Space

LASP scientists appointed to NASA astrobiology task force

Megan M Rogers — Thu, 05 Mar 2026 17:50:48 +0000

LASP scientists appointed to NASA astrobiology task force Megan M Rogers Thu, 03/05/2026 - 10:50

Dolon Bhattacharyya and Dave Brain have been selected to serve on NASA's Decadal Astrobiology Research and Exploration Strategy Task Force 2.

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Libera space instrument will continue 26-year unbroken record of Earth's 'energy budget'

Daniel William Strain — Wed, 25 Feb 2026 22:55:57 +0000

Libera space instrument will continue 26-year unbroken record of Earth's 'energy budget' Daniel William… Wed, 02/25/2026 - 15:55

Daniel Strain , Nicholas Goda

An instrument designed and built in Colorado will measure how much energy leaves Earth on a daily basis—shaping processes that sustain life from wind and weather to ocean currents and more.

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Largest image of its kind shows hidden chemistry at the heart of the Milky Way

Daniel William Strain — Wed, 25 Feb 2026 18:05:10 +0000

Largest image of its kind shows hidden chemistry at the heart of the Milky Way Daniel William… Wed, 02/25/2026 - 11:05

Largest ALMA image ever shows the molecular gas in the centre of the Milky Way Credit: ALMA(ESO/NAOJ/NRAO)/S. Longmore et al. Background: ESO/D. Minniti et al.

This article was adapted from a version originally published by the European Southern Observatory (ESO). Read the original here.

Astronomers have captured the central region of our Milky Way in a striking new image, unveiling a complex network of filaments of cosmic gas in unprecedented detail. Obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), this rich dataset—the largest ALMA image to date—will allow astronomers to probe the lives of stars in the most extreme region of our galaxy, next to the supermassive black hole at its center.

Images revealing the distributions of various molecules in the center of the galaxy: carbon monosulfide, isocyanic acid, silicon monoxide, sulfur monoxide and cyanoacetylene. Credit: ALMA (ESO/NAOJ/NRAO)/S. Longmore et al.

“It’s a place of extremes, invisible to our eyes, but now revealed in extraordinary detail,” said Ashley Barnes, an astronomer at the European Southern Observatory (ESO) in Germany who is part of the team that obtained the new data.

The research was led by an open collaboration of scientists known as the ALMA CMZ Exploration Survey (ACES). John Bally, professor emeritus in the Department of Astrophysical and Planetary Sciences at ��Ҵ�ý�ƽ��, serves as co-principal investigator for ACES. The collaboration also includes former ��Ҵ�ý�ƽ�� graduate students Cara Battersby and Adam Ginsburg.

The observations provide a unique view of the cold gas—the raw material from which stars form—within the so-called Central Molecular Zone (CMZ) of our galaxy. It is the first time the cold gas across this whole region has been explored in such detail.

The region featured in the new image spans more than 650 light-years. It harbors dense clouds of gas and dust, surrounding the supermassive black hole at the center of our galaxy.

The dataset reveals the CMZ like never before, from gas structures dozens of light-years across all the way down to small gas clouds around individual stars.

Bally studies how new stars emerge in this extreme environment. Fewer stars form in the galactic center than scientists once predicted—a long-running mystery that data like the news ACES observations could help to answer.

“Intense radiation, winds powered by massive stars, supernova explosions, and accreting neutron stars and stellar-mass black holes constitute ‘feedback’ that opposes the tendency of clouds to collapse due to their self-gravity and fragment into dense, star-forming cores,” Bally said.

The gas that ACES specifically explores is cold molecular gas. The survey unpacks the intricate chemistry of the CMZ, detecting dozens of different molecules, from simple ones such as silicon monoxide to more complex organic ones like methanol, acetone or ethanol.

Cold molecular gas flows along filaments feeding into clumps of matter out of which stars can grow. In the outskirts of the Milky Way we know how this process happens, but within the central region the events are much more extreme.

“The CMZ hosts some of the most massive stars known in our galaxy, many of which live fast and die young, ending their lives in powerful supernova explosions, and even hypernovae,” said ACES leader Steve Longmore, a professor of astrophysics at Liverpool John Moores University, UK.

To collect this new dataset, astronomers used ALMA, which is operated by ESO and partners in Chile’s Atacama Desert. In fact, this is the first time such a large area has been scanned with this facility, making this the largest ALMA image ever. Seen in the sky, the mosaic—obtained by stitching together many individual observations like putting puzzle pieces together—is as long as three full Moons side-by-side.

The data from ACES are presented in five papers accepted for publication in Monthly Notices of the Royal Astronomical Society, with a sixth in the final review stages.

“The upcoming ALMA Wideband Sensitivity Upgrade, along with ESO’s Extremely Large Telescope, will soon allow us to push even deeper into this region—resolving finer structures, tracing more complex chemistry, and exploring the interplay between stars, gas and black holes with unprecedented clarity,” said Barnes. “In many ways, this is just the beginning.”

New observations provide an extraordinarily detailed look at how stars are born in the extreme environment near the heart of the galaxy.

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Astrobiologists search for alien life and help life on Earth in the process

Daniel William Strain — Thu, 12 Feb 2026 20:16:28 +0000

Astrobiologists search for alien life and help life on Earth in the process Daniel William… Thu, 02/12/2026 - 13:16

Daniel Strain

Mammoth Hot Springs in Yellowstone National Park. (Credit: CC photo via Wikimedia Commons)

On Earth, life thrives in some of the most seemingly inhospitable environments.

Single-celled organisms like bacteria teem in the hot springs of Yellowstone National Park, where temperatures reach nearly 200 degrees Fahrenheit (93 degrees Celsius). Others dwell deep underground or several miles above Earth’s surface in the stratosphere.

For years, scientists in a field called astrobiology have sought out these organisms. They want to know not just how life evolved on Earth, but how it might evolve on other worlds. They investigate moons in our solar system like Europa and Enceladus where vast and salty oceans lie beneath thick layers of ice.

“There have been so many of these extreme niches that astrobiologists have discovered on Earth,” said Tristan Caro, an astrobiologist who earned his doctorate in geological sciences at ��Ҵ�ý�ƽ�� in 2024. “They expand what we can imagine as habitable environments.”

Now, a team of students and early-career researchers have published a perspectives article in the journal Nature Communications tackling the potential of this out-there field.

Srishti Kashyap kneels in front of a "hyper-alkaline" spring in Oman. (Credit: Srishti Kashyap)

Tristan Caro conducting astrobiology research in the crater of Mt. St. Helens. (Credit: Tristan Caro)

The authors include Caro, Alta Howells, Srishti Kashyap, Catherine Fontana and Sabrina Elkassas and hail from ��Ҵ�ý�ƽ��, the California Institute of Technology, Woods Hole Oceanographic Institution and the Massachusetts Institute of Technology.

This group argues that pursuing astrobiology may bring dual benefits for humanity. The study of astrobiology can help scientists answer some of the biggest questions ever asked, such as: “Are we alone in the universe?” The discipline also inspires new technologies that may one day make life better on Earth, such as cleaner sources of fuel and tools that pull greenhouse gases out of the atmosphere.

“Astrobiology might seem really esoteric, but it’s deeply tied to the search for new technologies and energy sources,” said Catherine Fontana, a co-author of the article and a graduate student in the Department of Geological Sciences at ��Ҵ�ý�ƽ��.

To mark the new publication, she, Caro and their colleagues discuss what gets them excited about astrobiology—from the almost unbelievable things microbes can do to the fascinating chemistry that exists deep under Earth’s crust. They also share advice for students hoping to get into the field.

As an undergraduate, for example, co-author Kashyap double-majored in astronomy and biology. Then she realized the two subjects weren’t as different as she thought.

“I quickly learned that if I wanted to understand how life could be sustained elsewhere in the universe, I needed to step back and think about the processes that sustain life here,” said Kashyap, now a research associate at ��Ҵ�ý�ƽ�� and staff scientist at Blue Marble Space Institute of Science.

Microbial ingenuity

For Caro, much of the fun of being an astrobiologist is diving into the world of microbes.

“What really excites me about astrobiology is its focus on what you could call microbial ingenuity, the ways that they have crafted a variety of strategies to survive and thrive in environments that are hostile to larger organisms like us,” said Caro, now a postdoctoral researcher at CalTech.

He noted that scientists employ a DNA synthesis method known as polymerase chain reaction for countless applications, including COVID screenings and ancestry tests. Researchers first discovered the enzyme that is key to this process inside bacteria living in Yellowstone hot springs.

Fontana studies cyanobacteria, a class of single-celled organisms sometimes known as blue-green algae, that have existed on Earth for 3.5 billion years. Roughly 2.4 billion years ago, they played a key role in causing oxygen concentrations in the atmosphere to spike. Those changes paved the way for the rise of animals, plants and other animals.

Today, researchers are also exploring whether these microbes can become tiny factories—churning out biofuels, biocements and biodegradable plastics.

Elkassas, a co-author the article, explores methanotrophs, microbes that get their energy from methane gas. These microbes live in underground fluids below mud volcanoes in the Pacific Ocean and may absorb large volumes of methane from this environment.

Methane is a potent greenhouse gas and a major contributor to climate change. Some scientists are investigating whether methanotrophs and similar organisms may one day be able to help pull methane from the environment and store it safely underground.

“This research exemplifies the ‘dual approach’ to astrobiology by using studies of extreme environments to better understand carbon sequestration processes on Earth, while simultaneously informing how similar metabolisms might operate on other ocean worlds,” said Elkassas, who recently earned her doctorate from the MIT-Woods Hole Joint Program.

Sabrina Elkassas

Catherine Fontana

Alta Howells

In the dark

Howells, who led the perspectives article, has been on track to become an astrobiologist since she was a kid in Bozeman, Montana. She grew up visiting hot springs in Yellowstone and enjoyed watching science fiction staples like “Star Trek” and “Contact.”

“I remember being 8 years old and explaining to my aunt that life likely originated from the ocean as single cells, so this curiosity was ingrained in me from an early age,” said Howells, a research associate at ��Ҵ�ý�ƽ�� and research scientist at Blue Marble.

Today, Howells looks for strange new worlds not in outer space, but deep below Earth’s surface.

Get involved

Are you an undergraduate or graduate student who wants to take part in astrobiology research? Check out these links to learn more:

��Ҵ�ý�ƽ�� resources

Outside resources

Howells studies a process known as serpentinization. Deep underground, she explained, certain iron-rich minerals react with water to produce hydrogen gas. Companies around the world have kicked off a race to see if they can mine that gas to make fuel. When burned, hydrogen gas only releases water and not pollutants like carbon dioxide.

Scientists have also discovered microbes living amid those same minerals—an environment that is dark and completely devoid of oxygen, Kashyap said. Many of those microbes also consume hydrogen gas, making them potential competitors for this valuable resource.

“There is a really massive microbial biosphere that resides in these rocks and fluids in Earth’s subsurface,” said Kashyap, who also studies serpentinizing minerals. “We’re trying to understand how they could be a bane or boon for extracting energy from these systems.”

Anne Sheehan, chair of the Department of Geological Sciences, noted that ��Ҵ�ý�ƽ�� has long been a leader in astrobiology research.

“One of ��Ҵ�ý�ƽ�� major strengths in astrobiology is how we develop and train the next generation of scientists,” she said. “Our students and early-career researchers are leading work that spans geology, biology, chemistry and planetary science in ways that are shaping the field of astrobiology. They continue to amaze us.”

Cold water

The five early career researchers are all eager to see more young scientists join astrobiology.

Because this field explores the unknown, including some of the most remote and inhospitable (at least for humans) environments on Earth, astrobiologists never get bored, they said.

“Astrobiology forces me to keep learning something new,” Kashyap said.

Fontana decided to get into the field after “Googling on a whim” and stumbling across a resource called “The Astrobiology Primer.” When talking to students, she borrows an analogy from a friend who’s a competitive swimmer.

“My advice for students is to figure out what you're willing to jump into a cold body of water for at 5 a.m.,” she said. “That is your calling.”

A team of early-career researchers say exploring how life may have evolved on far-away worlds could lead to advancements on Earth—from new sources of clean-burning fuels to technology that can pull greenhouse gases from the air.

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One-of-a-kind 'plasma tunnel' recreates extreme conditions spacecraft face upon reentry

Daniel William Strain — Mon, 02 Feb 2026 17:29:02 +0000

One-of-a-kind 'plasma tunnel' recreates extreme conditions spacecraft face upon reentry Daniel William… Mon, 02/02/2026 - 10:29

Daniel Strain , Nicholas Goda

For astronauts, coming back to Earth is one of the most dangerous parts of any mission. A new research facility addresses that challenge by creating streams of gas that flow at thousands of miles per hour and burn at temperatures of thousands of degrees Fahrenheit.

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Astronauts are going back to the moon. Planetary scientist talks about what we can learn

Daniel William Strain — Mon, 02 Feb 2026 17:21:24 +0000

Astronauts are going back to the moon. Planetary scientist talks about what we can learn Daniel William… Mon, 02/02/2026 - 10:21

A rocket carrying the Orion spacecraft rolls out for the launch pad at NASA's Kennedy Space Center in Florida. (Credit: NASA)

Update March 13, 2026: NASA announced that it seeks to launch Artemis II by as early as April 1, 2026.

Soon, four U.S. astronauts are slated to begin their history-making journey to the moon and back. The astronauts, the crew of NASA’s Artemis II mission, will blast off from the Kennedy Space Center in Florida as early as Wednesday, April 1. From there, they’ll fly on the Orion spacecraft to the moon, circle it from high above, then return to Earth.

Artemis II marks the first time that humans will leave the safety of Earth’s orbit since the Apollo 17 mission of 1972. It’s a precursor to Artemis III, which plans to land humans on the lunar surface once more.

Read more:

Paul Hayne, a planetary scientist at the Laboratory for Atmospheric and Space Physics (LASP) at ��Ҵ�ý�ƽ��, has spent years exploring the moon’s mysteries. He’s investigated, for example, whether the cold, dark craters that dot the lunar surface might harbor stores of ice—which astronauts could mine for drinking water or to make rocket fuel, splitting apart the molecules within to create hydrogen gas.

��Ҵ�ý�ƽ�� Today spoke with the lunar researcher about the biggest unanswered questions about the moon, and what it can tell us about humanity’s place in the solar system.

“I'm really interested in the terra incognita of the moon, the places that are so dark and inaccessible that they're very difficult to explore,” said Hayne, an associate professor in the Department of Astrophysical and Planetary Sciences at ��Ҵ�ý�ƽ��.

Why is it important for humans to go back to the moon?

The moon records what's going on in our space environment throughout its history. Unlike Earth, which has experienced weather and erosion that has removed the history of asteroid and comet impacts, the moon preserves all that history over billions of years.

The moon, in a way, is the history book of the solar system.

Paul Hayne

Photo of the Orion spacecraft during NASA's Artemis I mission in 2022, which traveled to the moon and back without astronauts aboard. (Credit: NASA)

How will Artemis be different than the Apollo missions?

Artemis is an opportunity to go to one of the least explored places on the moon, near the moon's South Pole where there are deep, dark shadows inside craters that have never seen sunlight—at least not in the last several billion years.

Because of those dark shadows, the craters are extremely cold. Those permanently shadowed regions are the solar system's garbage collector. Anything that gets collected there doesn't go anywhere for billions of years. This is a treasure trove, scientifically, of things like water and carbon that that we can go and access.

Humans have been studying the moon for a long time. Is there still a lot we don’t know about it?

One of the big-picture science questions we want to answer through the Artemis program is: How did the moon form? This gets at the heart of some of the questions we have about the whole solar system: How did Earth form? How did the planets form?

We think that the moon formed through a giant impact—a Mars-sized protoplanet that collided with Earth very early in its history. It may have stripped off a huge chunk of Earth's interior, and then that material coalesced into what became the moon.

There are some big questions about that history that we need samples from different parts of the moon to answer.

How does your own research connect to Artemis?

A key aspect of the Artemis program is the synergy between science and exploration. NASA is not only sending astronauts through the Artemis II, III and IV missions and beyond, but it’s also sending precursor missions that are using robotic explorers in the form of landers and rovers carrying scientific experiments.

The scientific experiments that I'm involved with include things like searching for ice at the poles of the moon. We have an infrared camera developed here in Boulder, Colorado, that will be deployed near the moon's South Pole. It's called the Lunar Compact Infrared Imaging System, or L-CIRiS. This is a heat-sensing camera that will look for the coldest places where we might identify the conditions for ice to exist.

How is this research critical for humans actually staying on the moon?

The moon, without an atmosphere, has extreme temperature variations—from higher than boiling temperatures in the sunlight to just 15 or 20 degrees above absolute zero in the deep, dark shadows. These are extreme temperature ranges that anything on the surface, including astronauts, will have to contend with. We’re studying the thermal environments by using instruments like L-CIRiS.

Why does space exploration inspire you?

It really takes the combined efforts of our whole society to do these kinds of things. To paraphrase John F. Kennedy, ‘We choose to go to the moon not because it's easy, but because it's hard.’

Doing so demonstrates that we do have the ability as a society to do things that are challenging—not just for the astronauts, but also for all the people, supporting them in this kind of grand project. I think that shows that we can do other hard things as a society.

��Ҵ�ý�ƽ�� Today regularly publishes Q&As on news topics through the lens of scholarly expertise and research/creative work. The responses here reflect the knowledge and interpretations of the expert and should not be considered the university position on the issue. All publication content is subject to edits for clarity, brevity and university style guidelines.

The crew of NASA's Artemis II mission are slated to launch for the moon in March. ��Ҵ�ý�ƽ�� researcher Paul Hayne talks about why it's important for humans to return to the moon—and search for water in its shadowy craters.

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What are the little red dots deep in space?

Megan M Rogers — Tue, 27 Jan 2026 16:33:51 +0000

What are the little red dots deep in space? Megan M Rogers Tue, 01/27/2026 - 09:33

Colorado Arts and Sciences Magazine

CU researchers worked with an international team to uncover more about the mysterious objects detected by the James Webb Space Telescope.

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A 'generationally defining moment': 40 years later, NASA alum reflects on Challenger disaster

Amber Carlson — Mon, 26 Jan 2026 17:08:29 +0000

A 'generationally defining moment': 40 years later, NASA alum reflects on Challenger disaster Amber Carlson Mon, 01/26/2026 - 10:08

Amber Carlson

The Challenger space shuttle is transported to the launch pad in December 1985, about a month before the fateful launch. (Credit: NASA)

On Jan. 28, 1986, NASA’s Challenger space shuttle disintegrated 73 seconds after launching from the Kennedy Space Center. All seven crew members aboard, including ��Ҵ�ý�ƽ�� alumnus Ellison Onizuka (AeroEngr ’69), tragically lost their lives.

David Klaus, professor emeritus from ��Ҵ�ý�ƽ�� Ann and H.J. Smead Department of Aerospace Engineering Sciences, started his career with NASA and was a shuttle launch control engineer at the time (although he did not work the Challenger mission).

��Ҵ�ý�ƽ�� Today spoke with Klaus about his memories of that day, the legacy of the crew and crucial lessons learned from the tragedy.

Where were you on the day of the Challenger incident?

NASA had plans to start launching Air Force payloads off the West Coast at Vandenberg Air Force Base in California in July of 1986. I was training to be on the Vandenberg launch team, and I would have been on the Challenger launch console, but I had just gone out to California for some work out there. So I was at the Vandenberg launch site when the Challenger launched from the Kennedy Space Center in Florida.

We happened to be sitting in the launch control center at Vandenberg. We pretty much saw what everybody else watching TV saw, although we could hear the comms loops. We could hear what was going on.

When did you realize that something was wrong?

All I saw was that infamous image with the solid rocket boosters going off in two directions. I was pretty new in the game at that point, so I didn't have a lot of insight. But I was sort of in disbelief at first. You don't really comprehend what you're seeing. It just doesn't look right. Something looks wrong. Your brain’s trying to process what's going on. But we realized pretty quickly that this was a bad event.

What caused the shuttle to break apart?

The actual root cause of the failure was the O-rings (gaskets) that keep the propellant pressure contained inside the two rockets. It was really cold in Florida that day, and my understanding is that the cold weather made the seals brittle. Because they were brittle, they allowed gas pressure to escape, and the escaping gas pressure is ultimately what caused the destruction of the vehicle.

The Challenger crew members are pictured in November 1985, about two months before the tragedy. Back row, from left: Ellison Onizuka, Sharon McAuliffe, Greg Jarvis and Judy Resnik. Front row, from left: Michael Smith, Dick Scobee and Ron McNair. (Credit: NASA)

What lessons were learned from the Challenger?

For every NASA mission, when something goes wrong or is unexpected, it gets documented as ‘lessons learned’, and you work to make sure it doesn't happen again. You either change operational requirements, or you change the design, or both.

After the Challenger accident, for example, NASA has had tighter weather criteria for launch. And they added heater strips around the O-ring joints on later flights as part of a redesign. So both operational and design changes were made.

It's a high-risk endeavor to start with, putting people into space. And I think it became very apparent at that point. The Challenger was the first in-flight fatal accident that had occurred in NASA's history. In the space domain, there are a lot of unknown unknowns, and those are the ones that can cause the biggest problem. But once they happen, they're not unknown anymore, and now you've got something you can design toward.

How do you view the legacy of the Challenger crew?

The Challenger incident was one of those generationally defining moments. It was a reminder that life is risky. If you're pushing the envelope, you accept the risks, and you do the best you can to mitigate those risks. But you can't ever make them go away. So the crew’s legacy was maybe a heightened awareness of the risk of space flight, but also the importance of continuing to go to space even when catastrophic events do occur.

Looking back 40 years later, what stands out the most about the Challenger?

The technical lessons learned made me start thinking more about risk analysis. It's one thing to design a vehicle that can meet all the needs and do the job, but once you get to that point in the design process, you now go back and start looking at it and saying, ‘What can go wrong? What happens if it goes wrong, and what can we do about it if it does go wrong?’

The human aspect, of course, goes without saying. These were some pretty outstanding individuals, and their lives were tragically cut short. But on the other hand, I don't think they would have stepped aside. Everyone understood that there was risk. The degree of risk might have been debatable, but anytime you're launching people into space—anytime you're walking across the street, for that matter—there's a degree of risk that you accept in your life to do what you want to do.

David Klaus

If you were speaking to young engineers now, what would you want them to understand?

When you're the one designing the rockets or the habitats or any of the infrastructure, pay attention to the details. Don't take shortcuts. Try to think beyond just ‘Here's an answer that's good enough.’

Consider risk analysis from the very beginning of the design. Think about all the things that can go wrong and try to design something that is what we call either fault tolerant or redundant. So, if something breaks, can the system continue working? Or do you have another way that you can provide that function in place of the thing that broke?

Think about what needs to be done and break it down into the functions that have to be accomplished to make that happen. Then brainstorm different ideas—not just one solution, but as many as you can come up with. And then work to find an optimal balance of risk and complexity from that process.

A former NASA engineer and retired aerospace engineering professor reflects on lessons learned from the space shuttle tragedy.

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Leading hands-on Earth research planning for life on Mars

Megan M Rogers — Fri, 23 Jan 2026 20:08:16 +0000

Leading hands-on Earth research planning for life on Mars Megan M Rogers Fri, 01/23/2026 - 13:08

Ann and H.J. Smead Department of Aerospace Engineering Sciences

��Ҵ�ý�ƽ�� carried out major research at the Mars Desert Research Station, a facility that gives scientists and engineers the opportunity to conduct complex experiments in a Mars-simulation habitat.

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New study examines a gravitational wave mystery

Daniel William Strain — Wed, 07 Jan 2026 18:26:52 +0000

New study examines a gravitational wave mystery Daniel William… Wed, 01/07/2026 - 11:26

Daniel Strain

Image collected by the Hubble Space Telescope of an object called NGC 2623, which is made up of two galaxies in the final stages of merging together. (Credit: ESA/Hubble & NASA)

Scientists at the University of Colorado Boulder may have solved a pressing mystery about the universe’s gravitational wave background.

That’s the name for the ripples in space and time that move constantly through the cosmos and “jiggle us almost like Jell-O,” according to ��Ҵ�ý�ƽ�� astrophysicist Julie Comerford.

The study, published recently in “The Astrophysical Journal,” reveals new insights into the evolution of the universe—namely, how smaller galaxies may have coalesced over billions of years to form larger and more complex galaxies like the Milky Way.

Comerford explained that, at any one time in the universe, countless galaxies are in the process of merging.

Each of those galaxies has an aptly named supermassive black hole at its center. As galaxies merge, these black holes spin around each other, whipping in circles until they eventually smack together. The resulting collisions create waves in space and time that are so subtle humans never feel them.

Artist's depiction of the gravitational wave background. (Credit: NANOGrav collaboration; Aurore Simonet)

“You can picture lots of people in a swimming pool,” said Comerford, lead author of the new study and professor in the Department of Astrophysical and Planetary Sciences at ��Ҵ�ý�ƽ��. “They’re all creating their own waves, and the waves overlap. That’s what the gravitational wave background is like.”

In 2023, several international collaborations, including the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) experiment, reported that they had detected the gravitational wave background for the first time.

There was just one problem: Based on the groups’ measurements, those waves were much larger than scientists had estimated. No one knew why.

In the new study, Comerford and study co-author Joseph Simon, a former postdoctoral researcher at ��Ҵ�ý�ƽ��, may have found the explanation.

Using observations of real galaxies and computer simulations the team discovered something that researchers hadn’t accounted for: When a smaller supermassive black hole merges with a larger one, the smaller black hole seems to gain a lot of mass.

That extra mass makes a difference. Just like swimmers doing cannonballs in a pool, larger supermassive black holes produce larger gravitational waves.

“We had a prediction for what the gravitational wave background should be, and what NANOGrav found was larger than expected,” Comerford said. “It was a surprise and a fun new puzzle to figure out.”

Growth spurts

Supermassive black holes, like galaxies themselves, come in all sorts of sizes. Some of these celestial objects are truly humongous, with a mass equal to billions of Earth’s suns. Others are still big, but slightly less so, with a mass millions of times larger than the sun.

Julie Comerford

For years, many scientists studying the gravitational wave background didn’t believe those smaller black holes mattered, Comerford said. They were too little, the thinking went, to make a meaningful contribution to the gravitational wave background.

Comerford and Simon weren’t so sure.

In part, that’s because galaxy mergers can be messy affairs. When two galaxies come together, gas from those galaxies begins to funnel toward the supermassive black holes at their centers. This gas forms a doughnut-shaped cloud outside the black holes spiraling around each other. Some of that gas falls back into the black holes and makes them larger in the process.

But previous simulations suggested something surprising: The black holes in a merging pair may not grow at the same pace.

“The more massive black hole sits closer to the center of the doughnut where there isn’t much gas,” Comerford said. “The smaller black hole is further out, so it’s closer to where the gas is.”

The beginning

That difference in growth rates, or what the scientists call “preferential accretion,” could matter a lot.

In the current study, Comerford designed a detailed set of equations capturing the physics of how galaxies merge. The group then adjusted those equations to make smaller black holes grow 10% more than larger ones.

That single tweak was enough to make estimates of the gravitational wave background line up with measurements from the NANOGrav experiment.

“They start out little, but because the little ones grow the most, they shouldn’t be discounted,” Comerford said.

She noted that the study doesn’t completely solve the mystery: Her team has launched a new effort to observe real galaxies in the act of merging to see if their physics line up with what the simulations found.

The effort, she said, is part of a larger push to understand some of the most fundamental questions about the universe. That includes how “primordial” galaxies at the dawn of the universe, which were tiny and made up mostly of gas, may have built the gigantic black holes that exist today.

“I’ve spent my career studying supermassive black holes, and we don’t even know how they form,” Comerford said.

Ripples in space and time constantly churn through the universe, forming what's called the "gravitational wave background." A new study examines why these waves are so much bigger than scientists once predicted.

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Space

LASP scientists appointed to NASA astrobiology task force

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���Ҵ�ý�ƽ������ resources

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Cold water

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Astronauts are going back to the moon. Planetary scientist talks about what we can learn

Why is it important for humans to go back to the moon?

How will Artemis be different than the Apollo missions?

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How does your own research connect to Artemis?

How is this research critical for humans actually staying on the moon?

Why does space exploration inspire you?

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What are the little red dots deep in space?

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A 'generationally defining moment': 40 years later, NASA alum reflects on Challenger disaster

Where were you on the day of the Challenger incident?

When did you realize that something was wrong?

What caused the shuttle to break apart?

What lessons were learned from the Challenger?

How do you view the legacy of the Challenger crew?

Looking back 40 years later, what stands out the most about the Challenger?

If you were speaking to young engineers now, what would you want them to understand?

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