Fused quartz fiber provided high temperature capability with low thermal conductivity;
  • Low viscosity cyanate ester resin system allowed hybrid resin infusion/resin transfer molding (RTM) processing to achieve full densification of large 3D woven preforms.

3D-MAT’s new approach uses a straight orthogonal 3D woven quartz material from Bally Ribbon Mills (Bally, PA, US), woven continuously at 76 mm thick and 305 mm wide using a jacquard loom (click here to learn more about 3D weaving). “This is the first application of a 3D woven material in a TPS application for NASA,” says Feldman, ceding that the Dept. of Defense has used 3D carbon/carbon composites in missiles systems. He notes that the 3D architecture places one-third of the fiber in each direction: x, y and, notably, z (through-the-thickness). “One of the challenges was scaling up the weaving process to increase the cross-sectional area by a factor of four in a continuous process,” says Feldman. The next challenge was how to infuse the fabric with cyanate ester resin from TenCate Advanced Composites (Morgan Hill, CA, US) and fully densify it to meet ablation requirements.

Bally Ribbon Mills

Bally Ribbon Mills was able to scale up the 3D preform cross-section by 400% in a continuous process using NASA-funded hardware. San Diego Composites then developed a modified RTM process to infuse the preform with resin. Source: Jay Feldman, NASA.

Hybrid RTM Infusion

To overcome this challenge, Feldman and team worked with San Diego Composites (SDC, San Diego, CA, US), a well-known manufacturer that is making a number of parts for Orion, including the ogive and launch abort system (LAS) fillet. As described in the video below by SDC chief technology officer Ken Mercer, the very dense 3D preform was placed into tooling that evacuated air first, and then injected the resin under pressure.

(click here to play video from beginning)

Feldman says the process started with a vacuum soak, followed by resin infusion, cure and post-cure. So, as Mercer says in the video, the process is more like infusion than traditional RTM, although pressure is used to achieve the final low void content. “Less than 2% voids was the limit,” notes Feldman, “but we were able to achieve 0.5%, thanks to SDC’s process development.” SDC then machined and supplied the final circular compression pads.

EM-1 and New Applications

Before SDC proceeded with compression pad production, a full suite of thermal and structural model development was completed, as was tension, compression, thermal conductivity and creep testing, arc jet testing to simulate reentry conditions and testing to simulate pyroshock during CM/SM separation. The 3D-MAT quartz/CE compression pads showed significant material property improvements vs. the CF/phenolic material used in EFT-1 and also resisted the interlaminar cracking that plagued that material.

The 3D-MAT solution achieved significantly improved properties vs. the CF/phenolic material used in EFT-1, resisted interlaminar cracking and achieved TRL5 within three years. Source: Jay Feldman, NASA.

The 3D-MAT solution achieved significantly improved properties vs. the CF/phenolic material used in EFT-1, resisted interlaminar cracking and achieved TRL5 within three years. Source: Jay Feldman, NASA.

SDC has now delivered 31 compression pads to NASA for use on Exploration Mission-1 (EM-1) and also in further TPS solutions development. EM-1, which is the second flight test and first time all Orion systems will be operational, is currently scheduled for 2018, but must undergo significant testing first. A crewed Orion atop the SLS will launch from a newly refurbished Kennedy Space Center in 2023, making it the first fully integrated mission of NASA’s deep space program.
Feldman considers 3D-MAT an innovative success, reaching TRL5 in just three years: “We went from concept to built flight hardware in that short timeframe.” He adds that the Orion team is so happy with the material’s performance that it is extending use of the 3D quartz/CE composite to various parts of the vehicle back-shell. Meanwhile, Feldman and his team are continuing to look at how 3D composites can be used to provide other TPS solutions. One example is the Heat Shield for Extreme Entry Environment Technology (HEEET) for Planetary Entry Probes project, which tailors the preform to achieve a higher-density surface layer and lower-density insulating layer made with blended carbon/phenolic yarns.


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