Space & Physics
Fusion Energy: The quest for unlimited power
The potential benefits of fusion energy are enormous. It could provide a nearly limitless supply of energy, reduce our reliance on fossil fuels, and help combat climate change
Imagine a world with a virtually unlimited source of clean energy that could power our cities, industries, and homes without the harmful emissions and environmental impacts of fossil fuels. This isn’t science fiction—it’s the promise of fusion energy. But what exactly is fusion energy, and how close are we to making it a reality?
Nuclear fusion involves combining light elements, such as hydrogen, to form heavier elements, releasing a significant burst of energy in the process. This process, which powers the heat and light of the Sun and other stars, is praised for its potential as a sustainable, low-carbon energy source.
This process contrasts with the nuclear fission process used in nuclear power plants, where heavy atomic nuclei are split into lighter ones. But this is fraught with radioactive waste and safety concerns.
The road to practical fusion energy is steep and fraught with challenges. The foremost obstacle is achieving and maintaining the extremely high temperatures and pressures required for fusion. Similar to those at the Sun’s core, these conditions are necessary to overcome the electrostatic forces that repel the positively charged atomic nuclei. For decades, scientists have experimented with different methods to achieve these conditions. The two primary approaches are magnetic confinement and inertial confinement.
Magnetic confinement, as seen in the tokamak design, employs powerful magnetic fields to contain hot plasma within a doughnut-shaped chamber. Inertial confinement, on the other hand, involves compressing a small pellet of fusion fuel with intense laser beams to achieve the conditions for fusion. Both methods have seen significant advancements but are yet to reach the break-even point, where the energy output from fusion equals the energy input required to sustain the reaction. However, recent breakthroughs have brought us closer than ever to this elusive goal.
The primary fuel for nuclear fusion is deuterium and tritium. Deuterium and tritium are isotopes of hydrogen, the universe’s most abundant element. Isotopes are members of a family of elements that all have the same number of protons but different numbers of neutrons. While all isotopes of hydrogen have one proton, deuterium has one neutron, and tritium has two, so their ion masses are heavier than those of protium, the isotope of hydrogen with no neutrons. Deuterium can be extracted from seawater, while tritium can be bred from lithium. When deuterium and tritium fuse, they form a helium atom, which has two protons and two neutrons, and release an energetic neutron. These energetic neutrons could serve as the foundation for generating energy in future fusion power plants.
Power plants today generate electricity using fossil fuels, nuclear fission, or renewable sources like wind or water. Regardless of the energy source, these plants convert mechanical power, such as the rotation of a turbine, into electrical power. In a coal-fired steam station, coal combustion turns water into steam, which then drives turbine generators to produce electricity.
The tokamak is an experimental machine designed to harness fusion energy. Inside a tokamak, the energy produced through atomic fusion is absorbed as heat by the vessel’s walls. Similar to conventional power plants, a fusion power plant will use this heat to produce steam, which then generates electricity via turbines and generators.
The international ITER project in France is the largest and most ambitious tokamak experiment to date. ITER aims to demonstrate the feasibility of fusion as a large-scale and carbon-free source of energy
At the core of a tokamak is a doughnut-shaped vacuum chamber. Under extreme heat and pressure inside this chamber, gaseous hydrogen fuel becomes plasma, creating an environment where hydrogen atoms can fuse and release energy. The plasma’s charged particles are controlled and shaped by large magnetic coils surrounding the vessel. This property allows physicists to confine the hot plasma away from the vessel walls. The term “tokamak” is derived from a Russian acronym for “toroidal chamber with magnetic coils.”

Fusion energy scientists consider tokamaks to be the leading plasma confinement design for future fusion power plants. In a tokamak, magnetic field coils confine plasma particles, enabling the plasma to reach the conditions necessary for fusion.
The international ITER project in France is the largest and most ambitious tokamak experiment to date. ITER aims to demonstrate the feasibility of fusion as a large-scale and carbon-free source of energy. It’s a collaboration involving 35 countries, including India, and is expected to produce first plasma in the coming years.
The primary objective of ITER is to investigate and demonstrate burning plasmas—plasmas where the energy from helium nuclei produced by fusion reactions is sufficient to maintain the plasma’s temperature, reducing or eliminating the need for external heating. ITER will also test the feasibility and integration of essential fusion reactor technologies, such as superconducting magnets, remote maintenance, and systems for exhausting power from the plasma. Additionally, it will validate tritium breeding module concepts that could enable tritium self-sufficiency in future reactors.
ITER made headlines just last year when it achieved a major milestone: the successful installation of its first-of-a-kind superconducting magnet system. This system is crucial for creating the powerful magnetic fields needed to contain the superheated plasma. This achievement brings us one step closer to achieving sustained fusion reactions.
On October 3, 2023, the Joint European Torus (JET) project in Oxford produced power for five seconds, resulting in a “ground-breaking record” of 69 megajoules of power. That energy was generated using only 0.2 milligrams of fuel.
An alternative method is inertial confinement fusion, where a compact fusion fuel pellet is compressed by high-powered lasers. The National Ignition Facility (NIF) in the United States is leading the way in this research. On December 5, 2022, the National Ignition Facility (NIF), located at the Lawrence Livermore National Laboratory in California, directed a series of lasers to emit 2.05 megajoules of energy towards a small cylinder containing a frozen pellet of deuterium and tritium, which are denser variants of hydrogen. The pellet underwent compression, resulting in the generation of temperatures and pressures of sufficient magnitude to induce fusion of the hydrogen contained inside it. During an extremely brief ignition, the merging atomic nuclei discharged 3.15 megajoules of energy, surpassing the amount of energy necessary to heat the pellet by approximately 50 percent. This stage is crucial in the journey towards the practical realisation of fusion energy production.
On October 3, 2023, the Joint European Torus (JET) project in Oxford produced power for five seconds, resulting in a “ground-breaking record” of 69 megajoules of power. That energy was generated using only 0.2 milligrams of fuel. In addition, many private companies are making waves in the fusion energy scene.
While these achievements are remarkable, there are still many technical hurdles to overcome. We need to improve the efficiency and durability of fusion reactors, develop materials that can withstand the extreme conditions inside them, and create systems for safely handling and breeding tritium.
Despite these challenges, the potential benefits of fusion energy are enormous. It could provide a nearly limitless supply of energy, reduce our reliance on fossil fuels, and help combat climate change. Imagine a world where energy is abundant, clean, and available to all—fusion energy could make this vision a reality. As we look to the future, the quest for fusion energy represents one of the greatest scientific and engineering challenges of our time. It’s a testament to human ingenuity and our unwavering determination to solve the world’s most pressing problems.
Space & Physics
Sophie Adenot Makes History as First Frenchwoman to Walk in Space
French astronaut Sophie Adenot has become the first Frenchwoman to perform a spacewalk, spending 6 hours 23 minutes outside the International Space Station.
French astronaut Sophie Adenot has become the first Frenchwoman to perform a spacewalk, spending 6 hours and 23 minutes outside the International Space Station to begin repairs to its exterior communications system.
French astronaut Sophie Adenot made European space history on Tuesday by becoming the first French woman to perform a spacewalk outside the International Space Station. Adenot, 44, stepped outside the orbiting laboratory alongside American astronaut Anil Menon, floating roughly 400 kilometres above the Earth for 6 hours and 23 minutes to begin a repair of the station’s exterior communications equipment.
“I’m out,” Adenot said as she exited the station. “I feel very good now.”
A Repair Job That Ran Long The astronauts’ task was to replace an aging space-to-ground antenna on the station’s Z1 truss — the primary link carrying high-speed data, voice calls and video between the station and mission control in Houston. The antenna had stopped tracking NASA’s data relay satellites since November and had been out of service since, with a second antenna carrying the station’s communications load in the meantime.
Menon and Adenot successfully removed the failed antenna and secured it to the truss structure, but disconnecting its electrical cables and loosening its mounting bolts took longer than planned, leaving no time to install the replacement unit. NASA has scheduled a second spacewalk for Tuesday, August 25, to complete the installation. The station’s communications were not affected by the delay, as the backup antenna continued operating throughout.
Inside the station, astronauts Jack Hathaway and Jessica Meir coordinated the operation from the control desk, operating the station’s robotic arm and monitoring the spacewalkers’ life support systems throughout.
Days of Preparation Before the Hatch Opened Spacewalks demand days of preparation before the airlock ever opens. In the lead-up, Adenot and Menon spent dozens of hours readying their gear inside the station — inspecting safety tethers, organising tools, servicing backup emergency jetpacks, charging suit batteries, checking for pressure leaks, and testing biomedical sensors and radios.
Spacewalk complete. ✅
After 6 hours and 23 minutes outside the International Space Station, @Soph_astro is safely back inside.
With today’s EVA, Sophie becomes the first French woman to perform a spacewalk. 🇫🇷 pic.twitter.com/i3BghrdaRK— European Space Agency (@esa) August 18, 2026
“A successful [spacewalk] starts long before the hatch opens, and that’s where my focus has been these past few days: rehearsing, preparing and focusing,” Adenot said on social media before the excursion.
Suit fitting was a major focus of the preparation: working inside a heavy, pressurised spacesuit for over six hours puts considerable strain on an astronaut’s hands and shoulders, and engineers on the ground worked closely with Adenot to customise her suit and reduce pressure points.
A Milestone for European Space Exploration Adenot brought extensive technical experience to the mission. A trained engineer and former helicopter test pilot, she was selected for astronaut training by the European Space Agency in 2022 and launched to the space station in February 2026, becoming only the second French woman in history to reach space, after physician-astronaut Claudie Haigneré in 1996. With Tuesday’s spacewalk, she also became the second European woman ever to conduct a spacewalk, after Italian astronaut Samantha Cristoforetti in 2022, and the fifth French citizen overall to do so. The last French citizen to walk in space was Thomas Pesquet.
Despite the milestone, Adenot credited the wider team behind the mission. “My deepest gratitude goes to everyone who made this possible — pioneers who came before us, but also the incredible teams working behind the scenes today,” she said after returning inside the station.
Space & Physics
Hubble and Gaia Uncover Evidence of Ancient Dwarf Galaxy Devoured by the Early Milky Way
Hubble and Gaia reveal evidence of an ancient Milky Way merger with a dwarf galaxy about 11.8 billion years ago, reshaping our understanding of the galaxy’s origins.
A Milky Way merger with a dwarf galaxy about 11.8 billion years ago has been uncovered by astronomers using the Hubble Space Telescope and ESA’s Gaia mission. The discovery provides new evidence about how the Milky Way formed and identifies a distinct population of ancient globular clusters linked to the merger.
Our home galaxy, the Milky Way, contains hundreds of billions of stars today. It grew to this size over billions of years by pulling in smaller neighbouring galaxies and absorbing them. Now, astronomers using the NASA/ESA Hubble Space Telescope and ESA’s Gaia mission have found evidence of a major merger that occurred near the very beginning of the Milky Way’s history.
By combining precise stellar age and chemical-composition measurements from Hubble with motion-mapping data from Gaia, the team pushed back the known timeline of the Milky Way’s formation by roughly 1.8 billion years. The findings, led by Davide Massari of the Astrophysics and Space Science Observatory of Bologna, Italy, were published this week in Nature Astronomy.
Evidence of an Ancient Milky Way Merger
Reconstructing the Milky Way’s earliest history is difficult: in its youth, the galaxy was smaller, more chaotic, and closer in size to the dwarf galaxies it collided with, and many physical traces of those early mergers have since been erased.
To work around this, the researchers studied 39 globular clusters — dense, ancient groupings of up to a few million stars — in the inner 20,000 light-years of the galaxy, where evidence of the earliest mergers is most likely to survive. Using Hubble’s high-resolution imaging, the team measured each cluster’s age and metallicity (its abundance of elements heavier than helium) with what the researchers describe as unprecedented precision.
“Thanks to the high resolution and depth of Hubble imaging, we could measure the age and the metal content of these clusters with unprecedented precision,” said Chiara Zerbinati, a co-author on the study at the University of Bologna, in a release issued by ESA Hubble. “Coupled with measurements from Gaia, this made it possible to distinguish a population of globular clusters that are different from the others.”
Identifying LKH
Cross-referencing Hubble’s age and metallicity data with Gaia’s motion measurements, the researchers identified a distinct third population of globular clusters — older than the ones known to have arrived during the Milky Way’s collision with the Gaia-Sausage-Enceladus dwarf galaxy about 10 billion years ago, but younger than the stars that formed within the Milky Way itself.
That pattern pointed to a separate, earlier merger: the absorption of a dwarf galaxy roughly 11.8 billion years ago — about two billion years after the Big Bang — carrying a total stellar mass of around 500 million times the mass of the Sun, a significant share of the Milky Way’s total mass at the time.
The researchers named the dwarf galaxy Low-energy-Kraken-Heracles, or LKH, after three earlier papers that had proposed the idea of an early merger in the Milky Way’s history.
“Our home is the Milky Way galaxy, but we do not know how our house was built,” Massari said. “In this paper we discover where the first significant batch of bricks came from: a dwarf galaxy that we call LKH.”
Rewriting Early Galactic History
The finding challenges an earlier assumption that the Milky Way’s oldest stellar populations formed almost entirely in place, showing instead that external galaxies contributed to its structure far earlier than previously established.
The team plans to extend the analysis to additional globular clusters across the galaxy, aiming to build a more complete map of the mergers that shaped the Milky Way over cosmic history.
Space & Physics
Total Solar Eclipse 2026: What Happened and Where Was It Visible?
The August 12, 2026 total solar eclipse saw the Moon completely cover the Sun along a narrow path across parts of Greenland, Iceland, northern Russia, Spain and Portugal. While much of Europe and parts of North America and northwestern Africa experienced a partial eclipse, the event was not visible from India.
On August 12, the Moon passed between the Sun and Earth, producing a total solar eclipse. Along a narrow path, the Moon completely covered the Sun, briefly darkening the daytime sky. Much of Europe and parts of North America and northwestern Africa saw a partial eclipse.
A solar eclipse occurs when the Moon passes between the Sun and Earth and casts its shadow on Earth’s surface. Because the Moon’s darkest shadow covers only a limited area, an eclipse can be total in one region, partial in another and invisible elsewhere.
Why did some places go dark?
The Moon casts two main shadows during a solar eclipse. The umbra is the central shadow, where the Sun is completely blocked. People within it experience totality.
The penumbra extends beyond the umbra. People in this larger region see only part of the Sun covered and therefore experience a partial eclipse.
This is why the same eclipse looks different from different locations. A place inside the path of totality can experience a few minutes of daytime darkness, while a location farther away may see only a portion of the Sun covered.
Where was the eclipse visible?
Totality was visible across parts of Greenland, Iceland, northern Russia, Spain and northeastern Portugal, as well as parts of the Atlantic and Arctic oceans.
A much larger area experienced a partial eclipse. This included much of Europe, parts of North America and northwestern Africa, along with areas over the Atlantic, Arctic and Pacific oceans.
For mainland Europe, the event was particularly notable because it brought totality to the region for the first time since 1999.
Why couldn’t India see it?
India was outside the eclipse’s visibility zone. The eclipse’s path of totality was concentrated much farther north, and India was not within the region from which the August 12 event could be observed.
This illustrates an important point about solar eclipses: an eclipse may occur over Earth without being visible from a particular country. The Moon’s shadow covers only a limited part of the planet.
How often do solar eclipses occur?
Solar eclipses are not exceptionally rare. There are generally two to five solar eclipses somewhere on Earth each year.
However, a total solar eclipse at a particular location is much rarer. A 2026 analysis by timeanddate estimates that, on average, a total solar eclipse occurs at a given location about once every 373 years. The actual interval can vary considerably between locations.
The reason is the geometry of the Moon’s orbit. It is tilted by about five degrees relative to Earth’s orbit around the Sun, so the Moon usually passes above or below the Sun rather than directly in front of it. Only when the alignment is sufficiently close does its shadow fall across Earth.

Why are total solar eclipses scientifically important?
During normal daylight, the Sun’s bright surface makes its faint corona difficult to observe. During totality, the Moon blocks the bright disk, revealing the corona around it.
Scientists study the corona to better understand the Sun’s atmosphere, magnetic activity and solar wind. These processes are also important to the study of space weather, which can affect satellites and communications.
The August 12 eclipse was therefore more than a striking change in the daytime sky. For observers along its narrow path, a few minutes of darkness provided a rare opportunity to see the Sun’s outer atmosphere—while much of the world saw only a partial eclipse or nothing at all.
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