TianQin: standard sirens point to dynamical dark energy

A study explores how the choice of background cosmological model affects mock catalogs of standard sirens from the future space-based gravitational-wave detector TianQin. Until now, all TianQin forecasts were generated assuming the ΛCDM model. In this work, two mock catalogs of bright TianQin standard sirens (TQSS1 and TQSS2) are built from massive black hole binary mergers, one generated under ΛCDM and the other under a redshift-binned dark energy reconstruction model (the wbin model). The cosmological implications are then analyzed within the CPL model. Differences between the two catalogs turn out to be small: the distance-redshift relation differs by at most 1.48%. Taken individually, TQSS1 and TQSS2 yield cosmological constraints similar to those provided by type Ia supernova data, suggesting that this kind of catalogs could complement mainstream cosmological observations. The study also combines TianQin forecasts with baryon acoustic oscillation data from DESI DR2, cosmic microwave background data from Planck 2018, and DESY5 supernova data. The most notable result is that, when combining either catalog with DESI DR2, CMB and DESY5, the preference for dynamical dark energy persists: TQSS1+DESI DR2+CMB+DESY5 shows a 2.3σ preference, while TQSS2+DESI DR2+CMB+DESY5 raises it to 3.8σ. Adopting different massive black hole seed models does not affect the cosmological implications of the mock catalogs. The authors stress the importance of taking into account cosmological models other than ΛCDM when generating standard siren forecasts for dark energy. The work paves the way for future studies systematically exploring how TianQin predictions depend on the underlying cosmological model.

NASA's simulated Mars crew marks one year inside habitat

The four crew members of NASA's simulated Mars mission have completed one year living and working in isolation inside a confined habitat at the Johnson Space Center in Houston. The experience replicates the conditions of a future crewed mission to the red planet, with the aim of studying how humans respond to prolonged cohabitation in a confined space cut off from the outside. The simulation is part of the agency's preparations for long-duration missions to Mars, in which astronauts will have to live together for months without any possibility of an immediate return and with limited communications with Earth. Studies of this kind make it possible to analyse human factors —physical and mental health, group dynamics, stress and teamwork management— that are as decisive for mission success as the engineering of the spacecraft itself. During their stay, the crew carries out operational tasks typical of a Mars mission, including simulated extravehicular activities, experiments and resource management inside the habitat. Prolonged cohabitation in a confined environment yields valuable data on how performance and well-being degrade over time, information that is difficult to obtain by other means. The results of this and other analogue missions will help NASA design selection, training and psychological support protocols for the crews that, in the coming decades, undertake the real journey to Mars.

Curiosity watches Martian clouds at the start of a new Mars year

On 9 October 2026, the Curiosity rover marked the beginning of a new Mars year, which is set at the vernal equinox of the northern hemisphere. The mission is using the change of season to track the evolution of the planet's atmosphere, with particular attention to the clouds forming in the sky above Gale crater. The observation plan for sols 5036 to 5042, coordinated by Alex Innanen, an atmospheric scientist at York University, includes cloud tracking and meteorological measurements. Curiosity's cameras allow the formation, movement and dissipation of these clouds to be recorded, data that complement measurements of pressure, temperature and humidity in the Martian environment. Tracking clouds is key to understanding the water and dust cycles on Mars, as well as to refining global atmospheric circulation models. Curiosity's long-term observations, now in its nineteenth Mars year, offer a unique time series that makes it possible to study how the Martian climate changes from one season to the next and from one year to the next. The data gathered in this campaign will add to those obtained by other missions, such as the MAVEN orbiter and the Perseverance rover, to build a more complete picture of the Martian atmosphere. The information is also relevant for future crewed missions, which will depend on precise knowledge of the climate and atmospheric conditions at the surface.

ESA image shows where winds blow and lava flows

The European Space Agency (ESA) has published an image titled «Where winds blow and lava flows», a outreach piece combining observations of atmospheric and volcanic phenomena in a single planetary setting. The photograph is part of the agency's multimedia collection and is available in its digital archive. The material released by ESA includes no technical data, no coordinates of the observed celestial body and no details about the instrument or mission responsible for the capture. The image is accompanied only by its title and a brief description, with no press release or additional scientific context. The subject matter — winds and volcanic activity — fits ESA's usual line of disseminating observations of solar system bodies with active geological and atmospheric dynamics, such as Mars, Venus or the Jovian moons. In the absence of further information, it is not possible to determine which of them appears in the photograph. The image is available in ESA's multimedia gallery, where the agency usually hosts material free for outreach and educational use.

Unusual X-ray-hot radio source nicknamed 'Treble Clef'

The APOD for 19 October 2026 features an unusual radio source, informally nicknamed the 'treble clef' after the shape traced by its emission. The image highlights that this object combines intense radio radiation with appreciable X-ray heating, an association that is not typical for radio sources of this kind and that has caught the attention of the astronomers studying it. The peculiarity lies precisely in that mix of wavelengths. Radio sources are usually linked to relativistic electrons moving through magnetic fields, whereas X-ray emission reveals gas at temperatures of millions of degrees. That both signals coincide in the same object suggests simultaneous energetic processes that call for a detailed explanation. The day's image, selected by NASA's Astronomy Picture of the Day project, serves as an entry point to an object that remains under observation. The accompanying description, written by a professional astronomer, invites readers to keep track of this source in order to understand what mechanism produces such a peculiar combination of emission.

Dark Matter in Neutron Stars and its Impact on the Trace Anomaly

A recent study has investigated how the presence of dark matter (DM) affects the conformal properties and phase structure of dense matter in neutron stars. Using a self-consistent single-fluid framework, researchers have developed an exact decomposition of the total trace anomaly (Δtot) into its microscopic contributions. This approach allows for the analysis of dark matter's impact not only on the composition but also on the fundamental physics of these stars, which serve as natural laboratories for matter under extreme conditions. For collider-motivated Higgs-portal dark matter benchmarks, direct contributions from Higgs, vector-mediator, and contact interactions are found to be negligible. However, heavy nonrelativistic dark matter possesses an intrinsic trace anomaly close to the nonrelativistic limit (Δχ ≈ 1/3). This implies that the dark matter rest-mass energy fraction is the dominant factor in modifying Δtot, producing a smooth upward shift of up to approximately 0.1 for a dark matter fraction Fχ of about 0.2% of the baryonic mass. In the pressureless, comoving heavy-WIMP regime, a universal dark-sector scaling governed by the mass-loading parameter λ = Fχmχ/mN, where mχ is the dark matter particle mass and mN is the nucleon mass, has been identified. Numerical calculations demonstrate that, for a fixed λ, different combinations of Fχ and mχ exhibit overlapping responses in the trace anomaly, sound speed, and mass-radius relations for a given baryonic equation of state. In hybrid stars, dark matter leaves the coexistence pressure and chemical potential essentially unchanged, whereas first-order hadron-quark deconfinement produces sharp discontinuities in the squared sound speed (c_s²), Δtot, and Δtot - ΔB. This combined softening substantially reduces the maximum stellar mass, placing predictions in tension with observed 2 M☉ neutron stars if Fχ is around 0.2%. These findings suggest that the trace anomaly and its density evolution provide sensitive diagnostics for distinguishing smooth dark matter-induced modifications from genuine first-order deconfinement. This opens new avenues for understanding the internal composition of neutron stars and potentially for detecting the presence of dark matter in these compact objects, which would have profound implications for astrophysics and particle physics.

NASA Seeks New Flight Directors for Future Space Missions

NASA has opened the selection process for the next generation of flight directors at its Johnson Space Center in Houston. This position is critical for managing human spaceflight missions and for advancing space exploration, including the agency's plans to establish a sustained human presence on the Moon. Flight directors are responsible for leading teams of engineers, scientists, and flight controllers, making critical real-time decisions to ensure astronaut safety and mission success. Their role spans from mission planning and preparation to live execution, coordinating all operations from mission control. The selection of new directors is a key step to support NASA's ambitious goals, which include the Artemis program and future expeditions to Mars. The agency is looking for candidates with experience in engineering, science, or technology-related fields, and with proven leadership and decision-making skills under pressure. Those selected will undergo a rigorous training program before assuming their responsibilities in mission control. This initiative underscores NASA's ongoing commitment to deep space exploration and expanding human presence beyond low Earth orbit.

NASA seeks new flight directors for space missions

NASA has opened applications for its next class of flight directors, one of the most prestigious leadership positions in human spaceflight. These professionals are essential for managing missions from the Johnson Space Center in Houston, Texas, and their role is fundamental to ensuring the safety and success of space operations, from the International Space Station to future deep-space exploration missions. Flight directors are responsible for leading teams of flight controllers, engineers, and mission specialists, making critical real-time decisions during all phases of a spaceflight. Their work involves a deep understanding of spacecraft systems, mission procedures, and the ability to react to unforeseen situations, often under extreme pressure. This selection process seeks individuals with a combination of technical expertise, leadership skills, and a proven ability to make decisions under stress. This call for applications underscores NASA's ongoing commitment to space exploration and the need to maintain a highly qualified leadership team. Those selected will join an elite group that has guided some of the most iconic missions in space history, contributing to the next era of discovery and human presence in space. The agency aims to strengthen its leadership to face the challenges of future missions, including the Artemis program, which seeks to return humanity to the Moon and, eventually, to Mars.

NASA’s DAVINCI Probe Passes Extreme Heat Tests for Venus Mission

The engineering development unit for NASA’s DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) mission has successfully completed rigorous thermal testing. This yoga ball-sized probe is designed to descend through Venus’s dense and corrosive atmosphere, facing extreme temperature and pressure conditions. The recent tests are crucial to ensure the spacecraft's survival during its mission. During the evaluation, the DAVINCI team placed the unit into a ceramic-lined chamber, where the walls were intensely heated. The temperature was gradually increased to 465 °C (869 °F), replicating the hellish conditions of the Venusian surface. This heating process was conducted over an extended period, simulating the thermal stress the probe will experience during its descent and operation on the neighboring planet. The probe's ability to withstand these extreme temperatures is a significant milestone, given that Venus has the hottest atmosphere in the solar system, with an average surface temperature of about 462 °C. The success of these tests validates the design and materials selected for DAVINCI, bringing the mission closer to its goal of studying Venus's atmospheric composition and searching for signs of past water.

NASA’s SpaceX Crew-12 Mission Concludes Station Science Expedition

The Crew-12 mission, a collaboration between NASA and SpaceX, is set to conclude its stay aboard the International Space Station (ISS) in early October. NASA astronauts Jessica Meir and Jack Hathaway, ESA (European Space Agency) astronaut Sophie Adenot, and Roscosmos cosmonaut Andrey Fedyaev will return to Earth after completing a series of scientific investigations. These research efforts are aimed at both benefiting life on our planet and laying the groundwork for future human space exploration missions. During their time aboard the ISS, the Crew-12 crew has actively participated in experiments spanning various scientific disciplines. While specific details of each investigation have not been outlined in this announcement, the general focus of ISS missions includes studies on human physiology in microgravity, the development of new materials, plant and microorganism biology, and technology demonstrations. This work is crucial for understanding the long-term effects of spaceflight on the human body and for developing more efficient and reliable life support systems.

Simulations Confirm Transition to Radiation Domination in Starobinsky Model

Researchers have used numerical simulations to model the dynamic evolution of the early Universe within the framework of the Starobinsky inflationary model. This model, which describes a phase of ultra-rapid exponential expansion of the early Universe, is one of the most successful and serves as a benchmark for other inflationary theories. The study focused on the interaction between the scalaron (the quantum field responsible for inflation) and the production of radiation from its decay, ensuring exact energy conservation in an expanding background. The simulations, starting with a radiation-free Universe and initial conditions based on standard slow-roll approximations, showed that inflationary dynamics are predominantly governed by the scalaron. Despite continuous radiation production, the radiation component remained subdominant during inflation, which lasted for approximately 60 *e*-folds. Following the inflationary phase, the scalaron entered a damped oscillatory phase, accompanied by rapid radiation growth. This transition represents a "graceful exit" from inflation and a smooth entry into the reheating phase. During reheating, the radiation energy density continuously increased as the scalaron's energy was depleted. Ultimately, the radiation energy density substantially exceeded the residual scalaron energy, indicating the onset of a hot, radiation-dominated phase. This result satisfies the Kofman-Yi criterion for successful reheating, demonstrating that the coupled scalaron-radiation dynamics provides a self-consistent realization of the graceful exit from inflation and the transition to radiation domination in the Starobinsky model.

Exceptional Points Identified in Black Hole Ringdowns

Researchers have developed a procedure to identify Exceptional Points (EPs) in the ringdown phase of black holes. This phase, which follows the merger of two black holes or the perturbation of a single one, is characterized by the emission of gravitational waves that act as a "fingerprint" of the resulting object. Ringdown spectroscopy is a crucial tool for probing black hole dynamics, and the detection of EPs could reveal fundamental underlying degrees of freedom in the theory of gravity or in the structure of spacetime near these objects. The proposed method relies on the use of a time-weighted Jordan term and a splitting bound. For a relative Jordan excitation proportional to separation, the researchers derived a sixth-order squared distance between split and EP waveforms after fitting the resonance center. Incorporating independent constraints on these quantities can improve the precision to fourth order. These EPs are points in the parameter space of a system where two or more eigenmodes (or eigenvalues) coalesce, becoming indistinguishable and exhibiting non-Hermitian behavior, which can have profound implications for understanding black hole physics. The study also highlights that omitting ordinary responses in complete waveforms can strengthen the evidence for EPs and, paradoxically, spuriously tighten splitting bounds. This finding underscores the importance of careful analysis of gravitational wave data to avoid misinterpretations. The ability to identify and characterize these Exceptional Points could open new avenues for testing general relativity in extreme regimes and searching for deviations that suggest new physics beyond the Standard Model or Einstein's theory of gravity.

Cosmic structure formation distinguishes holographic dark energy models

A new study has demonstrated that observations of large-scale structure formation in the universe, such as galaxies and galaxy clusters, can be a key tool to differentiate between various holographic dark energy models. Researchers utilized a combination of cosmological datasets, including Pantheon+ SN Ia, OHD, DESI DR2 baryonic acoustic oscillation data, and CMB distance prior measurements, to constrain the parameters of three specific models: HDE (Holographic Dark Energy), THDE (Thermal Holographic Dark Energy), and BHDE (Black Hole Holographic Dark Energy). The analysis focused on the evolution of two crucial cosmological parameters: fσ₈(z) and S₈(z), which describe the growth of structures and the amplitude of matter density fluctuations, respectively. The results showed that the evolutionary curves of both fσ₈(z) and S₈(z) for the HDE and BHDE models were nearly indistinguishable. However, the curves corresponding to the THDE model consistently lay lowest. Additionally, the χ² statistic indicated that the THDE model yielded the lowest value for both fσ₈ and S₈ measurements, suggesting a better fit to observational data. To visualize these differences, the authors constructed a diagnostic (fσ₈, S₈) plane and analyzed the trajectories of the models. In this plane, the trajectory of the THDE model was able to reach the current (fσ₈, S₈) data region, which was not the case for the other models. These findings confirm that cosmic structure formation offers a robust method to distinguish the THDE model from the HDE and BHDE models, and suggest that this approach can be extended to evaluate the viability of other holographic dark energy scenarios.

Falcon 9 Rocket and Dragon Spacecraft Ready for Crew-13 Mission

SpaceX's Falcon 9 rocket and Dragon spacecraft are now vertical at Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida. This preparation is in anticipation of the upcoming NASA SpaceX Crew-13 mission, scheduled for launch on September 27, 2026. The image documenting this milestone shows the vertical configuration of the rocket and capsule, a crucial step before any crewed mission. The Crew-13 mission will transport four astronauts to the International Space Station (ISS). The crew will consist of NASA astronauts Jessica Watkins and Luke Delaney, Canadian Space Agency (CSA) astronaut Joshua Kutryk, and Roscosmos cosmonaut Sergey […]. This international collaboration underscores the ongoing joint effort in space exploration and the maintenance of the ISS as a global orbital laboratory.

NASA Announces Coverage for Crew-13 Mission Launch to ISS

NASA has announced live coverage of pre-launch, launch, and docking activities for its SpaceX Crew-13 mission bound for the International Space Station (ISS). The broadcast will be available across various online platforms, including the agency's official website. This event marks a new milestone in the collaboration between NASA and SpaceX for transporting astronauts to low Earth orbit. The launch of the Crew-13 mission is scheduled for Thursday, October 1, at 11:10 a.m. EDT. The spacecraft will depart from Space Launch Complex 40, although the full location was not specified in the announcement. This mission is part of NASA's Commercial Crew Program, which aims to ensure safe and reliable access to the ISS, thereby enabling the continuity of scientific research and station maintenance.

NASA Adds Blue Origin's New Glenn Rocket to Launch Services Catalog

NASA has added Blue Origin's New Glenn 9×4 launch service to its NLS II (NASA Launch Services II) contract. This inclusion, made possible through a contract on-ramp clause, will allow NASA's Launch Services Program Office to utilize New Glenn for future missions. NLS II contracts are multiple-award, indefinite-delivery/indefinite-quantity agreements designed to provide the agency with flexible access to a wide range of commercial launch capabilities for its science and exploration missions. The New Glenn is a heavy-lift launch vehicle under development by Blue Origin, designed to be partially reusable. Its payload capacity and the 9×4 configuration, likely referring to a specific booster or stage setup, make it suitable for missions requiring the transport of significant payloads to various orbits. The inclusion of this rocket in NASA's catalog underscores the agency's increasing reliance on commercial launch services for its space operations. This decision reflects NASA's strategy to foster competition and innovation within the commercial space sector, while ensuring the availability of robust and diversified launch options for its future projects. The ability to choose from multiple providers and launch vehicles allows NASA to optimize the cost-effectiveness and reliability of its missions, from scientific satellites to interplanetary probes. This addition is expected to facilitate access to space for a variety of critical missions in the coming years.

NASA to Present Space Exploration and Science Advances at IAC

NASA will participate in the 77th International Astronautical Congress (IAC), to be held in Antalya, Turkey, from October 5 to 9. The U.S. space agency will highlight its leadership in human exploration of the Moon and Mars, as well as progress in responsible exploration under the Artemis Accords. Significant scientific advancements and NASA's support for the commercial space sector will also be presented. The congress is a key platform for NASA to share its plans and achievements with the international community. This participation underscores the agency's commitment to global collaboration in space research and development, encompassing everything from crewed missions to scientific research aimed at expanding knowledge about the universe.

Arp 78: A Peculiar Galaxy in the Constellation Aries

NASA's Astronomy Picture of the Day has featured Arp 78, a peculiar galaxy located in the constellation Aries. This galaxy is a fascinating example of how gravitational interactions can distort galactic morphology, offering astronomers a window into studying galactic evolution and star formation processes in perturbed environments. Although the original title does not provide specific details about Arp 78's peculiar characteristics, the "Arp" designation refers to Halton Arp's Atlas of Peculiar Galaxies, a seminal catalog documenting galaxies with unusual or disturbed shapes. These peculiarities are often the result of mergers, tidal interactions with nearby galaxies, or the presence of active galactic nuclei. Studying these structures helps in understanding galactic dynamics and the distribution of dark matter. Observations of Arp 78, like other peculiar galaxies, contribute to refining models of galaxy formation and evolution. Data obtained from these images allow scientists to analyze the distribution of gas and dust, the star formation rate, and the kinematics of stars within these complex structures. Such studies are crucial for unraveling the mechanisms that shape the universe on a large scale.

Juice probe successfully completes Earth flyby en route to Jupiter

The European Space Agency's (ESA) Jupiter Icy Moons Explorer (Juice) mission performed a close Earth flyby on September 28. This crucial gravitational maneuver allowed the probe to alter its course towards Jupiter with minimal fuel consumption. During the flyby, Juice approached the outer edge of Earth's atmosphere, leveraging our planet's gravity to gain the necessary speed and direction for its interplanetary journey. The Earth flyby is a standard technique in space exploration, known as a gravity assist, which uses a planet's gravitational force to accelerate or decelerate a spacecraft and adjust its trajectory without requiring large amounts of propellant. This phase is critical for long-duration missions like Juice, whose primary objective is to study Jupiter and its icy moons, especially Ganymede, Callisto, and Europa, in search of subsurface oceans and potential signs of life. This milestone marks a significant step in Juice's complex roadmap. The probe will now continue its journey through the solar system, with an expected arrival at Jupiter in July 2031. Once there, it will perform a series of flybys of the Galilean moons before entering orbit around Ganymede in 2034, becoming the first spacecraft to orbit a moon other than Earth's.

Space Weather Ruled Out as Cause of 1841 Train Delay

An international team of researchers has refuted the hypothesis that a space weather event, such as a geomagnetic storm, caused a train delay in 1841. This claim, had it been true, would have constituted the earliest known record of space weather interacting with human technology. The research analyzed historical records and geophysical conditions of the era to reach this conclusion. The idea that space weather could have affected railway infrastructure at such an early date had generated interest, as most documented events of this type and their impact on technology are much more recent. The study focused on verifying the validity of this historical anecdote, which suggested possible electromagnetic interference with the signaling or communication systems of the time, rudimentary as they were compared to current ones. The researchers examined data on solar and geomagnetic activity around 1841, as well as the details of the railway incident. Their analysis found no correlation between recorded solar or geomagnetic events and the train delay, suggesting that the problem's cause was terrestrial or mechanical in nature, rather than a space weather phenomenon. This finding underscores the importance of rigorous verification of historical records to better understand the history of space weather's impact on Earth.

Two cosmological models based on Kruglov entropy show differing predictions

Researchers have explored two late-time cosmological models derived from Kruglov's nonadditive entropy applied to the apparent horizon. These models aim to explain the dynamics of cosmic expansion and dark energy, an enigmatic component driving the universe's acceleration. The main difference between them lies in how the generalized horizon entropy is incorporated into the Friedmann equations, which describe the cosmos's evolution. Model I, a previous derivation by Kruglov, uses the Cai-Kim thermodynamic construction and results in an implicit modified Friedmann equation. Model II, proposed in this work, is obtained from an entropy-integral prescription and contains an effective vacuum contribution. Both models were formulated in terms of the dimensionless Hubble parameter, including radiation, and exact closure for the present day was imposed. The physical branch's evolution was performed using analytical derivatives of the implicit Friedmann equations. The models were constrained with observational data, including baryon acoustic oscillations (BAO) from DESI DR2 and a compressed CMB likelihood, with and without DES-Y5 Type-Ia supernovae data. Model I predicts a significantly lower Hubble constant (H₀) of approximately 62.4 km s⁻¹ Mpc⁻¹, and a dark energy equation of state parameter (wDE,0) of -0.814, making it strongly disfavored compared to the flat ΛCDM model. In contrast, Model II stays close to standard ΛCDM cosmological parameters, with a wDE,0 of -1.003, although its two entropy-sector parameters show strong degeneracy. Its best-fit likelihood is comparable to ΛCDM, but information criteria do not support the additional parameters. This highlights that the observational plausibility of entropy-based cosmology critically depends on how horizon entropy is implemented in Friedmann dynamics.

Impact of Gaps on Gravitational-Wave Data Analysis

A new study addresses the challenge of data gaps in gravitational-wave detectors, particularly for future missions like LISA. These gaps affect the stationarity of noise, a fundamental assumption for the Whittle likelihood method, widely used in gravitational-wave parameter inference. The research focuses on how noise mis-modeling, due to the presence of these gaps, impacts the joint inference of signal and noise parameters, a critical issue when interruptions overlap with astrophysical signals of interest. The researchers developed an analytical and numerical framework to assess this impact, using a Fisher-matrix formalism validated against Bayesian inference. This allowed them to obtain closed-form expressions for model uncertainties and their maximum-likelihood estimates. The study examined various gap families, from long, well-tapered interruptions to short, high-rate ones, injecting massive black-hole binary signals. They showed that, except in the case of frequent gaps, the windowed covariance is well approximated by its leading diagonal for both signal and noise parameter estimation. However, by omitting the convolution, noise parameters, particularly the optical-metrology noise dominant at high frequencies, can be displaced by over an order of magnitude in power. At the highest glitch rates, the diagonal approximation remains accurate but loses an order of magnitude in precision. To remedy this, the study proposes an exact time-domain likelihood for the surviving samples. This function can be efficiently and accurately solved via preconditioned conjugate gradient methods. This advance is crucial for missions like LISA, where the presence of gaps is an inherent feature of the data and correct inference of noise and signal parameters is essential for the detection and characterization of astrophysical sources.

New Map Reveals Hidden Valleys Beneath Greenland's Ice

A new topographic map of the bedrock surface beneath the Greenland Ice Sheet has revealed hundreds of valleys that were either missing from previous representations or appeared fragmented. This detailed mapping, which integrates data from various sources, offers an unprecedented view of the island's subglacial geomorphology, a crucial factor for understanding ice flow dynamics and its response to climate change. The existence of these interconnected valleys suggests a more complex subglacial drainage network than previously thought. The relevance of this discovery lies in the fact that the underlying topography plays a fundamental role in the speed at which ice slides towards the ocean. Deep valleys can channel ice flow, accelerating its movement and, consequently, contributing to greater ice discharge and sea-level rise. Understanding the configuration of these channels is essential for improving predictive models of the future behavior of the Greenland Ice Sheet, which is currently one of the largest contributors to sea-level rise. This advance in mapping has been achieved by compiling and analyzing ice-penetrating radar data obtained over decades by various missions, including airborne surveys. The combination of these heterogeneous datasets has allowed for a more precise reconstruction of the subglacial relief, revealing a network of valleys that, in some cases, extend for hundreds of kilometers. The higher resolution and coverage of this new map provide a more solid basis for future glaciological and climate research.

Hubble Uncovers Chaotic Secret in Spiral Galaxy NGC 4698

NASA’s Hubble Space Telescope has captured an image of the spiral galaxy NGC 4698, revealing an unexpected feature within its core. While NGC 4698 initially appears similar to our Milky Way, with spiral arms coiling within a thin disk of stars, gas, and dust, detailed observations have uncovered unusual dynamic behavior in its central region. NGC 4698 is a spiral galaxy, implying a morphology dominated by a flat disk. However, the new Hubble images suggest that its nucleus harbors a more complex and disordered component than would be expected for this type of galaxy. This discovery adds a layer of complexity to our understanding of the formation and evolution of spiral galaxies, particularly concerning the distribution of matter and internal dynamics near their centers. The presence of this "chaotic secret" in NGC 4698 raises questions about the mechanisms that can generate or sustain such structures in spiral galaxies. It could indicate past interactions with other galaxies, internal energy feedback processes, or the influence of a supermassive black hole at the center affecting the distribution of gas and stars in unconventional ways. Future observations and spectroscopic analyses will be crucial to unraveling the exact nature of this phenomenon and its implications for galactic astrophysics.

Improved Universal Relations for Neutron Star f-modes

A new study has refined the universal relations describing the fundamental mode (f-mode) oscillations in neutron stars. These relations are crucial for gravitational-wave asteroseismology of neutron stars. Researchers utilized a large sample of piecewise-parametric equations of state (EOSs) to analyze the f-mode frequency and damping time within full general relativity. The work demonstrates that existing universal relations, which depend only on neutron star mass and radius, exhibit significant residuals that are strongly correlated with the overall stiffness of the EOS. To address these residuals, the team introduced linear correction terms dependent on the characteristic radius predicted by the EOS and the slope of the mass-radius curve at intermediate masses. These corrections enhance the accuracy of the universal relations, transforming them from a single-parameter model to a three-parameter one. For instance, in the case of gravitational wave emission from a Vela-like pulsar, the signal-to-noise ratio estimation can be over/under-estimated by up to 10% with previous relations, whereas the new model provides a nearly exact prediction. In contrast, the study found that universal relations between the f-mode and tidal deformability show minimal EOS-dependent correlations in their residuals, maintaining high EOS-insensitivity. This advancement is fundamental for the next generation of gravitational wave detectors, which will enable the detection of these signals and, consequently, the detailed study of neutron star internal structure through gravitational-wave asteroseismology.

Gravitational Waveform of Scattering Black Holes Calculated

Researchers have calculated the time-domain gravitational waveform emitted during the scattering of two nonspinning compact bodies in the extreme-mass-ratio limit. This work provides a detailed description of the gravitational radiation emitted during such an encounter, complementing previous first-order self-force calculations that were primarily formulated in the frequency domain. This new approach facilitates a direct comparison between time-domain and frequency-domain descriptions of the gravitational-wave signal, offering a more complete representation of the radiative dynamics. The obtained waveform is accurate to the fifth post-Minkowskian (three-loop) level and seventh post-Newtonian order. This precision establishes it as a crucial benchmark for future calculations using other methods, especially for the first order in the mass ratio. The results have already been validated in previous work by constructing the energy and angular momentum fluxes, thereby calculating the corresponding radiative losses at the 5PM and 4PM levels, respectively, with the same post-Newtonian accuracy. These findings are in agreement with recent amplitude-based calculations. This advance is fundamental for gravitational-wave astrophysics, as it allows for more precise modeling of black hole scattering events, which are potential sources for detectors like LIGO and Virgo. The ability to describe these interactions in the time domain is vital for interpreting observational data and refining our understanding of gravity in strong-field regimes. Furthermore, the comparison between time-domain and frequency-domain approaches is essential for verifying the consistency of different theoretical methodologies in general relativity.

NASA and Boeing to Update Starliner Capsule Development

NASA and Boeing have announced a press conference for Monday, September 28, at 3 p.m. EDT (9 p.m. CEST) to provide an update on the development of the Starliner spacecraft. The primary objective of this session will be to discuss future plans for regular crew flights to and from the International Space Station (ISS) using this capsule. This update is crucial for NASA's commercial crew program, which aims to diversify access to the orbital laboratory. The Starliner capsule, developed by Boeing, is one of two vehicles selected by NASA to transport astronauts to the ISS, alongside SpaceX's Crew Dragon. The program has faced several technical challenges and delays in its development and testing. This conference will offer details on recent progress, solutions implemented to address previous issues, and the estimated timeline for operational crewed missions, allowing for an assessment of progress towards full certification and operability of the spacecraft. The conference will feature participation from senior NASA and Boeing officials, who will answer questions regarding Starliner's readiness for its future missions. Media accredited for the Crew-13 mission will have the opportunity to participate in person at NASA's Kennedy Space Center. For the general public and other interested parties, the conference will be broadcast live via NASA's website, nasa.gov/live, ensuring wide dissemination of information and transparency in the process.

NASA Assigns Crew for SpaceX Crew-14 Mission to International Space Station

NASA has announced the crew assignments for the SpaceX Crew-14 mission, scheduled to launch to the International Space Station (ISS) no earlier than spring 2027. This long-duration mission will conduct a science expedition and will comprise four crew members, representing three different space agencies. NASA astronauts Kayla Barron and Chris Birch have been designated as spacecraft commander and pilot, respectively. They will be joined by Makoto Suwa, an astronaut from the Japan Aerospace Exploration Agency (JAXA), and a Roscosmos cosmonaut, whose identity has not yet been revealed. This international collaboration underscores the global nature of space exploration and the shared commitment to scientific research in microgravity. The Crew-14 mission will continue the uninterrupted human presence on the ISS, a fundamental orbital laboratory for advancing scientific and technological knowledge. The International Space Station is a crucial testbed for future technologies and a unique environment for studying the effects of microgravity on biological systems and materials, which is vital for future human exploration missions to the Moon and Mars. Long-duration expeditions like Crew-14 allow researchers to conduct complex experiments and collect data over extended periods, maximizing the scientific return of each mission.

Testing Strong Equivalence Principle with Binary Neutron Star Mergers

A new study has utilized observations of gravitational waves and electromagnetic radiation from binary neutron star mergers to test the Strong Equivalence Principle (SEP) of General Relativity. The SEP postulates that all bodies fall with the same acceleration in a gravitational field, regardless of their composition or internal structure. This principle is fundamental to Einstein's General Relativity, and its verification in extreme gravitational field environments, such as those found in neutron star mergers, is crucial for confirming the theory's validity or identifying potential deviations that could point to new physics. The researchers analyzed data from multimessenger events, which include the simultaneous detection of gravitational waves by detectors like LIGO and Virgo, and the emission of light (gamma rays, X-rays, visible light, etc.) by telescopes. The key to this approach lies in the fact that gravitational waves and photons (light particles) propagate through the same gravitational field. If the SEP holds, both should experience the same acceleration and, therefore, arrive at Earth with a predictable time difference, influenced only by the speed of light and the speed of gravitational waves, as well as the distance traveled. By comparing the arrival times of gravitational waves and photons from events like GW170817, the first multimessenger event from a neutron star merger, the team was able to set stringent limits on possible violations of the SEP. Any deviation in arrival times that cannot be explained by known propagation effects would imply that different types of energy (the energy associated with the mass of the neutron stars generating gravitational waves, and the energy of photons) interact differently with the gravitational field. This would be a clear sign that General Relativity might require modifications in extreme gravity regimes.

Earth's Axial Tilt Reveals Seasonal Continental Shift

A NASA camera in deep space has captured a unique perspective of Earth, revealing how the apparent position of continents shifts with the seasons. This visual phenomenon is a direct consequence of our planet's rotational axis tilt, a fundamental factor governing seasonal cycles and the distribution of sunlight throughout the year. The observation, made from a significant distance, allows for a global appreciation of how Earth presents different faces as it orbits the Sun. Although continents remain fixed on the Earth's surface, their relative orientation to the camera's viewpoint subtly changes throughout the year due to the 23.5-degree axial tilt. This tilt is responsible for the Northern and Southern Hemispheres receiving varying amounts of solar radiation at different times, giving rise to the seasons we experience. This type of imagery not only offers an aesthetically stunning view of our planet but also serves as a powerful educational tool for understanding basic astronomical concepts. By visualizing the effect of axial tilt on Earth's global appearance, it reinforces the comprehension of how this factor influences everyday phenomena such as day and night length, average temperatures, and seasonal weather patterns in different regions of the world.

APOD: September 22, 2026 – Triple Alignment: Plane, Space Station, Sun

NASA's Astronomy Picture of the Day (APOD) for September 22, 2026, highlights a cosmic and terrestrial triple alignment event. The image shows the International Space Station (ISS) transiting the solar disk, an already remarkable phenomenon. However, what makes this snapshot particularly unique is the coincidence of a passenger airplane crossing the same field of view at the exact moment of capture. Such alignments, while photogenic, are extremely rare and require precise planning and a considerable amount of luck to be successfully observed and photographed. The photograph, captured by an amateur astronomer, illustrates the convergence of human technology in space (the ISS), terrestrial air transport (the airplane), and the most prominent celestial object in our solar system (the Sun). The ISS orbits Earth at an altitude of approximately 400 kilometers and travels at a speed of about 28,000 km/h, making its solar transits last only a fraction of a second. The addition of an airplane, moving at a much slower speed but at a significantly lower altitude, in the same visual and temporal plane, underscores the fortuitous nature of the event. These transits are of great interest to the astronomical community, both professional and amateur, as they offer unique opportunities for equipment calibration and the study of Earth's atmosphere if observed from different locations. Furthermore, the aesthetics of such images serve as a powerful tool for scientific outreach, capturing the public's imagination and highlighting the beauty and precision of the universe around us. APOD, in its daily mission to present a different image of our fascinating universe, has selected this alignment for its exceptional nature and its ability to inspire.

Perseverance Reveals Complex Water Systems in Mars' Jezero Crater

NASA's Perseverance rover has uncovered unexpected evidence of complex water systems within Mars' Jezero Crater. Upon reaching the inner edge of the crater in September 2023, mission scientists anticipated finding sedimentary rocks in the geological unit known as the “Margin Unit,” which stretches along the ancient shoreline of a Martian lake. However, initial findings suggest a much more intricate geological and aquatic history than predicted, with significant implications for understanding Mars' past habitability. Traditionally, lake shorelines are associated with the gradual deposition of sediments, forming layers that record the history of the water body. The discovery of rock formations differing from this expectation in the “Margin Unit” indicates that the geological processes and water interactions in this region were more dynamic and varied. These data compel researchers to re-evaluate existing models of Jezero Crater's hydrological evolution and, by extension, other aquatic environments on early Mars. Although the original text is concise, the scientists' surprise at the rocks found in the “Margin Unit” underscores the importance of this discovery. It suggests that Jezero Crater's geology was not solely formed by passive sedimentation in a lake, but may have involved more energetic water flows, volcanic activity, or tectonic processes that altered the expected formations. These new data are crucial for determining whether Jezero Crater once harbored conditions conducive to microbial life and for guiding future exploration and sample collection missions.

Constraining the Geometry of Rotating Black Holes with Eikonal QNMs

A new study has explored how the quasinormal modes (QNM) of black holes, the "waves" they emit after a perturbation, can be used to infer the properties of these objects and the surrounding spacetime. The work compares two approaches: one based on a specific metric model (the Konoplya-Rezzolla-Zhidenko parametrization) and another "agnostic" to the metric, which focuses on local properties near the light ring. Both models were applied to simulated data and the real gravitational wave observation GW250114, showing consistency with the Kerr metric of general relativity. The research connects a calibrated eikonal method, which relates quasinormal mode shifts to local metric properties near the light ring, with the underlying rotating black hole metric. Using Bayesian inference, both one-parameter and simultaneous multi-parameter analyses were performed. It was found that uniform priors on the metric-specific coefficients can induce strongly nonuniform and skewed priors on these local metric quantities. However, for data injections compatible with general relativity, both models remain consistent with Kerr and yield similar posteriors for the orbital frequency and Lyapunov exponent. For scenarios representing deviations from general relativity, one-parameter analyses can fail to recover the injected local deviations, and in the metric-specific case, can bias the global metric reconstruction. Multi-parameter analyses of both models, while introducing degeneracies and differences in marginalized parameters, yield consistent constraints, suggesting sufficient robustness. The application of this framework to approximate posterior information from the ringdown analysis of GW250114 confirms that both models are consistent with the Kerr metric in general relativity, strengthening our understanding of these extreme phenomena.

Perseverance captures 360-degree panorama of 'Turquoise Bay' on Mars

NASA’s Perseverance rover has utilized its Mastcam-Z camera to capture a 360-degree panorama of a Martian region known as “Turquoise Bay.” This geologically interesting area is located within the “Margin Unit” of Jezero Crater. The 818 images comprising this natural-color view were acquired between October 5 and October 16, 2023, corresponding to Martian sols 933 to 944 of the rover’s mission. Such detailed panoramas are crucial for the geological analysis of the Martian surface and for planning future exploration routes. Perseverance’s capability to generate high-resolution images and 360-degree panoramas allows scientists on Earth to study the composition and structure of Martian rocks and soil with unprecedented detail. The “Margin Unit” is of particular interest due to its potential to harbor evidence of past aqueous environments, which could provide clues about Mars’ habitability and the possible existence of ancient microbial life. The continuous collection of visual data is fundamental for identifying sampling targets and for understanding the geological history of the Red Planet.

ESA's Juice Mission to Perform Third Earth Gravity Assist Flyby

The European Space Agency's (ESA) Jupiter Icy Moons Explorer (Juice) mission will return to Earth on September 28 for a gravity assist maneuver. Flight controllers will guide the spacecraft close to our planet, using Earth's gravity to adjust its speed and direction. This marks the third of four planned gravity assist flybys, a crucial technique to propel the probe towards its ultimate destination: the Jovian system. These gravity assists are essential for Juice to achieve the necessary velocity for its interplanetary journey without requiring an excessive amount of fuel. The spacecraft, launched in April 2023, has already completed two previous flybys: one of Earth and the Moon in August 2024, and another of Venus in February 2025. The September 28, 2026 flyby will be one of the last opportunities to refine its trajectory before its arrival at Jupiter in 2031. Once at Jupiter, Juice will spend several years studying three of its icy ocean moons—Europa, Ganymede, and Callisto—which are believed to harbor subsurface oceans of liquid water. The mission's primary goal is to investigate the potential habitability of these worlds. The information gathered during this cruise phase, including data from the flybys, is vital to ensure the spacecraft arrives at its destination with the optimal trajectory and resources to conduct its ambitious scientific research.

COSI Telescope Assembles to Observe Cosmic Gamma Rays

The Compton Spectrometer and Imager (COSI), a gamma-ray telescope, has completed its assembly phase at the University of California, Berkeley. This milestone brings the mission, scheduled for launch in 2027, closer to its goal of mapping the sky for low-energy gamma-ray sources and studying extreme astrophysical phenomena. COSI is designed to detect and measure the polarization of gamma rays in the 0.2 to 5 MeV range. This capability will allow scientists to investigate the origin of positrons in our galaxy, study the explosive nucleosynthesis of heavy elements in supernovae and kilonovae, and explore particle acceleration mechanisms in compact objects such as pulsars and black holes. Gamma-ray polarization information is crucial for unraveling the geometry and magnetic fields of these cosmic sources. The assembly of the main detector, which includes four pieces of silver material covering the flex circuits for signal transmission, represents a critical step. Following this phase, COSI will undergo rigorous environmental and calibration tests to ensure its proper functioning in the extreme conditions of space. The COSI mission, selected by NASA in 2021 as part of its Small Explorer (SMEX) program, promises to open a new window into understanding the high-energy universe.

XRISM Mission Observes Pulsar Capturing Companion’s Stellar Wind

Astronomers have directly observed, for the first time, how the stellar wind from a giant star is captured by its compact companion, fueling intense X-ray flares. This discovery was made using data from the XRISM (X-ray Imaging and Spectroscopy Mission) observatory, a Japan-led mission with NASA participation. The observation provides crucial insight into the accretion mechanisms in extreme binary systems, where matter flows from one star to a compact object, such as a pulsar or a black hole. The study focused on an X-ray binary system, where the compact object is a pulsar. The stellar wind, a stream of charged particles emanating from the giant star, is gravitationally pulled towards the pulsar. As this matter falls onto the pulsar, it heats up to extreme temperatures and emits a large amount of X-rays, manifesting as flares. XRISM's capability for high-resolution X-ray spectroscopy has been instrumental in unraveling this process, allowing scientists to analyze the composition and properties of the plasma in the pulsar's vicinity. This research is part of NASA's program to explore the extreme universe and better understand high-energy phenomena. The direct observation of stellar wind capture and its role in generating X-ray flares is a significant step towards comprehending the dynamics of X-ray binary systems and the evolution of massive stars. Future observations with XRISM and other X-ray telescopes will allow for refinement of our accretion models and the interaction between stellar objects in extreme environments.

NASA Invests in Florida to Boost Aerospace Workforce

NASA has recently allocated $10.5 million to seven organizations across the United States through its new State Hubs initiative. Space Florida is one of the beneficiaries, selected for Project ORBIT. This initiative primarily aims to expand opportunities for middle and high school students, boost enrollment in key career and technical programs, and establish a statewide portal connecting skilled workers with aerospace employers. This effort seeks to strengthen the talent pipeline for the growing space industry. Project ORBIT focuses on creating an ecosystem that prepares the next generation of professionals for the demands of the aerospace sector. By targeting students in early educational stages, NASA and Space Florida intend to inspire scientific and technical vocations, ensuring a steady flow of skilled personnel. The investment underscores Florida's strategic importance as a central hub for space exploration and the need for a robust workforce to sustain its development. The creation of a portal connecting workers and companies is a key component to optimize job placement and meet the industry's staffing needs. This comprehensive approach, spanning from education to professional placement, reflects a long-term strategy to consolidate the talent infrastructure in the state. NASA's State Hubs initiative seeks to replicate this model in other regions, fostering capacity building nationwide.

DESI Suggests a Dark Force Violating the Equivalence Principle

Recent measurements of galaxy distribution by the Dark Energy Spectroscopic Instrument (DESI) show a mild tension with the standard ΛCDM cosmological model, particularly when extrapolated to low redshifts from Cosmic Microwave Background (CMB) data. To address this discrepancy, a proposed solution posits that the inertial and gravitational masses of dark matter particles are not the same, implying a violation of the Equivalence Principle within the dark sector. Analysis of CMB data, combined with Baryon Acoustic Oscillation (BAO) and Full Shape (FS) data from DESI DR1 (Data Release 1), or with BAO DR2 data alone, suggests the presence of a new long-range force in the dark sector. This force would have a strength of approximately β ~ 0.5% relative to gravity, at a statistical significance of ~2.5σ. A preliminary assessment combining FS DR1 and BAO DR2 data raises the evidence for these dark forces to ~3σ, though this figure ignores the not-yet-available cross-correlation between the two datasets. This finding, if confirmed, would have profound implications for our understanding of dark matter and cosmology. The existence of a dark force and the violation of the Equivalence Principle in this sector could necessitate a revision of current cosmological models and open new avenues for physics beyond the Standard Model. Confirmation of these results through future analyses and the incorporation of cross-data correlations will be crucial to validate this hypothesis.

Artemis III Astronauts Visit Rocket Assembly at Kennedy

A group of astronauts assigned to future Artemis missions, including NASA's Randy Bresnik and ESA's Luca Parmitano, visited the Kennedy Space Center facilities in Florida. The purpose of the visit was to observe the progress in the integration of the solid rocket boosters (SRBs) in High Bay 3 of the Vehicle Assembly Building (VAB), a crucial stage in preparing the Space Launch System (SLS) rocket for lunar missions. The visit underscores the advanced phase of preparation for the Artemis missions, which aim for humanity's return to the Moon. The VAB is an iconic NASA facility, where the most powerful rockets in space history have been assembled, from the Apollo program's Saturn V to the space shuttle and now the SLS. The integration of the SRBs is a fundamental step, as they provide most of the initial thrust needed to escape Earth's gravity.

NASA Invites Public to International Observe the Moon Night in September

NASA has announced the celebration of International Observe the Moon Night, an annual event inviting the public to look up at our natural satellite. This year, the event will take place on Saturday, September 19, and will feature activities organized by the U.S. space agency nationwide, including a main event at NASA's Goddard Space Flight Center. The initiative aims to foster interest in lunar science and space exploration, especially following recent milestones such as the Artemis II mission. In April, this mission marked a significant achievement by sending four astronauts to orbit the Moon, the first time in over 50 years that humans had made such a close approach to our satellite. These public events are crucial for connecting citizens with scientific advancements and future space missions.

NASA Hosts International Observe the Moon Night

NASA has announced the celebration of International Observe the Moon Night, an event dedicated to our natural satellite. The main activity will take place on Saturday, September 19, from 5:30 to 8:00 p.m. CST, at the U.S. Space & Rocket Center, the official visitor center for NASA’s Marshall Space Flight Center in Huntsville, Alabama. This annual event aims to foster public interest in the Moon, highlighting the science behind it and its deep connection to Earth. Although the original text does not detail specific activities, these celebrations typically include telescopes for observation, educational talks, and interactive exhibits on lunar geology, past and future space missions, and the Moon's role in the solar system. International Observe the Moon Night is a global initiative that invites people of all ages to observe and learn about the Moon, often with the participation of scientific institutions, museums, and astronomy clubs worldwide. It is an opportunity for the scientific community and the general public to share wonder for Earth's closest celestial body and better understand its importance in space exploration and astrophysical research.

LUX-ZEPLIN analyzes anomalous event to infer dark matter properties

The LUX-ZEPLIN (LZ) experiment, designed for the direct search for dark matter, has recorded a high-energy nuclear recoil event, approximately 248 keV, in a detector region with a very low expected background. This singular event has led to a detailed analysis to explore whether it could be a signature of dark matter particle interaction with xenon nuclei. Researchers have computed the posterior probability distribution of parameters that would describe dark matter scattering, considering both elastic and inelastic scatterings, where the mass of the dark matter particle could change after the interaction. The analysis of this single event reveals non-trivial, disconnected regions in the parameter space, corresponding to physically distinct regimes: endothermic and exothermic. In the endothermic regime, the observed recoil energy is generated close to a kinematic threshold, while in the exothermic regime, the interaction releases mass energy from the dark sector. The absence of accompanying events at lower recoil energies sharply constrains the viable parameter space. A kinematically tuned region of high-mass endothermic WIMP-like models with generic couplings has been identified, as well as exothermic models ranging from sub-GeV to heavy dark matter with sizable mass splittings. For the event to be compatible with elastic dark matter scattering, momentum-suppressed and/or nuclear-spin-dependent non-relativistic interactions would be required. This study highlights the complexity of interpreting individual events in the search for dark matter and the need for models that consider a wide range of possible interactions, beyond simple elastic scattering. Although a single event is not conclusive, its detailed analysis provides valuable insights into the possible properties of dark matter particles and guides future searches.

Neutron Disappearance by Dark Matter for LZ Event

Scientists propose a new dark matter (DM) interaction model to explain a high-energy nuclear recoil event detected by the LUX-ZEPLIN (LZ) experiment. The hypothesis suggests that an incoming DM particle annihilates a bound neutron within a nucleus, transforming it into an invisible scalar. This process leaves a recoiling daughter nucleus, whose recoil energy, in the zero-velocity limit, generates a line spectrum broadened by halo velocities. The study identifies parameter regions for DM masses of 5 and 50 GeV that could account for the observed event near 248 keV, without producing events at lower energies. This specificity is crucial for matching LZ observations, which search for direct interactions of dark matter with nuclei. The researchers also examined collider constraints in an illustrative ultraviolet completion and re-evaluated Borexino data to limit accompanying nuclear de-excitation signals. This "DM-induced neutron disappearance" mechanism offers a novel framework for interpreting localized nuclear recoil excesses in future direct-detection experiments. It could be key to understanding the nature of dark matter if similar events are confirmed and other explanations ruled out. The proposal opens new avenues for DM searches, focusing not only on elastic scattering but also on more complex annihilation processes.

NASA Boosts Research for Astronaut Food and Health

NASA has selected 12 new investigations aimed at supporting human explorers in space. Of these, six will focus on advancing the ability to produce food off-planet, while the other six aim to enhance the understanding of how the unique conditions associated with space exploration can impact the health and physiology of astronauts. This initiative is crucial for long-duration missions, where self-sufficiency and crew protection are paramount. The six food-focused investigations, supported by the agency's Space Biology program, seek to develop more efficient and sustainable systems for growing food in space environments. This includes studying new crop varieties, cultivation methods optimized for microgravity and limited resources, and evaluating their nutritional value and impact on astronaut diets. The ability to grow fresh, nutritious food in situ would significantly reduce reliance on Earth-based supplies and improve the quality of life for crews. On the other hand, the six health-focused investigations will address the physiological challenges astronauts face, such as bone and muscle loss, radiation effects, cardiovascular changes, and psychological impacts. These studies are fundamental for developing effective countermeasures and medical protocols to ensure the safety and well-being of astronauts during extended missions to destinations like the Moon or Mars. A deep understanding of these effects is essential to mitigate risks and ensure the success of future expeditions.

Cosmological Bounds on Neutrino Masses Are Robust

A new study has investigated the robustness of cosmological constraints on the sum of neutrino masses (Σmν) against variations in the early thermal history of the universe. The results indicate that, even under scenarios that alter the inferred neutrino abundance from the cosmic microwave background (CMB), the upper limits on their masses remain stringent, with small variations that do not significantly relax current bounds. This is crucial for precision cosmology and particle physics, as neutrino mass is one of the few Standard Model parameters not yet precisely determined. The researchers evaluated how the injection of photons or dark radiation after neutrino decoupling, due to the decay of massive particles, could affect the inference of neutrino abundance and, consequently, their masses. Using MCMC analyses with data from the Planck satellite (primary CMB and CMB lensing), ACT (CMB lensing), and DESI (baryon acoustic oscillations), they found that, for a degenerate mass ordering, the 95% credible limit for Σmν tightens slightly from 0.0691 eV in the standard model to 0.0652 eV if massive particles decay only into photons. If dark radiation is also injected, the limit relaxes marginally to 0.0710 eV. These changes are approximately 0.004 eV, demonstrating the stability of the constraints. To test the generality of this finding, the study also explored model-agnostic changes in the neutrino-to-photon temperature ratio, without assuming a specific physical mechanism. In this case, the 95% credible limit for Σmν in the degenerate ordering was 0.0724 eV. The positive correlation found between neutrino temperature and the sum of their masses suggests that reducing the pre-recombination radiation density would only worsen the emerging tension between cosmological bounds on neutrino masses and measured mass splittings. These results reinforce the robustness of current cosmological constraints on neutrino mass, a fundamental parameter for understanding the evolution of the universe and particle physics beyond the Standard Model.

The Cosmic Origin of Chemical Elements in the Universe

Astronomy has revealed that the chemical elements making up everything we know, including life on Earth, have diverse cosmic origins. From primordial hydrogen and helium, forged in the Big Bang, to heavier elements, each is the result of specific astrophysical processes that have occurred throughout the universe's history. Understanding these origins is fundamental to unraveling stellar and galactic evolution, and ultimately, the formation of planets and the emergence of life. Light elements like hydrogen and helium, along with traces of lithium, were created in the first few minutes of the universe during Big Bang nucleosynthesis. However, most of the elements we find today, from carbon and oxygen to iron, are synthesized within stars through nuclear fusion. Massive stars, at the end of their lives, explode as supernovae, dispersing these enriched elements into interstellar space, where they can form new generations of stars and planetary systems. Elements heavier than iron, such as gold, silver, or uranium, require even more extreme energetic conditions for their formation. These elements are believed to be primarily forged in cataclysmic events like the merger of neutron stars or in particularly powerful core-collapse supernovae. These events are crucial for "seeding" the universe with the necessary materials for the chemical diversity we observe. Studying the abundances of these elements in different stellar populations and galaxies provides vital clues about the history of star formation and the chemical evolution of the cosmos.

Pretelescopic Solar Activity Cycles Reconstructed from Auroral Records

A recent study has successfully reconstructed solar activity cycles, including periods before the invention of the telescope, by utilizing historical records of aurora borealis and australis. This research offers an unprecedented insight into long-term solar variability, extending our knowledge of our star's behavior beyond direct sunspot records, which began in the 17th century. The key to this advancement lies in the correlation between the intensity and frequency of auroras and the Sun's magnetic activity, which drives the approximately 11-year solar cycle. The researchers analyzed a vast collection of historical documents, including medieval chronicles, navigation logs, and astronomical records from various cultures, to identify and date auroral events. These data, spanning from 450 AD to the present, allowed for the inference of peaks and troughs in solar activity during times when telescopic observations did not exist. This method complements and validates previous reconstructions based on cosmogenic isotopes, such as carbon-14 in tree rings or beryllium-10 in ice cores, providing an independent and direct source of information on geophysical phenomena influenced by the Sun. The results reveal periods of unusually low solar activity, such as the Maunder Minimum (1645-1715), and others of moderate activity, confirming the Sun's fluctuating nature. The detailed reconstruction of these cycles is crucial for a better understanding of the Sun's internal mechanisms and its impact on Earth's climate and space environment. The ability to observe solar activity over millennia is fundamental for predicting future space weather events and assessing risks to technological infrastructures like satellites and power grids. This work lays the groundwork for future research that could further refine our understanding of solar history and its implications.

Direct Waves Reveal Kerr Black Hole Ergosphere

Researchers have formulated a theoretical framework for direct waves (DWs) in extreme-mass mergers, a type of gravitational signal arising from the interaction of a particle with a black hole. These waves, characterized by a complex frequency ωG, offer a unique window into the particle's orbital dynamics, including its motion within the ergosphere. The real part of ωG is influenced by the black hole's frame-dragging, while its imaginary part reflects the source's redshift, providing crucial information about the black hole's extreme environment. Using the Green's function technique, the study describes how this frequency ωG is generated and how it is screened by the black hole's potential barrier. A connection is established between direct waves and dynamically excited quasinormal modes (QNMs). Furthermore, the long-term decay of DWs is predicted to follow the third-order horizon mode. To analyze these complex signals, a "pole-splitting method" is introduced, dividing the complete waveform into a QNM-pole sector and a non-QNM sector. Unlike traditional QNM filtering, which can distort the spectrum, this new method separates the contributions without altering the original signal. Simulations of a quasi-circular plunge into a Kerr black hole with medium and rapid spins show that the frequency and decay rate of the non-pole sector in the dominant mode (ℓ = m = 2) evolve consistently with ωG, or its screened counterpart ωscreen. This finding validates direct waves as a sensitive tool for probing the ergosphere and redshift effects in the vicinity of black holes. The ability of these waves to directly probe the ergosphere opens new avenues for understanding physics in the most extreme regions of spacetime.

Multi-Axion Model Explains Dark Energy Across Cosmic History

A new cosmological model proposes that dark energy is not a singular, late-time phenomenon but a recurrent feature throughout the universe's history. This model, based on a homogeneous universe with multiple axion fields, suggests that transient episodes of scalar-field dark energy have influenced cosmic expansion at different epochs, including Big Bang nucleosynthesis (BBN), periods before recombination, and the current accelerated expansion. The proposal introduces four axion fields that activate sequentially as Hubble friction weakens. The transient fields have third-power cosine potentials, allowing for faster-than-radiation dilution during rapid, small-amplitude oscillations. Numerical calculations, using Planck 2018 matter and radiation densities, show that one transient field contributed approximately 0.99% to the energy density near z=10⁹ during nucleosynthesis. Subsequently, two early dark energy fields reached combined peaks of 9.7% near z=7.9×10³ and z=2.4×10³. The model also incorporates a "thawing" axion field to supply the currently observed dark energy density, which accounts for approximately 68.5% of the total density. The three transient fields combined leave a very small residual contribution of approximately 6.0×10⁻⁷. This approach offers a unified perspective on dark energy, suggesting that its presence at different cosmic stages could be a natural feature of the universe's evolution, rather than an anomaly. This theoretical framework not only addresses current dark energy but also opens avenues for investigating transient contributions to the expansion rate at other epochs, which could impose new constraints on axion scales. The model's ability to align multiple axion fields also suggests possible extensions to explain cosmic inflation, broadening its relevance in modern cosmology.