Science

Scientists are changing our understanding of climate and weather on Mars and providing critical insights into Earth's atmospheric processes as well.

A new study explores how variations in Mars' crustal thickness during its ancient history may have influenced the planet's magmatic evolution and hydrological systems. The research suggests that the thick crust of Mars' southern highlands formed billions of years ago generated granitic magmas and sustained vast underground aquifers, challenging long-held assumptions about the red planet's geological and hydrological past.

Scientists have performed computer simulations confirming a technique that prevents the production of unhelpful electromagnetic waves, boosting the heat put into fusion plasma.

Scientists have performed computer simulations confirming a technique that prevents the production of unhelpful electromagnetic waves, boosting the heat put into fusion plasma.

A new study has demonstrated for the first time how and why music can reduce distress and agitation for people with advanced dementia. The study involved interviews with staff and music therapists on inpatient mental health dementia wards, a review of published research, and a national survey of UK healthcare professionals.

Scientists have successfully achieved a quantum collective behavior of macroscopic mechanical oscillators, unlocking new possibilities in quantum technology.

Scientists have successfully achieved a quantum collective behavior of macroscopic mechanical oscillators, unlocking new possibilities in quantum technology.

Taking inspiration from how nature --including lightning -- produces ammonia, a team has developed a reactor that produces the chemical commodity from nitrogen in the air and water, without any carbon footprint.

In 1971, the Soviet Mars 3 lander became the first spacecraft to land on Mars, though it only lasted a couple of minutes before failing. More than 50 years later, it’s still there at Terra Sirenum. The HiRISE camera NASA’s Mars Reconnaissance Orbiter may have imaged some of its hardware, inadvertently taking part in what could be an effort to document our Martian artifacts.

Is it time to start cataloguing and even preserving these artifacts so we can preserve our history?

Some anthropologists think so.

Justin Holcomb is an assistant research professor of anthropology at the University of Kansas. He and his colleagues argue that it’s time to take Martian archaeology seriously, and the sooner we do, the better and more thorough the results will be. Their research commentary, “The emerging archaeological record of Mars,” was recently published in Nature Astronomy.

Artifacts of the human effort to explore the planet are littered on its surface. According to Holcomb, these artifacts and our effort to reach Mars are connected to the original human dispersal from Africa.

“Our main argument is that Homo sapiens are currently undergoing a dispersal, which first started out of Africa, reached other continents and has now begun in off-world environments,” said lead author Holcomb. “We’ve started peopling the solar system. And just like we use artifacts and features to track our movement, evolution and history on Earth, we can do that in outer space by following probes, satellites, landers and various materials left behind. There’s a material footprint to this dispersal.”

Tracks from Opportunity stretch across this vista taken by the rover on Sol 3,781 in September 2014. This is from only ten years ago, but those missions already seem historical. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

It’s tempting to call debris from failed missions wreckage or even space junk like we do the debris that orbits Earth. But things like spent parachutes and heat shields are more than just wreckage. They’re artifacts the same way other cast-offs are artifacts. In fact, what archaeologists often do in the field is sift through trash. “Trash is a proxy for human behaviour,” said one anthropologist.

In any case, one person’s trash can be another person’s historical artifact.

Spacecraft that land on Mars have to eject equipment – like this protective shell from Perseverance and imaged by Ingenuity– on their way to the Martian surface. Spacecraft can’t reach the surface without protection. As time passes, trash and debris like this become important artifacts. NASA/JPL-Caltech

“These are the first material records of our presence, and that’s important to us,” Holcomb said. “I’ve seen a lot of scientists referring to this material as space trash, galactic litter. Our argument is that it’s not trash; it’s actually really important. It’s critical to shift that narrative towards heritage because the solution to trash is removal, but the solution to heritage is preservation. There’s a big difference.”

14 missions to Mars have left their mark on the red planet in the form of artifacts. According to the authors, this is the beginning of the planet’s archaeological record. “Archaeological sites on the Red Planet include landing and crash sites, which are associated with artifacts including probes, landers, rovers and a variety of debris discarded during landing, such as netting, parachutes, pieces of the aluminum wheels (for example, from the Curiosity rover), and thermal protection blankets and shielding,” they write.

This figure from the research shows fourteen missions to Mars, along with key sites and examples of artifacts. MER A and B are NASA’s Spirit and Opportunity. a) Basemap generated from data derived from the Mars Orbiter Laser Altimeter (MOLA) and the High-Resolution Stereo Camera (HRSC)12. b) Viking-1
lander (NASA/JPL). c) Trackways created by NASA’s Perseverance rover (NASA/JPL-Caltech/Arizona State University). d) Dacron netting used in thermal blankets, photographed by NASA’s Perseverance rover using its onboard Front Left Hazard Avoidance Camera A (NASA/JPL-Caltech/Arizona State University).
e) China’s Tianwen-1 lander and Zhurong rover in southern Utopia Planitia photographed by HiRISE (NASA/JPL-Caltech/University of Arizona). f) The ExoMars Schiaparelli Lander crash site in Meridiani Planum (NASA/JPL-Caltech/University of Arizona). g) Illustration of the Soviet Mars Program’s Mars 3
space probe (NASA). h) NASA’s Phoenix lander with digital video disc (DVD) in the foreground (NASA/JPL-Caltech).

Other features include rover tracks and rover drilling and sampling sites.

Curiosity captured this self-portrait at the ‘Windjana’ Drilling Site in 2014. The right panel shows its work. Image Credit: NASA/JPL-Caltech/MSSS

We’re already partway to taking our abandoned artifacts seriously. The United Nations keeps a list of objects launched into space called the Register of Objects Launched into Outer Space. It’s a way of identifying which countries are liable and responsible for objects in space (but not which private billionaires.) The Register was first implemented in 1976, and it says that about 88% of crewed spacecraft, elements of the ISS, satellites, probes, and landers launched into space are registered.

UNESCO also keeps a register of heritage sites, including archaeological and natural sites. The same could be done for Mars.

This UNESCO list of heritage sites shows both natural and cultural heritage sites, including ones that are considered to be in danger. Click the image to visit the site and explore the map. Image Credit: UNESCO

There’s already one attempt to start documenting and mapping sites on Mars. The Perseverance Rover team is documenting all of the debris they encounter to make sure it can’t contaminate sampling sites. There are also concerns that debris could pose a hazard to future missions.

According to one researcher, there is over 1700 kg (16,000) pounds of debris on Mars, not including working spacecraft. While much of it is just scraps being blown around by the wind and broken into smaller pieces, there are also larger pieces of debris and nine intact yet inoperative spacecraft.

So far, there have been only piecemeal attempts to document these Martian artifacts.

“Despite efforts from the USA’s Perseverance team, there exists no systematic strategy for documenting, mapping and keeping track of all heritage on Mars,” the authors write. “We anticipate that cultural
resource management will become a key objective during planetary exploration, including systematic surveying, mapping, documentation, and, if necessary, excavation and curation, especially as we expand
our material footprint across the Solar System.”

Holcomb and his co-authors say we must understand that our spacecraft debris is the archaeological record of our attempt to explore not just Mars but the entire Solar System. Our effort to understand Mars is also part of our effort to understand our own planet and how humanity arose. “Any future accidental destruction of this record would be permanent,” they point out.

The authors say there’s a crucial need to preserve things like Neil Armstrong’s first footsteps on the Moon, the first impact on the lunar surface by the USSR’s Luna 2, and even the USSR’s Venera 7 mission, the first spacecraft to land on another planet. This is our shared heritage as human beings.

A bootprint in the lunar regolith, taken during Apollo 11 in 1969. Credit: NASA.

“These examples are extraordinary firsts for humankind,” Holcomb and his co-authors write. “As we move forward during the next era of human exploration, we hope that planetary scientists, archaeologists and geologists can work together to ensure sustainable and ethical human colonization that protects
cultural resources in tandem with future space exploration.”

There are many historical examples of humans getting this type of thing wrong, particularly during European colonization of other parts of the world. Since we’re still at (we hope) the beginning of our exploration of the Solar System, we have an opportunity to get it right from the start. It will take a lot of work and many discussions to determine what this preservation and future exploration can look like.

“Those discussions could begin by considering and acknowledging the emerging archaeological record on Mars,” the authors conclude.

The post Archaeology On Mars: Preserving Artifacts of Our Expansion Into the Solar System appeared first on Universe Today.

Did you find the cat amongst the owls in today’s Hili Dialogue? If not, I’ve circled it below.

There’s not much news today, it’s cold and gray, and my building is empty, as all the sane people appear to have already buggered off for the holidays. Feel free to talk or rant about what you want below. For example, here’s one thought I had: “Increasing decrepitude with age is nature’s way of preparing you for death. In other words, by the time one gets really old and hobbled with many ailments and pains, it becomes easier to die.”

In 2019, astronomers observed an unusual gravitational chirp. Known as GW190521, it was the last scream of gravitational waves as a black hole of 66 solar masses merged with a black hole of 85 solar masses to become a 142 solar mass black hole. The data were consistent with all the other black hole mergers we’ve observed. There was just one problem: an 85 solar mass black hole shouldn’t exist.

All the black hole mergers we’ve observed involve stellar mass black holes. These form when a massive star explodes as a supernova and its core collapses to become a black hole. An old star needs to be at least ten times the mass of the Sun to become a supernova, which can create a black hole of about 3 solar masses. Larger stars can create larger black holes, up to a point.

The first generation of stars in the cosmos were likely hundreds of solar masses. For a star above 150 solar masses or so, the resulting supernova would be so powerful that its core would undergo what is known as pair-instability. Gamma rays produced in the core would be so intense they decay into an electron-positron pair. The high-energy leptons would then rip apart the core before gravity could collapse it. To overcome the pair-instability, a progenitor star would need a mass of 300 Suns or more. This means that the mass range of stellar black holes has a “pair-instability gap.” Black holes from 3 solar masses to about 65 solar masses would form from regular supernovae, and black holes above 130 solar masses could form from stellar collapse, but black holes between 65-130 solar masses shouldn’t exist.

For GW190521, the 66 solar mass black hole is close enough to the limit that it likely formed from a single star. The 85 solar mass black hole, on the other hand, is smack-dab in the middle of the forbidden range. Some astronomers have argued that the larger black hole might have formed from a hypothetical boson star known as a Proca star, but if that’s true, then GW190521 is the only evidence that Proca stars exist. More likely, the 85 solar mass black hole formed from the merger of two smaller black holes, making GW190521 a staged merger. The difficulty with that idea is that black hole mergers are often asymmetrical, in a way that the resulting black hole is kicked out of its region of origin. Multiple black hole mergers would only occur under certain circumstances, which is where a new study in The Astrophysical Journal comes in.

The authors looked at how the mass, spin, and motion of a merging black hole pair determine the mass, spin, and recoil velocity of the resulting black hole. By creating a statistical distribution of outcomes, the team could then work backwards. Given the mass, spin, and velocity of a “forbidden” black hole relative to its environment, what were the properties of its black hole ancestors? When the authors applied this to the progenitors of GW190521, they found that the only possible ancestors would have given a relatively large recoil velocity. This means that the merger must have occurred within the region of an active galactic nucleus, where the gravitational well would be strong enough to hold the system together.

This work has implications for what are known as intermediate mass black holes (IMBHs), which can have masses of hundreds or thousands of Suns. It has been thought that IMBHs form within globular clusters, but if the recoil velocities of black hole mergers are large, this would be unlikely. As this study shows, GW190521 could not have occurred in a globular cluster.

Reference: Araújo-Álvarez, Carlos, et al. “Kicking Time Back in Black Hole Mergers: Ancestral Masses, Spins, Birth Recoils, and Hierarchical-formation Viability of GW190521.” The Astrophysical Journal 977.2 (2024): 220.

The post Building the Black Hole Family Tree appeared first on Universe Today.

Telling time in space is difficult, but it is absolutely critical for applications ranging from testing relativity to navigating down the road. Atomic clocks, such as those used on the Global Navigation Satellite System network, are accurate, but only up to a point. Moving to even more precise navigation tools would require even more accurate clocks. There are several solutions at various stages of technical development, and one from Germany’s DLR, COMPASSO, plans to prove quantum optical clocks in space as a potential successor.

There are several problems with existing atomic clocks – one has to do with their accuracy, and one has to do with their size, weight, and power (SWaP) requirements. Current atomic clocks used in the GNSS are relatively compact, coming in at around .5 kg and 125 x 100 x 40 mm, but they lack accuracy. In the highly accurate clock world terminology, they have a “stability” of 10e-9 over 10,000 seconds. That sounds absurdly accurate, but it is not good enough for a more precise GNSS.

Alternatives, such as atomic lattice clocks, are more accurate, down to 10e-18 stability for 10,000. However, they can measure .5 x .5 x .5m and weigh hundreds of kilograms. Given satellite space and weight constraints, those are way too large to be adopted as a basis for satellite timekeeping.

Rendering of a passive hydrogen maser atomic clock.

To find a middle ground, ESA has developed a technology development roadmap focusing on improving clock stability while keeping it small enough to fit on a satellite. One such example of a technology on the roadmap is a cesium-based clock cooled by lasers and combined with a hydrogen-based maser, a microwave laser. NASA is not missing out on the fun either, with its work on a mercury ion clock that has already been orbitally tested for a year.

COMPASSO hopes to surpass them all. Three key technologies enable the mission: two iodine frequency references, a “frequency comb,” and a “laser communication and ranging terminal.” Ideally, the mission will be launched to the ISS, where it will sit in space for two years, constantly keeping time. The accuracy of those measurements will be compared to alternatives over that time frame. 

Lasers are the key to the whole system. The iodine frequency references display the very distinct absorption lines of molecular iodine, which can be used as a frequency reference for the frequency comb, a specialized laser whose output spectrum looks like it has comb teeth at specific frequencies. Those frequencies can be tuned to the frequency of the iodine reference, allowing for the correction of any drift in the comb. 

engineerguy explains how atomic clocks work with the GNSS.
Credit – engineerguy YouTube Channel

The comb then provides a method for phase locking for a microwave oscillator, a key part of a standard atomic clock. Overall, this means that the stability of the iodine frequency reference is transferred to the frequency comb, which is then again transferred to the microwave oscillator and, therefore, the atomic clock. In COMPASSO’s case, the laser communication terminal is used to transmit frequency and timing information back to a ground station while it is active.

COMPASSO was initially begun in 2021, and a paper describing its details and some breadboarding prototypes were released this year. It will hop on a ride to the ISS in 2025 to start its mission to make the world a more accurately timed place—and maybe improve our navigation abilities as well.

Learn More:
Kuschewski et al – COMPASSO mission and its iodine clock: outline of the clock design
UT – Atomic Clocks Separated by Just a few Centimetres Measure Different Rates of Time. Just as Einstein Predicted
UT – Deep Space Atomic Clocks Will Help Spacecraft Answer, with Incredible Precision, if They’re There Yet
UT – A New Atomic Clock has been Built that Would be off by Less than a Second Since the Big Bang

Lead Image:
Benchtop prototype of part of the COMPASSO system.
Credit – Kuschewski et al

The post Need to Accurately Measure Time in Space? Use a COMPASSO appeared first on Universe Today.

Binary stars are common throughout the galaxy. Roughly half the stars in the Milky Way are part of a binary or multiple system, so we would expect to find them almost everywhere. However, one place we wouldn’t expect to find a binary is at the center of the galaxy, close to the supermassive black hole Sagittarius A*. And yet, that is precisely where astronomers have recently found one.

There are several stars near Sagittarius A*. For decades, we have watched as they orbit the great gravitational well. The motion of those stars was the first strong evidence that Sag A* was indeed a black hole. At least one star orbits so closely that we can see it redshift as it reaches peribothron.

But we also know that stars should be ever wary of straying too close to the black hole. The closer a star gets to the event horizon of a black hole, the stronger the tidal forces on the star become. There is a point where the tidal forces are so strong a star is ripped apart. We have observed several of these tidal disruption events (TDEs), so we know the threat is very real.

Tidal forces also pose a threat to binary stars. It wouldn’t take much for the tidal pull of a black hole to disrupt binary orbits, causing the stars to separate forever. Tidal forces would also tend to disrupt the formation of binary stars in favor of larger single stars. Therefore astronomers assumed the formation of binary stars near Sagittarius A* wasn’t likely, and even if a binary formed, it wouldn’t last long on cosmic timescales. So astronomers were surprised when they found the binary system known as D9.

Distance and age of D9 in the context of basic dynamical processes and stellar populations in the Galactic center. Credit: Peißker et al

The D9 system is young, only about 3 million years old. It consists of one star of about 3 solar masses and the other with a mass about 75% that of the Sun. The orbit of the system puts it within 6,000 AU of Sag A* at its closest approach, which is surprisingly close. Simulations of the D9 system estimate that in about a million years, the black hole’s gravitational influence will cause the two stars to merge into a single star. But even this short lifetime is unexpected, and it shows that the region near a supermassive black hole is much less destructive than we thought.

It’s also pretty amazing that the system was discovered at all. The center of our galaxy is shrouded in gas and dust, meaning that we can’t observe the area in the visible spectrum. We can only see stars in the region with radio and infrared light. The binary stars are too close together for us to identify them individually, so the team used data from the Enhanced Resolution Imager and Spectrograph (ERIS) on the ESO’s Very Large Telescope, as well as archive data from the Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI). This gave the team data covering a 15-year timespan, which was enough to watch the light of D9 redshift and blueshift as the stars orbit each other every 372 days.

Now that we know the binary system D9 exists, astronomers can look for other binary stars. This could help us solve the mystery of how such systems can form so close to the gravitational beast at the heart of our galaxy.

Reference: Peißker, Florian, et al. “A binary system in the S cluster close to the supermassive black hole Sagittarius A.” Nature Communications 15.1 (2024): 10608.

The post A Binary Star Found Surprisingly Close to the Milky Way's Supermassive Black Hole appeared first on Universe Today.

Using descriptions of flavours or chemical data, artificial intelligence can tell apart whiskies from different countries and identify their constituent aromas

Endangered skates and kingfishers were brought back from the brink this year and scientists found a way to protect frogs from deadly infections

The Science-Based Medicine blog was established way back in 2008. Since that time, contributors to this blog have been sounding the alarm about the harmful effects of pseudoscience and conspiracy theories related to health. Few people in positions of authority heeded these warnings or recognized the severity of the threat over the next decade. Sometimes we as health professionals were even mocked […]

The post Homeopathy: Magical thinking, not medicine first appeared on Science-Based Medicine.

A simple change to maize, sorghum and sugarcane that allows them to take advantage of rising CO2 levels can boost their growth by around a fifth

Advances in artificial intelligence mean that machines can now perform certain diagnostic tasks with far better accuracy than human doctors - but the picture is more complicated than you might think

Analysing footage of what happens when people jump into water, and using a robot to mimic them, has revealed how do the perfect dive-bomb using a Maori technique called the Manu

This year has delivered some awe-inspiring imagery of space, from the James Webb Space Telescope’s stunning shots of faraway stars and galaxies to images of the skies taken from here on planet Earth