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By NASA
7 min read
A New Alloy is Enabling Ultra-Stable Structures Needed for Exoplanet Discovery
A unique new material that shrinks when it is heated and expands when it is cooled could help enable the ultra-stable space telescopes that future NASA missions require to search for habitable worlds.
Advancements in material technologies are needed to meet the science needs of the next great observatories. These observatories will strive to find, identify, and study exoplanets and their ability to support life. Credit: NASA JPL One of the goals of NASA’s Astrophysics Division is to determine whether we are alone in the universe. NASA’s astrophysics missions seek to answer this question by identifying planets beyond our solar system (exoplanets) that could support life. Over the last two decades, scientists have developed ways to detect atmospheres on exoplanets by closely observing stars through advanced telescopes. As light passes through a planet’s atmosphere or is reflected or emitted from a planet’s surface, telescopes can measure the intensity and spectra (i.e., “color”) of the light, and can detect various shifts in the light caused by gases in the planetary atmosphere. By analyzing these patterns, scientists can determine the types of gasses in the exoplanet’s atmosphere.
Decoding these shifts is no easy task because the exoplanets appear very near their host stars when we observe them, and the starlight is one billion times brighter than the light from an Earth-size exoplanet. To successfully detect habitable exoplanets, NASA’s future Habitable Worlds Observatory will need a contrast ratio of one to one billion (1:1,000,000,000).
Achieving this extreme contrast ratio will require a telescope that is 1,000 times more stable than state-of-the-art space-based observatories like NASA’s James Webb Space Telescope and its forthcoming Nancy Grace Roman Space Telescope. New sensors, system architectures, and materials must be integrated and work in concert for future mission success. A team from the company ALLVAR is collaborating with NASA’s Marshall Space Flight Center and NASA’s Jet Propulsion Laboratory to demonstrate how integration of a new material with unique negative thermal expansion characteristics can help enable ultra-stable telescope structures.
Material stability has always been a limiting factor for observing celestial phenomena. For decades, scientists and engineers have been working to overcome challenges such as micro-creep, thermal expansion, and moisture expansion that detrimentally affect telescope stability. The materials currently used for telescope mirrors and struts have drastically improved the dimensional stability of the great observatories like Webb and Roman, but as indicated in the Decadal Survey on Astronomy and Astrophysics 2020 developed by the National Academies of Sciences, Engineering, and Medicine, they still fall short of the 10 picometer level stability over several hours that will be required for the Habitable Worlds Observatory. For perspective, 10 picometers is roughly 1/10th the diameter of an atom.
NASA’s Nancy Grace Roman Space Telescope sits atop the support structure and instrument payloads. The long black struts holding the telescope’s secondary mirror will contribute roughly 30% of the wave front error while the larger support structure underneath the primary mirror will contribute another 30%.
Credit: NASA/Chris Gunn
Funding from NASA and other sources has enabled this material to transition from the laboratory to the commercial scale. ALLVAR received NASA Small Business Innovative Research (SBIR) funding to scale and integrate a new alloy material into telescope structure demonstrations for potential use on future NASA missions like the Habitable Worlds Observatory. This alloy shrinks when heated and expands when cooled—a property known as negative thermal expansion (NTE). For example, ALLVAR Alloy 30 exhibits a -30 ppm/°C coefficient of thermal expansion (CTE) at room temperature. This means that a 1-meter long piece of this NTE alloy will shrink 0.003 mm for every 1 °C increase in temperature. For comparison, aluminum expands at +23 ppm/°C.
While other materials expand while heated and contract when cooled, ALLVAR Alloy 30 exhibits a negative thermal expansion, which can compensate for the thermal expansion mismatch of other materials. The thermal strain versus temperature is shown for 6061 Aluminum, A286 Stainless Steel, Titanium 6Al-4V, Invar 36, and ALLVAR Alloy 30.
Because it shrinks when other materials expand, ALLVAR Alloy 30 can be used to strategically compensate for the expansion and contraction of other materials. The alloy’s unique NTE property and lack of moisture expansion could enable optic designers to address the stability needs of future telescope structures. Calculations have indicated that integrating ALLVAR Alloy 30 into certain telescope designs could improve thermal stability up to 200 times compared to only using traditional materials like aluminum, titanium, Carbon Fiber Reinforced Polymers (CFRPs), and the nickel–iron alloy, Invar.
The hexapod assembly with six ALLVAR Alloy struts was measured for long-term stability. The stability of the individual struts and the hexapod assembly were measured using interferometry at the University of Florida’s Institute for High Energy Physics and Astrophysics. The struts were found to have a length noise well below the proposed target for the success criteria for the project. Credit: (left) ALLVAR and (right) Simon F. Barke, Ph.D. To demonstrate that negative thermal expansion alloys can enable ultra-stable structures, the ALLVAR team developed a hexapod structure to separate two mirrors made of a commercially available glass ceramic material with ultra-low thermal expansion properties. Invar was bonded to the mirrors and flexures made of Ti6Al4V—a titanium alloy commonly used in aerospace applications—were attached to the Invar. To compensate for the positive CTEs of the Invar and Ti6Al4V components, an NTE ALLVAR Alloy 30 tube was used between the Ti6Al4V flexures to create the struts separating the two mirrors. The natural positive thermal expansion of the Invar and Ti6Al4V components is offset by the negative thermal expansion of the NTE alloy struts, resulting in a structure with an effective zero thermal expansion.
The stability of the structure was evaluated at the University of Florida Institute for High Energy Physics and Astrophysics. The hexapod structure exhibited stability well below the 100 pm/√Hz target and achieved 11 pm/√Hz. This first iteration is close to the 10 pm stability required for the future Habitable Worlds Observatory. A paper and presentation made at the August 2021 Society of Photo-Optical Instrumentation Engineers conference provides details about this analysis.
Furthermore, a series of tests run by NASA Marshall showed that the ultra-stable struts were able to achieve a near-zero thermal expansion that matched the mirrors in the above analysis. This result translates into less than a 5 nm root mean square (rms) change in the mirror’s shape across a 28K temperature change.
The ALLVAR enabled Ultra-Stable Hexapod Assembly undergoing Interferometric Testing between 293K and 265K (right). On the left, the Root Mean Square (RMS) changes in the mirror’s surface shape are visually represented. The three roughly circular red areas are caused by the thermal expansion mismatch of the invar bonding pads with the ZERODUR mirror, while the blue and green sections show little to no changes caused by thermal expansion. The surface diagram shows a less than 5 nanometer RMS change in mirror figure. Credit: NASA’s X-Ray and Cryogenic Facility [XRCF] Beyond ultra-stable structures, the NTE alloy technology has enabled enhanced passive thermal switch performance and has been used to remove the detrimental effects of temperature changes on bolted joints and infrared optics. These applications could impact technologies used in other NASA missions. For example, these new alloys have been integrated into the cryogenic sub-assembly of Roman’s coronagraph technology demonstration. The addition of NTE washers enabled the use of pyrolytic graphite thermal straps for more efficient heat transfer. ALLVAR Alloy 30 is also being used in a high-performance passive thermal switch incorporated into the UC Berkeley Space Science Laboratory’s Lunar Surface Electromagnetics Experiment-Night (LuSEE Night) project aboard Firefly Aerospace’s Blue Ghost Mission 2, which will be delivered to the Moon through NASA’s CLPS (Commercial Lunar Payload Services) initiative. The NTE alloys enabled smaller thermal switch size and greater on-off heat conduction ratios for LuSEE Night.
Through another recent NASA SBIR effort, the ALLVAR team worked with NASA’s Jet Propulsion Laboratory to develop detailed datasets of ALLVAR Alloy 30 material properties. These large datasets include statistically significant material properties such as strength, elastic modulus, fatigue, and thermal conductivity. The team also collected information about less common properties like micro-creep and micro-yield. With these properties characterized, ALLVAR Alloy 30 has cleared a major hurdle towards space-material qualification.
As a spinoff of this NASA-funded work, the team is developing a new alloy with tunable thermal expansion properties that can match other materials or even achieve zero CTE. Thermal expansion mismatch causes dimensional stability and force-load issues that can impact fields such as nuclear engineering, quantum computing, aerospace and defense, optics, fundamental physics, and medical imaging. The potential uses for this new material will likely extend far beyond astronomy. For example, ALLVAR developed washers and spacers, are now commercially available to maintain consistent preloads across extreme temperature ranges in both space and terrestrial environments. These washers and spacers excel at counteracting the thermal expansion and contraction of other materials, ensuring stability for demanding applications.
For additional details, see the entry for this project on NASA TechPort.
Project Lead: Dr. James A. Monroe, ALLVAR
The following NASA organizations sponsored this effort: NASA Astrophysics Division, NASA SBIR Program funded by the Space Technology Mission Directorate (STMD).
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Last Updated Jul 01, 2025 Related Terms
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By NASA
Lisa Pace knows a marathon when she sees one. An avid runner, she has participated in five marathons and more than 50 half marathons. Though she prefers to move quickly, she also knows the value of taking her time. “I solve most of my problems while running – or realize those problems aren’t worth worrying about,” she said.
She has learned to take a similar approach to her work at NASA’s Johnson Space Center in Houston. “Earlier in my career, I raced to get things done and felt the need to do as much as possible on my own,” she said. “Over time, I’ve learned to trust my team and pause to give others an opportunity to contribute. There are times when quick action is needed, but it is often a marathon, not a sprint.”
Official portrait of Lisa Pace.NASA/Josh Valcarcel Pace is chief of the Exploration Development Integration Division within the Exploration Architecture, Integration, and Science Directorate at Johnson. In that role, she leads a team of roughly 120 civil servants and contractors in providing mission-level system engineering and integration services that bring different architecture elements together to achieve the agency’s goals. Today that team supports Artemis missions, NASA’s Commercial Lunar Payload Services initiative and other areas as needed.
Lisa Pace, seated at the head of the table, leads an Exploration Development Integration Division team meeting at NASA’s Johnson Space Center in Houston. NASA/James Blair “The Artemis missions come together through multiple programs and projects,” Pace explained. “We stitch them together to ensure the end-to-end mission meets its intended requirements. That includes verifying those requirements before flight and ensuring agreements between programs are honored and conflicts resolved.” The division also manages mission-level review and flight readiness processes from planning through execution, up to the final certification of flight readiness.
Leading the division through the planning, launch, and landing of Artemis I was a career highlight for Pace, though she feels fortunate to have worked on many great projects during her time with NASA. “My coolest and most rewarding project involved designing and deploying an orbital debris tracking telescope on Ascension Island about 10 years ago,” she said. “The engineers, scientists, and military personnel I got to work and travel with on that beautiful island is tough to top!”
Pace says luck and great timing led her to NASA. Engineering jobs were plentiful when she graduated from Virginia Tech in 2000, and she quickly received an offer from Lockheed Martin to become a facility engineer in Johnson’s Astromaterials Research and Exploration Science Division, or ARES. “I thought working in the building where they keep the Moon rocks would be cool – and it was! Twenty-five years later, I’m still here,” Pace said.
During that time, she has learned a lot about problem-solving and team building. “I often find that when we disagree over the ‘right’ way to do something, there is no one right answer – it just depends on your perspective,” she said. “I take the time to listen to people, understand their side, and build relationships to find common ground.”
Lisa Pace, right, participates in a holiday competition hosted by her division.Image courtesy of Lisa Pace She also emphasizes the importance of getting to know your colleagues. “Relationships are everything,” she said. “They make the work so much more meaningful. I carry that lesson over to my personal life and value my time with family and friends outside of work.”
Investing time in relationships has given Pace another unexpected skill – that of matchmaker. “I’m responsible for setting up five couples who are now married, and have six kids between them,” she said, adding that she knew one couple from Johnson.
She hopes that strong relationships transfer to the Artemis Generation. “I hope to pass on a strong NASA brand and the family culture that I’ve been fortunate to have, working here for the last 25 years.”
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By European Space Agency
Astronomers using the NASA/ESA/CSA James Webb Space Telescope have captured compelling evidence of a planet with a mass similar to Saturn orbiting the young nearby star TWA 7.
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By NASA
5 Min Read Heather Cowardin Safeguards the Future of Space Exploration
As branch chief of the Hypervelocity Impact and Orbital Debris Office at NASA’s Johnson Space Center in Houston, Dr. Heather Cowardin leads a team tasked with a critical mission: characterizing and mitigating orbital debris—space junk that poses a growing risk to satellites, spacecraft, and human spaceflight.
Long before Cowardin was a scientist safeguarding NASA’s mission, she was a young girl near Johnson dreaming of becoming an astronaut.
“I remember driving down Space Center Boulevard with my mom and seeing people running on the trails,” she said. “I told her, ‘That will be me one day—I promise!’ And she always said, ‘I know, honey—I know you will.’”
Official portrait of Heather Cowardin. NASA/James Blai I was committed to working at NASA—no matter what it took.
Heather Cowardin
Hypervelocity Impact and Orbital Debris Branch Chief
Today, that childhood vision has evolved into a leadership role at the heart of NASA’s orbital debris research. Cowardin oversees an interdisciplinary team within the Astromaterials Research and Exploration Science Division, or ARES. She supports measurements, modeling, risk assessments, and mitigation strategies to ensure the efficiency of space operations.
With more than two decades of experience, Cowardin brings expertise and unwavering dedication to one of the agency’s most vital safety initiatives.
Her work focuses on characterizing Earth-orbiting objects using optical and near-infrared telescopic and laboratory data. She helped establish and lead the Optical Measurement Center, a specialized facility at Johnson that replicates space-like lighting conditions and telescope orientations to identify debris materials and shapes, and evaluate potential risk.
Cowardin supports a range of research efforts, from ground-based and in-situ, or in position, observations to space-based experiments. She has contributed to more than 100 scientific publications and presentations and serves as co-lead on Materials International Space Station Experiment missions, which test the durability of materials on the exterior of the orbiting laboratory.
She is also an active member of the Inter-Agency Space Debris Coordination Committee, an international forum with the goal of minimizing and mitigating the risks posed by space debris.
Heather Cowardin, left, holds a spectrometer optical feed as she prepares to take a spectral measurement acquisition on the returned Wide Field Planetary Camera 2 radiator. It was inspected by the Orbital Debris Program Office team for micrometeoroid and orbital debris impacts at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in 2009, and later studied for space weathering effects on its painted surface. Her passion was fueled further by a mentor, Dr. James R. Benbrook, a University of Houston space physics professor and radar scientist supporting the Orbital Debris Program Office. “He was a hard-core Texas cowboy and a brilliant physicist,” she said. “He brought me on as a NASA fellow to study orbital debris using optical imaging. After that, I was committed to working at NASA—no matter what it took.”
After completing her fellowship, Cowardin began graduate studies at the University of Houston while working full time. Within a year, she accepted a contract position at Johnson, where she helped develop the Optical Measurement Center and supported optical analyses of geosynchronous orbital debris. She soon advanced to optical lead, later serving as a contract project manager and section manager.
Heather Cowardin inspects targets to study the shapes of orbital debris using the Optical Measurement Center at NASA’s Johnson Space Center in Houston. What we do at NASA takes new thinking, new skills, and hard work—but I believe the next generation will raise the bar and lead us beyond low Earth orbit.
Heather Cowardin
Hypervelocity Impact and Orbital Debris Branch Chief
Building on her growing expertise, Cowardin became the laboratory and in-situ measurements lead for the Orbital Debris Program Office, a program within the Office of Safety and Mission Assurance at NASA Headquarters. She led efforts to characterize debris and deliver direct measurement data to support orbital debris engineering models, such as NASA’s Orbital Debris Engineering Model and NASA’s Standard Satellite Breakup Model, while also overseeing major projects like DebriSat.
Cowardin was selected as the Orbital Debris and Hypervelocity Integration portfolio scientist, where she facilitated collaboration within the Hypervelocity Impact and Orbital Debris Office—both internally and externally with stakeholders and customers. These efforts laid the foundation for her current role as branch chief.
“I’ve really enjoyed reflecting on the path I’ve traveled and looking forward to the challenges and successes that lie ahead with this great team,” she said.
One of Cowardin’s proudest accomplishments was earning her doctorate while working full time and in her final trimester of pregnancy.
“Nothing speaks to multitasking and time management like that achievement,” Cowardin said. “I use that story to mentor others—it’s proof that you can do both. Now I’m a mom of two boys who inspire me every day. They are my motivation to work harder and show them that dedication and perseverance always pay off.”
From left to right: Heather Cowardin, her youngest child Jamie, her husband Grady, and her oldest child Trystan. The family celebrates Jamie’s achievement of earning a black belt. Throughout her career, Cowardin said one lesson has remained constant: never underestimate yourself.
“It’s easy to think, ‘I’m not ready,’ or ‘Someone else will ask the question,’” she said. “But speak up. Every role I’ve taken on felt like a leap, but I embraced it and each time I’ve learned and grown.”
She has also learned the value of self-awareness. “It’s scary to ask for feedback, but it’s the best way to identify growth opportunities,” she said. “The next generation will build on today’s work. That’s why we must capture lessons learned and share them. It’s vital to safe and successful operations.”
Heather Cowardin, fifth from left, stands with fellow NASA delegates at the 2024 Inter-Agency Space Debris Coordination Committee meeting hosted by the Indian Space Research Organisation in Bengaluru, India. The U.S. delegation included representatives from NASA, the Department of Defense, the Federal Aviation Administration, and the Federal Communications Commission. To the Artemis Generation, she hopes to pass on a sense of purpose.
“Commitment to a mission leads to success,” she said. “Even if your contributions aren’t immediately visible, they matter. What we do at NASA takes new thinking, new skills, and hard work—but I believe the next generation will raise the bar and lead us beyond low Earth orbit.”
When she is not watching over orbital debris, she is lacing up her running shoes.
“I’ve completed five half-marathons and I’m training for the 2026 Rock ‘n’ Roll half-marathon in Nashville,” she said. “Running helps me decompress—and yes, I often role-play technical briefings or prep conference talks while I’m out on a jog. Makes for interesting moments when I pass people in the neighborhood!”
About the Author
Sumer Loggins
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Last Updated Jun 18, 2025 LocationJohnson Space Center Related Terms
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