The night sky seems eternal and unchanging. But in cosmic time, nothing could be further from the truth.
Vasily Belokurov is one of three winners of the 2026 Kavli Prize in Astrophysics. The award is for uncovering fossil evidence of past galactic mergers that prove how the Milky Way evolved.
No matter the time or vantage point, from a pre-Neolithic cave to a post-lockdown London high-rise, the predictability of the night sky has always been humanity’s symbol of permanence and reassuring stability.
Yet this apparent calm is deceptive. Our galaxy, the Milky Way, emerged from chaos and turbulence, and its constellations are full of migrants, exiles and survivors. Right now, it has begun to stretch and distort again, pulled by a massive companion and heading for an inevitable collision.
How can I be so sure? As a galactic archaeologist, my job is to reconstruct the past of our galaxy and read the signs of its future.
Instead of digging through soil, I use the laws of dynamics and stellar evolution to sift through hundreds of millions of stars—searching for the most ancient and chemically peculiar among them, interpreting their orbits and piecing together the events that shaped the Milky Way. One ancient encounter left scars so deep that, billions of years later, they still define the galaxy around us.
I want to understand what governs the lives of these massive cosmic systems: which changes are nature—the slow internal evolution of a galaxy disk—and which are nurture, imposed by collisions and mergers.
Questions about the source of dark matter underpin it all. This is the invisible substance whose gravity holds galaxies together, but whose true identity remains one of the greatest unsolved puzzles in astrophysics.
The Milky Way is the one galaxy where stellar motions can be measured in extraordinary detail. This allows cosmologists including myself to construct our most precise map yet of dark matter: how far it reaches, how dense it is around the sun, what shape it has, and how smooth or lumpy it may be. If we can build this map in enough detail, we may begin to understand not just where dark matter is, but what it is.
A Cataclysmic Collision
Our work has been transformed by a revolution in open sky surveys. From 2000, the Sloan Digital Sky Survey showed what becomes possible when vast astronomical datasets are made public, enabling discoveries far beyond the goals for which the survey was first built.
And since 2014, Gaia, the European space telescope, has taken this transformation to another level by mapping the positions and motions of nearly 2 billion stars, turning the galaxy into a vast archaeological record. No ruins, no shards, and no bones—only stars that hold the clues.
The clearest giveaway that something cataclysmic took place long ago in our galaxy is the migrants we observe: stars that were not born in the Milky Way.
While native stars mostly travel together, circling the galactic center in the great rotating flow of the disk, migrants cut across that order. They slide past the locals, plunge into the inner galaxy, then fly back out to its outskirts, again and again.
These unusual orbits go hand-in-hand with unusual chemistry. Most of the migrant stars are less enriched in heavier elements than the locally born population. Their chemical composition is a sign of a slower rate of evolution that is typical of a dwarf galaxy.
This makes the migrants doubly valuable. They are both fossils of the Milky Way’s violent past and probes of its outer regions, traveling where the local stars rarely go.
How the Milky Way Was Rewired
One of the central ideas in the theory of cosmic structure formation is that galaxies grow hierarchically. Smaller galaxies fall into larger ones and are torn apart, leaving their stars behind as migrants.
In the Milky Way, the largest ancient structure of this kind is known as Gaia-Sausage-Enceladus. It is the remains of a vanished galaxy that collided with our own between 8 and 11 billion years ago (the “sausage” refers to a pattern in its stars’ motions).
The Milky Way also did not go through that crash unscathed. The collision rewired and reshaped it.
Some of these changes are easily visible in the data. Stars from the old disk were splashed into our galaxy’s halo, becoming exiles in the place where they were born. A new posse of star clusters were also acquired.
At the same time, we think something even more momentous was taking place. The encounter changed the orientation of the Milky Way’s disk, and its alignment with the dark matter halo.
Around the Milky Way, this dark matter forms a vast halo, much larger than the luminous part of our galaxy. We often imagine this halo as a sparse, round cloud, but Gaia has helped show this picture is too simple.
The dark halo can be stretched out of shape by a major encounter. Like a ship beginning to list, the Milky Way started to lean—not suddenly, not visibly, but over billions of years.
View of the Southern sky shows the Milky Way and (far right, close to horizon) two galactic neighbors, the Small and Large Magellanic Clouds. H.H. Heyer/ESO via Wikimedia Commons, CC BY-NC-ND
A New Galactic Dance
Unusually, compared with many galaxies of similar mass, the Milky Way was allowed ample time to recover from the shock of the “sausage merger.” No other cosmic cataclysm appears to have shaken our galaxy since, letting it settle into a quiet, uneventful life. That is, until now.
The Large Magellanic Cloud (LMC), currently our galaxy’s most massive companion, is already pulling at the Milky Way, disturbing its halo again. In an echo of what happened some 10 billion years ago, the Milky Way is being drawn into an accelerating dance with this neighboring dwarf galaxy, recoiling in response to the LMC’s approach.
This is a dance that only one galaxy is likely to survive intact. A new chapter of migration, survival and adaptation has begun.
None of this spoils the beauty of the night sky—it deepens it. The calm band of light above us is not a symbol of permanence, but the visible reminder of a long survival.
The Milky Way has been broken, rebuilt, and is now being disturbed again. Its stars remember the past; their motions reveal the future. What looks eternal is, in truth, a moment in a much longer story.
There’s a vast difference between launching satellites and operating an industrial-scale computing infrastructure in orbit.
Imagine if one company could become the railroad, electric utility, and cloud-computing provider of the emerging space economy. That potential fueled excitement around the long-anticipated initial public offering of SpaceX. Investors are not simply betting on rockets anymore. They are betting on an entire orbital ecosystem.
Among the most ambitious and challenging ideas riding this wave of enthusiasm is something that sounds almost like science fiction: orbital data centers. SpaceX may be one of the most well-known companies seeking to build them, but it is not the only one.
But there is a vast difference between launching satellites and operating an industrial-scale computing infrastructure in orbit. Space is unforgiving. Radiation damages electronics. The electronics generate enormous amounts of heat, and getting rid of that heat is surprisingly difficult in space. Repairs are extraordinarily expensive, and every pound launched into orbit still carries a significant cost.
First off, consider what goes into an Earth-based data center, like those that you’ve probably begun to see pop up everywhere. These facilities power cloud computing, video streaming, online banking, scientific computing, and increasingly, artificial intelligence. But a data center is much more than a room full of servers.
A data center needs several things to operate reliably. The first is electric power. Servers, networking equipment, and storage devices consume large amounts of electricity, and that power demand is growing rapidly with AI.
The second is cooling. Almost all the electricity consumed by servers eventually becomes heat. If that heat is not removed quickly and reliably, equipment performance drops, failures increase, and the data center can shut down. Cooling systems often include air handling units, chillers, cooling towers, pumps, and increasingly, liquid-cooling equipment. In many facilities, cooling is the largest energy consumer after the computing equipment itself.
The third is physical infrastructure, including the necessary land, buildings, structural support, backup power, water systems, communication networks, and maintenance access. Data centers also need to be close enough to users and network backbones to provide fast digital services.
In short, Earth-based data centers are large electrical and thermal infrastructure systems built around computing hardware.
Placing Them in Space
So what would it take to build these data centers in space, and why are companies finding this possibility such an interesting business proposition?
As on Earth, these data centers would require massive amounts of power. In space, this power would come from solar panels. The sun always shines in space and can’t be blocked by clouds. However, depending on the orbit the solar panels are put in, the Earth may shadow them for some portion of the orbit.
Another potential advantage found in space is cooling. The cold background of space (roughly -455 degrees Fahrenheit, or -270 degrees Celsius) creates an opportunity: Waste heat from the data center could escape into space through radiators, keeping the electronics cool.
In principle, that design could eliminate some of the bulky and water-intensive cooling infrastructure used on Earth. However, those thermal radiators would require a large amount of surface area, and that would be in addition to the area required by the solar panels.
In space, there is no air to blow across hot equipment and help heat escape. The heat has to leave as infrared radiation, which is a relatively slow process. As a result, removing 10 megawatts of waste heat can require radiator surfaces comparable to the size of two football fields.
A space-based system would avoid competing for local land and water resources, and it would not generate neighborhood noise or require local zoning approval in the same way.
However, space is already getting crowded, and launching thousands of large orbital data centers would accelerate this issue. Orbital debris and micrometeorites are hazards because they can puncture the space data center, and a worst-case collision could destroy it and create even more space debris.
The frequency of space launches necessary to send all the equipment to orbit may also become a concern for some communities. SpaceX has had protests at its launch complex in Boca Chica, Texas from local activists who argue its rocket testing and launches damage the surrounding environment.
All that data would need to be sent between Earth and these data centers—and between the data centers themselves—using radio waves or laser communications systems. Although satellite constellations such as Starlink and Amazon Leo have demonstrated that doing this is possible, the amount of data sent to and from space would balloon.
Additional Challenges
These data centers, along with their solar panels and radiators, cannot be launched in one piece and would need to be assembled in space. This process would require new equipment for in-space servicing, assembly, and manufacturing.
Another key challenge is the refresh cycle of computing hardware. Data-center servers are not built to last forever. Operators on Earth usually replace or upgrade hardware every three to five years as chips improve, workloads change, and equipment ages.
And equipment failures can require replacing components. The refresh and repair processes are relatively straightforward on Earth, where workers can physically remove and replace servers.
In space, refresh and repair becomes much harder. Hardware sent to orbit may be difficult or too expensive to upgrade. If the computing platform cannot be updated, or too many components fail, it may become obsolete long before the surrounding infrastructure reaches the end of its useful life.
In a field where performance improves so rapidly and demand from computing continues to increase, this hurdle could prove a major economic and operational challenge.
Then there is the harshness of space. These data centers would be in a near vacuum, with constant radiation hitting them. And depending on their orbit, they would go from hot when in the sunlight to cold in Earth’s shadow many times a day. All of these challenges, and more, are issues that will need to be addressed.
So, Do They Still Make Sense?
Despite these challenges, companies are moving forward with designing space-based data centers. SpaceX just announced the design for its AI1 Compute Satellite, which it hopes to use as an orbital data center spacecraft. However, this satellite is 100 to 1,000 times less capable than current Earth-based data centers.
Not every computing task makes sense to do in space. Many data center applications depend on fast response times and close connections to users on Earth. Financial transactions, interactive AI services, and most cloud applications are extremely sensitive to delay.
More feasible early applications may be those that are less latency-sensitive and more tightly connected to space operations. Examples could include processing Earth observation data from satellites, military or intelligence data processing, scientific computing related to space missions, or specialized computing for satellites and other space assets.
In other words, the first viable space data centers may serve space-based customers before they compete with mainstream cloud data centers on Earth.
A tiny robot developed by Japan’s space agency operated autonomously on the moon for more than 100 minutes and sent a series of images back to Earth.
Exploring the moon’s surface lays crucial groundwork for future crewed settlements, and swarms of tiny robots could be the key. Now researchers have given the first demonstration of the idea after a palm-sized rover autonomously navigated the moon and transmitted images back to Earth.
The moon is a tough environment for robots. Its surface is strewn with craters and abrasive moon dust, and communication delays make remotely piloting vehicles a painstaking and risky process. The cost of launching and landing hardware and the real prospect of losing expensive equipment justifies an extremely cautious approach that can significantly slow down exploration.
One way around these challenges is to replace traditional rovers with many small, cheap, and hardy robot explorers, which could increase coverage and introduce redundancy. And now Japan’s space agency JAXA has given us the first compelling demonstration of the approach.
In a paper published in Science Robotics, JAXA researchers provide a technical report detailing the successful deployment of the agency’s LEV-2 robot during the its SLIM mission, which touched down near the Shioli crater in January 2024. LEV-2 is a three-inch-wide sphere that converts into a wheeled robot after landing. The robot operated autonomously for more than 100 minutes, covering an estimated 24 meters and relaying a series of images back to Earth.
“Although the capabilities of an individual small rover are inherently limited, the results highlight the potential of such platforms as independent explorers, capable of accessing environments beyond the reach of a primary large spacecraft,” the authors write.
Nicknamed SORA-Q—derived from the Japanese words for space and sphere—the robot weighs just eight ounces. Upon arrival, the shiny metal sphere splits open and expands horizontally, allowing its two hemispheres to become wheels that spin around a central shaft. This central area also features a front-facing camera and a tail to help stabilize the robot.
JAXA developed the device in partnership with Sony and toymaker TOMY. The design borrows directly from technology used in transformer toys that convert from vehicles into robots. But the team had to make considerable modifications to account for the harsh lunar environment.
One of the biggest challenges for any lunar robot is maneuvering in the dust, or regolith, that coats the moon’s surface. The fine, powdery material can be hard for smaller wheeled robots to navigate as they lack the traction of their larger counterparts.
To solve this problem, the team designed the wheels to rotate around a point slightly offset from their center, causing a lopsided spinning motion that lifts the rover up slightly on every rotation. This helps the wheels to dig into the surface and generate enough traction to keep moving in the loose regolith.
Communication delays also present a significant barrier to smooth operation, so the team engineered the robot to handle most operations autonomously. An onboard image-processing system allowed the rover to detect the SLIM lander in its camera feed and use this as a navigational reference point, estimating its own position relative to the spacecraft in real time.
Because of its diminutive size, it was impractical to give SORA-Q the equipment needed to communicate directly with Earth, so the team paired it with a hopping robot called LEV-1 that can transmit data. Power constraints and narrow communication windows still cap the amount of data the robot can send to Earth, so SORA-Q has an onboard image-processing algorithm that picks out the best photos to share.
Due to power and mass constraints, the team fitted the robot with a low-power chip designed for small devices rather than complex tasks like image processing. The algorithm relies on a very simple approach—it detects the SLIM lander’s distinctive gold insulating material and then picks the photos where this is featured prominently in the frame.
Around seven minutes after activation, the rover had moved roughly five meters from the lander, selected the two best images from 12 it had captured, and transmitted them to LEV-1. One of those images actually proved unexpectedly useful as it showed the lander had landed at an odd angle with its solar panels facing the wrong direction. This gave ground teams critical information that helped them diagnose the spacecraft’s operational status.
Image SLIM lander taken by LEV-2. Image Credit: JAXA/TOMY/Sony Group Corporation/Doshisha University
But the system wasn’t flawless. It lost some data in transmission, partly because LEV-1’s hopping maneuvers appeared to disrupt the wireless link and partly due to changing antenna orientations as the rover moved. The team also lost telemetry data before the mission ended, making it impossible to determine exactly how far the rover ultimately traveled or when it stopped working.
Still, the mission was strong evidence that small, cheap vehicles like SORA-Q could greatly expand the scope of robotic exploration. That could prove invaluable as we attempt to scope out promising locations for future scientific missions or even permanent bases on the moon.
A planetary defense system would blunt solar storms with hundreds of tons of gas. Emerging heavy-lift rockets could deploy it in under two months.
Extreme space weather could wreak havoc on the satellites, communications networks, and electrical grids that modern society depends on. Researchers have now proposed an ambitious space-based planetary defense system that would weaken solar storms before they hit Earth.
The sun regularly emits massive pulses of radiation, energetic particles, and magnetic fields that interact with the Earth’s own magnetic field. This activity is the source of auroras like the northern lights, but the most violent eruptions can cause geomagnetic storms with the power to disrupt GPS and radio communications and fry electrical equipment.
While the impact of most of these events is limited, there is precedent for more catastrophic outcomes. In 1859, the Carrington Event, the most powerful solar storm ever recorded, knocked out telegraph lines across North America and Europe. In today’s highly electrified world, a similar event could cause between $2.4 and $3.4 trillion in damage to the power grid alone.
Now, researchers at Boston University and the University of Michigan have come up with a potential solution. In a paper published in Space Weather, they propose a constellation of satellites called StormWall that would release hundreds of tons of gas into orbit to blunt the force of an incoming solar storm.
“It’s as if you could install an airbag in the magnetosphere,” co-author Daniel Welling, a space physicist from the University of Michigan, told Science.
Solar storms have the potential to sow chaos because they weaken the magnetic shield protecting Earth from space radiation. Powerful enough storms disrupt the Earth’s magnetic field and cause it to reconnect to the sun’s, allowing energy from the solar storm to pour into the magnetosphere.
The Earth already has a natural defense against this—a doughnut-shaped reservoir of ionized gas, or plasma, sitting just above the atmosphere. When the planet’s magnetic field is disturbed, a plume of this plasma flows toward the sun and slows the rate at which the magnetic fields reconnect.
StormWall would turbocharge this process by releasing massive amounts of artificial plasma into the outer atmosphere. The researchers sketch out a system involving a constellation of satellites orbiting about 22,000 miles from Earth. The satellites would carry canisters of lithium, barium, or sodium gases to be ejected when a large solar storm is inbound. The gases, rapidly ionized by solar radiation, would add to the planet’s natural plasma shield.
Based on simulations, the researchers estimate that releasing around 400 tons of gas could reduce the strength of a major geomagnetic storm by over 50 percent. Crucially, the intervention would be swift and reversible. The plasma cloud could be in position by the time a storm hits, and it would dissipate just a few hours later.
Launching this much material into orbit would be a big undertaking, but the researchers say it could be within reach of emerging heavy-lift vehicles like SpaceX’s Starship or China’s Long March 9 rocket. They calculate that six launches could deploy the full constellation in under two months.
Outside experts have been broadly positive. Allison Jaynes, a space physicist at the University of Iowa, told Science the idea was “highly innovative and appears to be quite feasible in the near term.”
But getting the satellites into orbit is only part of the puzzle. Accurate and timely space weather forecasts would also be a prerequisite. And gaining international buy-in for a system that would drastically alter the near-Earth space environment, even if only temporarily, could be challenging.
The researchers flag potential side effects that need more study, including the generation of electromagnetic waves as the released material ionizes. Still, given the devastation a Carrington-sized event could unleash on the modern world, the potential downsides may be worth the risk.
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