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The reason we call dark matter dark isn’t because it’s some shadowy material. It’s because dark matter doesn’t interact with light. The difference is subtle, but important. Regular matter can be dark because it absorbs light. It’s why, for example, we can see the shadow of molecular clouds against the scattered stars of the Milky Way. This is possible because light and matter have a way to connect. Light is an electromagnetic wave, and atoms contain electrically charged electrons and protons, so matter can emit, absorb and scatter light. Dark matter isn’t electrically charged. It has no way to connect with light, and so when light and dark matter meet up they simply pass through each other.

All of our observations suggest that dark matter and light only have gravity in common. When dark matter is clustered around a galaxy, for example, its gravitational tug can deflect light. Because of this we can map the distribution of dark matter in the Universe by observing how light is gravitationally lensed around it. We also know that dark and regular matter interact gravitationally. The tug of dark matter causes galaxies to gather together into superclusters. But an unanswered question is whether dark and regular matter only interact gravitationally. If an atom and dark matter particle intersected, would they really just pass through each other?

Since we haven’t directly observed dark matter particles we can only speculate, but most dark matter models argue that gravity is the only common link with light and regular matter. Dark and regular matter clump around each other, but they don’t collide and merge like interstellar clouds. But a new study suggests the two do interact, which could reveal subtle aspects of the mysterious stuff.

The study looks at six ultrafaint dwarf galaxies, or UFDs. They are satellite galaxies near the Milky Way that seem to have far fewer stars than their mass would suggest. This is because they are mostly made of dark matter. If regular and dark matter only interact gravitationally, then the distribution of stars in these small galaxies should follow a certain pattern. If dark and regular matter interact directly, then this distribution will be skewed.

To test this the team ran computer simulations of both scenarios. They found that in the non-interacting model the distribution of stars should become more dense in the center of the UFDs and more diffuse at the edges. In the interacting model the stellar distribution should be more uniform. When they compared these models with observations of the six galaxies, they found the interacting model was a slightly better fit.

So it seems dark and regular matter interact in ways beyond their gravitational tugs. There isn’t enough data to pin down the exact nature of the interaction, but the fact there is any interaction at all is a surprise. It means that our traditional models of dark matter are at least partly wrong. It may also point the way toward new methods of detecting dark matter directly. In time we may finally solve the mystery of this dark, but not entirely invisible, material.

Reference: Almeida, Jorge Sánchez, Ignacio Trujillo, and Angel R. Plastino. “The Stellar Distribution in Ultrafaint Dwarf Galaxies Suggests Deviations from the Collisionless Cold Dark Matter Paradigm.” The Astrophysical Journal Letters 973.1 (2024): L15.

The post Dark Matter Could a Have Slight Interaction With Regular Matter appeared first on Universe Today.

Of every world known to humans outside the Earth, Mars is likely the most habitable. We have not found any genuinely Earth-like exoplanets. They are almost sure to exist, but we just haven’t found any yet. The closest so far is Kepler 452-b, which is a super Earth, specifically 60% larger than Earth. It is potentially in the habitable zone, but we don’t know what the surface conditions are like. Within our own solar system, Mars is by far more habitable for humans than any other world.

And still, that’s not very habitable. It’s surface gravity is 38% that of Earth, it has no global magnetic field to protect against radiation, and its surface temperature ranges from -225°F (-153°C) to 70°F (20°C), with a median temperature of -85°F (-65°C). But things might have been different, and they were in the past. Once upon a time Mars had a more substantial atmosphere – today its atmosphere is less than 1% as dense as Earth’s. That atmosphere was not breathable, but contained CO2 which warmed the planet allowing for there to be liquid water on the surface. A human could likely walk on the surface of Mars 3 billion years ago with just a face mask and oxygen tank. But then the atmosphere mostly went away, leaving Mars the dry barren world we see today. What happened?

It’s likely that the primary factor was the lack of a global magnetic field, like we have on Earth. Earth’ magnetic field is like a protective shield that protects the Earth from the solar wind, which is charged so the particles are mostly diverted away from the Earth or drawn to the magnetic poles. On Mars the solar wind did not encounter a magnetic field, and it slowly stripped away the atmosphere on Mars. If we were somehow able to reconstitute a thick atmosphere on Mars, it too would slowly be stripped away, although that would take thousands of years to be significant, and perhaps millions of years in total.

But this may not have been the only process at work.  A recent study models the chemistry at the surface of Mars to see if perhaps the abundant CO2 in the early Mars atmosphere might still be there. What the model shows, based on known chemical reactions on Earth, is that CO2 in the early Mars atmosphere would have dissolved in high concentrations in any liquid water. As the CO2-rich water percolated through the crust of Mars it would have combined with olivine, an abundant iron-containing mineral on Mars. The oxygen would have combined with the iron, forming the red rusty color for which Mars is famous, while releasing the hydrogen. This hydrogen would then combine with CO2 to form methane. Over time the olivine would be converted to serpentine, which would then further react with water to form smectite, which today is very common in the clays near the surface of Mars.

The researchers calculate that if Mars has smectite clays down to 1,100 meters deep, that could contain enough sequestered carbon to account for the original amount of carbon in the early atmosphere of Mars. It is possible, therefore, that the atmosphere of Mars may mostly still be there, bound up in clays.

Does this have any practical application? Even if not, it is helpful to add to our knowledge of planetary science – how planets evolve and change over time. But it might also have implications for future Mars missions. A vast store of carbon could be quite useful. If some of that carbon is in the form of methane, that could be a valuable energy source.

In theory we could also release the CO2 from the smectite clays back into the atmosphere. Would this be a good thing (assuming it’s feasible)? On the plus side a thicker atmosphere would warm the planet, making it more livable. It would also reduce the need for pressurized suits and living spaces. Humans could survive in as little at 6% of an atmosphere on Earth – not comfortably, but technically survivable. If you get to 30-40% that is basically like being on top of a mountain, something humans could adapt to. We could theoretically get back to the point where a human could survive with just a mask and oxygen tank rather than a pressure suit.

The potential downside is dust storms. They are already bad on Mars and would be much worse with a thicker atmosphere. These occur because the surface is so dry. Ideally as we released CO2 into the atmosphere that would also melt the ice caps and release water from the soil. Surface water would reduce the risk of dust storms.

Terraforming Mars would be extremely tricky, and probably not feasible. But it is interesting to think about how we could theoretically do it. Then we would have the problem of maintaining the atmosphere against further soil chemistry and the solar wind. There has been discussion of how we could create an artificial magnetic field to protect the atmosphere, but again we are talking about massive geoengineering projects. This is all still in the realm of science fiction for now, but it is fun to think about theoretical possibilities.

 

The post What Happened to the Atmosphere on Mars first appeared on NeuroLogica Blog.

Replacing some existing vegetable oil crops with camellia oil could boost production while reducing environmental impacts such as greenhouse gas emissions

We have known that water ice exists on the Moon since 1998. These large deposits are found in the permanently shadowed craters around the polar region. The challenge is how to get it since shadowed craters are not the best place for solar powered vehicles to operate. A team of engineers have identified a design for an ice-mining vehicle powered by americium-241. With a half-life of 432 years, this element is an ideal power source for a vehicle to operate in the dark for several decades. 

Ice in the polar regions of the Moon is of vital importance for our future space explorations, not just lunar visits but as we stretch our legs in the Solar System. Its thought to be ancient material deposited by comets or formed by interactions with solar wind. It is expensive to take materials to the Moon so harvesting on site is far more efficient. Ice on the Moon can provide drinking water, oxygen for breaking and even hydrogen for rocket fuel. Surveys suggest something in the region of 600 billion kilograms of ice deposited at the lunar poles. 

Exposed water ice (green or blue dots) in lunar polar regions and temperature. Credit: Shuai Li

The challenge facing future lunar harvesting missions is that operations in the permanently  shadowed regions (or PSRs as they have been called) cannot be powered by solar panels as is often the case. The environment is cold too, in the region of 40K, that’s -233?C and at those temperatures special power considerations are required. 

A team of researchers have been exploring the use of Radioisotope Power Systems (RPS) to provide thermal and electrical power systems. These power systems have been used before during deep space missions for example Voyager and New Horizons. They work by generating electricity using the heat that is released from the natural decay of a radioactive isotope usually plutonium-238.

Artist rendition of Voyager 1 entering interstellar space. (Credit: NASA/JPL-Caltech)

The team led by Marzio Mazzotti from the University of Leicester have explored an ice-mining rover using power generated by the radio activate decay fo Americium-241. It has a half-life of 432 years which means it takes 432 years for half of a sample of Americium to decay. During this time, half of the atoms in the substance will transform into a different element. Using this power source will provide a stable power supply for an ice-mining rover in the darkness of the lunar polar craters for decades.

Apollo 17 commander Eugene Cernan with the lunar rover in December 1972, in the moon’s Taurus-Littrow valley. Credit: NASA

Using a radioisotope power system is not new however the team came upon the idea that the excess heat that is not used can be used to thermally mine ice from samples of lunar material. The rover would be fitted with a sublimation plate that would turn any ice deposits into a gas which would be collected in a cold trap.

The team developed a model of its Thermal Management System and tested it for icy regolith (the fine dusty lunar surface) material with a water ice content of 0-10 vol %. Their simulations showed that it is possible to mine ice using thermal techniques in the PSR of the Moon using an RPS (I had to really concentrate writing that sentence!) powered lunar rover. 

Source : Ice-Mining Lunar Rover using Americium-241 Radioisotope Power Systems

The post A New Rover Design Could Crawl Across the Moon for Decades Harvesting Water appeared first on Universe Today.

A distant planet should have been consumed when its star expanded to become a red giant, perhaps offering insights into planetary migration

Women worldwide could see better treatment with new AI technology which enables better detection of damaged cells and more precisely predict the risk of getting breast cancer, shows new research.

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A research team has developed a method to recycle valuable metals from electronic waste more efficiently while significantly reducing the environmental impact typically associated with metal recycling.

New research suggests Mars' missing atmosphere -- which dramatically diminished 3.5 billion years ago -- could be locked in the planet's clay-covered crust. Water on Mars could have set off a chain reaction that drew CO2 out of the atmosphere and converted it into methane within clay minerals.

New research suggests Mars' missing atmosphere -- which dramatically diminished 3.5 billion years ago -- could be locked in the planet's clay-covered crust. Water on Mars could have set off a chain reaction that drew CO2 out of the atmosphere and converted it into methane within clay minerals.

It’s no secret that spending extended periods in space takes a toll on the human body. For years, NASA and other space agencies have been researching the effects of microgravity on humans, animals, and plants aboard the International Space Station (ISS). So far, the research has shown that being in space for long periods leads to muscle atrophy, bone density loss, changes in vision, gene expression, and psychological issues. Knowing these effects and how to mitigate them is essential given our future space exploration goals, which include long-duration missions to the Moon, Mars, and beyond.

However, according to a recent experiment led by researchers at Johns Hopkins University and supported by NASA’s Johnson Space Center, it appears that heart tissues “really don’t fare well in space” either. The experiment consisted of 48 samples of human bioengineered heart tissue being sent to the ISS for 30 days. As they indicate in their paper, the experiment demonstrates that exposure to microgravity weakens heart tissue and weakens its ability to maintain rhythmic beats. These results indicate that additional measures must be taken to ensure humans can maintain their cardiovascular health in space.

The study was led by Deok-Ho Kim and his colleagues from the Department of Biomedical Engineering at Johns Hopkins University (BME-JHU) and the JHU Center for Microphysiological Systems. They were joined by researchers from UC Boulder’s Ann and HJ Smead Department of Aerospace Engineering Sciences, the Institute for Stem Cell & Regenerative Medicine (ISCRM) and the Center for Cardiovascular Biology at the University of Washington, the Stanford Institute for Stem Cell & Regenerative Medicine, BioServe Space Technologies, and NASA’s Johnson Space Center. The paper that details their findings was published yesterday (September 23rd) in the Proceedings of the National Academy of Sciences.

Heart tissues within one of the launch-ready chambers. Credit: Jonathan Tsui

Previous research has shown that astronauts returning to Earth from the ISS suffer from a myriad of health effects consistent with certain age-related conditions, including reduced heart muscle function and irregular heartbeats (arrhythmias), most of which will dissipate over time. However, none of this research has addressed what happens at the cellular and molecular level. To learn more about these effects and how to mitigate them, Kim and his colleagues sent an automated “heart-on-a-chip” platform to the ISS for study.

To create this payload, the team relied on human-induced pluripotent stem cells (iPSCs), which can become many types of cells, to produce cardiomyocytes (heart muscle cells). These resulting tissues were placed in a miniaturized bioengineered tissue chip designed to mimic the environment of an adult human heart. The chips would then collect data on how the tissues would rhythmically contract, imitating how the heart beats. One set of biochips was launched aboard the SpaceX CRS-20 mission to the ISS in March 2020, while another was kept on Earth as a control group.

Once on the ISS, astronaut Jessica Meir tended the experiment, changing the liquid nutrients surrounding the tissues once each week while preserving tissue samples at specific intervals so gene readout and imaging analyses could be conducted upon their return to Earth. Meanwhile, the experiment sent real-time data back to Earth every 30 minutes (for 10 seconds at a time) on the tissue samples’ contractions and any irregular beating patterns (arrhythmias).

“An incredible amount of cutting-edge technology in the areas of stem cell and tissue engineering, biosensors and bioelectronics, and microfabrication went into ensuring the viability of these tissues in space,” said Kim in a recent Hub news release.

When the tissue chambers returned to Earth, he and his colleagues continued to maintain and collect data from the samples to see if there was any change in their abilities to contract. In addition to losing strength, the muscle tissues developed arrhythmias, consistent with age-related heart conditions. In a healthy human heart, the time between beats is about a second, whereas the tissue samples lasted nearly five times as long – though they returned to nearly normal once returned to Earth.

The team further found that the tissue cell’s protein bundles that help them contract (sarcomeres) were shorter and more disordered than those of the control group, another symptom of heart disease. What’s more, the mitochondria in the tissue samples grew larger and rounder and lost the characteristic folds that help them produce and use energy. Lastly, the gene readout in the tissues showed increased gene production related to inflammation and an imbalance of free radicals and antioxidants (oxidative stress).

This is not only consistent with age-related heart disease but also consistently demonstrated in astronauts’ post-flight checks. The team says these findings expand our scientific knowledge of microgravity’s potential effects on human health in space and could also advance the study of heart muscle aging and therapeutics on Earth. In 2023, Kim’s lab followed up on this experiment by sending a second batch of tissue samples to the ISS to test drugs that could help protect heart muscles from the effects of microgravity and help people maintain heart function as they age.

Meanwhile, the team continues to improve its tissue-on-a-chip system and has teamed up with NASA’s Space Radiation Laboratory to study the effects of space radiation on heart muscles. These tests will assess the threat solar and cosmic rays pose to cardiovascular health beyond Low Earth Orbit (LEO), where Earth’s magnetic field protects against most space radiation.

Further Reading: John Hopkins University, PNAS

The post Space Travel Weakens the Heart, New Study Finds appeared first on Universe Today.

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Fear of maths has been around for at least a century. Here are some ways to overcome it, says Sarah Hart, professor emerita of mathematics at Birkbeck, University of London