Astronomy

The emergence of satellite megaconstellations like SpaceX's Starlink offers great benefits for humanity. But there are also substantial costs, including a growing imposition on astronomy.

The upcoming launch of the Φsat-2 mission is a prime example of the pioneering work that ESA does in the field of AI in Earth observation.

But when it comes to AI, hopes and fears abound in equal measure. In this interview, ESA’s Rochelle Schneider sets the record straight on how this transformational technology is improving access to crucial information on the state and future of our planet.

Temperatures on Exoplanet WASP 43b

A new robotic hand can withstand being smashed by pistons or walloped with a hammer. It was designed to survive the trial-and-error interactions required to train AI robots

A new robotic hand can withstand being smashed by pistons or walloped with a hammer. It was designed to survive the trial-and-error interactions required to train AI robots

The quantum principle of superposition – the idea of particles being in multiple places at once – could help make quantum batteries that charge within minutes

The quantum principle of superposition – the idea of particles being in multiple places at once – could help make quantum batteries that charge within minutes

When astrophysicists observe the cosmos, they see different types of black holes. They range from gargantuan supermassive black holes with billions of solar masses to difficult-to-find intermediate-mass black holes (IMBHs) all the way down to smaller stellar-mass black holes.

But there may be another class of these objects: primordial black holes (PBHs) that formed in the very early Universe. If they exist, the Nancy Grace Roman Space Telescope should be able to spot them.

Stellar-mass black holes form when massive stars explode as supernovae. SMBHs grow over time by merging with other black holes. How IMBHs form is still unclear, but it could involve mergers between stellar-mass black holes or multiple stellar collisions in dense star clusters.

Primordial black holes, if they exist, didn’t have any of these mechanisms available to them.

“If we find them, it will shake up the field of theoretical physics.”

William DeRocco, postdoctoral researcher, University of California Santa Cruz. Artist’s impression of merging binary black holes. When they merge, they emit gravitational waves that observatories like LIGO can detect. Image Credit: LIGO/A. Simonnet.

Nobody knows if primordial black holes exist. They’re theoretical. No physical process we know of can form them. But the early Universe was much different.

New research published in Physical Review D shows how the upcoming Nancy Grace Roman Telescope could detect these primordial Earth-mass objects. It’s titled “Revealing terrestrial-mass primordial black holes with the Nancy Grace Roman Space Telescope.” The lead author is William DeRocco, a postdoctoral researcher at the University of California Santa Cruz.

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“Detecting a population of Earth-mass primordial black holes would be an incredible step for both astronomy and particle physics because these objects can’t be formed by any known physical process,” lead author DeRocco said. “If we find them, it will shake up the field of theoretical physics.”

In the modern Universe, only stars with at least eight stellar masses can become black holes. Less massive stars will become neutron stars or white dwarfs. (The Sun will become a white dwarf.)

But things were different in the early Universe. During a period of rapid inflation, space expanded faster than the speed of light. In these unusual conditions, dense areas could have collapsed into PBHs. The scale of these objects is remarkably small. They would be the size of Earth or smaller and have event horizons about as wide as a coin.

PBHs could’ve formed when overdense regions in the inflationary or early radiation-dominated universe collapsed. Image Credit: By Gema White – https://www.slideserve.com/gema/primordial-black-hole-formation-in-an-axion-like-curvaton-model slide 19. Cropped to remove all elements of original authorship.Based on Kawasaki, Masahiro (2013-03-18). “Primordial black hole formation from an axionlike curvaton model.” Physical Review D 87 (6): 063519. DOI:10.1103/PhysRevD.87.063519., Public Domain, https://commons.wikimedia.org/w/index.php?curid=131103715

The least massive of these ones would’ve disappeared due to evaporation. That’s what Stephen Hawking figured out. But some, the ones as massive as Earth, could’ve survived.

<Click on image for larger version> Stephen Hawking came up with the idea of black hole evaporation. He theorized that black holes slowly shrink as radiation escapes. The slow leak of what’s now known as Hawking radiation would, over time, cause the black hole to simply evaporate. This infographic shows the estimated lifetimes and event horizon –– the point past which infalling objects can’t escape a black hole’s gravitational grip –– diameters for black holes of various small masses. Image Credit: NASA’s Goddard Space Flight Center

Even though they’re theoretical, there are some evidential hints of their presence. Those hints come from gravitational microlensing.

Two efforts have used microlensing to study objects in the Universe. One is OGLE, the Optical Gravitational Lensing Experiment. Another is MOA, Microlensing Observations in Astrophysics. OGLE found 17 isolated Earth-mass objects in space.

Planet OGLE-2012-BLG-0950Lb was detected through gravitational microlensing, a phenomenon that acts as Nature’s magnifying glass. CREDIT: LCO/D. BENNETT

These objects could be PBHs, or they could be rogue planets. Unfortunately, it’s very difficult to differentiate on an individual basis. But since theory predicts the masses and the abundance of rogue planets, that could provide a way for the Roman Telescope to tell them apart from PBHs.

“There’s no way to tell between Earth-mass black holes and rogue planets on a case-by-case basis,” DeRocco said. “Roman will be extremely powerful in differentiating between the two statistically.”

In their research, the authors explain it more fully. “The key point is that though PBH and FFP events cannot be discriminated on an event-by-event basis, the two populations can be distinguished by the statistical distribution of their event durations.” Scientists think that Roman will find 10 times as many objects in this mass range than ground-based efforts like OGLE and MOA.

Artist’s impression of the Nancy Grace Roman Space Telescope, named after NASA’s first Chief of Astronomy. When launched later this decade, the telescope should make a significant contribution to the study of FFPs and will hopefully detect PBHs. Credits: NASA

Finding primordial black holes would create a big upheaval.

“It would affect everything from galaxy formation to the universe’s dark matter content to cosmic history,” said Kailash Sahu, an astronomer at the Space Telescope Science Institute in Baltimore. Sahu wasn’t involved in the research but understands the impact the results would have. “Confirming their identities will be hard work and astronomers will need a lot of convincing, but it would be well worth it.”

If the Roman Space Telescope can find the black holes and confirm them, it could be a defining moment in astronomical history. The discovery would be strong evidence in favour of a period of rapid inflation in the early Universe, an epoch that so far is unproven. Physicists think there must have been a period like this as it helps explain so much else about the Universe.

More excitingly, these primordial black holes could comprise a percentage of dark matter. A small percentage, but a massive improvement over our current understanding of what dark matter is. Scientists keep looking for things like WIMPs (Weakly Interacting Massive Particles) and other particles that could be dark matter, but they never find them.

“The nature of dark matter remains one of the most pressing open questions in fundamental physics. While multiple lines of compelling evidence indicate its existence, its microphysical nature remains unknown,” the authors explain.

The elegant thing about the Roman and PBHs is that it won’t require a special effort to find them. The Roman will already search for planets. “Roman’s Galactic Bulge Time Domain Survey is expected
to observe hundreds of low-mass microlensing events, enabling a robust statistical characterization
of this population,” the authors write in their paper.

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Each space telescope we launch is a new window into some aspect of the Universe. The Nancy Grace Roman Space Telescope sure will be. “Though its Galactic Bulge Time Domain Survey targets bound and unbound exoplanets, we have shown that it will have unprecedented sensitivity to physics beyond the Standard Model as well,” DeRocco and his co-researchers write in their paper. That’s because it can “probe the fraction of dark matter composed of primordial black holes,” they write.

“This is an exciting example of something extra scientists could do with data Roman is already going to get as it searches for planets,” Sahu said. “And the results are interesting whether or not scientists find evidence that Earth-mass black holes exist. It would strengthen our understanding of the universe in either case.”

And who doesn’t want a stronger understanding of the Universe?

The post Roman Space Telescope Will Be Hunting For Primordial Black Holes appeared first on Universe Today.

Boeing's Starliner spacecraft was rolled off the launch pad today (May 8) to replace a misbehaving valve on its Atlas V rocket.

The James Webb Space Telescope is teaching us about how planets form.

New images from the VLT Survey Telescope will help scientists learn about galaxy pasts, and perhaps futures.

Even though Venus and Earth are so-called sister planets, they’re as different as heaven and hell. Earth is a natural paradise where life has persevered under its azure skies despite multiple mass extinctions. On the other hand, Venus is a blistering planet with clouds of sulphuric acid and atmospheric pressure strong enough to squash a human being.

But the sister thing won’t go away because both worlds are about the same mass and radius and are rocky planets next to one another in the inner Solar System. Why are they so different? What do the differences tell us about our search for life?

The international astronomical community recognizes that understanding planetary habitability is a critical part of space science and astrobiology. Without a stronger understanding of terrestrial planets and their atmospheres, whether habitable or not, we won’t really know what we’re seeing when we examine a distant exoplanet. If we find an exoplanet that exhibits some signs of life, we’ll never visit it, never study it up close, and never be able to sample its atmosphere.

Artist’s impression of the exoplanet Ross 128 b orbiting its red dwarf star. Potentially habitable rocky worlds like this one are beyond our physical reach. Image Credit: ESO/M. Kornmesser. Public Domain

That shifts the scientific focus to the terrestrial planets in our own Solar System. Not because they appear to be habitable but because a complete model of terrestrial planets can’t be complete without including ones that are near-literal hellholes, like sister Venus.

A recent research perspective in Nature Astronomy examines how the two planets diverged and what might have driven the divergence. It’s titled “Venus as an anchor point for planetary habitability.” The lead author is Stephen Kane, from the Department of Earth and Planetary Sciences, University of California, Riverside. His co-author is Paul Byrne from the Department of Earth, Environmental, and Planetary Sciences, Washington University in St. Louis.

“A major focus of the planetary science and astrobiology community is understanding planetary habitability, including the myriad factors that control the evolution and sustainability of temperate surface environments such as that of Earth,” Kane and Byrne write. “The few substantial terrestrial planetary atmospheres within the Solar System serve as a critical resource for studying these habitability factors, from which models can be constructed for application to extrasolar planets.”

From their perspective, our Solar System’s twins provide our best opportunity to study how similar planets can have such divergent atmospheres. The more we understand that, the better we can understand how rocky worlds evolve over time and how different conditions benefit or restrict habitability.

This figure from the study presents some of the main, basic differences between Earth and Venus. Image Credit: Kane and Byrne, 2024.

Earth is an exception. With its temperate climate and surface water, it’s been habitable for billions of years, albeit with some climate episodes that severely restricted life. But when we look at Mars, it seems to have been habitable for a period of time and then lost its atmosphere and its surface water. Mars’ situation must be more common than Earth’s.

Artist’s impression of Snowball Earth 650 million years ago during the Marinoan glaciation. Earth has had episodes of extreme climates but is still going strong. Image Credit: University of St. Andrews.

It’s a monumental challenge to understand an exoplanet when we know nothing of its history. We only see it at one epoch of its climate and atmospheric history. But the discovery of thousands of exoplanets is helping. “The discovery of thousands of exoplanets, and the confirmation that terrestrial planets are among the most common types, provides a statistical framework for studying planetary properties and their evolution generally,” the authors write.

A narrow range of properties allows biochemistry to emerge, and those properties may not last. We need to identify these properties and their parameters and build a better understanding of habitability. From this perspective, Venus is a treasure trove of information.

But Venus is a challenge. We can’t see through its dense clouds except with radar, and nobody’s tried landing a spacecraft there since the USSR in the 1980s. Most of those attempts failed, and the ones that survived didn’t last long. Without better data, we can’t understand Venus’ history. The simple answer is that it’s closer to the Sun. But it’s too simple to be helpful.

“The evolutionary pathway of Venus to its current runaway-greenhouse state is a matter of debate, having traditionally been attributed to its closer proximity to the Sun,” Kane and Byrne explain.

We don’t know why Venus is a greenhouse effect. Volcanoes may have played a role. They emit carbon dioxide, and without oceans and tectonic plates, the planet can’t remove the carbon from its atmosphere. Image Credit: NASA/JPL-Caltech/Peter Rubin

But when scientists look closer at Venus and Earth, they find many fundamental differences between them beyond their distances from the Sun. They have different rotation rates, they have differing obliquities, and they have different magnetic fields, to name a few. That means that we can’t measure the precise effect greater solar insolation has on the planet.

This is the authors’ main point. The differences between Earth and Venus make Venus a powerful part of understanding rocky exoplanet habitability. “Venus thus offers us a critical anchor point in the planetary habitability discourse, as its evolutionary story represents an alternate pathway from the Earth-based narrative—even though the origins of both worlds are, presumably, similar,” they write.

The authors point out that the basic requirement for life is surface water. But the bigger question is what factors govern how long surface water can persist. “By this measure, investigations of planetary habitability can then focus on the conditions that allow surface liquid water to be sustained through geological time,” they write.

This figure from the research illustrates some of the factors that can influence surface water and planetary habitability. Image Credit: Kane and Byrne 2024, National Academies Press, Ron Pettengill.

Earth and Venus are on opposite ends of the spectrum of rocky planet habitability. That’s an important lesson we can learn from our own Solar System. For that reason, “…understanding the pathway to a Venus scenario is just as important as understanding the pathway to habitability that characterizes Earth,” the authors write.

The pair of researchers created a list of some of the factors that govern habitability on Earth and Venus.

Most of these factors are self-explanatory. CHNOPS is carbon, hydrogen, nitrogen, oxygen, phosphorous, and sulphur, the life-supporting elements. Redox is the potential for an element or molecule to be reduced or oxidized and made available as chemical energy for life. The fact that there’s a question mark beside for Venus’s redox environment is a major stumbling block. Image Credit: Kane and Byrne, 2024.

There’s so much we don’t know about Venus. How big is its core? Did it ever have water? Some research shows that when the planet lost its water and became totally inhabitable, there was lots of oxygen in its atmosphere. If we saw that same amount of oxygen on a distant exoplanet, we might interpret it as a sign of life. Big mistake. “Venus thus acts as a cautionary tale for interpretations of apparently oxygen-rich atmospheres,” the authors write.

Kane and Byrne’s research perspective is a call to action. It mirrors what recent Decadal Surveys have said. “The recent astronomy and astrophysics, and planetary science and astrobiology decadal surveys both emphasize the need for an improved understanding of planetary habitability as an essential goal within the context of astrobiology,” they write. For the authors, Venus can anchor the effort.

But for it to serve as an anchor, scientists need answers to lots of questions. They need to study its atmosphere more thoroughly at all altitudes. They need to study its interior and determine the nature and size of its core. Critically, they need to get a spacecraft to its surface and examine its geology up close. In short, we need to do at Venus what we’ve done at Mars.

That’s challenging, considering Venus’ hostile environment. But missions are being prepared to explore Venus in more detail. VERITAS, DAVINCI, and EnVision are all Venus missions scheduled for the 2030s. Those missions will start to give scientists the answers we need.

As we learn more about Venus, we also need to learn more about exo-Venuses. “A parallel approach to studying the intrinsic properties of Venus is the statistical analysis of the vast (and still rapidly growing) inventory of terrestrial exoplanets,” the authors write.

This figure from the research represents the Venus zone and the habitable zone as a function of stellar effective temperature and insolation flux received by the planet. The Venus zone is shaded in red, and the habitable zone is in blue. The images on the left show main sequence stars of various effective temperatures. The images of Venus indicate the location of Kepler candidates that lie within the Venus zone, scaled by the size of the planet. The Solar System planets of Venus, Earth and Mars are also shown. Image Credit: Habitable Zone Gallery/Chester Harman; Planets: NASA/JPL. Kane and Byrne, 2024.

We’re living in an age of exoplanet discovery. We’ve discovered over 5,000 confirmed exoplanets, and the tally keeps growing. We’re launching spacecraft to study the most interesting ones more thoroughly. But at some point, things will shift. How many of them do we need to catalogue? Is 10,000 enough? 20,000? 100,000?

It’s all new right now, and the enthusiasm to find more exoplanets, especially rocky ones in habitable zones, is understandable. But eventually, we’ll reach some kind of threshold of diminishing returns. In order to understand them, our effort might be more wisely spent studying Venus and how it evolved so differently.

Just as Kane and Byrne suggest.

The post What Deadly Venus Can Tell Us About Life on Other Worlds appeared first on Universe Today.

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Egg whites are key to so many baked goods but can be tricky to work with. These tips will help you master the technique, says Catherine de Lange

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