Category: 7. Science

NASA is having trouble tracking down two of its spacecraft. One of the TRACERS spacecraft has lost contact with Earth while the Athena EPIC satellite failed to send an important beacon signal.

Both were launched on July 23 on a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California. Communicating with both has, thus far, proven a challenge for controllers.

The TRACERS (Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites) SV1 spacecraft, one of a pair of vehicles launched to study how the Sun interacts with the Earth’s magnetic field, began having issues with its power system on July 25, which resulted in a loss of communication. Engineers believe the problem is a lack of sunlight on the solar panels and hope that later in August, when more sunlight reaches the arrays, they can reestablish contact and diagnose the problem.

The other TRACERS spacecraft, imaginatively called Space Vehicle 2 (SV2), is in good health and engineers have started the commissioning process.

The TRACERS satellites are slightly larger than washing machines and orbit the Earth at the North and South poles. The duo is designed to fly in tandem, with one trailing the other in orbit by around two minutes (although sometimes as close as 10 seconds). The orbit itself is relatively low at around 360 miles above the Earth.

Two spacecraft mean that scientists will be able to observe changing patterns rapidly, but, as of right now, only one appears to be functioning.

The borked TRACERS spacecraft is not alone. The same Falcon 9 launch included the Athena EPIC (Economical Payload Integration Cost), a pathfinder for a scalable satellite design to support future missions through partnerships. The plan is that the satellite platform will be able to share resources among multiple payloads, meaning that those individual payloads can focus on their core missions.

The problem is that, according to NASA, “the small satellite has yet to send an expected beacon signal to help track its orbit.” This is making communication difficult. The US space agency noted that it has received some signals and teams were “investigating received signals to positively confirm the location of Athena EPIC and its operational status.”

“The team is also working to determine the cause of the initial missed signal acquisition and any factors that may have contributed to the delayed communication downlinks.”

NASA reported the communication problems after it finally gave up trying to contact the Lunar Trailblazer probe, which is missing and presumed lost. ®

Spaceships modelled on jellyfish, 3D-printed homes, polyamorous relationships and vegetarian diets are among the ways in which experts have envisaged making interstellar travel feasible.

The ideas from scientists, engineers, architects and social theorists came in response to a global competition to develop plans for “generation ships”, self-sustaining crafts capable of supporting up to 1,500 people on a 250-year journey to a habitable planet.

Entrants to the Project Hyperion design competition, launched last year, could only incorporate current technologies or those expected to emerge in the near future, such as nuclear fusion, into their proposals.

An expert panel, including Nasa scientists, judged the viability of almost 100 submissions, assessing how their habitats, architecture and social structures would allow the crew to not only survive but flourish as a society across multiple generations of space flight.

The winner was Chrysalis, a 58km cigar-shaped craft, designed around a series of concentric cylinders, each dedicated to a different function: 3D-printed living quarters; communal spaces, including parks, libraries and galleries; and farms and biomes of different Earth environments, such as tropical forests.

As animals would be brought onboard only to maintain biodiversity, a vegetarian diet would be necessary.

The design won praise for its detailed plans, particularly how the psychological resilience of the crew would be vetted by living in isolated Antarctic bases.

The proposal also explained how family structures would change, with individuals’ sense of belonging based more on being part of the starship community. Inhabitants would be allowed to have children but not necessarily with the same partners.

The second place design was Hyperion, a spacecraft which resembles the space station from 2001: A Space Odyssey. The twin rings of this design are engineered to generate an Earth-like magnetic field, which would be essential for a successful pregnancy in deep space, without which the mission would be doomed.

The proposal also includes designs for loose-fitting clothes with large sealable pockets to prevent items from falling out in low gravity. The mission would include three pairs of turtles, chosen for their longevity, relatively inactive, and resistance to disease.

The third place design, Systema Stellare Proximum, is modelled after the shape of a jellyfish and uses a hollowed-out asteroid as a shield against impacts. It envisages a society guided by a non-human collective intelligence and human council, as well as the potential emergence of new religions, such as neopaganism that deifies “nature and man, in all his forms”.

Other notable entires included Endless Beyond the Stars, which includes floating light created from biogas, generated from the bodies of the dead.

Dr Andreas Hein, the executive director of the Initiative for Interstellar Studies, which ran the competition, said it was “part of a larger exercise to explore if humanity can travel to the stars” and how “a civilisation might live, learn and evolve in a highly resource-constrained environment”.

He added: “We asked participants to integrate architecture, technology and social systems to conceptualise a functional society spanning centuries – and the outcome was beyond expectations.”

Before Nathan Jermyn could dig into the legal frameworks at NASA, he had to answer a different call.

Jermyn participated in a one-day orientation in the summer of 2023 to begin work as an attorney-advisor supporting NASA’s Stennis Space Center and the NASA Shared Services Center near Bay St. Louis, Mississippi.

However, the Biloxi, Mississippi, native shipped out just a week later with the Mississippi Army National Guard to provide military legal counsel for nearly six months in support of Operation Spartan Shield and Operation Inherent Resolve.

The decorated military veteran returned to NASA in January 2024 to fully immerse himself as a member of the contract and procurement practice group for the NASA Office of the General Counsel.

“Even though I have been working here for two years, sometimes it does not feel real,” Jermyn said.

As a member of the contract and procurement law team, Jermyn assists with contract- and procurement-related topics for NASA Stennis and the NASA Shared Services Center to ensure taxpayer funds are used responsibly.

He also is a member of NASA’s Freedom of Information Act (FOIA) team and provides legal reviews and advice for FOIA requests as the agency creates a cohesive and effective knowledge-sharing environment.

The most interesting thing about his work is seeing how the big picture comes together, how each small detail and decision adds up to something more meaningful.  

“Our office is a small piece, and it is amazing to see how our efforts intertwine with NASA Stennis and the NASA Shared Services Center operations and NASA,” he said. “It is also amazing the lengths everyone will go to help each other accomplish the mission.”

Before joining NASA, Jermyn graduated from The University of Southern Mississippi with a bachelor’s degree in business administration and a law degree from Mississippi College School of Law.

The Gulfport, Mississippi, resident initially practiced criminal law. Jermyn credits the team he works with at NASA for helping him navigate the complexities of government contract law.

“Having a team that supports you and teaches you every day really expedites the learning process,” he said. “Our team puts a heavy emphasis on learning, development, and teamwork.”

Jermyn is most excited to see how NASA continues to explore the universe moving forward, which includes the Artemis campaign of exploring the Moon for scientific discovery, economic benefits, and to build the foundation for the first crewed missions to Mars. Artemis II is scheduled for 2026.

“I wholeheartedly believe humanity is destined for the stars and NASA is in prime position to lead that charge,” he said.

It is a hot debate bracketed by cold hard facts: What are the best methods for handling Mars samples here on Earth?

Planetary protection is a measure to safeguard our world from any contamination that could result from bringing home any potential biological material from the Red Planet that might lurk in bits of rocks, dust and atmospheric samples. Yes, the specter of “The Andromeda Strain” still lingers, as introduced in the 1969 novel written by Michael Crichton and later turned into a techno-thriller of a movie.

BYLINE: Jamie Oberdick

Newswise — UNIVERSITY PARK, Pa. — Could clothing monitor a person’s health in real time, because the clothing itself is a self-powered sensor? A new material created through electrospinning, which is a process that draws out fibers using electricity, brings this possibility one step closer.  

A team led by researchers at Penn State developed a new fabrication approach that optimizes the internal structure of electrospun fibers to improve their performance in electronic applications. They published their findings in the Journal of Applied Physics. 

This novel electrospinning approach could open the door to more efficient, flexible and scalable electronics for wearable sensors, health monitoring and sustainable energy harvesting, according to Guanchun Rui, a visiting postdoctoral student in the Department of Electrical Engineering and the Materials Research Institute and co-lead author of the study. 

The material is based on poly(vinylidene fluoride-trifluoroethylene), or PVDF-TrFE, a lightweight, flexible polymer known for its ability to generate an electric charge when pressed or bent. That quality, called piezoelectricity, makes it a strong candidate for use in electronics that convert motion into energy or signals. 

“PVDF-TrFE has strong ferroelectric, piezoelectric and pyroelectric properties,” Rui said, explaining that like piezoelectricity, pyroelectricity can generate electric charges when temperature change and thus influence the material. “It’s thermally stable, lightweight and flexible, which makes it ideal for things like wearable electronics and energy harvesters.” 

Electrospinning is a technique that uses electric force to stretch a polymer solution into extremely thin fibers. As the fibers dry, the way the polymer chains pack together determines their performance. The researchers hypothesized that altering the concentration and molecular weight of the polymer solution could lead to more organized molecular structures. 

“Crystallinity means the molecules are more ordered,” Rui said, noting that the team also theorized the structure could have higher polar phase content. “And when we talk about polar phase content, we mean that the positive and negative charges in the molecules are aligned in specific directions. That alignment is what allows the material to generate electricity from motion.” 

The researchers explained that electrospinning plays a key role in enabling this alignment.  

“The process stretches the fibers in a highly mobile state, which predisposes the polymer chains to crystallize into the form we want,” said Patrick Mather, a co-author of the study and professor of chemical engineering and dean of the Schreyer Honors College. “You start with a liquid, and it dries over a split second as it travels to the collector. All the packing happens during that brief flight.” 

One surprising discovery, Mather said, came from experimenting with unusually high concentrations of polymer in the solution. 

“These were very high concentrations, roughly around 30%, and much higher than we typically use,” Mather said. “My initial thought was that this isn’t going to work. But we were using a low molecular weight polymer, and that turned out to be essential. The chains were still mobile enough to pack well during crystallization. That was the biggest surprise. Sometimes, as scientists, we have doubts even when the theory says it should work. But Rui boldly proceeded, and it worked.” 

The implications are significant, according to Mather. By improving the internal structure of the fibers without requiring high-voltage treatment or complex post-processing, the team created a material that could be both low-cost and scalable. 

Rui noted that the material’s first intended application was actually for face masks, with funding from the National Institutes of Health (NIH).  

“When electrospun into a mask, the material holds a charge that can attract and trap bacteria or viruses,” Rui said. “But it also has broader uses in sensors and energy harvesters. If you press it, it can generate electricity.” 

Qiming Zhang, professor of electric engineering and Harvey F. Brush Chair in the College of Engineering and co-lead author of the study, added that the material’s cloth-like texture could make it more comfortable than traditional plastic-based sensors — it could even be directly incorporated into clothing. 

“If you wear it like clothing, it’s much better,” he said. “You could even incorporate sensors into bandages.” 

Mather pointed out that electrospinning is well suited to producing large sheets, which could be important for energy-harvesting systems. Currently, he notes, most sensors and actuators, material that will change or deform via external stimuli, are small films. 

“Most sensors or actuators are small films,” he said. “But this process could be scaled to wide-area sheets. The equipment exists, but we’d just need to pair it with an electrode manufacturing process.” 

Looking ahead, the researchers said they see opportunities to further improve the material through post-processing. Right now, the electrospun sheets are about 70% porous. Applying heat and pressure could densify them and increase sensitivity and output. 

“We already have ideas about the next steps,” Mather said. “One is densification. We could remove the air between fibers by compacting the sheets after electrospinning, which could boost their performance for certain applications.” 

For broader adoption, the team said industrial partners will be key. 

“We need to find an industrial partner,” Mather said. “Someone in the device space or energy harvesting who’s interested in taking this to the next level. In my experience, if something works early, it will work commercially. If it’s very delicate, it won’t hold up. This is a very robust system.” 

Along with Rui, Mather and Zhang, other authors of the study are Wenyi Zhu, graduate research assistant in electric engineering at Penn State; and Yongsheng Chen, Bo Li and Shihai Zhang, PolyK Technologies. 

The U.S. National Institutes of Health and U.S. National Science Foundation supported this research.  

At Penn State, researchers are solving real problems that impact the health, safety and quality of life of people across the commonwealth, the nation and around the world.

For decades, federal support for research has fueled innovation that makes our country safer, our industries more competitive and our economy stronger. Recent federal funding cuts threaten this progress.

Learn more about the implications of federal funding cuts to our future at Research or Regress.

A faint bridge of starlight, stretching nearly a million light years, has emerged between two galaxies in the Abell 3667 cluster. Located 700 million light years from Earth, this remarkable feature shows stars in the act of being stripped from one galaxy and pulled into another. It offers direct optical evidence of a major galactic merger.

“This is the first time a feature of this scale and size has been found in a local galaxy cluster,” said Anthony Englert, a Ph.D. candidate at Brown University.

“We knew that it was possible for a bridge like this to form between two galaxies, but it hadn’t been documented anywhere before now. It was a huge surprise that we were able to image such a faint feature.”

A faint trail of stars

Englert and his team used the Dark Energy Camera (DECam) on the Víctor M. Blanco Telescope in Chile. By combining 28 hours of observations, they captured an ultra-faint trail of stars.

The resulting image, stitched together from years of archived data, reveals an intergalactic bridge of light.

“Because Blanco has been imaging with DECam for the past decade, there is a ton of archival data available,” said Englert. “It was just a happy coincidence that so many people had imaged Abell 3667 over the years, and we were able to stack all of those observations together.”

The accumulation of data helped expose a process called intracluster light (ICL), where stars exist outside galaxies due to gravitational stripping.

Two galaxies merging violently

This ICL bridge shows that Abell 3667 is the product of two smaller galaxy clusters. Each has a brightest cluster galaxy (BCG), and they are now locked in a violent merger.

Normally, a single BCG grows by pulling in stars from several smaller galaxies. But here, both BCGs are fighting for dominance.

Abell 3667 is a clear example of an aggressive merger. X-ray and radio observations had already suggested such activity, but this optical evidence confirms it.

The smaller BCG is losing stars to the larger one, and their surrounding galaxies are also blending into one massive cluster.

This merger didn’t start yesterday. Data suggests that Abell 3667 began forming about a billion years ago when the two smaller clusters collided.

A glimpse of what’s to come

The discovery gives scientists a glimpse of what to expect from the Vera C. Rubin Observatory, which will soon begin a decade-long survey of the southern sky.

The observatory uses a telescope twice the size of Blanco and carries the largest camera ever built for astronomy.

“Rubin is going to be able to image ICL in much the same way as we did here, but it’s going to do it for every single local galaxy cluster in the southern sky,” Englert said. “What we did is just a small sliver of what Rubin is going to be able to do. It’s really going to blow the study of the ICL wide open.”

The project, called the Legacy Survey of Space and Time, may change how we understand cluster formation, galaxy evolution, and cosmic structure.

Light bridge confirms merging galaxies

Intracluster light isn’t just beautiful – it’s also useful. Scientists believe its distribution matches the pattern of dark matter, which makes up most of the universe’s mass but doesn’t emit light.

“ICL is quite important for cosmology,” said Ian Dell’Antonio, professor of physics at Brown. “The distribution of this light should mirror the distribution of dark matter, so it provides an indirect way to ‘see’ the dark matter.”

The light, in a way, acts like a tracer. It maps gravitational forces where direct observation fails. That’s why the discovery of this bridge in Abell 3667 is more than just a visual marvel.

Galaxies do not evolve alone

The Blanco Telescope and the upcoming Rubin Observatory are both operated by NOIRLab. This center runs America’s nighttime optical telescopes and is funded by the National Science Foundation.

The Abell 3667 research received support from several U.S. institutions. The National Science Foundation, the Department of Energy, and NASA’s Rhode Island Space Grant all helped make it happen.

As stars travel across this light bridge, they also carry stories about the formation of cosmic giants and the secrets of dark matter.

What began as scattered archival images became one of the clearest signs yet that galaxies do not evolve alone – they collide, merge, and reshape the universe.

The study is published in The Astrophysical Journal.

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Using a hollow needle no wider than a speck of dust, Holly Cheng sucked up viscous blobs from within the nucleus of a frog egg cell. As the fluorescent blobs squeezed through the needle, she captured their deformations on video as she watched through a microscope.

The experiment was the culmination of more than a year of meticulous trial and error to hone the process’s many steps: extracting the nucleus from the egg cell, keeping it intact and immobile under a microscope, and preventing the needle from getting “clogged with all sorts of junk” from other parts of the egg cell.

These are just a few of the challenges Cheng worked through during her senior thesis, which is now yielding significant insights into how internal structures of the nucleolus relate to its functions, and how these functions are disrupted in disease. She is the lead author on a paper published on May 28, 2025, in the Proceedings of the National Academy of Sciences.

Cheng’s research was in the laboratory of Clifford Brangwynne, Princeton’s June K. Wu ’92 Professor of Chemical and Biological Engineering. She graduated from Princeton in 2024 with an A.B. in molecular biology and is now a Ph.D. student at the Massachusetts Institute of Technology.

Brangwynne has called the process that Cheng honed a microscopic version of bubble tea, referring to the popular creamy drink laced with tapioca pearls sucked through a wide straw. The technique, called micropipette aspiration, has long been used to study the properties of whole cells, and in recent years has been applied to cell components synthesized in test tubes. But Cheng and her colleagues were the first to successfully use it to measure parts from a living cell while they were still biologically active.

“The excitement when I had something that even partially worked” kept her motivated through some of the more frustrating times in the laboratory, said Cheng. “There’s this tiny amount of fluid under the microscope that I’m applying pressure to, and it’s interacting with the pipette. It felt kind of sci-fi, because you’re in this dark room and there’s lasers shooting at your sample and you have these joysticks controlling stuff that’s super tiny.”

Specifically, Cheng was controlling the movements of layers of the nucleolus. Inside the nucleus of plant and animal cells, the nucleolus produces ribosomes, the molecular machines that make proteins. Proteins are key to all life’s functions, from growth and metabolism to stress responses and repair.

Irregularities in nucleoli and their role in producing proteins have been linked to cancer and neurodegenerative diseases. Indeed, much remains unknown about how parts of the nucleolus work in concert to assemble ribosomes from 80 different proteins and four RNA molecules.

Cheng’s work is a major step forward. Previously, researchers tried to understand cells’ ribosome-making machines using artificial nucleoli, which are far simpler than natively produced nucleoli but don’t retain the same material properties. Cheng’s study measured the properties of nucleoli in their native environment as they actively produced ribosome components.

Direct measurements of nucleolus layers begin to link structure and function

The nucleolus is an example of a biomolecular condensate, a compartment within a cell that, rather than being bound by a biological membrane, separates from its surroundings like a drop of oil in water.

The aspiration technique, combined with microscopy-aided measurements, allowed Cheng and her co-authors to zoom in on this phenomenon. Their experiments showed how the layers of the nucleolus have different levels of viscosity and surface tension. They also revealed the crucial role of RNA molecules in maintaining these distinct properties.

“This paper shows that you can measure those properties in this living context,” said Brangwynne, who directs Princeton’s Omenn-Darling Bioengineering Institute. “I think that’s really exciting. It’s the beginning of applying of this technique in other contexts where we can embrace the full complexity of a living cell.”

Brangwynne is a pioneer in the study of biomolecular condensates, and the nucleolus has long been a key focus of his research. His team recently published a study that tracked the movements and processing of RNA molecules within the nucleolus during ribosome assembly.

“The really interesting thing about the nucleolus is that it looks different in different contexts,” said Cheng.

Nucleoli with irregular shapes can be correlated with negative cancer prognosis, she said. “And the nucleolus has this cool structure,” said Cheng. “It has three concentrically arranged sub-compartments that are each responsible for different parts of ribosome production.”

At the core of the nucleolus, the dense fibrillar component produces densely packed ribosomal RNA molecules. Within this core, smaller structures called fibrillar centers contain the genes encoding this RNA. Surrounding the core is the granular component, where the RNA is packaged together with proteins to form nascent ribosomes.

“We were studying nucleoli inside frog oocytes because these nucleoli are biochemically and structurally very similar to the nucleoli that we [humans] have, but they’re much, much larger,” said Cheng. The diameter of a single frog cell nucleolus is comparable to that of an entire average human cell — big enough to manipulate the structure’s different layers with a needle.

Cheng used micropipette aspiration to suck up successive layers of fluorescently labeled nucleoli from frog egg cells (oocytes), recording the process on video under the microscope.

She worked with James Roggeveen, then a graduate student in Howard Stone’s lab in the Department of Mechanical and Aerospace Engineering, to convert the video data into measurements of the compartments’ physical properties. Roggeveen is now a postdoctoral fellow at Harvard University.

These measurements showed that the outer layer of the nucleolus, the granular component, is liquid-like, and the inner core is more solid-like, much like a tapioca bubble floating in a glass of tea. In one set of experiments, Cheng treated nucleoli with an enzyme to degrade RNA molecules. After this treatment, the core was more liquid-like — showing that its material properties are dependent on the RNA itself.

Frustration, persistence, and the excitement of discovery

Cheng began working on the project during her sophomore year at Princeton. She had just joined Brangwynne’s lab and learned about the recent work of Zheng Shi, an assistant professor at Rutgers University. Shi’s lab was using micropipette aspiration to study droplets made from purified proteins. Brangwynne and Cheng wondered if they could use the technique to look at nucleoli in their native context, and because of their size, nucleoli from frog egg cells seemed like ideal candidates.

Cheng spent the following summer in Shi’s lab at Rutgers, bringing frog eggs from Princeton to test as she learned the minutiae of micropipette aspiration. She worked closely with graduate student Huan Wang, who completed a Ph.D. this spring and is also a co-author on the paper.

“Holly just ran with the idea and made it all work — learning the technique and bringing it to Princeton and combining it with the frog system,” said Brangwynne. It was a “really incredible” example of the transformative potential of undergraduate thesis research, he said.

During that summer in Shi’s lab, Cheng said, she only got the technique to work on frog cell nucleoli a couple of times.

In the fall, she waited for new equipment to arrive at Brangwynne’s lab before beginning the experiments again in December. By February, she succeeded in aspirating the nucleolus layers carefully enough to produce a video, “but it wasn’t very usable,” she said. “The resolution was way too low. The whole setup was pretty shaky and difficult to analyze.”

It took another year to perfect the technique to the point where she consistently got usable data, she said. She experimented with different ways of steadying the needle and different coatings to keep the nucleus in place and prevent the needle from getting clogged.

Timing was also a challenge, since the nuclei only remain biologically active for about two hours after being put in a petri dish. Even before that time, because the nucleus is separated from the cell, “the quality of the preparation is going to degrade,” said Cheng.

“I would prepare [the nucleus] at my bench and then run it over to the microscope room, stick it under the microscope and try to put everything together pretty quickly,” she said.

In the end, most of the data analyzed for the publication was produced during just a few weeks — and those weeks were exhilarating for Cheng.

“The first few times I got really high-resolution videos, I was super excited,” she said. “I sprinted up the stairs and grabbed my friend”— another undergraduate doing research in the Brangwynne lab. “Sometimes she would be in the middle of something and then I would just FaceTime and show her the video from the microscopy room.”

Working with researchers from different departments to refine her experiments and measurements was a highlight of her Princeton experience, said Cheng. Her senior thesis research was honored with a Sigma Xi Book Award from the Department of Molecular Biology and a Calvin Dodd MacCracken Senior Thesis/Project Award from the School of Engineering and Applied Science.

“I learned so much from getting to work with all these incredible scientists who have different expertise. It’s very cool to see how you can combine biology with materials science and fluid dynamics to answer these questions,” she said. The experience “made me really excited to continue doing research and want to pursue a Ph.D.”

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The paper, “Micropipette aspiration reveals differential RNA-dependent viscoelasticity of nucleolar subcompartments,” was published May 28 in the Proceedings of the National Academy of Sciences. Co-authors included Cheng, Roggeveen, Wang, Stone, Shi and Brangwynne. Support for this project was provided in part by the Princeton Center for Complex Materials, the St. Jude Research Collaborative on the Biology and Biophysics of RNP granules, and the Howard Hughes Medical Institute. Cheng received support from the Elkins Family Senior Thesis Fund.

The German aerospace agency DLR has completed the manufacturing of a key component of the thermal protection system for the landing legs of its Callisto reusable booster demonstrator.

The Callisto project is a trilateral initiative between DLR, the French space agency CNES, and the Japanese space agency JAXA. The primary aim of the project is to mature key technologies for the development of future reusable rocket boosters.

On 30 July, the DLR Institute for Frontier Materials on Earth and in Space announced the completion of the first reusable clip-on Thermal Protection System (TPS) for the Callisto demonstrator’s landing legs. The component measures 180 by 90 centimetres and is designed to reduce thermal stress on the landing legs during final approach and landing.

According to the 30 July update, the clip-on TPS is manufactured from an oxide ceramic matrix composite using a proprietary vacuum-assisted slurry infusion fabrication process, which involves infusing a porous fibre preform with a ceramic slurry under vacuum.

The completed clip-on TPS will now be shipped to the DLR Institute of Space Systems in Bremen, where it will undergo qualification testing. Once qualified, the Institute for Frontier Materials on Earth and in Space expects to complete the fabrication of six clip-on TPS sets in 2026.

In April, DLR completed an even more significant milestone on the road to the launch pad by qualifying the demonstrator’s “Top Block”, which includes the demonstrator’s avionics, telemetry, communications, and flight control systems. With the completion of the first clip-on TPS and the start of its qualification, the Callisto project, which has often felt stalled, finally appears to be coming together.

An initial hop test flight of the completed Callisto reusable booster demonstrator is expected to lift off from the Guiana Space Centre in 2026. A total of ten flights are then planned to take place over a period of six months.

Solid gold samples have been superheated to more than 14 times the material’s melting point without losing their crystalline structure. The researchers behind the work say that the experiments suggest that, as long as a material is heated fast enough, there may potentially be no limit to how high a solid sample can be superheated before it loses its structure.

For decades, scientists thought it was impossible to heat solid materials to more than three times their melting point.

‘Back in the 1940s and 1980s, there were a series of papers asking the question: “How hot can you heat something before it melts?”’ explains Thomas White, a physicist at the University of Nevada in the US, who led the project. ‘In the 1980s, [Hans] Fecht and [William] Johnson proposed this ultimate limit of superheating, which is that you can never heat anything up to more than three times the melt temperature – they called this the entropy catastrophe.’

‘If you go beyond that point, you create a state of matter that just cannot exist,’ adds White. ‘The simple way of thinking about it is that you would have a crystal or a solid that is more disordered than liquid.’

Beyond the entropy catastrophe threshold

However, exploring this theoretical upper temperature limit has, until now, been extremely challenging due to intermediate destabilising events – colloquially known as the hierarchy of catastrophes – that occur at far lower temperatures, typically resulting in the material melting before the threshold is reached.

In their experiment, White and his team used high energy, highly focused lasers to rapidly heat 50-nanometre thick gold films. This fast heating rate meant that they bypassed these destabilising processes, enabling them to show that the metal could reach over 14 times its melting point without changing state and losing its crystalline structure.

‘What we’ve done in our experiment is heat this gold up so rapidly that it doesn’t have time to expand. If you heat it up faster than that expansion then you redo this entropy calculation, you find that the lines don’t cross anymore. We’re not breaking any laws of physics, we’re just able to heat far beyond this three times the melt temperature.’

White explains that while this level of superheating may have been done before, measuring these upper temperature limits has been a long-standing challenge. However, the team was able to overcome this by using a technique called inelastic x-ray scattering, in which the atoms or molecules in a sample absorb photons from an x-ray laser and re-emit photons of a different frequency.

‘This is a very cool, 3km-long x-ray laser,’ he says. ‘We were able to scatter the x-rays off the atoms as they move, and measure that Doppler shift, just to get the atom velocities and relate that to temperature.’

‘Technically, it’s quite a hard experiment and one of the reasons is that we don’t get much scattering from the sample. One way to increase the scattering is to use a higher atomic number element. Gold is a pretty high atomic number element, so it makes the experiment, technically quite easy.’

However, White and his team didn’t originally set out to investigate entropy catastrophe or superheating in gold at all. ‘We wanted to look at the rate at which it heated, that was what we were focusing on,’ he explains. ‘And after the experiment, we were looking at this temperature rise in the gold … and somebody just said, “Wait a minute, that’s really hot. Is that real? Is it really that hot?” It got to 19,000 Kelvin before it melted – that is really hot, but I didn’t know if it meant anything.’

‘Now we have this temperature diagnostic, we can investigate a whole range of interesting materials,’ adds White. ‘And so just last week, we did the experiment on compressed hot iron and conditions that you find inside planets. That’s pretty exciting for us.’

Martin Thuo, an expert in materials science and engineering at North Carolina State University in the US, told Chemistry World the method could be ‘very revolutionary’ but there are still some unanswered questions. ‘To be able to superheat any object to this extent is amazing. What is however missing is an understanding of “why”– what is the driving force?’ he says.

Thuo adds that he had some concerns about how the temperature was measured. ‘I don’t see any corrections for surface mobility or plasmonic transfer of incident light along the surface,’ he explains.

‘In the [experiment], the entropy of the ‘solid’ gold film would be way past the entropy catastrophe point proposed by [Robert] Cahn. However, this was not measured so I hope the study can be validated as this is a whole new area in the gold energy landscape.’