Researchers at Finland’s Aalto University have engineered a wafer-thin “cloud” metasurface that can flip between bright white and deep grey, shifting a surface from powerful daytime cooling to rapid solar heating while remaining almost invisible to infrared cameras. The invention, achieved without dedicated project funding, could reshape how buildings, vehicles, and textiles manage heat and hide from thermal sensors.
Unlike conventional white paints that scatter sunlight but glow hot in thermal imaging, the new white state of the plasmonic metasurface bounces sunlight back into space while keeping mid-infrared emissivity so low that heat cameras see almost nothing.
Switch the same film to its grey state, and the material absorbs sunlight more efficiently than matte black, yet still refuses to radiate tell-tale warmth. Inspired by how cumulus clouds brighten or darken as they evolve, the dual behavior answers a growing demand for passive, energy-free solutions that can cool, heat, or camouflage on command.
Cloud physics on a chip
The metasurface owes its versatility to an ensemble of disordered metallic nanostructures that manipulate light through multiple scattering, strong absorption, and what the team calls “polarizonic reflection.” In the white state, solar photons ricochet through the labyrinth of nanoscale features and back into the sky, providing radiative cooling under full sun.
In the grey state, those same nanostructures trap visible light and convert it to heat. Crucially, both modes keep emissivity in the 8–13 micron range, where most thermal cameras peer, well below the threshold that would reveal the material.
“We’ve engineered a nanoscale cloud on every surface. It can tune its colour and temperature like a real cloud, between cooling white and heating grey, while staying hidden from thermal cameras,” Professor Mady Elbahri from Aalto University said.
Traditional coatings face a trade-off, Elbahri’s group notes. White titanium dioxide paints cool reasonably well in shade but lose their edge under direct sun and glow brightly in thermal imaging. Black surfaces absorb but radiate heat as efficiently, lighting up infrared sensors. The new metasurface sidesteps both problems.
Cooling white, heating grey, and both are invisible
Graduate student Adel Assad, who helped fabricate the coatings, contrasted the approach with today’s best “cool white” paints. “This new white plasmonic metasurface scatters sunlight through disordered metallic nanostructures while minimising thermal emission, cooling surfaces in full sunlight and remaining thermally camouflaged. This feature makes the innovation groundbreaking,” he said.
In tests, the grey mode reached temperatures higher than conventional black coatings but still emitted little infrared. “This grey surface gets hotter than black, but without sending out heat that heat sensors can see. This could be a game-changer for smart textiles, building materials, and camouflage,” added post-doctoral researcher Moheb Abdelaziz in an article on the university website.
Potential applications span zero-energy façades that swap from cooling to heating with the seasons, garments that keep wearers comfortable without electronics, and low-visibility drones or sensors that need to evade infrared detection. Because the metasurface is only a few hundred nanometres thick, it could be deposited on steel panels, polymer films, or even fibres without adding weight.
Next steps and a lesson in persistence
The team aims to integrate electrochromic or phase-change layers so users can trigger the white-to-grey transformation in real time, perhaps through a small voltage or environmental cue. The researchers also plan durability studies under UV exposure, humidity, and mechanical stress to qualify the coating for outdoor use.
Elbahri said the breakthrough rarely happened. “With no dedicated funding after initial setbacks, we relied on shared vision and collaboration, especially with our partners in Germany, to turn doubt into discovery. It’s proof that science, like clouds, can rise against the odds,” he reflected.
If the technology moves from lab benches to factory lines, surfaces could soon act like programmable skies, reflecting, absorbing, or concealing heat as effortlessly as a passing cloud.
The findings were published in the journal Advanced Materials in June 2025.
CHAMPAIGN, Ill. — By combining artificial intelligence with automated robotics and synthetic biology, researchers at the University of Illinois Urbana-Champaign have dramatically improved performance of two important industrial enzymes — and created a user-friendly, fast process to improve many more.
Led by Huimin Zhao, a professor of chemical and biomolecular engineering at the U. of I., the team reported its findings in the journal Nature Communications.
“Enzymes have been increasingly used in energy production, in therapeutics, even in consumer products like laundry detergent. But they are not as widely used as they could be, because they still have limitations. Our technology can help address those limitations efficiently,” said Zhao, who also is affiliated with the Carl R. Woese Institute for Genomic Biology at the U. of I.
Enzymes are proteins that carry out specific catalytic functions that drive many biological processes. Those seeking to harness enzymes to advance medicine, technology, energy or sustainability often run into roadblocks involving an enzyme’s efficiency or its ability to single out a desired target amidst a complex chemical environment, Zhao said.
“Improving protein function, particularly enzyme function, is challenging because we don’t know exactly what kinds of mutations we should introduce — and it’s usually not just a single mutation; it’s a lot of synergistic mutations,” Zhao said. “With our model of integrating AI and automated synthetic biology, we offer an efficient way to solve that problem.”
Zhao’s group previously reported an AI model to predict an enzyme’s function based on its sequence. In the new paper, the researchers take their AI a step farther: predicting what changes to a known protein would improve its function.
“In a typically sized enzyme, the possible number of variations is larger than the number of atoms in the universe,” said Nilmani Singh, the co-first author of the paper. “So we use the AI method to help us create a relatively small library of potentially useful variant combinations, instead of randomly searching the whole protein sequence.”
However, training and improving an AI model is more than just code; it requires a lot of input, data and feedback. So the Illinois team coupled their AI models with the automated capabilities offered by the iBioFoundry, a center at the U. of I. dedicated to quick, user-friendly engineering and testing of biological systems ranging from enzymes to whole cells. Zhao directs the iBioFoundry, which is supported by the National Science Foundation.
In the new paper, the researchers lay out their process: First, they ask the AI tool how to improve a desired enzyme’s performance. The AI tool searches datasets of known enzyme structures and suggests sequence changes. The automated protein-building machines at the iBioFoundry produce the suggested enzymes, which are then rapidly tested to characterize their functions. The data from those tests are fed into another AI model, which uses the information to improve the next round of suggested protein designs.
“It’s a step toward a self-driving lab: a lab that designs its own proteins, makes the proteins, tests them and makes the next one,” said Stephan Lane, the manager of the iBioFoundry and co-first author. “The designing and learning is done by an AI algorithm, and the building and testing is done by robotics.”
Using this method, the team produced variants of two key industrial enzymes with substantially improved performance. One enzyme, added to animal feed to improve its nutritional content, increased its activity by 26 times. The other, a catalyst used in industrial chemical synthesis, had 16 times greater activity and 90 times greater substrate preference, meaning it was far less likely to grab molecules that were not its target.
“We described two enzymes in the paper, but it’s truly a generalized approach. We only need a protein sequence and an assay,” Zhao said. “We want to try to apply it to as many enzymes as possible.”
Next, the researchers plan to continue improving their AI models and upgrade equipment for even faster, higher-throughput synthesis and testing. They also have developed a user interface, enabling the system to run with a simple typed query. Their aim is to offer their method as a service for other researchers seeking to improve enzymes and speed drug development and innovations in energy and technology.
“For the user interface, the motivation is to allow people with different backgrounds to use the tool,” said graduate student Tianhao Yu, a coauthor of the paper. “If an experimental scientist doesn’t know how to run Python programs, then they can use our interface to help them run the program. They just need to use English to describe their needs, and it will automatically run.”
The National Science Foundation and the U.S. Department of Energy supported this work.
At the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), the 88-Inch Cyclotron is a powerful machine built to accelerate ions and explore the atomic nucleus. For decades, it has helped scientists probe the building blocks of matter.
There’s another side to this machine that is less well known but equally impactful: It’s an indispensable testbed for electronics, materials, and medical isotopes. By delivering beams of charged particles that can be tuned to different energies and compositions, the 88-Inch Cyclotron plays a surprising and wide-ranging role in science and technology – advancing energy technologies, helping spacecraft survive radiation, and improving cancer treatments.
In collaboration with companies, universities, and government partners, here are a few examples of how the 88-Inch Cyclotron has made modern technology more reliable, resilient, and revolutionary:
Ensuring Sturdy Satellites for GPS
Much of the 88-Inch Cyclotron’s work is in testing electronics components – think microchips and circuit boards – to make sure they can stand up to harsh environments. These efforts are concentrated at the Berkeley Accelerator Space Effects (BASE) Facility, which can emulate years of exposure to space radiation in just hours. Since pioneering this type of heavy ion testing in 1979, researchers have used the 88-Inch Cyclotron to test every generation of GPS – the system behind smartphone directions, app-based location services, shipping logistics, emergency response, and many more everyday applications. By assessing how cosmic rays deposit energy and damage electronics on satellites, manufacturers can then design resilient components to keep this crucial tool running smoothly.
Developing Tougher Materials for Fusion Energy
Nuclear fusion could provide a huge supply of power, but building a fusion plant that can handle the intense process requires solving fundamental engineering problems. Using an intense beam of high-energy neutrons produced by the 88-Inch Cyclotron, researchers and companies can test materials under consideration for fusion energy machines; for example: optics that focus the laser, structural materials, and the superconducting wire for magnets.
Previous tests at other facilities used X-rays, beams of charged particles, or low-energy neutrons, which don’t fully replicate the reactions from fusion. Berkeley Lab’s more realistic neutron beam helps teams know how their materials might respond with far greater accuracy, and, in turn, design more resilient equipment up to the challenge. “No one wants to use a poor surrogate for their tests if they can use what’s basically the real thing,” said Andrew Voyles, a UC Berkeley research engineer at the 88-Inch Cyclotron who leads that research program.
Getting Rockets Ready for Launch
To prepare for extreme conditions, launch vehicles like the Atlas, Delta, and Falcon rockets have tested their electronics at the BASE Facility. Prototype components undergo rigorous trials that reveal design vulnerabilities and allow for crucial improvements before launch. The impact of even a single high-energy particle – a “single event effect” – can disrupt or disable an unprotected microchip. BASE Facility research coordinator Mike Johnson estimates that over 90% of the U.S. spacecraft that have ever gone to space have at least some of their electronics evaluated at the 88-Inch Cyclotron.
Accelerating Access to Cancer Therapies
Actinium-225 is a promising isotope for targeted cancer treatments, but it’s notoriously difficult to produce. It has been called “the rarest drug on Earth,” with a global supply of about 1,000 doses a year. Researchers used the 88-Inch Cyclotron’s neutron beam to pioneer a new method to make the isotope more efficiently. The team also designed and tested a piece of equipment that industry can license and pair with the technique to produce actinium-225 in far larger quantities – potentially thousands of doses per week. In addition, experts at the facility research the optimal ways to make other medical isotopes used in PET scans, diagnostics, and potential treatments, and have shared that knowledge with industry and academic partners across the country.
“We do these basic measurements to find the optimum recipes for making these rare isotopes, then hand it off to production facilities that can start making it in large quantities,” Voyles said. “We sit at this intersection of really interesting scientific challenges with massive societal benefits on a time scale faster than you usually see in physics. It’s the best of both possible worlds: We get to do impactful work while figuring out some cool science in the process.”
Powering Space Science to Explore Our Universe
At the BASE Facility, researchers can tune the particle beam and adjust the “cocktail” of ions and energies to simulate different radiation conditions that you might find in low-Earth orbit, deep space, or on the surface of another planet. That adjustability helps space agencies like NASA, the European Space Agency (ESA), and the Japan Aerospace Exploration Agency (JAXA) assess their equipment as precisely as possible. The 88-Inch Cyclotron has tested electronics for dozens of high-profile missions, including multiple Mars rovers, the New Horizons mission to Pluto, and the James Webb Space Telescope. “We’ve tested parts for spacecraft that have gone to all the planets in the solar system,” Johnson said.
Keeping Astronauts and Missions Safe
When astronauts venture into space, the stakes are even higher. The 88-Inch Cyclotron has supported human spaceflight efforts for decades, testing electronics for the Space Shuttle, International Space Station, and spacesuits. Recently, it’s been used to evaluate the electronics in the latest generation of extravehicular mobility units, spacesuits designed for NASA’s Artemis program and future missions to the Moon and Mars. These tests help engineers identify how radiation might affect systems, allowing teams to troubleshoot and safeguard those technologies before astronauts rely on them in the field.
Lowering Costs for Molten Salt Reactors
Molten salt reactors are a next-generation nuclear energy design that use liquid salts (similar to sodium chloride, or table salt) to transfer heat and eventually create electricity. Designers had theorized that chlorine isotope impurities in the salt might absorb too many neutrons, limiting reactor performance – and filtering out the impurities was expected to cost hundreds of millions of dollars. But the reaction had never been tested directly. Using a neutron beam at the 88-Inch Cyclotron, researchers measured the process and found that the impact was negligible. Filtering the chlorine wouldn’t be necessary, saving potential commercial developers money and making molten salt reactors more viable.
Supporting National Defense with Hardened Tech
Electronics used in national defense systems must withstand extreme conditions. The Missile Defense Agency and Test Resource Management Center are among those who use the BASE Facility to test and strengthen critical components. By replicating challenging radiation environments, the cyclotron ensures that these systems remain reliable under stress. “Even on land, depending on what a computer is doing, you might have sensitive parts,” Johnson said. “It highlights the importance of this kind of testing. Whether damaging particles come from the sun or a nuclear incident, if you have these parts fail, you could lose crucial systems.”
Making Travel Safer by Testing Parts for Cars and Planes
While much of the 88-Inch Cyclotron’s testing focuses on electronics destined for space, its capabilities are also important for systems on Earth that require high reliability and safety. Modern commercial aircraft and vehicles rely on increasingly complex electronics, from autonomous navigation systems and flight control computers to advanced driver-assist features in cars. These systems must be able to withstand single event effects from cosmic rays that find their way to Earth. Companies working on aviation and automotive technologies use the BASE Facility to rapidly put their electronics through their paces.
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Quantum dots infuse a machine vision sensor with superhuman adaptation speed.
Fabrication of nanoscale light-sensitive materials, known as quantum dots, created a device that reacts to light faster than the human eye. It could revolutionize autonomous vehicles. Credit: Lin et al.
WASHINGTON, July 1, 2025 — In blinding bright light or pitch-black dark, our eyes can adjust to extreme lighting conditions within a few minutes. The human vision system, including the eyes, neurons, and brain, can also learn and memorize settings to adapt faster the next time we encounter similar lighting challenges.
In an article published this week in Applied Physics Letters, by AIP Publishing, researchers at Fuzhou University in China created a machine vision sensor that uses quantum dots to adapt to extreme changes in light far faster than the human eye can — in about 40 seconds — by mimicking eyes’ key behaviors. Their results could be a game changer for robotic vision and autonomous vehicle safety.
“Quantum dots are nano-sized semiconductors that efficiently convert light to electrical signals,” said author Yun Ye. “Our innovation lies in engineering quantum dots to intentionally trap charges like water in a sponge then release them when needed — similar to how eyes store light-sensitive pigments for dark conditions.”
The sensor’s fast adaptive speed stems from its unique design: lead sulfide quantum dots embedded in polymer and zinc oxide layers. The device responds dynamically by either trapping or releasing electric charges depending on the lighting, similar to how eyes store energy for adapting to darkness. The layered design, together with specialized electrodes, proved highly effective in replicating human vision and optimizing its light responses for the best performance.
“The combination of quantum dots, which are light-sensitive nanomaterials, and bio-inspired device structures allowed us to bridge neuroscience and engineering,” Ye said.
Not only is their device design effective at dynamically adapting for bright and dim lighting, but it also outperforms existing machine vision systems by reducing the large amount of redundant data generated by current vision systems.
“Conventional systems process visual data indiscriminately, including irrelevant details, which wastes power and slows computation,” Ye said. “Our sensor filters data at the source, similar to the way our eyes focus on key objects, and our device preprocesses light information to reduce the computational burden, just like the human retina.”
In the future, the research group plans to further enhance their device with systems involving larger sensor arrays and edge-AI chips, which perform AI data processing directly on the sensor, or using other smart devices in smart cars for further applicability in autonomous driving.
“Immediate uses for our device are in autonomous vehicles and robots operating in changing light conditions like going from tunnels to sunlight, but it could potentially inspire future low-power vision systems,” Ye said. “Its core value is enabling machines to see reliably where current vision sensors fail.”
###
Article Title
A back-to-back structured bionic visual sensor for adaptive perception
Authors
Xing Lin, Zexi Lin, Wenxiao Zhao, Sheng Xu, Enguo Chen, Tailiang Guo, and Yun Ye
Author Affiliations
Fuzhou University, Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China
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NASA’s Curiosity rover takes photos of low-ridges across Mars. | Credit: NASA/JPL-Caltech/MSSS
For over a decade, NASA’s Curiosity rover has been capturing images of Mars as scientists continue to study the planet’s structures and surface.
Curiosity’s goal as it travels across Mars is to look for unique signs of life, including signs of possible ancient life on the planet.
What is it?
Curiosity captured this 360-degree image after traveling to an area full of low ridges called boxwork patterns. These patterns look like spiderwebs, as NASA’s Mars Reconnaissance Orbiter saw in 2006.
Since its arrival on Mars from Cape Canaveral Air Force Station via an Atlas V rocket in 2012, Curiosity has been exploring the surface of the Red Planet, including these low ridges. In the middle of the photo, Curiosity’s tracks can be seen as its wheels its way across the dust.
Where is it?
Curiosity took this photo at the base of Mount Sharp, a 3 mile (5 km) tall mountain within Mars’ Gale Crater. In the far distance of the image to the right is the “Texoli” butte, according to NASA’s Jet Propulsion Laboratory (JPL).
The 360-degree panorama shows the low-ridge boxwork pattern of Mars’ landscape, with Curiosity’s tire tracks in the center of the image and the “Texoli” butte in the back right. | Credit: NASA/JPL-Caltech/MSSS
Why is it amazing?
This panorama image was created by combining 291 images from Curiosity’s Mast Camera, or Mastcam, taken over three days in mid-May 2025, according to JPL.
The boxwork pattern Curiosity captured is of particular interest to astronomers because its ridges were created by ancient groundwater flowing across Mars surface. The minerals in this groundwater helped harden the surface, and after thousands of years of being sandblasted by atmospheric winds, low ridges appeared at the foot of Mount Sharp.
While this ancient groundwater eventually disappeared from the planet entirely, astronomers believe it might have had nutrients to sustain ancient microbes. Using rovers like Curiosity, astronomers can get samples to determine whether there was life on Mars at some point in the planet’s past.
Want to learn more?
You can read more about ancient Martian water and NASA’s rovers as astronomers continue to study the red planet.
For over a decade, NASA’s Curiosity rover has been capturing images of Mars as scientists continue to study the planet’s structures and surface.
Curiosity’s goal as it travels across Mars is to look for unique signs of life, including signs of possible ancient life on the planet.
What is it?
Curiosity captured this 360-degree image after traveling to an area full of low ridges called boxwork patterns. These patterns look like spiderwebs, as NASA’s Mars Reconnaissance Orbiter saw in 2006.
Since its arrival on Mars from Cape Canaveral Air Force Station via an Atlas V rocket in 2012, Curiosity has been exploring the surface of the Red Planet, including these low ridges. In the middle of the photo, Curiosity’s tracks can be seen as its wheels its way across the dust.
Where is it?
Curiosity took this photo at the base of Mount Sharp, a 3 mile (5 km) tall mountain within Mars’ Gale Crater. In the far distance of the image to the right is the “Texoli” butte, according to NASA’s Jet Propulsion Laboratory (JPL).
The 360-degree panorama shows the low-ridge boxwork pattern of Mars’ landscape, with Curiosity’s tire tracks in the center of the image and the “Texoli” butte in the back right. (Image credit: NASA/JPL-Caltech/MSSS)
Why is it amazing?
This panorama image was created by combining 291 images from Curiosity’s Mast Camera, or Mastcam, taken over three days in mid-May 2025, according to JPL.
The boxwork pattern Curiosity captured is of particular interest to astronomers because its ridges were created by ancient groundwater flowing across Mars surface. The minerals in this groundwater helped harden the surface, and after thousands of years of being sandblasted by atmospheric winds, low ridges appeared at the foot of Mount Sharp.
Breaking space news, the latest updates on rocket launches, skywatching events and more!
While this ancient groundwater eventually disappeared from the planet entirely, astronomers believe it might have had nutrients to sustain ancient microbes. Using rovers like Curiosity, astronomers can get samples to determine whether there was life on Mars at some point in the planet’s past.
Want to learn more?
You can read more about ancient Martian water and NASA’s rovers as astronomers continue to study the red planet.
A vast cloud of energetic particles surrounding a cluster of galaxies that existed around four billion years after the Big Bang could help scientists discover how the early universe took shape.
But was the halo of the massive cluster of galaxies — called SpARCS104922.6+564032.5, and located 9.9 billion light-years from Earth— built by erupting supermassive black holes or a cosmic particle accelerator?
This envelope of radio-emitting particles — a so-called “radio mini-halo,” though it isn’t really mini at all — is the most distant example of such a structure ever detected. Its distance is double that of the next farthest radio mini-halo, with its radio signal having taken 10 billion years to reach Earth — the majority of the universe’s 13.8 billion-year lifespan.
The discovery, made with the LOFAR (LOw Frequency ARray) radio instrument in Europe, indicates that galaxy clusters, which are some of the largest structures in the known universe, spend most of their existence wrapped in envelopes of high-energy particles.
This insight gives scientists a better idea of how energy flows around galaxy clusters. And that in turn could improve our picture of cosmic evolution, study members said.
“It’s astonishing to find such a strong radio signal at this distance,” study co-leader Roland Timmerman, an astronomer at Durham University in England, said in a statement. “It means these energetic particles and the processes creating them have been shaping galaxy clusters for nearly the entire history of the universe.”
What gave this cluster its halo?
The team posited two possible explanations for the formation of this mini-halo.
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One possibility is that the supermassive black holes at the hearts of the galaxies in the cluster are ejecting jets of high-energy particles and settling around their home cluster.
One problem with this theory, however, is explaining how these particles have managed to maintain their energy as they take their place in a gigantic cloud.
Illustration of a supermassive black hole at the heart of a galaxy emitting a stream of high-energy particles (Image credit: Robert Lea (created with Canva))
The second possible explanation is the existence of a natural particle collider around the galactic cluster.
Particles in the hot ionized gas, or plasma, around the cluster may be slamming together at near light-speeds, resulting in the highly energetic particles in the halo.
The team behind the new research believes their results offer a rare chance to observe a galaxy cluster just after it has formed.
It also suggests that galactic clusters are filled with energetic particles for billions of years longer than had previously been thought. And further study of this distant radio mini-halo should reveal just where these charged particles originated, according to the scientists.
The team’s research has been accepted for publication in the Astrophysical Journal Letters, with a preprint version available on the research repository arXiv.
Stellar Cartography tracking session for New Horizons — Paramount/Astrobiology.com
Editor’s note: Those of you in the space community know that NASA Science is facing an immense budget cut. Dozens of missions have been cancelled and many missions that are still returning valuable data are being shut off – in many cases to save a few million dollars – a tiny fraction of what it took to mount the missions in the first place. This data will be lost. In the case of New Horizons, currently traversing the outer solar system, NASA is going to forfeit a third interstellar mission (after the twin Voyagers). This latest interstellar mission would be done with a healthy spacecraft outfitted with 21st century instrumentation. We could continue to expand America’s pre-eminent exploration of interstellar space until the middle of this century. And that lead will last unchallenged for a generation or more to come. But instead we are going to shut off this explorer – and many others – long before they cease to explore the unknown.
As NASA’s New Horizons spacecraft exits the Solar System bound for interstellar space, it has traveled so far that the nearest stars have shifted markedly from their positions seen from Earth.
We demonstrated this by imaging the Proxima Centauri and Wolf 359 fields from Earth and New Horizons on 2020 April 23, when the spacecraft was 47.1 au distant. The observed parallaxes for Proxima Centauri and Wolf 359 are 32.4″ and 15.7″, respectively.
These measurements are not of research grade, but directly seeing large stellar parallaxes between two widely separated simultaneous observers is vividly educational. Using the New Horizons positions of the two stars alone, referenced to the three-dimensional model of the solar neighborhood constructed from Gaia DR3 astrometry, further provides the spacecraft spatial position relative to nearby stars with 0.44 au accuracy.
The range to New Horizons from the Solar System barycenter is recovered to 0.27 au accuracy, and its angular direction to 0.4∘ accuracy, when compared to the precise values from NASA Deep Space Network tracking. This is the first time optical stellar astrometry has been used to determine the three-dimensional location of a spacecraft with respect to nearby stars, and the first time any method of interstellar navigation has been demonstrated for a spacecraft on an interstellar trajectory.
We conclude that the best astrometric approach to navigating spacecraft on their departures to interstellar space is to use a single pair of the closest stars as references, rather than a large sample of more distant stars.
The location of New Horizons on 2020 April 23 as derived from the directions to Proxima Cen and Wolf 359 measured from the spacecraft. The view is from the ecliptic north pole; the vertical axis is at zero RA. Gray circles show the orbits of the outer planets. Line of position P passes through the Gaia 3-D location of Proxima Cen, in the direction measured from the spacecraft; the observations of Proxima Cen thus constrain the spacecraft to lie on line P. Similarly, observations of Wolf 359 constrain the spacecraft to lie on line of position W. The faint dotted lines show how much P and W would be displaced by a 1 ′′ change in line direction; the transverse displacement in au is just the distance to the star in pc (1.30 for P, 2.41 for W). The trajectory NH is the actual path of the spacecraft from launch in 2006 through 2023, marked with yearly tickmarks. The actual angular uncertainties are much less than the 1′′ indicated by the dotted lines. Line P is inclined ∼ 45◦ from the ecliptic plane; line W and the NH trajectory are inclined less than 2◦ from the ecliptic. — — astro-ph.IM
The Earth-based and New Horizons images of Proxima Centauri and its star field are shown side by side to demonstrate the large Earth-spacecraft parallax. Proxima Cen is the bright star near the center of the field. The field shown is 10′ × 10′ . North is at the top. The image pairs have been prepared to a common image scale, field, and orientation so that the parallax can also be recognized with stereo imaging. The top pair is positioned for “cross-eyed” viewing. Crossing your eyes to view the NH-based image with the left eye, and the Earth-based image with the right eye, will create the appearance of Proxima Cen floating in front of the background stars. The two images are swapped in position in the bottom row to allow for parallel viewing. In this case, the left eye views the left panel, and the right eye the right panel. Parallel viewing can also be done by mounting the images in a stereoscopic viewer. Our experience on the New Horizons team is that there is no clear preference between cross-eyed vs. parallel viewing. — astro-ph.IM
Tod R. Lauer, David H. Munro, John R. Spencer, Marc W. Buie, Edward L. Gomez, Gregory S. Hennessy, Todd J. Henry, George H. Kaplan, John F. Kielkopf, Brian H. May, Joel W. Parker, Simon B. Porter, Eliot Halley Vrijmoet, Harold A. Weaver, Pontus Brandt, Kelsi N. Singer, S. Alan Stern, Anne. J. Verbiscer, Pedro Acosta, Nicolás Ariel Arias, Sergio Babino, Gustavo Enrique Ballan, Víctor Ángel Buso, Steven J. Conard, Daniel Das Airas, Giorgio Di Scala, César Fornari, Jossiel Fraire, Brian Nicolás Gerard, Federico González, Gerardo Goytea, Emilio Mora Guzmán, William Hanna, William C. Keel, Aldo Kleiman, Anselmo López, Jorge Gerardo Machuca, Leonardo Málaga, Claudio Martínez, Denis Martinez, Raúl Meliá, Marcelo Monópoli, Marc A. Murison, Leandro Emiliano Fernandez Pohle, Mariano Ribas, José Luis Ramón Sánchez, Sergio Scauso, Dirk Terrell, Thomas Traub, Pedro Oscar Valenti, Ángel Valenzuela, Ted von Hippel, Wen Ping Chen, Dennis Zambelis
Comments: Accepted for publication in the Astronomical Journal. The introduction includes a link to the Jupyter notebook and images used in the analysis Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM) Cite as: arXiv:2506.21666 [astro-ph.IM] (or arXiv:2506.21666v1 [astro-ph.IM] for this version) https://doi.org/10.48550/arXiv.2506.21666 Focus to learn more Submission history From: Tod R. Lauer [v1] Thu, 26 Jun 2025 18:00:02 UTC (4,720 KB) https://arxiv.org/abs/2506.21666
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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NASA has extended recovery efforts for its stricken Lunar Trailblazer spacecraft to mid-July, but is warning that if the probe remains silent, the mission could end.
Contact with the small satellite was lost the day after its launch on February 26. Controllers were initially able to receive engineering data from the vehicle, but the telemetry indicated power system issues, and the spacecraft eventually fell silent.
The theory is that the spacecraft entered a low-power state, with its solar panels incorrectly oriented, thus generating insufficient power to charge its batteries.
Since then, the Lunar Trailblazer team has attempted to contact the probe. If control can be regained, the instruments are still functional, and the propulsion system is not frozen, there’s a chance that the spacecraft can be inserted into an elliptical orbit and complete its lunar science objectives – if not the mission as initially envisaged.
Ground-based optical and radio telescopes have been used to track the satellite’s position and rate of spin, and radio antennas belonging to various organizations worldwide have provided time to listen for a signal from the Lunar Trailblazer.
However, the further away it travels, the weaker its communication with Earth becomes, should it be re-established, to the point where controllers would be unable to command the probe or receive telemetry.
A few extra weeks were added to recovery efforts after updated models suggested that light conditions might be right for the probe to generate enough power for its batteries to reach an operational state and its radio to switch on. However, once those weeks are exhausted, NASA will have to consider its options, including ending the mission.
The Lunar Trailblazer is a 200 kg (440 lb) spacecraft designed to generate high-resolution maps of the Moon’s surface to determine the location of water, its abundance, form, and how it changes over time. It was supposed to orbit the Moon approximately 100 km (60 miles) from the surface.
The mission came out of NASA’s SIMPLEx (Small Innovative Missions for Planetary Exploration) competition, which was all about low-cost, high-risk missions that could ride share with primary payloads. SIMPLEx missions also have less stringent requirements for oversight and management. ®
