Space biweekly vol.99, 30th May — 14th June
TL;DR
- Researchers have provided a simple and comprehensive — if less dramatic — explanation for bright radar reflections initially interpreted as liquid water beneath the ice cap on Mars’ south pole.
- Research reveals a shocking discovery about the history of our universe: the Milky Way Galaxy’s last major collision occurred billions of years later than previously thought.
- In the first quintillionth of a second, the universe may have sprouted microscopic black holes with enormous amounts of nuclear charge, MIT physicists propose. The gravitational pull from these tiny, invisible objects could potentially explain all the dark matter that we can’t see today.
- Scientists have detected what they believe to be a neutron star spinning at an unprecedentedly slow rate — slower than any of the more than 3,000 radio emitting neutron stars measured to date.
- A rare exoplanet that should have been stripped down to bare rock by its nearby host star’s intense radiation somehow grew a puffy atmosphere instead — the latest in a string of discoveries forcing scientists to rethink theories about how planets age and die in extreme environments. Nicknamed ‘Phoenix’ for its ability to survive its red giant star’s radiant energy discovered planet illustrates the vast diversity of solar systems and the complexity of planetary evolution — especially at the end of stars’ lives.
- And more!
Space industry in numbers
The global smart space market size is projected to grow from USD 9.4 billion in 2020 to USD 15.3 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 10.2% during the forecast period. The increasing venture capital funding and growing investments in smart space technology to drive market growth.
Analysts at Morgan Stanley and Goldman Sachs have predicted that economic activity in space will become a multi-trillion-dollar market in the coming decades. Morgan Stanley’s Space Team estimates that the roughly USD 350 billion global space industry could surge to over USD 1 trillion by 2040.
Space industry news
- China selects new batch of astronauts with an eye on the moon
- New direct-to-cell satellite tech could disrupt billion-dollar military satcom programs
- Yahsat orders LEO satellites from Airbus
- Scout Space telescope to hitch a ride on ABL rocket
- Assured Space and Phantom Space seek to disrupt data-backhaul business
- NASA selects seven companies for MSR studies
- Space Development Agency calls on satellite builders to diversify suppliers
- Virgin Galactic conducts final VSS Unity commercial suborbital spaceflight
- Planet’s first hyperspectral satellite is ready to launch
- Space Force agency taps 20 companies for $1 billion ground systems IDIQ
- ESA and Vast to study cooperation on future commercial space stations
- AI powering commercial insights into the final frontier
- Space startup funding rounds lift Seraphim’s investment portfolio
- Starliner docks with International Space Station on crewed test flight
- Space Pioneer raises $207 million for reusable rocket
- Starship survives reentry during fourth test flight
- Chang’e-6 spacecraft dock in lunar orbit ahead of journey back to Earth
- Astroscale shares soar in Tokyo stock market debut
- First Ariane 6 launch set for July 9
Latest research
Small variations in ice composition and layer thickness explain bright reflections below martian polar cap without liquid water
by Daniel E. Lalich, Alexander G. Hayes, Valerio Poggiali in Science Advances
Cornell University researchers have provided a simple and comprehensive — if less dramatic — explanation for bright radar reflections initially interpreted as liquid water beneath the ice cap on Mars’ south pole.
Their simulations show that small variations in layers of water ice — too subtle for ground-penetrating radar instruments to resolve — can cause constructive interference between radar waves. Such interference can produce reflections whose intensity and variability match observations to date — not only in the area proposed to be liquid water, but across the so-called south polar layered deposits.
“I can’t say it’s impossible that there’s liquid water down there, but we’re showing that there are much simpler ways to get the same observation without having to stretch that far, using mechanisms and materials that we already know exist there,” said Daniel Lalich, research associate in the Cornell Center for Astrophysics and Planetary Science. “Just through random chance you can create the same observed signal in the radar.”
Robotic explorers have provided extensive evidence that water flowed on the surface of ancient Mars, including at a former river delta now under investigation by NASA’s Perseverance rover. Relying on a radar instrument that can probe below the surface to detect water ice and potentially hidden aquifers, members of the European Space Agency-led Mars Express orbiter’s science team in 2018 announced they’d discovered a lake buried below the south polar cap.
The implications were enormous: Where there is liquid water, there could be microbial life. But while the same bright radar reflections would likely indicate a subglacial lake on Earth, Lalich said, the temperature and pressure conditions on Mars are very different. Using simpler models, Lalich previously showed that the bright radar signals could be created in the absence of liquid water, but he said assumptions about layers of frozen carbon dioxide below the ice cap likely were incorrect.
The new research tells a more complete story, he said, closing gaps in the radar interference hypothesis with more realistic modeling. The thousands of randomly generated layering scenarios were based only on conditions known to exist at the Martian poles, and varied the ice layers’ composition and spacing in ways that would be expected over tens or hundreds of miles.
Those slight adjustments sometimes produced bright subsurface signals consistent with observations in each of the three frequencies used by the Mars Express orbiter’s MARSIS radar instrument, a partnership between NASA and the Italian Space Agency. Likely for a simple reason, Lalich argues: Radar waves bouncing off layers spaced too closely for the instrument to resolve may be combined, amplifying their peaks and troughs.
“This is the first time we have a hypothesis that explains the entire population of observations below the ice cap, without having to introduce anything unique or odd,” Lalich said. “This result where we get bright reflections scattered all over the place is exactly what you would expect from thin-layer interference in the radar.”
While not ruling out the potential for some future detection by more capable instruments, Lalich said he suspects the story of liquid water and potential life on the red planet ended long ago.
“The idea that there would be liquid water even somewhat near the surface would have been really exciting,” Lalich said. “I just don’t think it’s there.”
The debris of the ‘last major merger’ is dynamically young
by Thomas Donlon, Heidi Jo Newberg, Robyn Sanderson, Emily Bregou, Danny Horta, Arpit Arora, Nondh Panithanpaisal in Monthly Notices of the Royal Astronomical Society
Rensselaer Polytechnic Institute’s Heidi Jo Newberg, Ph.D., professor of astronomy; Tom Donlon, Ph.D., a visiting researcher at Rensselaer and a postdoctoral researcher at the University of Alabama; and their team have recently published research that reveals a shocking discovery about the history of our universe: the Milky Way Galaxy’s last major collision occurred billions of years later than previously thought.
The discovery was made possible by the European Space Agency’s Gaia spacecraft, which is mapping more than a billion stars throughout the Milky Way and beyond, tracking their motion, luminosity, temperature, and composition. Newberg, a renowned astrophysicist and Milky Way expert, and Donlon focused on the so-called “wrinkles” in our galaxy, which are formed when other galaxies collide with the Milky Way.
“We get wrinklier as we age, but our work reveals that the opposite is true for the Milky Way. It’s a sort of cosmic Benjamin Button, getting less wrinkly over time,” said Donlon, lead author of the new Gaia study, which also served as his doctoral thesis at Rensselaer. “By looking at how these wrinkles dissipate over time, we can trace when the Milky Way experienced its last big crash — and it turns out this happened billions of years later than we thought.”
By comparing their observations of the wrinkles with cosmological simulations, the team was able to determine that our last significant collision with another galaxy did not, in fact, occur between eight and 11 billion years ago, as previously believed.
“For the wrinkles of stars to be as obvious as they appear in Gaia data, they must have joined us no less than three billion years ago — at least five billion years later than was previously thought,” said Newberg, Donlon’s thesis adviser at Rensselaer. “New wrinkles of stars form each time the stars swing back and forth through the center of the Milky Way. If they’d joined us eight billion years ago, there would be so many wrinkles right next to each other that we would no longer see them as separate features.”
The collision is thought to have resulted in a large number of stars with unusual orbits. Previously, scientists dated it at between eight and 11 billion years ago in a collision called the Gaia-Sausage-Enceladus (GSE) merger. Rather, Newberg and Donlon’s findings indicate that the stars may have resulted from the Virgo Radial Merger, which crashed through the center of the Milky Way less than three billion years ago.
“Gaia is a hugely productive mission that’s transforming our view of the cosmos,” says Timo Prusti, Ph.D., Project Scientist for Gaia at the European Space Agency. “Results like this are made possible due to incredible teamwork and collaboration between a huge number of scientists and engineers across Europe and beyond.”
“Through this study, Doctors Newberg and Donlon have made a startling discovery about the history of the Milky Way galaxy,” said Curt Breneman, Ph.D., dean of the School of Science. “Gaia data is offering unprecedented opportunities to better understand our universe, and I am thrilled that Rensselaer researchers were able to harness the power of this incredibly detailed new data.”
Primordial Black Holes with QCD Color Charge
by Elba Alonso-Monsalve, David I. Kaiser in Physical Review Letters
For every kilogram of matter that we can see — from the computer on your desk to distant stars and galaxies — there are 5 kilograms of invisible matter that suffuse our surroundings. This “dark matter” is a mysterious entity that evades all forms of direct observation yet makes its presence felt through its invisible pull on visible objects.
Fifty years ago, physicist Stephen Hawking offered one idea for what dark matter might be: a population of black holes, which might have formed very soon after the Big Bang. Such “primordial” black holes would not have been the goliaths that we detect today, but rather microscopic regions of ultradense matter that would have formed in the first quintillionth of a second following the Big Bang and then collapsed and scattered across the cosmos, tugging on surrounding space-time in ways that could explain the dark matter that we know today. Now, MIT physicists have found that this primordial process also would have produced some unexpected companions: even smaller black holes with unprecedented amounts of a nuclear-physics property known as “color charge.”
These smallest, “super-charged” black holes would have been an entirely new state of matter, which likely evaporated a fraction of a second after they spawned. Yet they could still have influenced a key cosmological transition: the time when the first atomic nuclei were forged. The physicists postulate that the color-charged black holes could have affected the balance of fusing nuclei, in a way that astronomers might someday detect with future measurements. Such an observation would point convincingly to primordial black holes as the root of all dark matter today.
“Even though these short-lived, exotic creatures are not around today, they could have affected cosmic history in ways that could show up in subtle signals today,” says David Kaiser, the Germeshausen Professor of the History of Science and professor of physics at MIT. “Within the idea that all dark matter could be accounted for by black holes, this gives us new things to look for.”
The black holes that we know and detect today are the product of stellar collapse, when the center of a massive star caves in on itself to form a region so dense that it can bend space-time such that anything — even light — gets trapped within. Such “astrophysical” black holes can be anywhere from a few times as massive as the sun to many billions of times more massive.
“Primordial” black holes, in contrast, can be much smaller and are thought to have formed in a time before stars. Before the universe had even cooked up the basic elements, let alone stars, scientists believe that pockets of ultradense, primordial matter could have accumulated and collapsed to form microscopic black holes that could have been so dense as to squeeze the mass of an asteroid into a region as small as a single atom. The gravitational pull from these tiny, invisible objects scattered throughout the universe could explain all the dark matter that we can’t see today. If that were the case, then what would these primordial black holes have been made from? That’s the question Kaiser and Alonso-Monsalve took on with their new study.
“People have studied what the distribution of black hole masses would be during this early-universe production but never tied it to what kinds of stuff would have fallen into those black holes at the time when they were forming,” Kaiser explains.
The MIT physicists looked first through existing theories for the likely distribution of black hole masses as they were first forming in the early universe.
“Our realization was, there’s a direct correlation between when a primordial black hole forms and what mass it forms with,” Alonso-Monsalve says. “And that window of time is absurdly early.”
She and Kaiser calculated that primordial black holes must have formed within the first quintillionth of a second following the Big Bang. This flash of time would have produced “typical” microscopic black holes that were as massive as an asteroid and as small as an atom. It would have also yielded a small fraction of exponentially smaller black holes, with the mass of a rhino and a size much smaller than a single proton.
What would these primordial black holes have been made from? For that, they looked to studies exploring the composition of the early universe, and specifically, to the theory of quantum chromodynamics (QCD) — the study of how quarks and gluons interact.
Quarks and gluons are the fundamental building blocks of protons and neutrons — elementary particles that combined to forge the basic elements of the periodic table. Immediately following the Big Bang, physicists estimate, based on QCD, that the universe was an immensely hot plasma of quarks and gluons that then quickly cooled and combined to produce protons and neutrons.
The researchers found that, within the first quintillionth of a second, the universe would still have been a soup of free quarks and gluons that had yet to combine. Any black holes that formed in this time would have swallowed up the untethered particles, along with an exotic property known as “color charge” — a state of charge that only uncombined quarks and gluons carry.
“Once we figured out that these black holes form in a quark-gluon plasma, the most important thing we had to figure out was, how much color charge is contained in the blob of matter that will end up in a primordial black hole?” Alonso-Monsalve says.
Using QCD theory, they worked out the distribution of color charge that should have existed throughout the hot, early plasma. Then they compared that to the size of a region that would collapse to form a black hole in the first quintillionth of a second. It turns out there wouldn’t have been much color charge in most typical black holes at the time, as they would have formed by absorbing a huge number of regions that had a mix of charges, which would have ultimately added up to a “neutral” charge.
But the smallest black holes would have been packed with color charge. In fact, they would have contained the maximum amount of any type of charge allowed for a black hole, according to the fundamental laws of physics. Whereas such “extremal” black holes have been hypothesized for decades, until now no one had discovered a realistic process by which such oddities actually could have formed in our universe.
The super-charged black holes would have quickly evaporated, but possibly only after the time when the first atomic nuclei began to form. Scientists estimate that this process started around one second after the Big Bang, which would have given extremal black holes plenty of time to disrupt the equilibrium conditions that would have prevailed when the first nuclei began to form. Such disturbances could potentially affect how those earliest nuclei formed, in ways that might some day be observed.
“These objects might have left some exciting observational imprints,” Alonso-Monsalve muses. “They could have changed the balance of this versus that, and that’s the kind of thing that one can begin to wonder about.”
An emission-state-switching radio transient with a 54-minute period
by M. Caleb, E. Lenc, D. L. Kaplan, T. Murphy, Y. P. Men, R. M. Shannon, L. Ferrario, K. M. Rajwade, T. E. Clarke, S. Giacintucci, N. Hurley-Walker, S. D. Hyman, M. E. Lower, Sam McSweeney, V. Ravi, E. D. Barr, S. Buchner, C. M. L. Flynn, J. W. T. Hessels, M. Kramer, J. Pritchard, B. W. Stappers in Nature Astronomy
Scientists have detected what they believe to be a neutron star spinning at an unprecedentedly slow rate — slower than any of the more than 3,000 radio emitting neutron stars measured to date.
Neutron stars — the ultra-dense remains of a dead star — typically rotate at mind-bendingly fast speeds, taking just seconds or even a fraction of a second to fully spin on their axis. However, the neutron star, newly discovered by an international team of astronomers, defies this rule, emitting radio signals on a comparatively leisurely interval of 54 minutes. The team was led by Dr Manisha Caleb at the University of Sydney and Dr Emil Lenc at CSIRO, Australia’s national science agency and includes scientists at The University of Manchester and the University of Oxford.
Ben Stappers, Professor of Astrophysics at The University of Manchester, said: “In the study of radio emitting neutron stars we are used to extremes, but this discovery of a compact star spinning so slowly and still emitting radio waves was unexpected. It is demonstrating that pushing the boundaries of our search space with this new generation of radio telescopes will reveal surprises that challenge our understanding.”
At the end of their life, large stars use up all their fuel and explode in a spectacular blast called a supernova. What remains is a stellar remnant called a neutron star, made up of trillions of neutrons packed into a ball so dense that its mass is 1.4 times that of the Sun is packed into a radius of just 10km.
The unexpected radio signal from the stellar object detected by the scientists travelled approximately 16,000 light years to Earth. The nature of the radio emission and the rate at which the spin period is changing suggest it is a neutron star. However, the researchers have not ruled out the possibility of it being an isolated white dwarf with an extraordinarily strong magnetic field. Yet, the absence of other nearby highly magnetic white dwarfs makes the neutron star explanation more plausible.
Further research is required to confirm what the object is, but either scenario promises to provide valuable insights into the physics of these extreme objects. The findings could make scientists reconsider their decades-old understanding of neutron stars or white dwarfs; how they emit radio waves and what their populations are like in our Milky Way galaxy.
Dr Kaustubh Rajwade, an Astronomer at the University of Oxford, said: “This discovery relied on the combination of the complementary capabilities of ASKAP and MeerKAT telescopes as well as the ability to search for these objects on timescales of minutes while studying how their emission changes from second to second! Such synergies are allowing us to shed new light on how these compact objects evolve.”
The discovery was made using CSIRO’s ASKAP radio telescope on Wajarri Yamaji Country in Western Australia, which can see a large part of the sky at once and means it can capture things researchers aren’t even looking for. The research team were simultaneously monitoring a source of gamma rays and seeking a fast radio burst when they spotted the object slowly flashing in the data.
Lead author Dr Manisha Caleb from the University of Sydney Institute for Astronomy, said: “What is intriguing is how this object displays three distinct emission states, each with properties entirely dissimilar from the others. The MeerKAT radio telescope in South Africa played a crucial role in distinguishing between these states. If the signals didn’t arise from the same point in the sky, we would not have believed it to be the same object producing these different signals.”
The origin of such a long period signal remains a profound mystery, with white dwarfs and neutron stars the prime suspects. But as further investigations continue, this discovery is set to deepen our understanding of the universe’s most enigmatic objects.
TESS Giants Transiting Giants. IV. A Low-density Hot Neptune Orbiting a Red Giant Star
by Samuel K. Grunblatt, Nicholas Saunders, Daniel Huber, Daniel Thorngren, Shreyas Vissapragada, Stephanie Yoshida, Kevin C. Schlaufman, Steven Giacalone, Mason Macdougall, Ashley Chontos, Emma Turtelboom, Corey Beard, Joseph M. Akana Murphy, Malena Rice, Howard Isaacson, Ruth Angus, Andrew W. Howard in The Astronomical Journal
A rare exoplanet that should have been stripped down to bare rock by its nearby host star’s intense radiation somehow grew a puffy atmosphere instead — the latest in a string of discoveries forcing scientists to rethink theories about how planets age and die in extreme environments.
Nicknamed “Phoenix” for its ability to survive its red giant star’s radiant energy, the newly discovered planet illustrates the vast diversity of solar systems and the complexity of planetary evolution — especially at the end of stars’ lives.
“This planet isn’t evolving the way we thought it would, it appears to have a much bigger, less dense atmosphere than we expected for these systems,” said Sam Grunblatt, a Johns Hopkins University astrophysicist who led the research. “How it held on to that atmosphere despite being so close to such a large host star is the big question.”
The new planet belongs to a category of rare worlds called “hot Neptunes” because they share many similarities with the solar system’s outermost, frozen giant despite being far closer to their host stars and far hotter. Officially named TIC365102760 b, the latest puffy planet is surprisingly smaller, older, and hotter than scientists thought possible. It is 6.2 times bigger than Earth, completes an orbit around its parent star every 4.2 days, and is about 6 times closer to its star than Mercury is to the Sun.
Because of Phoenix’s age and scorching temperatures, coupled with its unexpectedly low density, the process of stripping its atmosphere must have occurred at a slower pace than scientists thought possible, the scientists concluded. They also estimated that the planet is 60 times less dense than the densest “hot Neptune” discovered to date, and that it won’t survive more than 100 million years before it begins dying by spiraling into its giant star.
“It’s the smallest planet we’ve ever found around one of these red giants, and probably the lowest mass planet orbiting a [red] giant star we’ve ever seen,” Grunblatt said. “That’s why it looks really weird. We don’t know why it still has an atmosphere when other ‘hot Neptunes’ that are much smaller and much denser seem to be losing their atmospheres in much less extreme environments.”
Grunblatt and his team were able to gain such insights by devising a new method for fine-tuning data from NASA’s Transiting Exoplanet Survey Satellite. The satellite’s telescope can spot low-density planets as they dim the brightness of their host stars when passing in front of them. But Grunblatt’s team filtered out unwanted light in the images and then combined them with additional measurements from the W.M. Keck Observatory on Hawaii’s Maunakea volcano, a facility that tracks the tiny wobbles of stars caused by their orbiting planets.
The findings could help scientists better understand how atmospheres like Earth’s might evolve, Grunblatt said. Scientists predict that in a few billion years the sun will expand into a red giant star that will swell up and engulf Earth and the other inner planets.
“We don’t understand the late-stage evolution of planetary systems very well,” Grunblatt said. “This is telling us that maybe Earth’s atmosphere won’t evolve exactly how we thought it would.”
Puffy planets are often composed of gases, ice, or other lighter materials that make them overall less dense than any planet in the solar system. They are so rare that scientists believe only about 1% of stars have them. Exoplanets like Phoenix are not as commonly discovered because their smaller sizes make them harder to spot than bigger, denser ones, Grunblatt said. That’s why his team is searching for more of these smaller worlds. They already have found a dozen potential candidates with their new technique.
“We still have a long way to go in understanding how planetary atmospheres evolve over time,” Grunblatt said.
Subscribe to Paradigm!
Medium. Twitter. Telegram. Telegram Chat. Reddit. LinkedIn.
Main sources
Research articles
