Monday, October 7, 2024

Hera Probe Heads Off to See Aftermath of DART’s Asteroid Impact

The European Space Agency’s Hera spacecraft is on its way to do follow-up observations of Dimorphos, two years after an earlier probe knocked the mini-asteroid into a different orbital path around a bigger space rock.

Scientists say the close-up observations that Hera is due to make millions of miles from Earth, starting in 2026, will help them defend our planet from future threats posed by killer asteroids.

“Hera’s ability to closely study its asteroid target will be just what is needed for operational planetary defense,” Richard Moissl, who heads ESA’s Planetary Defense Office, said today in a news release. “You can imagine a scenario where a reconnaissance mission is dispatched rapidly, to assess if any follow-up deflection action is needed.”

The car-sized probe lifted off from Cape Canaveral Space Force Station in Florida atop a SpaceX Falcon 9 rocket at 10:52 a.m. ET (14:52 UTC) today, just as Hurricane Milton was approaching from the Gulf of Mexico. The day before the launch, forecasters put the chances of acceptable weather at just 15 percent. Nevertheless, SpaceX persisted.

Due to the mission’s requirements, the first-stage booster couldn’t be recovered this time, as has become the norm for Falcon 9 missions. This was the booster’s 23rd and final mission. A little more than an hour after liftoff, the rocket’s second stage put Hera on its interplanetary trajectory.

During the spacecraft’s two-year cruise to Dimorphos, it’s due to execute a series of course-changing maneuvers, including a swing past Mars that will provide an opportunity for observations of Deimos, one of the Red Planet’s moons.

Hera is returning to the scene of a cosmic crash in 2022 between Dimorphos — which is about 530 feet across, or the size of the Great Pyramid in Egypt — and NASA’s Double Asteroid Redirection Test spacecraft, or DART.

DART was intentionally sent to a collision with Dimorphos to gauge the impact’s effect on the asteroid’s orbit around a larger asteroid known as Didymos. After the crash, scientists determined that Dimorphos’ orbital period had been shortened by 33 minutes, which represented a reduction of roughly 5%. They also identified a plume of debris that extended thousands of miles into space.

Hera is designed to conduct a more detailed “crash scene investigation,” providing data about Dimorphos’ shape and composition as well as the characteristics of the crater left behind by the smash-up.

The spacecraft will deploy two nanosatellites to aid in the investigation: One of the CubeSats, known as Milani, will survey the makeup of Dimorphos and the dust that surrounds it. Meanwhile, the Juventas mini-satellite will perform the first-ever subsurface radar probe of an asteroid. In the later phases of its six-month survey, Hera will test out an experimental self-driving mode as it navigates around Didymos and Dimorphos autonomously.

Data about the aftereffects of DART’s crash will be factored into the plans for deflecting the orbital paths of asteroids, if those paths are ever found to pose a substantial threat of a collision with Earth. Such strategies might require taking action years in advance of an encounter.

“By the end of Hera’s mission, the Didymos pair should become the best-studied asteroids in history, helping to secure Earth from the threat of incoming asteroids,” said Hera mission scientist Michael Kueppers.

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Sunday, October 6, 2024

Primordial Holes Could be Hiding in Planets, Asteroids, and Here on Earth

Small primordial black holes (PBHs) are one of the hot topics in astronomy and cosmology today. These hypothetical black holes are believed to have formed soon after the Big Bang, resulting from pockets of subatomic matter so dense that they underwent gravitational collapse. At present, PBHs are considered a candidate for dark matter, a possible source of primordial gravitational waves, and a resolution to various problems in physics. However, no definitive PBH candidate has been observed so far, leading to proposals for how we may find these miniature black holes.

Recent research has suggested that main-sequence neutron and dwarf stars might contain small PBHs in their interiors that are slowly consuming their gas supply. In a recent study, a team of physicists extended this idea to include a new avenue for potentially detecting PBHs. Basically, we could search inside objects like planets and asteroids or employ large plates or slabs of metal to detect PBHs for signs of their passage. By detecting the microchannels these bodies would leave, scientists could finally confirm the existence of PBHs and shed light on some of the greatest mysteries in cosmology today.

The research was conducted by De-Chang Dai, a physicist at National Dong Hwa University in Taiwan and the Center for Education and Research in Cosmology and Astrophysics (CERCA) at Case Western Reserve University, and Dejan Stojkovic, a physicist from High Energy Physics and Cosmology group at the State University of New York Buffalo. The paper that details their findings recently appeared online and is being reviewed for publication in the journal Physics of the Dark Universe.

How we might discover primordial black holes and help solve the dark matter mystery. Credit: ESA
How we might discover primordial black holes and help solve the dark matter mystery. Credit: ESA

Scientists have been fascinated by PBHs for decades since Russian scientists Igor D. Novikov and Yakov Zeldovich predicted their existence in 1966. They were also a source of interest for Stephen Hawking, whose work on PBHs led to his breakthrough discovery in 1974 that black holes can evaporate over time. While larger and intermediate black holes would take longer to evaporate than the current age of the Universe (ca. 13.8 billion years), smaller PBHs may have already or could be in the process of doing so.

However, interest in PBHs has experienced a renaissance in recent years because they serve as dark matter candidates, a source of primordial gravitational waves (GWs), and more. Like Dark Matter, their existence could help resolve some major cosmological mysteries, but no confirmed observations have been made yet. As De-Chang and Stojkovic told Universe Today via email, this is what motivated them to propose novel detection methods:

“If an asteroid, or a moon, or a small planet (planetoid) has a liquid core surrounded by a solid crust, then a small PBH will consume the dense liquid core relatively quickly (within weeks to months). The crust will remain intact if the material is strong enough to support gravitational stress. Thus, we will end up with a hollow structure. If the central black hole is ejected (due to collisions with other objects), the density will be lower than the usual density of a rocky object with a liquid core.”

In addition, De-Chang and Stojkovic calculated the gravitational stress small PBHs would generate. They then compared this to the compressive strength of materials that make up a planet’s crust – such as silicate minerals (rock), iron, and other elements. They also considered the strongest manufactured materials, such as multiwall carbon nanotubes. “We found, for example, that granite can support hollow structures up to the radius of 1/10 of the Earth’s radius,” said Stojkovic. “That is why we should concentrate on planetoids, moons, or asteroids.”

An image based on a supercomputer simulation of the cosmological environment where primordial gas undergoes the direct collapse to a black hole. Credit: Aaron Smith/TACC/UT-Austin.
An image based on a supercomputer simulation of the cosmological environment where primordial gas undergoes direct collapse to create black holes. Credit: Aaron Smith/TACC/UT-Austin.

These calculations offer a means to search for evidence of PBHs in space and here on Earth. Possible candidate planetoids, moons, or asteroids could be identified in our Solar System by observing their mass and radius to provide estimates of their density. This would allow astronomers to identify potentially hollow objects for follow-up studies by probes, landers, and other robotic space missions. Alternatively, they recommend that sensors be built to search for PBHs by detecting their passage. Said Stojkovic:

“If a small PBH passes through some solid material, it will leave a straight long tunnel of the radius comparable to the PBH’s radius. For example, a 1023 g PBH should leave a tunnel with a radius of 0.1 micron. [The energies] that such PBHs can have are significant, but [the energies] which they deposit into the material are very low. In fact, such a PBH can even pass through a human body, and we would not even notice because human body tissue has a very low tension.”

In this vein, scientists can scan for micro tunnels in commonplace materials we find lying around (like glass or rocks). At the same time, say De-Chang and Stojkovic, large slabs of polished metal could be prepared for this purpose. Similar to neutrino detection, these slabs would need to be isolated so that any sudden change in their properties could be recorded. “The expected flux of these PBHs is very small and we may end up finding nothing, but a possible payoff of finding a PBHs will be huge, especially since such experiments will be very cheap,” said Stojkovic.

As De-Chang added, it has been proposed in recent years that some primordial black holes may be hidden in stars. Stephen Hawking once proposed the idea, which became the basis of two studies, one released in 2019 and another this past year. “It is also proposed that primordial black holes may radiate Gamma rays. Strong gamma rays in the Milky Way’s dark matter halo can be a good hint for the existence of primordial black holes,” said De-Chang. “Gravitational microlensing can be another way to identify the primordial black holes.”

Further Reading: arXiv

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Saturday, October 5, 2024

The Milky Way Might be Part of an Even Larger Structure than Laniakea

If you want to pinpoint your place in the Universe, start with your cosmic address. You live on Earth->Solar System->Milky Way Galaxy->Local Cluster->Virgo Cluster->Virgo Supercluster->Laniakea. Thanks to new deep sky surveys, astronomers now think all those places are part of an even bigger cosmic structure in the “neighborhood” called The Shapley Concentration.

Astronomers refer to the Shapley Concentration as a “basin of attraction”. That’s a region loaded with mass that acts as an “attractor”. It’s a region containing many clusters and groups of galaxies and comprises the greatest concentration of matter in the local Universe. All those galaxies, plus dark matter, lend their gravitational influence to the Concentration. There are many of these basins in the Universe, including Laniakea. Astronomers are working to survey them more precisely, which should help provide a more precise map of the largest structures in the Universe.

A slice of the Laniakea Supercluster -- a local basin of attraction. This structure contains many galaxies and clusters, including our own Milky Way Galaxy. Credit: SDvision interactive visualization software by DP at CEA/Saclay, France.
A slice of the Laniakea Supercluster, a local basin of attraction. This structure contains many galaxies and clusters, including our own Milky Way Galaxy. Credit: SDvision interactive visualization software by DP at CEA/Saclay, France.

One group, led by astronomer R. Brent Tully of the University of Hawai’i measured the motions of some 56,000 galaxies to understand these basins and their distribution in space. “Our universe is like a giant web, with galaxies lying along filaments and clustering at nodes where gravitational forces pull them together,” said Tully. “Just as water flows within watersheds, galaxies flow within cosmic basins of attraction. The discovery of these larger basins could fundamentally change our understanding of cosmic structure.”

Cosmic Flows and Mapping Structures

Tully’s team is called CosmicFlows and they study the motions through space of those distant galaxies. The team’s “redshift” surveys revealed a possible shift in the size and scale of our local galactic basin of attraction. We already know that we “live” in Laniakea, which is about 500 million light-years across. However, the motions of other clusters indicate there’s a larger “attractor” directing the cluster flow. The CosmicFlows data suggest that we could be part of the Shapley Concentration, which could be 10 times the volume of Laniakea. It’s about half the volume of the largest structure in space, known as “the Great Wall”, which is a string of galaxies stretching across 1.4 billion light-years.

Several superclusters revealed by the 2dF Galaxy Redshift Survey. This contains the structure known as the "Sloan Great Wall". Courtesy 2dF Galaxy Redshift Survey.
Several superclusters were revealed by the 2dF Galaxy Redshift Survey. This contains the structure known as the “Sloan Great Wall”. Courtesy 2dF Galaxy Redshift Survey.

The Shapley Concentration was first observed by astronomer Harlow Shapley in the 1930s as a “cloud” in the constellation Centaurus. This supercluster appears along the direction of motion of the Local Group of galaxies (where we live). Because of that, scientists speculated that it could be influencing our galaxy’s peculiar motion. Interestingly, the Virgo Supercluster (and the Local Group and Milky Way Galaxy) appears to be moving toward the Shapley Concentration. The surveys that Tully and others are doing should confirm that motion toward whatever is attracting them.

Exploring Ever-larger Structures in the Universe

Where do these basins of attraction come from? In one sense, they’re as old as the Universe and its cosmic web of matter that Tully references. The seeds for the web and those basins of attraction were planted some 13.8 billion years ago. After the Big Bang, the infant Universe was in a hot dense state. As it expanded and cooled, the density of matter started to fluctuate. There were tiny differences in those density fluctuations. Think of them as the earliest “seeds” of galaxies, galaxy clusters, and even vaster structures that we see in today’s Universe.

This detailed map of the cosmic microwave background is created from seven years worth of data. It shows the "seed" structures of galaxies in the infant Universe. Image Credit: NASA
This detailed map of the cosmic microwave background is created from seven years worth of data. It shows the “seed” structures of galaxies in the infant Universe. Image Credit: NASA

As astronomers survey the sky, they find evidence for all those different structures. Now, they have to explain them. The idea that the Shapley Concentration is the large basin that our Laniakea belongs to means that current cosmological models don’t quite explain its existence.

“This discovery presents a challenge: our cosmic surveys may not yet be large enough to map the full extent of these immense basins,” said UH astronomer Ehsan Kourkchi. “We are still gazing through giant eyes, but even these eyes may not be big enough to capture the full picture of our universe.”

Measuring the Attractors

The main actor in all these galaxies, clusters, and superclusters, is gravity. The more mass, the more gravity influences motions and matter distribution. For these basins of attraction, Tully’s research team examined their impact on galaxy motions in the region. The basins exert a sort of “tug of war” on galaxies that lie between them. That influences their motions. In particular, redshift surveys like Tully’s team is doing will map the radial motion (along the line of sight), velocities (how fast they’re moving), and other related motions. By mapping the velocities of galaxies throughout our local Universe, the team can define the region of space where each supercluster dominates.

Of course, these motions are tricky to define. That’s why the team does different types of measurements. They aren’t mapping just the luminous material in galaxies. They also have to take into account the inferred existence of dark matter. There are other complications as well. For example, not all galaxies are the same—that is, they differ in their shapes (morphology) and matter density. Astronomers can get around this by measuring something called “galaxy peculiar velocity”. That’s the difference between its actual velocity and the expected “Hubble flow” velocity (which reflects gravitational interactions between galaxies).

The results of the Tully team surveys should provide ever more precise 3D maps of these regions of space. That includes their structures as well as their motions and velocities. Those maps, in turn, should give greater insight into the distribution of all matter (including cold dark matter) throughout the Universe.

For More Information

Identification of Basins of Attraction in the Local Universe (journal)
Identification of Basins of Attraction in the Local Universe (arXiv pdf)
The Shapley Supercluster: the Largest Matter Concentration in the Local Universe (PDF)

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Webb Detects Carbon Dioxide and Hydrogen Perodixe on Pluto’s moon Charon

The James Webb Space Telescope (JWST) has revealed magnificent things about the Universe. Using its sophisticated infrared optics, it has peered deeper into space (and farther back in time) than any observatory to date, gathering data on the first galaxies to form in our Universe. It has also obtained spectra from exoplanets, revealing things about the chemical composition of their atmospheres. In addition, Webb has provided some stunning views of objects within our Solar System, like Jupiter and its auroras, Saturn’s rings and moons, and Neptune and its satellites.

Recently, a team led by researchers from Southwest Research Institute (SwRI) used Webb Near-Infrared Spectrograph (NIRSpec) to closely examine the Pluto-Charon system. Their observations detected frozen carbon dioxide and hydrogen peroxide on the surface of Pluto’s largest moon for the first time. These discoveries add to what scientists learned about Charon’s chemical inventory from ground-based telescopes and the New Horizons mission. It also reveals more about the chemical composition of the many objects that make up the Kuiper Belt.

The team was led by Silvia Protopapa, a Principal Scientist with the SwRI Department of Space Studies and a co-investigator of the New Horizons mission. She was joined by members from the Space Telescope Science Institute (STScI), the Florida Space Institute, the Lowell Observatory, the SETI Institute, the Pinhead Institute, the Institut d’Astrophysique Spatiale, the Johns Hopkins University Applied Physics Laboratory (JHUAPL), the Association of Universities for Research in Astronomy (AURA), and NASA Goddard Space Flight Center. The paper that details their findings recently appeared in Nature Communications.

The observations were part of Webb’s Guaranteed Time Observation (GTO) program 1191, which relied on Webb’s Near Infrared Camera (NIRCam) to study Kuiper Belt Objects (KBO). Dr. John Stanberry, the program’s Principal Investigator, is an instrument scientist for Webb’s NIRCam at the Space Telescope Science Institute (STScI). The team used Webb’s NIRSpec to conduct four observations of the Pluto-Charon system between 2022 and 2023, which provided full coverage of Charon’s northern hemisphere.

Webb spectroscopic measurements revealed signatures of carbon dioxide, which the team compared with laboratory measurements and detailed spectral models of the surface. They concluded that carbon dioxide is present primarily as a surface veneer on a subsurface rich in water ice. As Dr. Protopapa explained in a recent SwRI press release:

“Charon is the only midsized Kuiper Belt object, in the range of 300 to 1,000 miles in diameter, that has been geologically mapped, thanks to the SwRI-led New Horizons mission, which flew by the Pluto system in 2015. Unlike many of the larger objects in the Kuiper Belt, the surface of Charon is not obscured by highly volatile ices such as methane and therefore provides valuable insights into how processes like sunlight exposure and cratering affect these distant bodies.

“Our preferred interpretation is that the upper layer of carbon dioxide originates from the interior and has been exposed to the surface through cratering events. Carbon dioxide is known to be present in regions of the protoplanetary disk from which the Pluto system formed.”

Pluto and Charon. Credit: NASA/JHUAPL/SwRI

Hydrogen peroxide forms when water ice is broken down at the atomic level through exposure to ultraviolet light, charged particles from the Sun (solar wind), and galactic cosmic rays. Its presence on the surface of Charon indicates that the water ice-rich surface is subject to photolysis. This is similar to how exposure to solar radiation causes methane to create tholins, which explains why bodies in the outer Solar System are ruddy in appearance. Said SwRI’s Dr. Ujjwal Raut, leader of the Cornell Laboratory for Accelerator-based ScienceS and Education (CLASSE) and second author of the paper:

“Laboratory experiments conducted at SwRI’s CLASSE (Center for Laboratory Astrophysics and Space Science Experiments) facility were instrumental in demonstrating that hydrogen peroxide can form even in mixtures of carbon dioxide and water ice under conditions analogous to those at Charon.”

The team’s findings demonstrate Webb’s ability to uncover complex surface signatures, which can tell astronomers more about the chemical composition, formation, and evolution of bodies in our Solar System and beyond. These same capabilities allow astronomers to characterize exoplanets’ atmospheres to see if they have the necessary ingredients to support life (as we know it).

“The new insights were made possible by the synergy between Webb observations, spectral modeling, and laboratory experiments and are possibly applicable to other similar midsized objects beyond Neptune,” said Protopapa.

Further Reading: SWRI, Nature Communications

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Friday, October 4, 2024

The GALAH Fourth Data Release Provides Vital Data on One Million Stars in the Milky Way.

For the past ten years, Australia’s ARC Centre of Excellence in All Sky Astrophysics in 3 Dimensions (ASTRO 3D) has been investigating star formation, chemical enrichment, migration, and mergers in the Milky Way with the Anglo-Australian Telescope (AAT). Their work is part of the GALactic Archaeology with HERMES (GALAH) project, an international collaboration of more than 100 scientists from institutes and universities worldwide. These observations have led to the highest spectral resolution multi-dimensional datasets for over a million stars in the Milky Way.

Previous GALAH data releases have led to many significant discoveries about the evolution of the Milky Way, the existence of exoplanets, hidden star clusters, and many more. In the fourth data release (DR4), the GALAH team released the chemical fingerprints (spectra) for almost 1 million stars. This data is the pinnacle of the 10-year project and was released during the 50th anniversary celebration of the AAT. According to the study that accompanied the release, the data will inform decades of research into the formation and evolution of our galaxy.

The study was led by Sven Buder, a research fellow at ASTRO 3D and the Australian National University (ANU). He was joined by an international team of researchers from ANU’s Research School of Astronomy and Astrophysics, ASTRO 3D, ACCESS-NRI, the UNSW Data Science Hub, the Sydney Institute for Astronomy, Astrophysics and Space Technologies Research Centre, Space Telescope Science Institute (STScI), the Stellar Astrophysics Centre, the International Space Science Institute, and multiple universities. The paper describing the data release recently appeared in the Publications of the Astronomical Society of Australia.

The GALAH survey relies on the High Efficiency and Resolution Multi-Element Spectrograph (HERMES) working in conjunction with the 2-degree field (2dF) positioner. Both instruments are part of the Anglo-Australian Telescope (AAT) located at the Siding Spring Observatory in Coonabarabran, New South Wales. The 2dF positioner places a fiber at a star’s location in order for the light to pass to the HERMES instrument, which obtains detailed spectra of 392 objects at a time over two degrees of the sky. As Dr. Buder explained in a recent Science in Public news release:

“Our work is focused on collecting as much quality data as we can,” said ASTRO 3D’s Sven Buder, a research fellow at the Australian National University. GALAH has shown us which chemical elements make up the stars of the Milky Way. This dataset now helps further our ability to accurately age the stars in our neighborhood and understand where they came from. This data becomes a powerful tool for astronomers to test new theories and make new scientific discoveries about the Universe.”

The project scientists also rely on data from the Gaia, Kepler, and CoRoT missions, which have gathered optical data on countless stars in our galaxy. The GALAH project aims to determine the ages of these stars via their chemical signatures to get a clearer picture of the assembly of the Milky Way. This will allow astronomers to estimate a timeline of the Galaxy’s chemical and dynamical evolution and to investigate changes in the rate of star formation rate over time.

“We have measured the elements within these stars, like carbon, nitrogen, oxygen, as well as heavy elements found in our smartphones and electric vehicles,” added Dr. Buder. “This data will help us figure out how these elements are produced in stars, which is fundamental to explaining the origins of the building blocks of life.”

The spectral data consists of the visible spectrum with overlapping barcodes that indicate at which wavelengths light is being absorbed. These are the “chemical fingerprints” of the star, revealing their overall composition. This data will also help astronomers understand how the elements were formed and distributed throughout the Universe, offering hints about cosmic evolution. As if that wasn’t enough, the spectra can also be used for potentially detecting signatures of planetary systems.

The colorful spectra taken at Siding Spring Observatory with the element barcode of the pointer stars alpha Centauri, our Sun, and stars with very little elements. Credit: Sven Buder, ANU/ASTRO 3D

In the past, GALAH data has shown stars that may have consumed planets as the Milky Way developed. Said co-author Professor Daniel Zucker of Macquarie University:

“The GALAH survey has detected signs that some stars may have ‘eaten’ planets that were orbiting them. This can be observed by looking at the chemical composition of the star, as the elements from the consumed planet would show up as markers in the star’s spectrum.”

The GALAH datasets have had a profound impact on the global astronomical community and led to 290 scientific studies to date. The previous data release (DR3) paper covered 300,000 stars and became the most cited work of the year for the journal responsible. With data on almost 1,000,000 stars, the scientific impact of this latest release is expected to be tremendous. The GALAH dataset is also expected to play a vital role in training the next generation of machine-learning tools, which are increasingly important to astronomy.

“We are really looking towards an incredibly exciting period over the next few years where all of these discoveries about what’s happening in our Universe are going to flow from the data that we’ve collected right here in Australia using Australian telescopes and building on Australian research,” said Associate Professor Sarah Martell of UNSW, a key member of the project. Professor Emma Ryan-Weber, the Director of ASTRO 3D, added that the GALAH project is directly aligned with ASTRO 3D’s mission:

“It helps us understand how galaxies build mass over time. The chemical information the research team has gathered is like stellar DNA – we can use it to tell where each star has come from. We can also determine their ages and movements and gain a deeper understanding of how the Milky Way and other galaxies formed and have evolved. What’s more, as the ASTRO 3D mission comes to a close, the GALAH project will leave a lasting legacy of Australian science informing astronomical discoveries about the Universe’s origins and development for decades to come.”

The DR4 release can be found here, while the entire list of GALAH datasets can be found here.

Further Reading: Science in Public

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The Sun Unleashes its Strongest Flare This Cycle

Yesterday the Sun released a huge solar flare, and it’s heading toward Earth! It’s nothing to worry about since it’s nowhere near as large as the Carrington Event of 1859, but it is large enough to give us some amazing aurora.

Large solar flares happen periodically. Quite literally, because the Sun goes through an 11-year cycle of lower and higher activity. Right now the Sun is near the maximum of a cycle, so we see lots of sunspots and flares. When astronomers first studied the cycle they could only measure the number of sunspots at a given time. Solar flares were largely invisible to early telescopes. But now with orbiting observatories such as the Solar Dynamics Observatory, we can capture images of solar flares in real time. Astronomers now categorize the strength of solar flares by the intensity of x-rays they emit, known as their x-class. The categories are numbered by power level, with each category double the previous one. So, for example, an X2 flare is twice as powerful as an X1 and half as strong as an X3.

This latest flare is rated as X9, which is much stronger than most solar flares. But stronger events have reached Earth before. In 1989 an X15 event triggered a regional blackout event in Quebec. In November of 2003 the Sun released an X28 solar flare, but most of it missed Earth. The 1859 Carrington Event occurred before astronomers developed the x-class rating, but it’s estimated to have been around X45. So this flare is huge, but it won’t put our electrical infrastructure at serious risk.

What it will provide, however, is an auroral light show. As the charged particles released by the flare reach Earth’s magnetosphere, many of them will be caught by our magnetic field and spiral along the field lines to strike Earth’s atmosphere in the polar regions. The impact will trigger the subtle and beautiful light shows known as aurora. If you happen to live far enough from the equator you might be able to see them in the next few days. To find out your chances, you can check out the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center.

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Thursday, October 3, 2024

What Does a Trip to Mars Do to the Brain?

It’s not long before a conversation about space travel is likely to turn to the impact on the human body. Our bodies have evolved to exist on Earth with a constant force of 1G acting upon them but up in orbit, all of a sudden that force is apparently lacking. The impact of this is well known; muscle loss and reduction in bone density but there are effects of spaceflight. Cosmic radiation from the Galaxy has an impact on cognition too, an effect that has recently been studied in mice!

When an object like the space station is in orbit around the Earth it is in a state known as freefall. This means it is constantly falling to Earth but the curvature of the Earth is constantly falling away from it. In other words, it is constantly falling but never reaches the ground. This state means anyone or anything inside the space station would also fall at the same rate but this would be experienced as floating. Muscle loss and reduction in bone density are the well known impacts of such an environment but there are more that await a space traveller. 

ESA astronaut Alexander Gerst spent six hours and 13 minutes outside the International Space Station with NASA astronaut Reid Wiseman on Tuesday, 7 October 2014. This was the first spacewalk for both astronauts but they performed well in the weightlessness of orbit. Credit: NASA/ESA

Galactic cosmic radiation (GCR) is made up of energy originating from sources outside of our Solar System. These tend to be from supernova explosions and other energetic events in deep space. The particles from GCR are mostly protons and electrons along with some heavier nuclei. They can penetrate our atmosphere but the Earth’s magnetic field offers some protection to those on the surface. To those venturing out into space, things are a little less rosey for GCR can have quite an impact on astronauts. 

Sources of Ionizing Radiation in Interplanetary Space. The Radiation Assessment Detector (RAD) on NASA’s Curiosity Mars rover monitors high-energy atomic and subatomic particles coming from the sun, distant supernovae and other sources. The two types of radiation are known as Galactic Cosmic Rays and Solar Energetic Particles. RAD measured the flux of this energetic-particle radiation while shielded inside the Mars Science Laboratory spacecraft on the flight delivering Curiosity from Earth to Mars, and continues to monitor the flux on the surface of Mars. Credit: NASA/JPL-Caltech/SwRI

GCR is a real problem for longer duration space exploration like trips to Mars since currently, the radiation can penetrate spacecraft shielding and be a real threat to human health. Studies to date have shown that GCR can have an effect cognitive abilities on mice in the short term however a new study paints a rather more bleak picture. The paper published in the Journal of Neurochemistry reports that GCR exposure can have long lasting effects too. 

Surprisingly, the team studied the impact on both male and female mice by subjecting them to a multi-particle spectrum GCR similar to the radiation that would be experienced on a deep space mission. The experiment was undertaken at Brookhaven National Laboratory where a 33-ion beam was used to simulate radiation from space. The team found that the radiation impaired numerous central nervous system functions from memory, pattern separation (when the brain minimises overlap between patterns of neuronal activity that represents similar experiences), anxiety, vigilance, social novelty (tendency to spend time with a previously unknown mouse rather than a familiar mouse!) and motor controls.

The discovery that the impact on females was more pronounced was unexpected but the team also established that mice which were fed an antioxidant and anti-inflammatory drugs known as CDDO-EA were less effected. The findings will be of immediate benefit to space exploration but will also help us to understand the long term impact on our cognition from radiation.

Source : Can cosmic radiation in outer space affect astronauts’ long-term cognition?

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