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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 European Space Agency
The Meteosat Third Generation Sounder (MTG-S1) satellite, which is hosting the instrument for the Copernicus Sentinel-4 mission, has been placed inside the nose cone of the Falcon 9 launch rocket and is ready for the scheduled liftoff at 23:03 CEST on Tuesday, 1 July.
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
NASA Ames research scientist Kristina Pistone monitors instrument data while onboard the Twin Otter aircraft, flying over Monterey Bay during the October 2024 deployment of the AirSHARP campaign. NASA/Samuel Leblanc In autumn 2024, California’s Monterey Bay experienced an outsized phytoplankton bloom that attracted fish, dolphins, whales, seabirds, and – for a few weeks in October – scientists. A team from NASA’s Ames Research Center in Silicon Valley, with partners at the University of California, Santa Cruz (UCSC), and the Naval Postgraduate School, spent two weeks on the California coast gathering data on the atmosphere and the ocean to verify what satellites see from above. In spring 2025, the team returned to gather data under different environmental conditions.
Scientists call this process validation.
Setting up the Campaign
The PACE mission, which stands for Plankton, Aerosol, Cloud, ocean Ecosystem, was launched in February 2024 and designed to transform our understanding of ocean and atmospheric environments. Specifically, the satellite will give scientists a finely detailed look at life near the ocean surface and the composition and abundance of aerosol particles in the atmosphere.
Whenever NASA launches a new satellite, it sends validation science teams around the world to confirm that the data from instruments in space match what traditional instruments can see at the surface. AirSHARP (Airborne aSsessment of Hyperspectral Aerosol optical depth and water-leaving Reflectance Product Performance for PACE) is one of these teams, specifically deployed to validate products from the satellite’s Ocean Color Instrument (OCI).
The OCI spectrometer works by measuring reflected sunlight. As sunlight bounces off of the ocean’s surface, it creates specific shades of color that researchers use to determine what is in the water column below. To validate the OCI data, research teams need to confirm that measurements directly at the surface match those from the satellite. They also need to understand how the atmosphere is changing the color of the ocean as the reflected light is traveling back to the satellite.
In October 2024 and May 2025, the AirSHARP team ran simultaneous airborne and seaborne campaigns. Going into the field during different seasons allows the team to collect data under different environmental conditions, validating as much of the instrument’s range as possible.
Over 13 days of flights on a Twin Otter aircraft, the NASA-led team used instruments called 4STAR-B (Spectrometer for sky-scanning sun Tracking Atmospheric Research B), and the C-AIR (Coastal Airborne In-situ Radiometer) to gather data from the air. At the same time, partners from UCSC used a host of matching instruments onboard the research vessel R/V Shana Rae to gather data from the water’s surface.
Ocean Color and Water Leaving Reflectance
The Ocean Color Instrument measures something called water leaving reflectance, which provides information on the microscopic composition of the water column, including water molecules, phytoplankton, and particulates like sand, inorganic materials, and even bubbles. Ocean color varies based on how these materials absorb and scatter sunlight. This is especially useful for determining the abundance and types of phytoplankton.
Photographs taken out the window of the Twin Otter aircraft during the October 2024 AirSHARP deployment showcase the variation in ocean color, which indicates different molecular composition of the water column beneath. The red color in several of these photos is due to a phytoplankton bloom – in this case a growth of red algae. NASA/Samuel Leblanc
The AirSHARP team used radiometers with matching technology – C-AIR from the air and C-OPS (Compact Optical Profiling System) from the water – to gather water leaving reflectance data.
“The C-AIR instrument is modified from an instrument that goes on research vessels and takes measurements of the water’s surface from very close range,” said NASA Ames research scientist Samuel LeBlanc. “The issue there is that you’re very local to one area at a time. What our team has done successfully is put it on an aircraft, which enables us to span the entire Monterey Bay.”
The larger PACE validation team will compare OCI measurements with observations made by the sensors much closer to the ocean to ensure that they match, and make adjustments when they don’t.
Aerosol Interference
One factor that can impact OCI data is the presence of manmade and natural aerosols, which interact with sunlight as it moves through the atmosphere. An aerosol refers to any solid or liquid suspended in the air, such as smoke from fires, salt from sea spray, particulates from fossil fuel emissions, desert dust, and pollen.
Imagine a 420 mile-long tube, with the PACE satellite at one end and the ocean at the other. Everything inside the tube is what scientists refer to as the atmospheric column, and it is full of tiny particulates that interact with sunlight. Scientists quantify this aerosol interaction with a measurement called aerosol optical depth.
“During AirSHARP, we were essentially measuring, at different wavelengths, how light is changed by the particles present in the atmosphere,” said NASA Ames research scientist Kristina Pistone. “The aerosol optical depth is a measure of light extinction, or how much light is either scattered away or absorbed by aerosol particulates.”
The team measured aerosol optical depth using the 4STAR-B spectrometer, which was engineered at NASA Ames and enables scientists to identify which aerosols are present and how they interact with sunlight.
Twin Otter Aircraft
AirSHARP principal investigator Liane Guild walks towards a Twin Otter aircraft owned and operated by the Naval Postgraduate School. The aircraft’s ability to perform complex, low-altitude flights made it the ideal platform to fly multiple instruments over Monterey Bay during the AirSHARP campaign. NASA/Samuel Leblanc
Flying these instruments required use of a Twin Otter plane, operated by the Naval Postgraduate School (NPS). The Twin Otter is unique for its ability to perform extremely low-altitude flights, making passes down to 100 feet above the water in clear conditions.
“It’s an intense way to fly. At that low height, the pilots continually watch for and avoid birds, tall ships, and even wildlife like breaching whales,” said Anthony Bucholtz, director of the Airborne Research Facility at NPS.
With the phytoplankton bloom attracting so much wildlife in a bay already full of ships, this is no small feat. “The pilots keep a close eye on the radar, and fly by hand,” Bucholtz said, “all while following careful flight plans crisscrossing Monterey Bay and performing tight spirals over the Research Vessel Shana Rae.”
Campaign Data
Data gathered from the 2024 phase of this campaign is available on two data archive systems. Data from the 4STAR instrument is available in the PACE data archive and data from C-AIR is housed in the SeaBASS data archive.
Other data from the NASA PACE Validation Science Team is available through the PACE website: https://pace.oceansciences.org/pvstdoi.htm#
Samuel LeBlanc and Kristina Pistone are funded via the Bay Area Environmental Research Institute (BAERI), which is a scientist-founded nonprofit focused on supporting Earth and space sciences.
About the Author
Milan Loiacono
Science Communication SpecialistMilan Loiacono is a science communication specialist for the Earth Science Division at NASA Ames Research Center.
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Last Updated Jun 26, 2025 Related Terms
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By NASA
What does it take to gaze through time to our universe’s very first stars and galaxies?
NASA answers this question in its new documentary, “Cosmic Dawn: The Untold Story of the James Webb Space Telescope.” The agency’s original documentary, which chronicles the story of the most powerful telescope ever deployed in space, was released Wednesday, June 11.
Cosmic Dawn offers an unprecedented glimpse into the delicate assembly, rigorous testing, and triumphant launch of NASA’s James Webb Space Telescope. The documentary showcases the complexity involved in creating a telescope capable of peering billions of years into the past.
Cosmic Dawn is now available for streaming on NASA’s YouTube, NASA+, and select local theaters. The trailer is available on NASA+ and YouTube.
Relive the pitfalls and the triumphs of the world’s most powerful space telescope—from developing the idea of an impossible machine to watching with bated breath as it unfolded, hurtling through space a million miles away from Earth. Watch the Documentary on YouTube The film features never-before-seen footage captured by the Webb film crew, offering intimate access to the challenges and triumphs faced by the team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland — the birthplace of Webb.
“At NASA, we’re thrilled to share the untold story of our James Webb Space Telescope in our new film ‘Cosmic Dawn,’ celebrating not just the discoveries, but the extraordinary people who made it all happen, for the benefit of humanity,” said Rebecca Sirmons, head of NASA+ at the agency’s headquarters in Washington.
From its vantage point more than a million miles from Earth and a massive sunshield to block the light of our star, Webb’s First Deep Field the deepest and sharpest infrared images of the universe that the world had seen.
Webb’s images have dazzled people around the globe, capturing the very faint light of the first stars and galaxies that formed more than 13.5 billion years ago. These are baby pictures from an ancient past when the first objects were turning on and emitting light after the Big Bang. Webb has also given us new insights into black holes, planets both inside and outside of our own solar system, and many other cosmic phenomena.
Webb was a mission that was going to be spectacular whether that was good or bad — if it failed or was successful. It was always going to make history
Sophia roberts
NASA Video Producer
NASA’s biggest and most powerful space telescope was also its most technically complicated to build. It was harder still to deploy, with more than 300 critical components that had to deploy perfectly. The risks were high in this complicated dance of engineering, but the rewards were so much higher.
“Webb was a mission that was going to be spectacular whether that was good or bad — if it failed or was successful,” said video producer Sophia Roberts, who chronicled the five years preceding Webb’s launch. “It was always going to make history.”
NASA scientists like Nobel Laureate Dr. John Mather conceived Webb to look farther and deeper into origins of our universe using cutting edge infrared technology and massive mirrors to collect incredibly rich information about our universe, from the light of the first galaxies to detailed images of planets in our own solar system.
To achieve this goal, NASA and its partners faced unprecedented hurdles.
Webb’s development introduced questions that no one had asked before. How do you fit a telescope with the footprint of a tennis court into a rocket? How do you clean 18 sensitive mirrors when a single scratch could render them inoperable? How do you maintain critical testing while hurricane stormwater pours through ceilings?
A technician inspects the James Webb Space Telescope primary mirrors at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.NASA/Sophia Roberts Cosmic Dawn captures 25 years of formidable design constraints, high-stake assessments, devastating natural disasters, a global pandemic and determined individuals who would let none of that get in the way of getting this monumental observatory to its rightful place in the cosmos.
“There was nothing easy about Webb at all,” said Webb project manager Bill Ochs. “I don’t care what aspect of the mission you looked at.”
Viewers will experience a one-of-a-kind journey as NASA and its partners tackle these dilemmas — and more — through ingenuity, teamwork, and unbreakable determination.
“The inspiration of trying to discover something — to build something that’s never been built before, to discover something that’s never been known before — it keeps us going,” Mather said. “We are pleased and privileged in our position here at NASA to be able to carry out this [purpose] on behalf of the country and the world.”
Bound by NASA’s 66-year commitment to document and share its work with the public, Cosmic Dawn details every step toward Webb’s launch and science results.
Learn more at nasa.gov/cosmicdawn By Laine Havens,
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Katie Konans,
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Jun 11, 2025 Related Terms
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By NASA
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Electrical engineer Nikolas Gibson performs calibration tests on the MODIS/ASTER Airborne Simulator (MASTER) spectrometer, co-developed by NASA’s Ames Research Center and NASA’s Jet Propulsion Laboratory. Gibson works at the Airborne Sensor Facility at Ames, which builds, maintains, miniaturizes, and calibrates instruments.NASA/Milan Loiacono
NASA’s Ames Research Center in Silicon Valley houses a unique laboratory: the Airborne Sensor Facility (ASF). The engineers at the ASF are responsible for building, maintaining, and operating numerous instruments that get deployed on research aircraft, but one of their most important roles is instrument calibration.
Think of calibration like tuning a piano between performances: A musician uses a tuner to set the standard pitch for each string, ensuring that the piano remains on pitch for every concert.
The “tuners” at ASF include lasers, mirrors, and a light source called an integrating sphere – a hollow sphere about 36 inches in diameter that emits a set amount of light from a hole in the top. By checking an instrument against this baseline between each mission, engineers ensure that the instrument sensors provide accurate, reliable data every time.
In the photo above, electrical engineer Nikolas Gibson performs calibration tests on the MODIS/ASTER Airborne Simulator (MASTER) spectrometer, co-developed by NASA Ames and NASA’s Jet Propulsion Laboratory in Southern California.
A spectrometer separates light into individual wavelengths, providing researchers with information about the properties of whatever is creating or interacting with that light. The MASTER instrument measures about 50 individual spectral channels, providing data on wavelengths from the visible spectrum through the infrared.
When it comes to calibration, each of these channels functions like a specific key on a piano and needs to be individually checked against the “tuner.” By pointing the instrument’s sensor at a known quantity of light coming from the integrating sphere, the team checks the accuracy of MASTER’s data output and repairs or adjusts the sensor as needed.
In this image, MASTER had returned from an April 2025 scientific campaign observing prescribed fires in Alabama and Georgia with NASA’s FireSense project. It was recalibrated before heading back into the field for the Geological Earth Mapping Experiment, or GEMx, mission in late May 2025, which will use the instrument to help map critical minerals across the southwestern United States.
About the Author
Milan Loiacono
Science Communication SpecialistMilan Loiacono is a science communication specialist for the Earth Science Division at NASA Ames Research Center.
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Last Updated Jun 11, 2025 Related Terms
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