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Space & Physics

Need of the Hour – Evading the Kessler Syndrome

In 1978, Donald J. Kessler, an astrophysicist, predicted collisions between satellites can get out of hand as their population keeps increasing.

Karthik Vinod

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Illustration of space debris and defunct launcher stages in the Geostationary Orbit (GSO). Credit: ESA

In 2009, the Iridium 33 and Kosmos 2251 satellites collided to produce as many as 2,000 debris fragments, spraying 10 cm wide pieces in every direction – at speeds faster than a bullet

If any of these ever struck the ISS, orbiting closely, then all hell can break loose! Remember that scene in Gravity (2013) when Sandra Bullock’s character gets flung around? Well, it’s just one of several worse-case scenarios.

Even today, these space debris hover there, too close to be completely risk-free to the ISS. 

The US’ operate a Space Surveillance Network that tracks these debris, along with more than 20,000 fragments. They comprise old rocket booster stages, junk satellites, missile components from anti-satellite launches. 

However, very tiny pieces of fragments (<10 cm) can still be missed by ground radars. Space debris can include spent rocket stages, or defunct satellites drifting in space.

And a technical fix in orbital debris removing technology arose. 

Last month February 18th saw the launch of the Active Debris Removal by Astroscale-Japan (or ADRAS-J) satellite from Rocket Lab’s launch station in New Zealand. ADRAS-J is yet to actually demonstrate debris removal, as it’s parked in a rendezvous orbit in preparation for the demonstration later this month.

In 2022, the UK stated Active Debris Removal (ADR) as being vital to their Plan for Space Sustainability to “become tomorrow’s norms in space operation”. 

Space agencies across the world now issue commands for ‘collision avoidance maneuvers’ (CAM) when satellites cross within a certain radius. 

In fact, the Indian Space Research Organization (ISRO) actually made public a trend showing the number of CAM commands issued rising every year. Such close-calls will only increase with the cumulative increase of satellites in orbit. 

Here’s a plot from the European Space Agency’s (ESA) 2022 Space Environment Report.

A plot of the number of space debris against time. The legend indicates the various types of space debris (rocket, satellite parts etc.). Credit: ESA 

But the problem is that – these satellite numbers are rising exponentially in such a short time – with mega-constellations entering center stage.

SpaceX launched the Starlink initiative, to demonstrate connectivity even in the remotest parts of the world. 

However, they alone have 5,504 satellites out there to date, all at low-earth orbit – under 600 km, which is quite where the crowd of satellites are now. That’s about 58% of the 9,414 operational satellites out there. And this happened metaphorically overnight – in the past few years. SpaceX plans to operate some 42,000 satellites in a decade.

The fear is that unregulated growth of satellites – or even satellite litter that are defunct – can make what is known as the Kessler syndrome, a reality. 

When Donald Kessler anticipated a chain reaction …

In 1978, Donald J. Kessler, an astrophysicist, predicted that collisions between satellites can trigger a domino effect of other satellite collisions above a certain threshold. Dubbed the Kessler syndrome, it’s a worst-case scenario possible in outer space, when earth’s orbit becomes impossible to thrive in or operate from.

To partly address the growing clutter of low-earth orbit satellites, the US’ Federal Communications Council (FCC) has put up legislation to have newly launched satellites deorbit 5 years after operations.

The irony is that the Kessler syndrome was foreseeable, except it was ignored by policymakers until they simply couldn’t.

Scientists building a satellite at RAL Space. Credit: UK STFC / Wikimedia

Western countries have taken some onus of responsibility into these space sustainability initiatives, simply because countries like the US own most of the satellite infrastructure operating in orbit.  

From space shuttles, rockets, space planes and the lunar lander that brought Neil Armstrong and Edwin Aldrin to the moon, the Space Age heralded a brand new era for space technologies and research. But no space technology probably had more societal impact than the satellite. 

Seen vital for development and infrastructure, satellites are now ubiquitous, manufactured not just by space agencies, but also by engineering labs in universities, private companies and start-ups across the world. 

However, our costly endeavor to improve human lives are breeding new problems. And as a last resort, engineers are at it again to come up with technical fixes. 

But weren’t the technical risks understood if Kessler expressed his concern in the 1970s? 

Satellites, just like any technology, come with its set of benefits and risks. The benefits of satellites are obvious to many – phone connections, weather forecasting, banking, studying climate change, and the list goes on. 

At the end of a satellite’s lifespan though, many just stay there, as defunct satellites. 

Sure, there’s a ‘graveyard’ orbit where satellites can be made defunct after pushing them to a higher orbit to lay to rest forever. But not every defunct satellite is. In fact, 60% of all satellites are defunct. The operational satellites constitute a tiny minority. 

Partly to do with this mess is a lack of priority. The Space Race played out during the peak of the Cold War when both the US and Soviets wanted to demonstrate technological superiority. 

However, the outer orbit isn’t just a matter of mediating traffic or cleaning debris either. 

Space militarization has raised fears. Much of the initial Space Race began with the US and Soviets fearing the other could surveil over their national boundaries. But the tensions have now made headlines, with the ongoing Russian invasion of Ukraine, with the US alleging that the Russians are developing a satellite that can drop nuclear weapons against the West. Building such a weapon would be violative of the 1967 Outer Space Treaty, in addition to several other regulations against weapons of mass destruction (WMDs).

There’s also anti-satellite launch systems firing repurposed ballistic missiles into space missiles. The US, Russia, China and India all possess this technology – and have the capacity to threaten orbital infrastructure – civilian or military. But the consequence of losing control over the weapons, is to hit the threshold dictated by the Kessler syndrome.

We’ll need to bear in mind that even technical fixes can’t fix design thinking. When planners aren’t held accountable, for their individual decisions – such avoidable doomsday disasters become a talking point.

Space & Physics

Nobel Prize in Physics: Clarke, Devoret, and Martinis Honoured for Pioneering Quantum Discoveries

The 2025 Nobel Prize in Physics honours John Clarke, Michel H. Devoret, and John M. Martinis for revealing how entire electrical circuits can display quantum behaviour — a discovery that paved the way for modern quantum computing.

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The 2025 Nobel Prize in Physics has been awarded to John Clarke, Michel H. Devoret, and John M. Martinis for their landmark discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit, an innovation that laid the foundation for today’s quantum computing revolution.

Announcing the prize, Olle Eriksson, Chair of the Nobel Committee for Physics, said, “It is wonderful to be able to celebrate the way that century-old quantum mechanics continually offers new surprises. It is also enormously useful, as quantum mechanics is the foundation of all digital technology.”

The Committee described their discovery as a “turning point in understanding how quantum mechanics manifests at the macroscopic scale,” bridging the gap between classical electronics and quantum physics.

John Clarke: The SQUID Pioneer

British-born John Clarke, Professor Emeritus at the University of California, Berkeley, is celebrated for his pioneering work on Superconducting Quantum Interference Devices (SQUIDs) — ultra-sensitive detectors of magnetic flux. His career has been marked by contributions that span superconductivity, quantum amplifiers, and precision measurements.

Clarke’s experiments in the early 1980s provided the first clear evidence of quantum behaviour in electrical circuits — showing that entire electrical systems, not just atoms or photons, can obey the strange laws of quantum mechanics.

A Fellow of the Royal Society, Clarke has been honoured with numerous awards including the Comstock Prize (1999) and the Hughes Medal (2004).

Michel H. Devoret: Architect of Quantum Circuits

French physicist Michel H. Devoret, now the Frederick W. Beinecke Professor Emeritus of Applied Physics at Yale University, has been one of the intellectual architects of quantronics — the study of quantum phenomena in electrical circuits.

After earning his PhD at the University of Paris-Sud and completing a postdoctoral fellowship under Clarke at Berkeley, Devoret helped establish the field of circuit quantum electrodynamics (cQED), which underpins the design of modern superconducting qubits.

His group’s innovations — from the single-electron pump to the fluxonium qubit — have set performance benchmarks in quantum coherence and control. Devoret is also a recipient of the Fritz London Memorial Prize (2014) and the John Stewart Bell Prize, and is a member of the French Academy of Sciences.

John M. Martinis: Building the Quantum Processor

American physicist John M. Martinis, who completed his PhD at UC Berkeley under Clarke’s supervision, translated these quantum principles into the hardware era. His experiments demonstrated energy level quantisation in Josephson junctions, one of the key results now honoured by the Nobel Committee.

Martinis later led Google’s Quantum AI lab, where his team in 2019 achieved the world’s first demonstration of quantum supremacy — showing a superconducting processor outperforming the fastest classical supercomputer on a specific task.

A former professor at UC Santa Barbara, Martinis continues to be a leading voice in quantum computing research and technology development.

A Legacy of Quantum Insight

Together, the trio’s discovery, once seen as a niche curiosity in superconducting circuits, has become the cornerstone of the global quantum revolution. Their experiments proved that macroscopic electrical systems can display quantised energy states and tunnel between them, much like subatomic particles.

Their work, as the Nobel citation puts it, “opened a new window into the quantum behaviour of engineered systems, enabling technologies that are redefining computation, communication, and sensing.”

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Space & Physics

The Tiny Grip That Could Reshape Medicine: India’s Dual-Trap Optical Tweezer

Indian scientists build new optical tweezer module—set to transform single-molecule research and medical Innovation

Joe Jacob

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Advanced optical tweezers manipulate single molecules with laser precision, enabling breakthroughs in biomedical and neuroscience research

In an inventive leap that could open up new frontiers in neuroscience, drug development, and medical research, scientists in India have designed their own version of a precision laboratory tool known as the dual-trap optical tweezers system. By creating a homegrown solution to manipulate and measure forces on single molecules, the team brings world-class technology within reach of Indian researchers—potentially igniting a wave of scientific discoveries.

Optical tweezers, a Nobel Prize-winning invention from 2018, use focused beams of light to grab and move microscopic objects with extraordinary accuracy. The technique has become indispensable for measuring tiny forces and exploring the mechanics of DNA, proteins, living cells, and engineered nanomaterials. Yet, decades after their invention, conventional optical tweezers systems sometimes fall short for today’s most challenging experiments.

Researchers at the Raman Research Institute (RRI), an autonomous institute backed by India’s Department of Science and Technology in Bengaluru, have now introduced a smart upgrade that addresses long-standing pitfalls of dual-trap tweezers. Traditional setups rely on measuring the light that passes through particles trapped in two separate beams—a method prone to signal “cross-talk.” This makes simultaneous, independent measurement difficult, diminishing both accuracy and versatility.

Comparison of conventional and newly developed dual-trap optical tweezer designs, highlighting how the Indian innovation eliminates signal interference for more precise measurements

The new system pioneers a confocal detection scheme. In a media statement, Md Arsalan Ashraf, a doctoral scholar at RRI, explained, “The unique optical trapping scheme utilizes laser light scattered back by the sample for detecting trapped particle position. This technique pushes past some of the long-standing constraints of dual-trap configurations and removes signal interference. The single-module design integrates effortlessly with standard microscopy frameworks,” he said.

The refinement doesn’t end there. The system ensures that detectors tracking tiny particles remain perfectly aligned, even when the optical traps themselves move. The result: two stable, reliable measurement channels, zero interference, and no need for complicated re-adjustment mid-experiment—a frequent headache with older systems.

Traditional dual-trap designs have required costly and complex add-ons, sometimes even hijacking the features of laboratory microscopes and making additional techniques, such as phase contrast or fluorescence imaging, hard to use. “This new single-module trapping and detection design makes high-precision force measurement studies of single molecules, probing of soft materials including biological samples, and micromanipulation of biological samples like cells much more convenient and cost-effective,” said Pramod A Pullarkat, lead principal investigator at RRI, in a statement.

By removing cross-talk and offering robust stability—whether traps are close together, displaced, or the environment changes—the RRI team’s approach is not only easier to use but far more adaptable. Its plug-and-play module fits onto standard microscopes without overhauling their basic structure.

From the intellectual property point of view, this design may be a game-changer. By cracking the persistent problem of signal interference with minimalist engineering, the new setup enhances measurement precision and reliability—essential advantages for researchers performing delicate biophysical experiments on everything from molecular motors to living cells.

With the essential building blocks in place, the RRI team is now exploring commercial avenues to produce and distribute their single-module, dual-trap optical tweezer system as an affordable add-on for existing microscopes. The innovation stands to put advanced single-molecule force spectroscopy, long limited to wealthier labs abroad, into the hands of scientists across India—and perhaps spark breakthroughs across the biomedical sciences.

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Space & Physics

New Magnetic Transistor Breakthrough May Revolutionize Electronics

A team of MIT physicists has created a magnetic transistor that could make future electronics smaller, faster, and more energy-efficient. By swapping silicon for a new magnetic semiconductor, they’ve opened the door to game-changing advancements in computing.

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Illustration of an advanced microchip with visualized magnetic fields, representing MIT's breakthrough in magnetic semiconductor transistors for next-generation electronics.

For decades, silicon has been the undisputed workhorse in transistors—the microscopic switches responsible for processing information in every phone, computer, and high-tech device. But silicon’s physical limits have long frustrated scientists seeking ever-smaller, more efficient electronics.

Now, MIT researchers have unveiled a major advance: they’ve replaced silicon with a magnetic semiconductor, introducing magnetism into transistors in a way that promises tighter, smarter, and more energy-saving circuits. This new ingredient, chromium sulfur bromide, makes it possible to control electricity flow with far greater efficiency and could even allow each transistor to “remember” information, simplifying circuit design for future chips.

“This lack of contamination enables their device to outperform existing magnetic transistors. Most others can only create a weak magnetic effect, changing the flow of current by a few percent or less. Their new transistor can switch or amplify the electric current by a factor of 10,” the MIT team said in a media statement. Their work, detailed in Physical Review Letters, outlines how this material’s stability and clean switching between magnetic states unlocks a new degree of control.

Chung-Tao Chou, MIT graduate student and co-lead author, explains in a media statement, “People have known about magnets for thousands of years, but there are very limited ways to incorporate magnetism into electronics. We have shown a new way to efficiently utilize magnetism that opens up a lot of possibilities for future applications and research.”

The device’s game-changing aspect is its ability to combine the roles of memory cell and transistor, allowing electronics to read and store information faster and more reliably. “Now, not only are transistors turning on and off, they are also remembering information. And because we can switch the transistor with greater magnitude, the signal is much stronger so we can read out the information faster, and in a much more reliable way,” said Luqiao Liu, MIT associate professor, in a media statement.

Moving forward, the team is looking to scale up their clean manufacturing process, hoping to create arrays of these magnetic transistors for broader commercial and scientific use. If successful, the innovation could usher in a new era of spintronic devices, where magnetism becomes as central to electronics as silicon is today.

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