An experimental aircraft just achieved a “major milestone” that NASA officials say brings the future of quiet supersonic flight closer to being a reality.

The test flights involved the American space agency’s secretive X-59 aircraft, which reportedly reached speeds of 1.4 Mach—roughly 924 miles per hour—during a flight last Friday.

Reaching an altitude of 55,000 feet, the experimental aircraft’s speed and height during last week’s test flight met the conditions the agency says are required for future flights aiming to achieve supersonic flight without the noisy booms it usually generates.

In a statement, NASA said the aircraft’s tests are far from complete, although Friday’s test marks a significant milestone toward reaching its current mission goals.

“The X-59 still has months of performance testing ahead, but after those are complete, NASA’s Quesst mission will fly the aircraft over several U.S. communities to collect data on public perception of the quiet sonic thump it will make at supersonic speeds,” NASA’s statement on Friday read. “Those community overflights will include flights at Mach 1.4 and 55,000 feet.”

Another Milestone for NASA’s X-59

Last week’s test occurred within days of an earlier takeoff that sent the X-59 on its first successful supersonic flight, where the plane reached a top speed of Mach 1.1.

The earlier test also marked a leap forward for the Quesst mission, which is in the process of completing several crucial steps that are expanding the X-59’s capabilities.

Deployed for test flights at various speeds and at different altitudes, flight engineers are currently gauging the aircraft’s flight envelope by having it perform in a range of different flight conditions.

During its current test flights, NASA said the supersonic aircraft was accompanied by a NASA F-15 research aircraft, which still produces a sonic boom when it flies, unlike the X-59. NASA engineers plan to mount a shock-sensing probe on the accompanying aircraft during future flights, which the agency says will collect vital information about the shock waves the experimental aircraft produces.

The resulting experiments will help engineers measure the exact capabilities of the new aircraft and its supersonic performance.

Additional Prep for NASA’s Quesst Mission

Although designed to function as a “quiet” supersonic aircraft, the X-59 still produces audible signatures, which NASA likens more to being a soft “thump” than a sonic boom.

During its final testing phases, the X-59’s supersonic acoustic signature will also be measured.

If all goes according to plan, the supersonic aircraft will complete its full round of testing in the months ahead, marking a successful series of demonstrations that it meets all the requirements for quiet flight under a range of different altitudes and other flight conditions.

Ultimately, the technologies being innovated by this experimental plane will help to enable the first supersonic flight over land in decades, paving the way toward a new future of commercial flight faster than the speed of sound.

Additional details about NASA’s Quesst program can be found on its official site.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

Future interstellar travelers who hope to reach distant star systems will likely need better propulsion technologies than the chemical rockets humans currently rely on for our exploration of space.

Among the range of proposed alternatives, one potential candidate involves what are called solar light sails, a theoretical propulsion system that relies on pressure generated from solar radiation against a large surface to move a spacecraft.

Such concepts have been proposed since the 1980s, some of which combine the idea of using sunlight as a power source with the implementation of lasers, which could propel such futuristic starships to speeds our best current technologies cannot attain.

However, not all spacecraft propulsion experts are necessarily sold on the idea of solar light sails just yet. According to new findings detailed in a paper by researchers Jiaze Li and Chao Shen of the Harbin Institute of Technology in China, this novel form of propulsion may have a few hurdles to cross before it can attain the near-light-speeds many experts had hoped for.

A Tale of Three Forces

According to Shen and Li’s recent research, a key problem arises once a solar light sail spacecraft begins nearing the speed of light: drag forces resulting from the very source of energy used to propel the devices could place significant limitations on their maximum attainable speeds.

A combination of different forces can be expected to occur as sunlight strikes a light sail, the authors say, which includes incident light, specular reflection, and diffuse scattering.

Incident light describes the physical momentum generated by light energy in the form of photons as they strike the sail, whereas specular reflection describes the momentum produced as photons reflect off the sail. Finally, diffuse scattering is a separate form of momentum generated by photons, which, rather than bouncing away upon impact, is actually absorbed by the sail, the energy from which is thereafter released in random directions.

New Limitations on Solar Light Sails

Based on these primary forces, the authors identify that once a light sail begins reaching relativistic speeds, it also becomes subjected to intense Doppler effect—the phenomenon that occurs as changes in the frequency of waves result as their source and an object or observer’s distance changes in relation to it.

In the case of solar light sails, the more the frequency of light waves striking the sail decreases, the less the amount of thrust generated by the three forces the paper identifies. In simpler terms, the faster a solar light sail spacecraft attempts to travel, the harder it becomes for it to accelerate.

Relativistic Light Aberration

At approximately 75% of the speed of light, the researchers say that an additional hindrance emerges, as what physicists call relativistic light aberration takes over. This phenomenon, first described by Einstein more than a century ago, involves relativistic corrections of light sources for observers who move at velocities approaching light speed.

In the case of our prospective future solar light sailors, this would mean that the weakest of the three forces impacting the sail (diffuse scattering) would begin to impose an active drag once the sail reaches approximately three-quarters of light speed. While the overall force of lasers helping to propel the light sail would remain positive at this stage in the system’s acceleration, the authors note an inevitable decline in efficiency.

The authors do concede that while their paper examines the radiative dynamics of solar light sail propulsion, it does not account for other factors that may include drag resulting from encounters with materials like gases, dust, or other physical sources (i.e., non-radiative sources), which could also impact overall speeds.

Additional factors worthy of consideration, but which the authors do not directly address in their paper, include the melting point of any materials used for solar light sail propulsion, which could be heated to extreme temperatures due to combined exposure to solar radiation, laser energy, and friction from movement.

Fundamentally, the team reports that their paper “provides a rigorous and in-depth theoretical foundation for lightsail dynamics,” which illustrates that while this future propulsion concept has its merits, we may still be far from seeing its realization for practical space travel.

By outlining the factors that contribute to constraints on light sail propulsion, Li and Shen aim to improve our overall understanding of this prospective future technology, thereby helping engineers to realize its potential for use in space exploration at some point in the future.

The team’s paper, “Relativistic Lightsail Propulsion Dynamics,” appeared on the preprint arXiv.org server.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

Scientists from the Southwest Research Institute’s Center for Lunar Origin and Evolution (CLOE) have revealed new models of the Moon’s oldest and largest impact crater, the South Pole-Aitken (SPA) basin, providing fresh insights into the event and resulting material deposition on the lunar surface.

The SwRI team behind the new models, which is part of NASA’s Solar System Exploration Research Virtual Institute, said such details will help prepare future Artemis astronauts for what they could encounter during their upcoming missions.

Impact Study Reveals Details About Moon’s Oldest and Largest Crater

In a statement announcing the new models, Dr. William Bottke, director of CLOE and executive director of SwRI’s Science Directorate in Boulder, Colorado, said that the basin is an attractive potential target for future Artemis missions since it offers a “rare opportunity” to study an earlier era in the Moon’s history.

“The collision struck the lunar surface with such force that it may have excavated material from deep inside the Moon, including portions of the lunar mantle,” explained the co-author of the impact study detailing the new research.

Although previous studies have modeled impacts that may have caused the Moon’s oldest and largest crater, the team’s new effort has revealed new evidence about the composition of the impacting object and its likely direction and angle.

“Our simulation produces the right shape and nature of the impact basin,” explained the impact study’s lead author, Dr. Shigeru Wakita of Purdue University. “It also tells us about the projectile that created it and the direction of the impact.”

For example, the new model suggests that the object was not a single, uniform object. Instead, the team found that the impactor was likely a “differentiated” object, such as a protoplanet or asteroid, composed of rock and surrounded by an iron core. The models also found that the object approached from the north “at a low angle” before impacting the Moon’s surface on a southward trajectory.

According to the impact study authors, the impact excavated a deep, “asymmetric” cavity and generated enough energy to melt the rock within the crater’s central basin, resulting in the SPA basin’s elongated, tapered shape. Their models also indicated that the object’s lunar collision “lofted” large amounts of material into the air. Critically, their models also revealed that material from both the lunar crust and mantle was likely ejected before ultimately settling back onto the basin floor.

Exploring Gravity’s Role and the Possibility of ‘Valuable’ Mantle in the Impact Ejecta

To help potential future lunar astronauts, including members of NASA’s Artemis mission, target the most scientifically valuable lunar samples, a second companion study explored the effects of gravity on ejecta distribution beneath and around the impact basin. According to the team behind that effort, their effort involved direct comparisons of high-resolution gravity data with models. Specifically, they wanted to determine if pieces of the Moon’s crust and mantle were included in the ejection.

After comparing the two, the authors of the second study determined that the SPA basin “likely contains substantial amounts of mantle-derived rocks” both within its interior and mixed into the wider ejecta blanket surrounding the basin. Also critical for future missions, the analysis revealed that this material was not all scattered during the initial impact.

Instead, the new models showed that subsequent, smaller impacts appear to have “excavated” these underlying mantle deposits. As a result, the team suggests that there is likely enough material on the surface of the Moon’s oldest and largest crater “where it could be readily sampled by robotic rovers or astronauts during future missions.”

The Studies Provide Future Lunar Missions with a “Powerful Roadmap”

When discussing the significance of the gravity study’s findings, lead author Dr. Gabriel Gowman of the University of Arizona said that before now, the “precise distribution” of lunar mantle material on the Moon’s surface “has been a big unknown.” For example, some previous theories suggested that the deepest ejecta might be found only in parts of the basin that are not currently included in planned Artemis missions.

Now, the team’s new models suggest that the impact that formed the SPA basin “ejected enough deep material to form a significant deposit that should still be accessible today.” More importantly, Dr. Gowman added, some of that scientifically valuable mantle material “at a trace level” may exist in regions currently under consideration for upcoming Artemis landings. Taken together, Bottke said, the two studies can provide a “powerful roadmap” for future lunar scientific missions to the Moon’s oldest and largest crater.

“It tells us not just how SPA formed, but where to look for the rocks that can answer some of our biggest questions about the Moon’s origin and evolution,” the researcher explained.

The Impact study “A southward differentiated impactor forms the tapered shape of the South Pole-Aitken impact basin on the Moon” was published in Science Advances.

The gravity study “Gravity Mapping of Lunar Mantle Material in South Pole-Aitken Basin Ejecta” was published in the Journal of Geophysical Research: Planets.

Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.

Consciousness may arise in systems far different than the biology on Earth we are used to, according to University of California, Riverside (UCR) researchers, who argue that many forms of conscious experience may be possible in alien lifeforms.

Eric Schwitzgebel of UCR worked with Jeremy Pober, a former graduate student, not to understand what consciousness is, but rather, to explore whether it could arise in beings that differ radically from Earth’s biological standards.

At a time when questions about the possibility of alien life visiting Earth are on many minds, their work examines what unexpected forms might achieve consciousness—the first step toward intelligence.

Substrates and Consciousness 

Central to the pair’s work is the idea of “substrates,” from the Latin for “the level below,” referring to the underlying material base from which something is made. Although the term may be most familiar from geology, it can be applied conceptually across many disciplines, from biology to linguistics, to describe an underlying structure or form.

The researchers framed their core question around what they call “substrate flexibility”: can a specific property be achieved across many substrates, or is it more limited? One example they use is computer data storage. Information can be stored in many ways, including optical, magnetic, and solid-state media, indicating that storage exhibits a high degree of substrate flexibility.

But what about consciousness? Can it also be achieved flexibly? Perhaps the answer depends on the specificity of the question and whether we are considering human consciousness or a broader concept of consciousness itself.

A Diverse Universe

The researchers began by considering the scale and nature of our universe as it is presently understood. That includes roughly a trillion galaxies containing countless planets unlike our own, which they estimate may have given rise to more than a thousand alien civilizations during the 13.8 billion years since the Big Bang. Notably, they do not focus solely on Earth-like planets that might theoretically harbor biological life recognizable to us.

“With that many draws from the lottery, some of these life forms will be strange indeed,” the pair writes in their paper.

This idea is not far-fetched, as astrobiologists have long hypothesized that life in the cosmos may take forms radically different from those on Earth, composed of available local materials, possibly including entirely different chemical structures.

The pair does not argue that such exotic lifeforms definitely exist in some corner of the universe, only that, in such a large and diverse universe, it is relatively unlikely that the same building blocks would commonly arrange themselves in precisely the same way as on Earth.

Consciousness Isn’t Special

Taking inspiration from the idea of Nicholas Copernicus, the researchers argue that since the Earth, and thereby humanity, are not the center of the universe, it is likely that consciousness is also not a unique feature of our planet, or even recognizable biology.

However, the authors are quick to note that simply because consciousness may exist in multiple substrates does not mean it must exist in every substrate. AI systems, for example, may represent a form of silicon-based life, but they are not necessarily conscious at present. Additionally, perhaps how they are conscious should be considered more broadly, taking into account the variety of possible substrates, rather than simply assessing how well AI models the human brain.

That broader perspective is a crucial element of the pair’s conclusions. Consciousness should be considered in terms wider than simply assessing how well something replicates the human mind. While the authors concede that a similar substrate may be required to perfectly reproduce human consciousness, a broader view of the phenomenon may be necessary to recognize forms of consciousness that are fundamentally alien to our own.

The paper, “Substrate Flexibility and the Copernican Principle of Consciousness,” appeared in draft form on the University of California, Riverside website on May 28, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.

New analysis of ancient frozen Greenland rubbish heaps, called middens, has revealed new insights into several ancient societies that have passed through the country over the last five millennia. The findings include insights into ancient diseases and animals that the inhabitants kept but didn’t eat.

Although the team noted the potential risk that climate change could release dangerous ancient microbes into the modern environment, their analysis found little evidence that the pathogens they identified could pose a threat beyond the immediate area around the middens.

Ancient Middens Offer Historical Insights Beyond Traditional Artifacts

Archaeologists have often excavated items discarded by ancient societies from trash heaps to learn more about the people who lived there. Although such excavations often unearth things like animal bones and mollusk shells, offering insights into diet and hunting habits, these ancient rubbish heaps can also contain human artifacts, such as discarded blades and other tools.

In a country like Greenland, where different peoples have settled the region since 2,500 BCE, the ancient middens may also contain microbes that could offer researchers an entirely different type of historical data. For example, microbial data from middens could reveal which diseases ancient populations had to survive. The team notes that microbes could also help determine what ancient societies kept “but perhaps didn’t eat.”

Still, studies of ancient midden microbes are limited, leaving a gap in historical knowledge. The authors of the new paper also highlight that rapidly increasing Arctic warming could release infectious diseases to which humans have lost immunity over the ensuing generations.

Over One Thousand New Species Were Identified

To bridge the information gap, Dr Frank Møller Aarestrup, a professor at the National Food Institute of Denmark Technical University and corresponding author of the article detailing the team’s research, examined samples collected during 2020 and 2021 expeditions in West and South Greenland. During those expeditions, scientists collected samples from middens locked in time by permafrost, dating back as far as 4,500 years.

Among the middens sampled were the ancient Norse sites of Kapisilit and Narsarsuaq, where researchers collected soil samples from what the new paper’s authors termed “historic winter enclosures.” The site also contained evidence that it was a summer grazing ground for livestock.

After selecting several soil samples, Dr. Aarestrup’s team sequenced the DNA of ancient microbes found in the midden samples. Next, they compared the data, including entire bacterial communities, to 143 soil samples previously collected from areas of permafrost far away from any known historical human settlements.

According to the team’s statement, the sequencing revealed a total of 1,207 species and differing ranges of bacterial species per midden. In denser areas, the team identified as many as 202 species, whereas less microbe-dense middens had as few as nine.

The team’s analysis also found several species that had not been previously identified. This resulted in the team labeling the unidentified microbes using what they termed “broad taxonomic categories” above the genus and species level, such as family and order.

Preserving the ‘Biological Legacy’ of Human Activity

When comparing the microbial communities in the ancient middens with those from samples collected away from human settlements, the team found a significantly richer community of ancient bacteria preserved in the middens. The team notes that this discrepancy confirms that the middens “preserved the biological legacy of human activity.”

The most soil-like bacterial communities were identified within the oldest Paleo-Inuit middens. The researchers said the finding suggests that the microbial “imprint” left behind by humans and animals diminishes over time.

Bacterial communities were also associated with the types of waste discarded in each ancient midden. For example, although most middens contained bacteria associated with human and animal hosts, middens from colonial-era Nuuk contained decomposing seal skins. The middens from colonial-era sites were also rich in the bacterium Clostridium perfringens, which the team notes is “a major cause of food poisoning.”

Risk of Ancient Pathogens is Low

Although the team identified strains of bacteria that can cause botulism or other life-threatening conditions, such as toxic shock syndrome, sepsis, and gangrene, they also found a diversity of antimicrobial-resistance genes in the genomes of bacteria collected from the same middens.

According to the study authors, finding the two sets of genes in ancient and modern soil layers “signaled that microbes resistant to antimicrobials can linger in permafrost for centuries.”

Fortunately, the team’s analysis found that most of the identified microbes, including potentially dangerous pathogens, don’t spread far from middens, even those undergoing defrosting. As a result, the team said that these ancient microbes  “pose little risk to public health,” at least for the time being.

“Here we show that the risk of release of ancient pathogens from ancient middens in Greenland is currently low,” Dr. Aarestrup explained.

Instead, the researcher noted that Arctic middens appear to function like “long-term natural experiments,” in which both human- and animal-associated bacteria, including “opportunistic” species carrying resistance genes, remain detectable centuries later as a broader “legacy of human activity.”

The study “Microbial composition of archaeological middens: Tracing Human Footprints Through Centuries in Greenland’s Ancient Settlements” was published in Frontiers in Microbiology.

Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.