Month: March 2026

A strange lack of stellar orbits around the core of the Small Magellanic Cloud (SMC) puzzled astronomers for decades. In addition, the SMC has a strange, irregular shape and exhibits a tidal current. Now a team of observers led by graduate student Himansch Rathore from the University of Arizona has discovered the reason why the stars don’t orbit. This is because the SMC crashed in the distant past directly through its neighbor, the Large Magellanic Cloud (LMC). This massive collision disrupted the star’s movements and sent them on completely different trajectories. It also disrupted the gas clouds within the SMC, creating a gas tail that stretched across space.

The team’s work provides unique insights into the way galaxies change over time. “We see a galaxy changing in live action,” Rathore said. “The SMC gives us a unique front-row view of a very transformative process that is critical to the evolution of galaxies.”

A closer look at the SMC

The Small Magellanic Cloud is a member of a trio of interacting galaxies that includes the Large Magellanic Cloud and our own Milky Way. The SMC is about 200,000 light-years away, while the LMC is about 158,000 light-years away. Both have sites of active star formation. The SMC is categorized as a dwarf irregular galaxy and has a mass equivalent to about 7 billion solar masses. However, not all of the mass is contained in stars. Most of the SMC’s mass is contained in huge clouds of gas that eventually become star formation sites. This happens when the clouds cool and gather. When conditions are right, this process creates hot, young stars that astronomers can study to understand the star formation process.

This visible light mosaic shows the LMC and SMC in relation to the plane of our own galaxy, the Milky Way. Dusty filaments create dark trails on the Milky Way’s bright midplane, visible at the top of the image. Below, about 21 degrees apart, lie the LMC and SMC, the closest large galaxies to our galaxy. The LMC and SMC orbit each other as well as our own Milky Way Galaxy. Photo credit: Axel Mellinger, Central Michigan University (via NASA Goddard Scientific Visualization Studio).

Astronomers have measured the movement of stars existing in the SMC using data from the Hubble Space Telescope and the Gaia mission. They discovered that the stars of the SMC do not orbit around the center of this galaxy like the stars in most other galaxies. This lack of orbital activity was puzzling until Rathore’s team thought about the impact of a collision on the SMC and LMC. A few hundred million years ago, the SMC crashed directly through the disk of the LMC. The LMC’s gravity destroyed the SMC’s internal structure and sent its stars into random, disordered motion. In addition, the gas in the LMC exerted enormous pressure on the gas of the SMC, destroying its gas rotation.

Because the LMC, SMC, and the Milky Way interact with each other, astronomers want to understand how this interaction affects all three galaxies. Astronomers found a gas bridge between the LMC and SMC, which was likely pulled from one of the galaxies during tidal interactions between the two galaxies. This bridge is busy forming stars in the shocked gas.

Large and small Magellanic clouds from GAIA data. Image credit: ESA/Gaia/DPAC – CC BY-SA 3.0 IGO.

Solve the mystery of disturbed stellar orbits

According to Gurtina Besla, a senior author of an article on the finding, the crash between LMC and SMC caused great damage to both. “The SMC experienced a catastrophic crash that injected a lot of energy into the system. It is by no means a ‘normal’ galaxy,” Besla said. To understand this crash, the team turned to computer simulations. First, they compared the known properties of the SMC and the LMC – their gas content, the star’s total mass and their positions relative to the Milky Way. They combined the simulations with theoretical calculations of how the collision affected the SMC’s gas as it plowed through the LMC’s dense gas environment. They also developed new methods for reading the scrambled stellar motions in a post-collision galaxy, tools that can now be used to properly interpret what telescopes are actually measuring in the SMC.

This is important because the SMC is small, gas-rich and poor in heavy elements – properties that made it a standard benchmark for the types of galaxies that existed early in the universe. A galaxy still affected by a collision may not be a clean reference point, Besla said. However, it can shed light on what impact collisions and interactions have had on galaxies over time.

This diagram shows the simulated gas distribution of the Magellanic System resulting from the tidal encounter between the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) as they orbit our home galaxy, the Milky Way. The solid line shows the calculated path of the LMC and the dotted line is the path of the SMC. Plot by G. Besla, background image of the Milky Way by Axel Mellinger (used with permission)

Other effects of a collision

Another study published by the team in 2025 showed that the collision also left a physical trace on the LMC that could help scientists study dark matter. At the center of the LMC is a rod-shaped structure that has tilted out of the plane of the galaxy due to the collision. Rathore, the lead author of the 2025 study, said the degree of tilt depends on how much dark matter the SMC contains, giving researchers a new way to measure a substance that has never been directly detected but could only be inferred from its gravitational effects.

“We are used to thinking of astronomy as a snapshot of time,” Rathore said. “But these two galaxies came very close together, passed right through each other and turned into something else.”

In addition, the interaction between the LMC, SMC and the Milky Way influences the shape of our galaxy. It appears that the LMC causes a deformation in the shape of the Milky Way’s star disk. It also pulls on our galaxy’s core, disrupting the halo and accelerating its speed through space. The SMC also contributes to this warping and pulling, contributing to the formation of the Magellanic Current. This is a trail of gas and stars that contributes to the colonization of the Milky Way.

More information

A Galactic Transformation – Understanding the Structural and Kinematic Imbalance of the SMC

A galaxy next door is changing, and astronomers can see it happening

This is part 4 of a series on topological defects. Read parts 1, 2 and 3.

That what? Yes, the Vortons. It’s not an anime monster hunting show. It is not an AI startup company. It’s a… it’s a thing. I find.

Listen, what I’m about to tell you is so hypothetical that even a string theorist might blush. Here we are deep in the annals of physics. I don’t want you to trust ANYTHING I’m about to say.

But that has never stopped us. So why stop now?

You see, cosmic string loops are supposed to be suicidal. They are these high voltage whips of spacetime that vibrate and oscillate so quickly that they SCREAM gravitational waves until they disappear into nothingness. Usually that’s the end of the story. The loop shrinks, it disappears and the universe is defective.

But that doesn’t HAVE to be the end of the story. I mean, cosmic strings are super hypothetical themselves, so we have a few possibilities.

Imagine a cosmic loop of strings that doesn’t just vibrate. It also rotates. Really, really fast. Why should they rotate? Why NOT, buddy? Who are you to say they could never turn? And when they spin, they have angular momentum (that’s kind of the definition). But as the loop releases energy, it becomes smaller. But you can’t just get rid of the angular momentum. This means that the smaller it gets, the faster it spins. And at a certain point, that internal spin is so strong that it begins to push OUTWARD.

That creates tension. The loop wants to shrink in on itself from its own tension. But the spinning mill wants to expand it again.

When these two forces find a perfect balance, shrinkage stops. The loop does not evaporate. It doesn’t disappear. It forms a permanent, indestructible, subatomic ring of pure field energy.

We call this a pretone. It is a small lump of cosmic thread, a defect that stubbornly refuses to disappear in this long night.

Oh, and it could be dark matter.

We don’t know what dark matter is, but we know what it does. It must be a particle or something like a particle. It must be hard. It has to be almost invisible. And it must have been there since the earliest moments of the Big Bang for it to take part in all the building of the cosmic web that it is so good at.

A pretone is…not a particle. But it’s small, about the size of a proton. It does not glow or emit light – it is a defect in space-time, not a “thing” in the usual sense of the word “thing”. There could be a billion of them passing through you and you would never notice… except that you would suddenly weigh more than a mountain. So I guess that counts as “noticing.” Because that’s the highlight. These things are sealed. They consist of the enclosed, high-energy vacuum of the early universe. And if the early universe was as chaotic as we think, then the Big Bang would have had to have been a presound-producing factory. A Vorton forge? I don’t know the right word – it just created a lot of buzz.

This is the story: phase transitions created many cosmic strings. Inflation has dragged it out. Then they vibrated against each other, creating an enormous number of loops that shrank until they became stuck as vortices. That would explain why we don’t see any cosmic strings anywhere. These missing defects are not really missing. They have just evolved into a nebula of dark matter that fills every galaxy.

This means that dark matter may not be an additional ingredient added to the cosmic recipe. It could simply be the remnants of the Big Bang. They are the scratch marks on the ground from when the universe was formed. It’s the construction debris we forgot to sweep up. The universe is anything but perfect. This is one of our reasons for existing. But do the imperfections stop with us – the dust and the stars – or do they extend to a much deeper, more fundamental level – a level so deep that it is frozen in the fabric of space-time? We don’t know if vortices exist, if they are responsible for dark matter, or if they even CAN exist. But that doesn’t matter. The truth is that we owe our existence to the fact that the universe is a bit messed up. If the Big Bang had been perfect, there would be no errors that could promote the growth of galaxies. There would be no branches in the field to provide the dark mass.

I don’t know about you, but I say it’s our mistakes that make us most beautiful.

The International Space Station (ISS), which has been continuously occupied for 26 years, is approaching retirement. By 2030, all participating space agencies will bring their astronauts home for the last time, and the station will be maneuvered so it burns up in Earth’s atmosphere. The legacy of this station is unmatched, and its successors (of which several are planned) will have extremely big shoes to fill. Nevertheless, there’s no shortage of space programs and commercial interests looking to place new space stations in orbit.

Some space agencies, such as NASA and the Indian Space Research Organization (ISRO), hope to deploy new stations. At the same time, China aims to expand its existing Tiangong station to double its current size while Roscosmos recently announced that it will recycle its existing ISS modules to create a space station crewed by Russian cosmonauts and international partners. As for the commercial sector, the companies hoping to participate, and the concepts they’re proposing are legion!

With multiple space agencies planning on taking the “next great leap” – going back to the Moon, to Mars, and beyond – space stations are part of an incremental approach to secure those next great leaps. And the orbital lanes in LEO could be getting a little crowded as a result.

The First Stations

Space stations are a means of establishing an enduring human presence in space. First deployed at the end of the Apollo Era, they represented humanity’s next step in space exploration. Before this, NASA and the Soviet space program were locked in a state of competition – the Space Race – where they were dedicated to “getting there first.” This included being the first to send a satellite (Sputnik) to space, the first man to space (Yuri Gagarin), and the first astronauts to land on the Moon (Neil Armstrong and Edwin “Buzz” Aldrin).

But with the success of the Apollo missions, which landed a total of six lunar modules and twelve astronauts on the lunar surface, the Space Race was officially over. It was at this point, during the early to mid-1970s, that NASA and the Soviets began contemplating their next moves. Having reached space many times over, they decided to focus on technologies that would enable long-duration stays in space. In essence, they shifted from getting to space to staying there.

*The Soviet Salyut-7 (left) and NASA’s Skylab (right). Credit: RKK Energia/NASA*

Having ceded the “Race to the Moon,” the Soviets achieved an early lead with the Salyut program. The program ran from 1971 to 1986 and launched four crewed scientific research stations and two crewed military stations that operated under the guise of the program (Almaz stations). The Salyut stations conducted research on the challenges of long-term spaceflight, as well as a variety of scientific experiments.

The stations also set several spaceflight records, including mission duration, extravehicular activities (EVAs), and the first crew handover in space. Salyut established a legacy for modular space stations and represented a critical step from single-module and docking-port stations to more complex ones. This would be realized with the Soviet-Russian Mir space station (Russian for “peace”), which remained in operation from 1986 until it was deorbited in 2001.

This station was made up of seven modules, including the Salyut-derived Mir core module*, the Kvant-1 and -2 modules (where scientific research was conducted), Kristall (microgravity manufacturing), Spektr (Earth-related studies), Priroda (Earth-sensing), and the docking module. Mir also established a precedent for international cooperation in space through the Interkosmos, Euromir, and Shuttle–Mir* programs.

Meanwhile, the U.S. responded with its own single-module station, Skylab, which was occupied between 1973 and 1974 but remained in orbit until 1979. The station was created from the third stage of a repurposed Saturn V rocket and deployed as a payload by the same rocket. Skylab was America’s first long-duration space station, containing an orbital workshop, a solar laboratory, and an Earth observatory, and was the site of hundreds of experiments.

While NASA hoped to create its own Space Station Freedom to succeed Skylab, and Roscosmos hoped to succeed Mir with Mir-2, these were cancelled in 1993 in favor of participation in the ISS. By 1998, NASA and Roscosmos had placed the foundational elements of the ISS in orbit, and expeditions commenced by 2000. Since then, NASA, Roscosmos, the Canadian Space Agency (CSA), the European Space Agency (ESA), and the Japan Aerospace Exploration Agency (JAXA) have added modules and elements that have enhanced the Station’s capabilities.

*Image of Space Shuttle Atlantis connected to Russia’s Mir Space Station by the crew of Mir-19 on July 4th, 1995. Credit: NASA*

ISS Retiring

Originally, the ISS was intended for a 15-year mission, and NASA planned to deorbit the station by 2016. But the mission has been repeatedly extended due to the vital research it enables and the international support its received. This culminated in the Space Frontier Act of 2018 in July 2018 and the Leading Human Spaceflight Act a few months later, both of which extended ISS operations until 2030.

In August 2022, Congress passed similar provisions in the Creating Helpful Incentives to Produce Semiconductors (CHIPS) and Science Act, which President Biden signed into law. While Russian officials have announced that they will withdraw from the ISS after 2024 (later pushed to 2025), Russian cosmonauts have continued to participate in joint missions with NASA and other space agencies. As of the publication of this article, no final departure date has been formalized.

Unfortunately, the continued occupation means that the oldest modules in the ISS are more than 20 years old. This has led to all kinds of maintenance issues over the years, not to mention health-related concerns. In terms of the former, the modules have experienced structural fatigue, persistent air leaks, and degrading hardware, with maintenance costs hovering around $1 billion annually. In September 2019, the Zvezda Service Module began experiencing higher-than-normal air leaks, which have persisted despite multiple repairs.

In terms of the latter, more than 25 years of continuous occupation by astronauts and cosmonauts have left the station filled with microorganisms that could pose health risks. In 2019, NASA shared the results of a comprehensive study of the microorganisms and fungi present on the ISS, which found diverse populations of both that “may include opportunistic pathogens.” In a 2022 interview with Russia’s state-owned RIA Novosti news agency, the Director of the Institute of Biomedical Problems at the Russian Academy of Sciences (RAS), Oleg Orlov, addressed these risks:

An analysis of the results of microbiological monitoring of the habitat of the ISS RS modules, carried out within the framework of the full-time medical control operations, indicates that the state of the ISS habitat is deteriorating. It is an objective process. Generalized results show that in 65% of the analyzed samples of the latest expeditions, microorganisms were found in quantities exceeding regulatory requirements.

Among the representatives of bacterial flora isolated from the habitat of the ISS, species that are of medical importance and are capable of causing allergic reactions and some types of soft tissue and upper respiratory tract diseases have been identified.

With the ISS slouching toward retirement and space agencies expressing doubts about further extensions, attention is shifting to what will replace this venerable workhorse and research platform in space.

The Lunar Gateway

In the near future, NASA hopes to deploy the Lunar Gateway in orbit around the Moon. This station is a collaborative project between NASA, the European Space Agency (ESA), the Japan Aerospace Exploration Agency (JAXA), and the Canadian Space Agency (CSA). This space station was conceived through concept studies conducted between 2012 and 2018, and was originally designated the Deep Space Habitat (DSH). By 2015, it was approved as part of NASA’s NextSTEP (Space Technologies for Exploration Partnerships) studies and began receiving funding for development.

In 2018, the International Space Exploration Coordination Group (ISECG) identified the Gateway as essential to lunar exploration, missions to Mars, and beyond. The modular design consists of a core composed of the Power and Propulsion Element (PPE) and the Habitation and Logistics Outpost (HALO). These modules will launch no sooner than 2027, followed by the European System Providing Refueling, Infrastructure and Telecommunications (ESPRIT), the Lunar International Habitation Module (Lunar I-HAB Module), the Canadarm3 robotic manipulator arms, and the Crew and Science Airlock Module.

The station will also be paired with reusable surface elements, collectively known as the “Artemis Base Camp,” which were announced in 2020 as part of NASA’s Lunar Surface Sustainability Concept. The base will include a Lunar Terrain Vehicle (LTV) to transport crew members around the landing zone, a pressurized Habitable Mobility Platform (HMP) for longer trips across the surface, and a lunar Foundation Surface Habitat (FSH) that will house up to 4 crew members during shorter surface stays.

On May 2nd, 2025, the second Trump administration released its FT 2026 budget request, which proposed canceling the Lunar Gateway program. However, the budget, signed into law on July 4th, allocated $2.6 billion to the Gateway, requiring $750 million to be spent between 2026 and 2028. Similarly, discussions have arisen about repurposing the Lunar Gateway for other missions.

This includes now-Administrator Jared Isaacman’s policy blueprint, “Project Athena,” in which he explored repurposing modules or propulsion-related hardware for a nuclear-powered tug vehicle. However, neither Isaacman nor NASA has announced any such plans.

Tiangong

The construction of China’s Tiangong (‘Heavenly Palace”) modular space station began with the deployment of the Tianhe (“Harmony of the Heavens”) core module in April 2021, and finished the following year with the deployment of the Wentian (“Quest for the Heavens”) and Mengtian (“Dreaming of the Heavens”) laboratory modules. The station is based on experience gained from its predecessors, Tiangong-1 (2011-2016) and Tiangong-2 (2016-2019), and has been continuously occupied by taikonauts since June 5th, 2022.

As of 2026, a total of 30 taikonauts have launched to Tiangong (Shenzhou-10 to -22), serving in crews of three for periods of about six months – though the station can accommodate up to six taikonauts during mission handovers. According to the China Manned Space Agency (CMSA), the station has conducted research into spacecraft rendezvous, permanent human operations in orbit, long-term autonomous spaceflight, bioregenerative life support systems (BRLSS), and autonomous cargo and fuel supply.

On October 4th, 2023, the Chinese Academy of Space Technology (CAST) announced that three new modules will be added, effectively doubling its size and crew capacity. Chinese state media have also stated that the station will foster international cooperation by accommodating crews from “several countries,” which may include ESA members. This is in keeping with plans to make Tiangong a successor to the ISS.

The planned expansion will also extend the mission’s duration to 2037, 10 years longer than previously announced. The research activities that are planned will include further studies into long-duration stays in space, space medicine, agriculture, technological innovations, and tests involving the Mengzhou spacecraft – Shenzhou’s replacement, which is designed to transport six or seven taikonauts to orbit or the Moon.

In this respect, Tiangong will also play a role in China’s plans to construct the International Lunar Research Station (ILRS) in collaboration with Roscosmos. Speaking of which…

Russian Orbital Station

In recent years, Russia has announced similar plans to build a successor station to the ISS. However, in December 2025, the Director of the Institute of Biomedical Problems of the Russian Academy of Sciences (RAS), Greg Orlov, announced that Russia would continue using the modules that make up the Russian Orbital Segment of the ISS after 2030, which would henceforth be known as the Russian Orbital Station (ROS), or *Rossiyskaya orbital’naya stantsiya*.

This represents a major change from what Russian officials have stated in recent years, which was their intent to create a new station to succeed the ISS. Plans for a Russian space station began in earnest in 2009 with the proposed Orbital Piloted Assembly and Experiment Complex (OPSEK). This plan called for a station that would include the six modules that make up the Russian Orbital Segment, but it was abandoned in 2017 in favor of maintaining participation in the ISS program.

*Artist’s concept for the Russian Orbital Station (ROS). Credit: Roscosmos*

The plans were revived after 2021, when Roscosmos announced it would terminate its involvement in the ISS by 2024, citing concerns about the condition of its aging modules. At this point, the OPSEK concept was renamed the Russian Orbital Service Station (ROSS), which would no longer include Russia’s ISS modules. The updated plan included launching the four core modules between 2027 and 2030, including the scientific and energy module, the Universal Node (UNM), the Gateway (SM), and the Base Module (BM). By 2035, up to three more modules were to be added, with the possibility of a private habitat for space tourism.

However, due to budget constraints arising from sanctions and the termination of international agreements (due to Russia’s invasion of Ukraine in 2022), Russian planners returned to the idea of reusing its ISS modules. Per this new plan, Russia will separate its modules from the ISS once the program is completed in 2030, forming the core of the ROS, with other modules to follow. However, given the age of the modules and associated health concerns (which Orlov addressed as recently as 2022), there is significant doubt that this plan will remain in place for long.

Bharatiya Antariksh

In 2019, the Indian Space Research Organization (ISRO) announced that it would build the Bharatiya Antriksh Station (BAS) in orbit by 2035. According to repeated ISRO statements, the station will build on the agency’s plans to begin sending crewed missions to orbit (Gaganyaan). As then-ISRO chief Sreedhara Somanath stated in October 2023:

Our Gaganyaan program is towards a human space flight capability to space, and once that happens, we will be able to look at space station building in subsequent modules. The timeline for this space station project spans the next 20 to 25 years. We will be definitely looking at manned exploration, a human spaceflight for a longer duration, space exercise there in our agenda.

Similar to China, India views this station as integral to its plans of becoming a major power in space exploration, science, and research in the coming decade. This will include completing the Ganganyaan program and conducting a crewed Moon landing by the year 2040. The development of the BAS is scheduled to begin with the launch of the first module (BAS-1), along with solar panels and a docking port compatible with ISS, in 2028.

*Artist’s impression of India’s proposed Bharatiya Antariksh Station (BAS). Credit: IBEF*

The BAS will feature a five-module configuration consisting of the Base Module (BAS-1), the Core-Docking Module (BAS-2), the Science research Module (BAS-3), the Laboratory Module (BAS-4), and the Common Working Module (BAS-5). The station will measure 27 by 20 meters (88.5 by 65.5 feet), orbit at an altitude of 400-450 km (250-280 mi), and house a crew of three to four. The ISRO has also stated that the station will be accessible by all major space agencies, including NASA, Roscosmos, the ESA, and JAXA.

And these are just the plans proposed by the world’s major or rising space agencies. Stay tuned for part II, where we will address the many concepts being explored by commercial space companies.