Science

Volcanoes have been proposed as the reason for the extinction of the Neanderthals and the hobbits of Indonesia, but the end of those species may not have come from a single, dramatic event

Bats depend on open bodies of water such as small ponds and lakes for foraging and drinking. Access to water is particularly important for survival in the increasingly hot and dry summers caused by climate change, the time when female bats are pregnant and rear their young. A scientific team has now shown that access to drinking sites is hampered by wind turbines in agricultural landscapes: Many bat species avoid the turbines and water bodies located close to the turbines for several kilometers.

The night sky has always played a crucial role in navigation, from early ocean crossings to modern GPS. Besides stars, the United States Navy uses quasars as beacons. Quasars are distant galaxies with supermassive black holes, surrounded by brilliantly hot disks of swirling gas that can blast off jets of material. Following up on the groundbreaking 2020 discovery of newborn jets in a number of quasars, aspiring naval officer Olivia Achenbach of the United States Naval Academy has used NASA's Hubble Space Telescope to reveal surprising properties of one of them, quasar J0742+2704.

The name 'blue lurker' might sound like a villainous character from a superhero movie. But it is a rare class of star that NASA's Hubble Space Telescope explored by looking deeply into the open star cluster M67, roughly 2,800 light-years away.

The Sun can kill. Until Earth developed its ozone layer hundreds of millions of years ago, life couldn’t venture out onto dry land for fear of exposure to the Sun’s deadly ultraviolet radiation. Even now, the 1% of its UV radiation that reaches the surface can cause cancer and even death.

Astronauts outside of Earth’s protective ozone layer and magnetic shield are exposed to far more radiation than on the planet’s surface. Exposure to radiation from the Sun and elsewhere in the cosmos is one of the main hurdles that must be cleared in long-duration space travel or missions to the lunar and Martian surfaces.

Unfortunately, there’s no harmonized approach to understanding the complexity of the hazard and protecting astronauts from it.

Astronauts haven’t gone further into space than the ISS for decades. But if Artemis lives up to its promise, they’re about to leave Earth and its protective environment behind. Artemis will land astronauts on the Moon, which could be an intermediate step to an eventual landing on Mars. What hazards does radiation pose, and how can astronauts be protected?

A new research editorial in the Journal of Medical Physics examines the issue. It is titled “System of radiological protection: Towards a consistent framework on Earth and in space.” The lead author is Werner Rühm from the Federal Office for Radiation Protection, München (Neuherberg), Germany. The same issue of the Journal of Medical Physics contains several other articles about radiation exposure. Together, they’re part of a research effort by the International Commission on Radiological Protection (ICRP) to update and harmonize radiation exposure guidelines.

The term ‘radiation’ is descriptive enough that most of us recognize the potential threat. However, when it comes to variable space environments and human physiology, the word holds a lot more detail. The authors use the term ‘mixed radiation field’ to describe the radiation environment astronauts must endure.

“The mixed-radiation field outside and within a space vehicle is of particular complexity involving not only low-linear energy transfer (LET) radiation such as gamma radiation, electrons, and positrons but also high-LET radiation such as neutrons and heavy ions,” the authors write. The components of the field contain a wide span of particles with different energy levels. “The quantitative and even qualitative risks of exposure to the combined impact of a complex radiation environment, microgravity, and other stressors remain unclear,” they explain.

One problem in preparing for exposure to these mixed radiation fields is the different approaches taken by different countries and space agencies.

NASA astronauts exploring Mars on future missions, perhaps starting in the 2030s, will require protection from long-term exposure to the cancer-causing space radiation environment. Credit: NASA.

According to lead author Rühm, this disharmony is caused by “the complex and dynamic radiation environments and an incomplete understanding of their biological consequences. Because of this, space agencies follow somewhat different concepts to quantify radiation doses and their resulting health effects.”

This paper and its companions are part of an effort to unify our understanding of radiation and its hazards and to harmonize the various approaches to dealing with them. The goal is to develop a “consistent radiological protection framework.” To do that, the authors explain that several questions need answers:

• Which radiation-induced health effects should be considered?
• What dose quantities are the best for the radiological protection of astronauts?
• Which metrics should be used to quantify radiation-related health risks?
• How do we address sex and age differences in radiation risk?
• What kind of protection criteria should be applied?
• How do we decide on the tolerability of radiation-induced risks, given that astronauts are exposed to many other occupation-related risks?
• How do we deal with the fact that increased health risks due to radiation exposure may persist after an astronaut’s career ends?
• How do we communicate radiation risk and make a comparison with other health hazards in a meaningful way?
• How do we harmonize national radiological protection guidelines, given that different subpopulations might have different levels of risk tolerance?

This list of questions vividly illustrates the complexity of the radiation exposure problem. Answering them will help harmonize the approach to radiation on space missions.

Rühm and his colleagues want to support space agencies as they harmonize and coordinate their guidelines for astronauts’ exposure to radiation. The goal is to develop an approach consistent with the thorough guidelines followed here on Earth.

The difference between how males and females respond to radiation illustrates one of the problems in developing radiation exposure guidelines. In past decades, much medical research was based on males and the results were applied to females as well. According to Rühm, the same thing has happened with radiation.

“It is worth mentioning that on Earth, the System developed by ICRP does not include any systematic differentiation between recommendations on limits for males and females,” the authors write. This is in spite of the fact that it is “well known that there are individual differences in radiation sensitivity between males and females.” The difference is largely because reproductive tissue is more susceptible to radiation than other tissue, and women have more of it.

This infographic shows how men’s and women’s bodies react differently to spaceflight. It’s also becoming well-known that women are more sensitive to radiation exposure. Image Credit: NASA/NSBRI

NASA has developed a different approach to radiation exposure because of this. “This standard is based on a REID (Risk of Exposure-Induced Death) of 3% calculated for cancer mortality in the most vulnerable group of astronauts––35-year-old females,” the authors write. Scientists understand that females are more vulnerable to radiation than males and that younger females are more sensitive than older females. It’s worth noting that astronauts are unlikely to be under the age of 35.

The difference between the sexes isn’t the only thing that needs to be addressed when it comes to astronauts’ exposure to radiation. Different sub-populations might have different risk factors; there are lifestyle-related risks, different mission architectures hold different risks, and many other factors come into play. Harmonizing an approach with all of these different factors is a daunting task.

Difficult or not—and there’s nothing easy about space travel—a harmonized and coordinated approach to understanding the radiation risk is the logical next step. Artemis itself is a collaboration between different nations and agencies, and it’s only fair to the astronauts themselves that they have the same protections and considerations when it comes to radiation exposure.

Rühm and his colleagues hope that their work will help lead to a harmonized approach to assessing the radiation hazards faced by astronauts in mixed radiation fields. We owe it to the people willing to put their lives on the line and serve as astronauts.

“Adventurous people have always tried to widen their horizon, this is part of our very nature as humans,” Rühm says. “Our work contributes to and supports one of the most exciting and challenging human endeavors ever undertaken.”

The post As We Explore the Solar System, Radiation Will Be One of Our Greatest Threats appeared first on Universe Today.

The tattoos of 1200-year-old mummies from Peru can now be seen in exquisite detail, showing fine markings that may have been made with cactus needles or animal bones

In February 2016, scientists working for the Laser Interferometer Gravitational-Wave Observatory (LIGO) made history by announcing the first-ever detection of gravitational waves (GW). These waves, predicted by Einstein’s Theory of General Relativity, are created when massive objects collide (neutron stars or black holes), causing ripples in spacetime that can be detected millions or billions of light years away. Since their discovery, astrophysicists have been finding applications for GW astronomy, which include probing the interiors of neutron stars.

For instance, scientists believe that probing the continuous gravitational wave (CW) emissions from neutron stars will reveal data on their internal structure and equation of state and can provide tests of General Relativity. In a recent study, members of the LIGO-Virgo-KAGRA (LVK) Collaboration conducted a search for CWs from 45 known pulsars. While their results showed no signs of CWs emanating from their sample of pulsars, their work does establish upper and lower limits on the signal amplitude, potentially aiding future searches.

The LVK Collaboration is an international consortium of scientists from hundreds of universities and institutes worldwide. This collaboration combines data from the Laser Interferometer Gravitational-Wave Observatory’s (LIGO) twin observatories, the Virgo Observatory, and the Kamioka Gravitational Wave Detector (KAGRA). The preprint of the paper, “Search for continuous gravitational waves from known pulsars in the first part of the fourth LIGO-Virgo-KAGRA observing run,” recently appeared online.

First discovered in 1967, pulsars are a class of neutron stars that have strong magnetic fields, causing them to emit beams of electromagnetic radiation from their poles. They also rotate rapidly, creating a strobing effect reminiscent of a lighthouse. Given their stability and predictability, pulsars present an opportunity to search for continuous gravitational waves (CWs). Unlike transient GW, which are produced by binary black hole and neutron star mergers, CWs are long-lasting signals expected to come from massive, spinning objects (like pulsars).

To date, all GW events observed by astronomers have been transient in nature. To find evidence of these events, the team searched for signals from 45 known pulsars (and a narrowband search for 16 pulsars) from the first part of the fourth LIGO-Virgo-KAGRA observing run (O4a). They also employed three independent data analysis methods and two different emission models. As they indicated in their paper, no CW signals were detected, but the results were still informative:

“No evidence of a CW signal was found for any of the targets. The upper limit results show that 29 targets surpass the theoretical spin-down limit. For 11 of the 45 pulsars not analyzed in the last LVK targeted search, we have a notable improvement in detection sensitivity compared to previous searches. For these targets, we surpass or equal the theoretical spin-down limit for the single-harmonic emission model. We also have, on average, an improvement in the upper limits for the low-frequency component of the dual-harmonic search for all analyzed pulsars.”

The team also conducted a search for polarization that is consistent with a theory of gravitation alternative to General Relativity (Brans–Dicke theory). While CWs remain unconfirmed, the team predicts that a full analysis of the full O4 dataset will improve the sensitivity of targeted/narrowband searches for pulsars and CWs.

Further Reading: arXiv

The post LIGO Fails to Find Continuous Gravitational Waves From Pulsars appeared first on Universe Today.

A new analysis of marsquakes measured by NASA’s InSight lander indicates Mars has a solid inner core – but other researchers say the evidence is thin

Scientists have succeeded in controlling the structure and function of biological membranes with the help of 'DNA origami'. The system they developed may facilitate the transportation of large therapeutic loads into cells. This opens up a new way for the targeted administration of medication and other therapeutic interventions. Thus, a very valuable instrument can be added to the toolbox of synthetic biology.

In a significant step toward creating a sustainable and circular economy, researchers have demonstrated that carbon nanotube (CNT) fibers can be fully recycled without any loss in their structure or properties. This discovery positions CNT fibers as a sustainable alternative to traditional materials like metals, polymers and the much larger carbon fibers, which are notoriously difficult to recycle.

A thorough analysis of market, technological, and supply chain outcomes for sodium-ion batteries finds that significant advances are needed before commercialization.

Scientists have come a step closer to understanding how collisionless shock waves -- found throughout the universe -- are able to accelerate particles to extreme speeds.

Scientists have taken a major step forwards in tackling one of the greatest abiding challenges in chemistry, by learning how to program the self-assembly of molecules in such a way that the end result is predictable and desirable. Their 'Malteser-like' molecules could one day have a suite of applications -- from highly sensitive and specific sensors, to next-gen, targeted drug delivery agents.

In order to recover valuable substances from CO2, it must be reduced in many individual steps. If electrocatalysis is used for this, many potentially different potential molecules are formed, which cannot necessarily be used. Biocatalysts, on the other hand, are selective and only produce one product -- but they are also very sensitive. An international research team has developed a hybrid catalysis cascade that makes use of the advantages of both processes.

Giving people better data about their energy use, plus some coaching, can help them substantially reduce their consumption and costs, according to a new study.

The process of updating deep learning/AI models when they face new tasks or must accommodate changes in data can have significant costs in terms of computational resources and energy consumption. Researchers have developed a novel method that predicts those costs, allowing users to make informed decisions about when to update AI models to improve AI sustainability.

The process of updating deep learning/AI models when they face new tasks or must accommodate changes in data can have significant costs in terms of computational resources and energy consumption. Researchers have developed a novel method that predicts those costs, allowing users to make informed decisions about when to update AI models to improve AI sustainability.

It's long been known that different positions on the football field fit different body types. A study led by the University of Kansas has gone beyond knowing that linemen are bigger with more body mass than receivers and tested a team of college football starters, finding differences in strength, power, jumping ability and more. The findings could help improve strength training designed to optimize performance for different types of players, researchers argue.

Astronomers observed flashes of X-rays coming from a supermassive black hole at a steadily increasing clip. The source could be the core of a dead star that's teetering at the black hole's edge.

A new study overcomes a key obstacle to switching commercial aircraft from their near-total reliance on fossil fuels to more sustainable aviation fuels. The study details a cost-effective method for producing ethylbenzene -- an additive that improves the functional characteristics of sustainable aviation fuels -- from polystyrene, a hard plastic used in many consumer goods.