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Oct. 4th, 1957: Sputnik launches

On Oct. 4th, 1957, at 10:29 PM Moscow time, the Soviet Union successfully launched Sputnik 1 into space on a repurposed R-7 rocket. The world’s first artificial satellite, Sputnik was about 22 inches (58 centimeters) in diameter and weighed 184 pounds (84 kilograms). Although there were no scientific instruments aboard, the transmitter it carried sentContinue reading "Oct. 4th, 1957: Sputnik launches"

The post Oct. 4th, 1957: Sputnik launches appeared first on Astronomy Magazine.

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Les États-Unis ont des armes dans l'espace : ce qu'on peut déduire de ce que Washington refuse de dire

C’est un coup de tonnerre dans le silence de l’espace. Les États-Unis viennent d’affirmer qu’ils disposent d’armes en orbite. Une annonce qui fait immédiatement réagir la Russie et la Chine. Mais de quoi s’agit-il et pourquoi cette annonce marque l’entrée dans une nouvelle ère.

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UVSQ-SAT NG : un laboratoire du New Space académique à la française

Mis en orbite en mars 2025, UVSQ-SAT NG a été développé au Latmos (Laboratoire Atmosphères et Observations spatiales – CNRS, Sorbonne Université, UVSQ), avec de nombreux partenaires académiques et industriels. Ce nanosatellite poursuit une démarche engagée avec les missions qui l’ont précédé :...

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U.S. Has Deployed Weapons in Space, Air Force Secretary Says

Troy E. Meink’s comments were the first public acknowledgment of American weapons in orbit. The Pentagon has been preparing for potential conflict in space with Russia or China.
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US Space Force says it operates weapons in orbit: 'Our aim is deterrence'

The U.S. Space Force is opening up about its operation of orbital weapons, but not much beyond admitting that they exist.

During a "State of the Space Force" address at the Air & Space Forces Association’s Air, Space & Cyber Conference in National Harbor, Maryland, on Tuesday (Sept. 15), Chief of Space Operations Gen. Douglas Schiess stated unequivocally that the Space Force uses active space-based weaponry to support United States national defense.

“Let me be crystal clear: Today, Guardians operate on-orbit weapons that can defend the joint force against space-enabled attacks,” Schiess said, referring to the official name for Space Force personnel.

Space is central to national security infrastructure and warfighting efforts, and serves a critical role in how the military communicates, navigates, conducts operations and tracks threats globally. It’s become an increasingly contested domain, with adversaries developing technologies designed to disrupt or destroy satellites in orbit as well as hypersonic weapons that challenge ground-based-only defenses.

Schiess didn’t specify what kind of weapons the U.S. operates in orbit, how many there are, or what exactly they do. But the revelation that the Space Force is operating those kinds of assets is by itself a pretty hefty admission. The news expands the known scope of U.S. military activity in the final frontier, which already included the use of satellites for GPS, communications, missile warnings and other targeting and intelligence operations.

“Space is both a battlefield and the backbone of our joint force,” Schiess said. “We face determined and credible adversaries who are building counter-space systems at incredible speeds to target directly the United States’ space advantage.”

The chief adversaries are China and Russia, experts have said. Both nations have developed a range of counterspace capabilities intended to threaten or interfere with other satellites, including through electronic warfare and anti-satellite (ASAT) systems. Russia demonstrated as much in 2021, when it destroyed one of its own spacecraft with an ASAT missile, which created a cloud of more than 1,500 pieces of orbital debris.

The U.S. has been rapidly expanding its own military presence in orbit over the past decade or so, and is ramping up those efforts even more with plans for the implementation of President Trump’s Golden Dome missile interception system. In the last year alone, the Space Force has awarded more than $12 billion in major contracts to companies like SpaceX, Rocket Lab, L3Harris and Boeing for a wide range of services, including national security launches, space-based tracking satellites and other defense technologies.

Schiess pointed to the Victus Haze mission as an example of how the Space Force is getting ready to react to orbital threats on short notice. Rocket Lab carried out Victus Haze in June, launching an Electron rocket and interceptor spacecraft within just 17 hours of receiving notice from the Space Force, setting a launch turnaround record.

a constellation of satellites shoots beams to each other and down to Earth.

Illustration of part of a Golden Dome satellite constellation. (Image credit: L3Harris)

Schiess also highlighted the Space Force’s critical role in Operation Epic Fury and the ongoing engagement of U.S. military forces in Iran. “Guardians are not supporting from the sidelines as a nice-to-have, but we are delivering space power directly into the fight as a need-to-have,” he said. Schiess even gave an anecdotal example of the actions of one Guardian, “Specialist Gray,” in the heat of battle.

“Even as alarm red sirens were blaring and incoming missiles targeted her site, she courageously held the line, protecting forces, denying adversary capability, and delivering space effects until her commander had to literally pull her from the console to safety,” Schiess said.

Schiess described her operations before she was pulled from that console, giving some clue as to what exactly is meant by “on-orbit weapons.”

He said the Guardian in question needed to “reconfigure her weapon system and execute critical non-kinetic fires,” and went on to add, “She locked onto the target, optimized her weapon system and waged electromagnetic warfare against a determined adversary.”

Those descriptions offer at least some clues about the technologies involved. Phrases like “electromagnetic warfare” and “non-kinetic” could point to signal jamming technology or other non-physical means of disrupting a target.

Schiess said the Space Force intends to continue expanding its combat power with more robust architectures and the ability to respond with increasing speed to evolving threats. That proliferation on behalf of Golden Dome and other national security programs stands to deliver substantially more military hardware into orbit in the coming years, but Schiess framed the buildup around the prevention of conflict, rather than its provocation.

“Our aim is deterrence,” he said.

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'The violence leaves a mark': How satellites are helping the world monitor war and atrocities

For decades, researchers have been monitoring armed conflict around the world by analyzing news reports and collecting oral testimonies. This approach, while valuable, has its limitations. A new study suggests that a satellite's view from above might fill the gaps in our understanding of the grim realities of war.

In 2017, the Myanmar Army murdered several hundred Muslim Rohingya civilians in the village of Chut Pyin near the country's western coast. Reports of the massacre in the settlement of about 2,000 reached the world through the testimonies of survivors who fled to neighboring Bangladesh. The massacre was part of a years-long campaign of brutality against the Muslim minority conducted by the Buddhist-run state. Satellite data later showed that houses in the predominantly Rohingya neighborhood were burned down by the Myanmar military during the atrocity, providing undeniable proof that the ethnic minority was targeted.

The incident is one of many demonstrating the advantage of adding views from space into conflict research, study lead author Valerie Sticher, a political science researcher at the University of Zurich in Switzerland, told Space.com.

"We have huge data sets about wars around the world going back 40 years," Sticher said. "But those datasets are based mostly on media reports. And these reports are not always available and not always reliable. Media can have biases and often focus only on certain types of violence."

For example, human reporters are more likely to focus on the numbers of people killed rather than the number of houses destroyed, she said. Satellites, on the other hand, provide a broad sweep over vast areas of land and, crucially, revisit the same location repeatedly. They can reveal patterns in conflicts and trends that could otherwise go undetected, while providing an overview of areas controlled by authoritarian regimes.

The researchers are now developing a methodology to integrate satellite observations into conflict research and create automated image analysis pipelines that would generate early warnings and alert the world to what's happening on the ground.

"Automated satellite data analysis would allow us to respond faster," said Sticher. "For example, in Myanmar, the area affected by ethnic cleansing was closed to independent journalists and investigators. Satellite data was the earliest reliable information to reach the outside world."

satellite photo of a circular, blue launch pad in the desert with black smoke rising from it

A SkySat Earth-observation satellite operated by the California company Planet spotted the wreckage of a failed launch out of Iran's Imam Khomeini Space Center on Aug. 29, 2019. (Image credit: Planet Labs, Inc.)

Hannes Mueller, a conflict researcher at the Spanish National Research Council, said that totalitarian governments can be very good at preventing information about atrocities from reaching the world. However, they can hardly fool satellites.

"In Myanmar, for example, when the military clears villages, they frequently kill everybody in those villages," he said. "Then you don't have any eyewitnesses for you to find out what's going on. But they usually also destroy the entire village, and so the violence leaves a mark from space."

Mueller was not involved in the new study but has used satellites in his work since the conflict in Syria in the early 2010s. He lauds the new paper for trying to "plot the road" for a more systematic integration of satellite data into conflict-monitoring data sets.

"Imagine we could generate a data stack of the entire world of all housing destruction since 2020 without any gaps in it," he said. "That would be a complete breakthrough!"

But satellites, too, have their limitations, he said. Currently, spacecraft must be tasked to take images and beam them to Earth. Because of the limited download availability, they can't image every spot they fly over, meaning they usually only reveal the aftermath of catastrophic incidents. For example, the Syrian city of Homs only became the focus of satellite imaging campaigns after the Syrian military attacked it with heavy artillery to suppress pro-democracy protests.

"There are no images of Homs before it got attacked," said Mueller. "There is no archival data of the city from before. Then, after the attack, you suddenly get lots."

In the future, onboard AI image processing — which some of the commercial satellite Earth-observation companies have already rolled out — might solve the problem. Machine learning algorithms running on computers on board the satellites will be able to detect incidents of potential interest and autonomously select significant images to send to the ground.

But there are other concerns. Just as authoritarian regimes can deny access to warzones to independent journalists, governments can order Earth-observation companies to restrict access to images of specific areas. In fact, the U.S. government did just that earlier this year when it ordered American commercial Earth-observation providers like Planet Labs to stop releasing high-resolution images of the Gulf of Oman and the Strait of Hormuz amid the escalating conflict in the region. The U.S also asked Europe to delay releasing images of that region captured by the European Sentinel satellites by 24 hours.

"With that, we are back to the same biases that we have with the news reporting," Mueller said. "We need to think about infrastructure that would provide us with transparency. That would really be a revolution in conflict research."

The new study was published in the journal Nature on Sept. 9.

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2 private spacecraft zoom within 650 feet of each other to showcase 'advanced capabilities' in orbit (photos)

A pair of private spacecraft just showed off some impressive maneuverability high above Earth.

The two probes — Mira satellites operated by the California startup Impulse Space — zoomed within 650 feet (200 meters) of each other in low Earth orbit (LEO) recently. The rendezvous demonstrated skills that could be useful to a variety of customers down the road, according to the company.

"These types of dynamic, agile maneuvers are how we unlock full access to space after launch and create new mission possibilities," Tom Mueller, CEO and founder of Impulse Space (and, prior to that, the first person Elon Musk ever hired at SpaceX), said in a statement on Tuesday (Sept. 8). "Our teams that design, build and operate Mira are leading the way toward a true space age, and customers across all sectors will be the beneficiaries."

photo of a cube-shaped satellite in deep space, taken from a distance by another satellite

The LEO-3 Mira vehicle, taken from a distance of approximately 700 meters (2,300 feet) by a camera onboard LEO-2. (Image credit: Starfish Space/Impulse Space)

Mira is an orbital transfer vehicle — a spacecraft designed to deliver customer payloads to precise locations in Earth orbit or beyond. The dishwasher-sized Mira can carry up to 660 pounds (300 kilograms) of gear and is highly maneuverable, as the recent rendezvous showed.

The operation involved Mira satellites that launched in January 2025 and November 2025, on missions that Impulse calls LEO Express 2 (LEO-2) and LEO Express 3 (LEO-3), respectively.

a white cube on a black background

Impulse Space's LEO-2 Mira vehicle, as seen from a telescope onboard LEO-3 from a distance of approximately 5,000 meters (16,400 feet). (Image credit: HEO/Impulse Space)

The action began this past February, when the LEO-2 Mira conducted a lengthy engine burn to close in on its counterpart. LEO-2 performed additional, smaller burns throughout the spring and summer, coming into orbital alignment with LEO-3.

"Then in July, LEO-2 executed a series of close approaches to LEO-3, starting at about 820 meters [2,690 feet] apart and subsequently moving closer to LEO-3," Impulse Space wrote in the Tuesday update. "Ultimately, for the closest approach, LEO-2 maneuvered to within about 200 meters of LEO-3."

Both Miras chronicled the rendezvous, snapping photos of each other with onboard camera gear. Two other companies, Starfish Space and HEO, worked with Impulse Space to pull off this orbital photo shoot.

Two Miras — less than 200 meters apart! Our LEO Express 2 and LEO Express 3 spacecraft recently met for a family reunion in orbit, following a series of carefully coordinated maneuvers that brought the two vehicles within approximately two football fields of each other.The… pic.twitter.com/XoHgOzjuaLSeptember 8, 2026

Impulse has worked with Starfish before. The duo collaborated late last year on a rendezvous between LEO-2 and the first space-flown Mira, which launched on the Leo Express 1 mission in November 2023.

On that operation, called Remora, LEO 2 used Starfish Space navigation software to get within 4,100 feet (1,250 m) of LEO 1.

"We're showcasing some of the advanced capabilities that set Mira apart from other vehicles," Drew Damon, vice president of spacecraft programs at Impulse, said in Tuesday's statement. "Twice now, we've demonstrated that Mira has the agility and propulsion to support a new class of dynamic operations on orbit, and our team is excited to continue tackling the mission sets Mira is uniquely qualified to handle."

Impulse is not alone in developing and demonstrating orbital maneuverability. Such skills are a key priority of national governments, which want to service and upgrade their own satellites — and keep tabs on the activities of adversary craft. For example, earlier this year, two Russian spacecraft got within a mere 10 feet (3 m) of each other high above Earth.

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Nanosatellites : la révolution de la revisite

Plus petits, plus rapides à développer et capables de voler en constellation, les nanosatellites font progresser l’observation de la Terre. En multipliant les passages, ils permettent de suivre les phénomènes environnementaux et climatiques avec une résolution temporelle accrue. C’est la...

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US military practices orbital dogfighting in 1st-ever 'live fly' exercise in space

United States Space Command just held its first-ever "Apollo Maneuvers" exercise, which saw spacecraft maneuvering through simulated contested environments.

U.S. Space Command combines assets and personnel from each U.S. military branch (including the U.S. Space Force) to project American military power into and from orbit. It's unclear which or how many satellites or spacecraft took place in Space Command's recent Apollo Maneuvers 2026, but the exercise involved international partners, according to a command statement. What is known is that the exercise aimed to demonstrate "dynamic on-orbit operations, validate contested logistics and advance collective space maneuver doctrine."

To put it in plain English, this means that Space Command practiced maneuvering satellites and other spacecraft in proximity to one another in a simulated conflict environment, in order to continue refining the "orbital dogfighting" that the U.S. military has been hinting at for some years.

In military terms, dogfighting refers to the close aerial combat that fighter jets engage in, pitting two or more pilots against one another in contests of flying ability and firepower.

In terms of space, this involves "objects in space maneuvering in and out and around each other in synchronicity, and in control," according to Space Force's Vice Chief of Space Operations Gen. Michael A. Guetlein.

“That's what we call dogfighting in space," Guetlein told attendees at a conference in 2025, according to Air & Space Forces, while speaking about Chinese satellite operations observed in 2024.

From statements that U.S. Space Command leadership gave about its recent exercise, it sounds like Apollo Maneuvers practiced just that, but in space.

"We will take some of our existing satellites and work with partners to demonstrate what are some of the requirements and capabilities to be able to maneuver for advantage, not just maneuver when you have to change your orbital position," Space Force Gen. Stephen N. Whiting, commander of U.S. Space Command, told reporters last month during a briefing at Redstone Arsenal in Alabama, according to Air & Space Forces.

"The side that can maneuver persistently and at scale will set the operational rhythm in orbit."

a man in a black military dress uniform speaks on a stage in front of an image of earth seen from space

Space Force Gen. Stephen N. Whiting, commander of U.S. Space Command, delivers a keynote address at the Space Foundation's 40th annual Space Symposium in Colorado Springs, Colorado on April 8, 2025. (Image credit: Space Foundation)

When it comes to space and what appears to be the inevitability of a conflict extending to Earth orbit, we're still not quite sure what that will look like. But several nations have been developing capabilities and concepts for maneuvering satellites in close proximity to other satellites with the intent to destroy or disable them, or to deny or degrade their communications or intelligence-gathering capabilities.

The U.S. Space Force, in particular, has been developing an operations framework for fighting a war in space and has held multiple training exercises aimed at practicing "orbital warfare."

But Space Force and U.S. Space Command still appear to lack many of the technologies they say they need to wage such warfare. Speaking at the Space Foundation's Space Symposium in 2025, Whiting stated that that the United States needs "orbital interceptors" to fight in space.

"And what do we call these?" Whiting rhetorically asked attendees. "We call these weapons, and we need them to deter a space conflict and to be successful if we end up in such a fight."

But U.S. Space Force has ordered and executed recent missions that have demonstrated capabilities and technologies along the lines of what Whiting described.

In June 2026, for example, a Rocket Lab Electron rocket sent one of the company's Puma satellites to orbit, where it rendezvoused with a True Anomaly Jackal spacecraft that launched a month earlier. Once both spacecraft were in orbit, they maneuvered close to one another to simulate "dynamic engagements."

The mission showed Space Force's "readiness to lean on our commercial partners to deny, disrupt and counter any adversarial advantage — no matter where they try to operate in space," according to a Space Force statement.

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A New Cold War Is Unfolding in Orbit as China Advances Satellite Surveillance

Chinese scientists at the Beijing Institute of Technology have run satellite proximity simulations to extend potentially hostile observation of U.S. space assets in Geostationary Earth Orbit (GEO), seemingly inching both countries closer to a potential war in space.

Although the new simulations focus on orbital adjustments to extend observation times and increase proximity to U.S. satellites, including critical missile warning and other space defense-oriented systems, Chinese scientists also plan to integrate reinforcement learning methods into future space assets to give satellites even more independence from human operators.

Study Includes Accusations of Cold War in Space Activities

In the 20th century, the concept of war in space remained mostly in the realm of science fiction, as depicted in popular films like Star Wars. Today, advances in space access, orbital maneuvering technologies, and weapons systems have made the possibility of a future conflict in space a very real security concern, and several nations engage in espionage using reconnaissance spacecraft to obtain information on valuable defense targets in Earth’s orbit.

According to the authors of the new study, “acquiring multi-aspect payload information of non-cooperative targets to infer their functions and mission statuses is of great significance for space security assessment.”

The study authors highlight a series of relative motion configurations that modern spy satellites employ, including fly-around, hovering, and drifting flight. They also point to real-world “adversarial” U.S missions they suggest were designed to gather intelligence on their GEO defense assets.

“Since 2014, the US GSSAP (United States Geosynchronous Space Situational Awareness Program) satellite has carried out hundreds of maneuvers and has conducted close observation operations on dozens of normally working satellites near GEO orbit,” the Beijing University of Technology scientists write.

The study authors also include a specific July 2021 accusation, where they charge that “the U.S. satellite ‘USA-271’ deliberately approached the operational ‘Practice 20’ satellite in geostationary orbit and flew in close proximity.”

In an email to The Debrief, a U.S. Space Command Spokesperson did not address the specific incident or the accusations of “dozens” of similar operations, but offered some insight into the agency’s thinking.

“USSPACECOM, working with allies and partners, plans, executes, and integrates military spacepower into multi-domain global operations in order to deter aggression, defend national interests, and when necessary, defeat threats,” the spokesperson told The Debrief, adding that “we have nothing additional to add in response to the article.”

Getting Closer to Adversarial Satellites and Extending Observation Time

In a step toward potential dogfights between satellites, the Chinese scientists looked at several challenges faced by current spy satellites.

For example, they explain, since most spacecraft observation cameras are mounted in a fixed position, “frequent large-angle attitude maneuvers are time-consuming and consume substantial fuel.” The researcher also noted that several different angles and approaches could yield different categories of intelligence data.

However, changing angles and orbital planes requires fuel, an extremely limited resource in GEO. Therefore, the researcher accounting for all the variables required to gather intelligence on adversarial spacecraft as efficiently as possible “has become a key bottleneck in enhancing space situational awareness capabilities.”

To find an optimized solution, the team designed what they called a “waypoint trajectory planning scheme” and a “multi-impulse maneuver strategy” using a common game-theory tool called “minimum integral squared control” theory. Unlike previous research aimed at extending spy satellite observation time and fuel efficiency, the Chinese scientists said their use of sequential coalition game theory “is introduced for the first time into the multi-model combined observation problem.”

Next, the researchers designed a “game tree.” A press release said this approach lets the spacecraft select the “optimal combination of initial motion points and close-range operation models at each stage under minimum fuel constraints, thereby generating an optimal observation strategy sequence.”

Finally, the researchers ran simulations to see whether their approach improved sensor observation times and field of view while reducing fuel use.

Successful Simulations and Future Reinforcement Learning Plans

As hoped, the Beijing University of Technology team said their simulations supported the theories. Specifically, the study authors said the simulations showed that their spacecraft efficiency algorithm “can successfully generate a multi-model combined observation strategy sequence under minimum fuel constraints.”

“The effective observation time increases with larger observation distances and field-of-view angles, and reducing the model configuration size also contributes to improved observation performance,” they explained. The study authors also said that the simulation results “demonstrate that the algorithm can successfully generate the optimal combined observation sequence under minimum fuel constraints.”

When discussing next steps, the Chinese scientists said they will explore optimal initial points to further improve maneuver efficiency. They also plan to explore a “reinforcement learning method,” suggesting future spacecraft could learn and adapt to evolving conditions to further enhance their cold war in space information-gathering capabilities.

Study’s War in Space Implications “Extends Beyond any Single Algorithm”

To understand the potential implications of the Chinese study, including its impacts on a potential future war in space, The Debrief reached out to former U.S. Air Force officer Shelli Brunswick, CEO and Founder, SB Global LLC.

According to the author and futurist, the Chinese team’s research matters not just because it proves China has deployed a “new operational surveillance capability.” Instead, Brunswick said that the work is significant because it “illustrates how sophisticated coordination and optimization could make spacecraft observation more efficient, persistent, and strategically useful.”

The Blue Marble Space Visiting Scholar also told The Debrief that the work “should not be interpreted as demonstrating a complete pursuit-and-evasion capability against a spacecraft that is actively responding,” since the work assumes a stationary target without maneuvering capabilities. Still, Brunswick noted, the Chinese framework “shows how game-theoretic planning could help an observing satellite gather information from multiple angles while managing limited resources.”

When discussing the potential implications for the broader U.S.-China space-security competition, including how such enhanced spacecraft could lead to more activities that could be construed as hostile, the space strategist said this area of research “extends beyond any single algorithm.”

“As rendezvous and proximity operations become more sophisticated, the line between inspection, space situational awareness, intelligence gathering, and potentially threatening behavior becomes increasingly difficult to interpret,” she explained.

When suggesting what potential strategic responses the U.S. and its allies might employ in the emerging cold war in space, Brunswick told The Debrief that they should include “more resilient architectures, improved space-domain awareness, clearer expectations for close approaches, stronger communication mechanisms, and deeper coordination with commercial and international partners.”

“The challenge is not simply detecting another spacecraft—it is understanding capability and intent early enough to respond responsibly and effectively,” Brunswick explained.

The study “Spacecraft Proximity Operation Model-Based Sequential Coalitional Observation Game Strategy Design” was published in Space: Science & Technology. 

Christopher Plain has spent the last six years as Associate News Editor and Head Science Reporter at The Debrief. Follow and connect with him on X, learn about his novels at plainfiction.com, or email him at christopher@thedebrief.org.

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2 satellites just burned up in Earth's atmosphere — and scientists were watching from a private jet. Here's why

A team of researchers just chased a pair of reentering satellites in a private jet to learn about the pollution caused by space debris burning up in Earth's atmosphere.

The satellites in question were the European Space Agency's (ESA) Tango and Samba spacecraft, which once formed the Cluster constellation, together with the already de-orbited Rumba and Salsa. The quartet used to study the interaction of Earth's magnetic field with the solar wind. After 25 years of service, ESA took advantage of the Tango and Samba's controlled demise to help scientists learn what happens when satellites break apart and burn up during their spiral back to Earth.

The international team of researchers chased the two reentries, which occurred one day apart — on Aug. 31 and Sept. 1 — above the southern Pacific Ocean a few hundred miles from the Polynesian archipelago of Tonga.

Their goal was to understand what happens when satellites disintegrate and what chemical compounds arise in the process. Although companies such as SpaceX, Amazon and Blue Origin want to launch huge numbers of satellites to space in the next decade — SpaceX alone plans to loft 100,000 of its Starlink V3 spacecraft — very little is known about the effects of satellite reentries on Earth's atmosphere. Researchers are also still unsure which spacecraft burn up completely and how many fragments may reach the ground, putting lives and property at risk.

"We want to understand what happens to these bodies as they fly through the atmosphere, which causes friction and very high temperatures," Jiří Šilha, CEO of the Slovak company Astros Solutions, and one of the researchers aboard the plane, told Space.com. "We know that those satellites break up into fragments, which subsequently melt in the atmosphere."

The researchers chased the reentering spacecraft following exact calculations provided by ESA controllers, who were able to maintain connection with the spacecraft until the very last moment before they plunged into the atmosphere.

six people inside a private jet, with computer equipment strewn around the cabin

Researchers inside a private jet during a campaign observing the reentry of ESA's Cluster Tango satellite on Sept. 1, 2026. (Image credit: Jiří Šilha)

The satellite reentries, although they occurred during daylight, were visible from aboard the plane even to the naked eye, said Šilha, and created spectacular fireballs that lasted tens of seconds.

"Bolides and meteors only last a few seconds or less," said Šilha. "But satellites are slower. They enter the atmosphere at a shallower angle, and the atmosphere slows them down further."

But the researchers were there for science, not for a sky show. And it was a rare opportunity: The Cluster trajectories were so precisely known that the scientists could prepare for them and be at the exact spot at the exact time to witness those explosions from only a couple of hundred miles away.

The aircraft, a small commercial business jet, was packed with 30 cameras and spectrometers fitted with special filters to capture not only how the satellites disintegrated but also detect the spectral signatures of the chemical elements released as their bodies burned up.

Eight scientists were squashed on board the darkened jet operating the instruments through the aircraft's six windows as the pilots navigated to the vicinity of the spot where ESA analysts had predicted the breakup would occur.

"We were flying toward the object, and first it looked like a compact source of light as the material ablated," said Šilha. "At some point, there was a sudden explosion as the satellite disintegrated."

The plane allowed the researchers to overcome any clouds that could obscure the view from the ground, and also to bypass the thickest layer of the atmosphere, which would distort the measurements. As the satellites hurtled through the air, slowing down from the mind-boggling speed of 22,370 mph (36,000 kph) at which they hit the upper atmosphere, the jet approached them to within a distance of around 75 miles (120 kilometers).

"We begin observing it when it's at about 90 kilometers [56 miles] and it stops being visible at about 65 to 70 kilometers [40 to 44 miles]," Šilha said. "For about thirty to forty seconds after the explosion, you can observe an interesting structure as all those various fragments ablate in the atmosphere. Then they all either burn up or slow down."

Šilha said the cameras captured tens of fragments, in detail that had never been observed before.

The researchers also attempted to trace seven chemical compounds, including titanium, sodium and potassium, which get released as satellites burn up. The team was especially interested in aluminum, which makes up the majority of a satellite body. Aluminum is not naturally present in Earth's atmosphere and most likely forms aluminum oxide during the incineration. The potential presence of aluminum oxide in the atmosphere in higher concentrations worries scientists, as it could potentially trigger ozone depletion in the stratosphere.

"We tried to measure the aluminum at different altitudes, using specialized filters, which could tell us when this aluminum interacts with the atmosphere," said Šilha. "That's when the aluminum oxide likely forms, and that's something that has never been observed before. We don't know exactly how and in what quantities the aluminum oxide might be forming."

The researchers will now analyze the data to learn exactly what chemical reactions may be occurring during every second of the breakup and burn-up process. The data will help atmospheric physics and chemistry researchers improve their models to further our understanding of the potential damage the growing satellite industry might do to the planet and its climate in the future.

"The data will help us validate whether the models agree with reality," said Šilha.

The team previously chased the reentry of the first of the four Cluster satellites — Salsa — in September 2024. The lessons from that campaign helped the team get closer to the Tango and Samba spacecraft and obtain more and more accurate data.

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The Vela Incident: Did an American satellite detect a secret nuclear test in 1979?

It began with an unusual flash detected off the coast of South Africa by an aging American satellite — and to this day, debate continues over whether this odd Cold War event involved an illicit atmospheric nuclear test.

The strange story of the "South Atlantic Flash," better known as the Vela Incident, began on Sept. 22, 1979. At that time, Vela 6911, a satellite in a constellation developed by the United States for the specific purpose of detecting nuclear detonations, observed something that immediately alarmed officials: a peculiar flash of light emanating from somewhere over the South Atlantic Ocean.

A significant part of what concerned U.S. officials at the time had been the double flash of light detected during the event — a distinctive feature that strongly resembled the flashes produced by a nuclear explosion in Earth's atmosphere. The characteristic double flash results from the rapidly changing brightness of the fireball and shock wave produced by an atmospheric nuclear detonation, creating a distinctive optical signature that Vela's sensors were specifically designed to recognize. The South Atlantic event, therefore, seemed like a prime candidate for a secretive nuclear test being carried out by an unknown party — but if that were the case, who was responsible?

What do we know?

U.S. officials responded to a possible nuclear test

Then-President Jimmy Carter was promptly alerted to the situation, as evidenced in diaries the former U.S. leader would publish years later. "There was indication of a nuclear explosion in the region of South Africa," Carter wrote in an entry on the same date of the event. A later entry penned the following February would go on to add that "We have a growing belief among our scientists that the Israelis did indeed conduct a nuclear test explosion in the ocean near the southern end of Africa."

a man in a suit sits at a large wooden desk beside a globe

President Jimmy Carter, seated at a desk in the Oval Office of the White House in 1980. (Image credit: Bettmann/Getty Images)

Despite that belief regarding the possibility of a clandestine nuclear test, a scientific panel assembled in 1980, chaired by MIT professor Jack Ruina, eventually put forward an alternative explanation: that the flash had more likely been an anomaly caused by a small meteoroid striking the satellite.

Notably, the panel did not rule out the possibility of a nuclear explosion at the time, although the alternative they put forward remained controversial among scientists and intelligence officials.

a memorandum on white house stationary

A memorandum to Director of Central Intelligence Stansfield Turner from Frank Press, White House science adviser, in which Press explains the reasoning behind the Ruina panel's conclusion that the Vela flash was "probably not from a nuclear explosion" and was therefore more likely "caused by a natural event." (Image credit: Public Domain/National Security Archive)

Documents and government insiders surface

By the turn of the 21st century, formerly classified documents began to surface that revealed the extent of the inner tensions between U.S. government agencies over what caused the Vela incident.

Among the critics of the debris-induced "anomaly" hypothesis had been Defense Intelligence Agency Vice Director Jack Varona. According to documents released in 2006, Varona said the investigations by the 1980 scientific panel had been a politically motivated "whitewash," and that evidence collected by the U.S. intelligence community included detections "unique to nuclear shots in a maritime environment," based on an analysis by the Naval Research Laboratory.

Varona wasn't alone. Other former intelligence officials who came forward over the years included Stansfield Turner, the former Director of Central Intelligence during the Carter administration, who in 2003 described the Vela detection as a "man-made phenomenon."

Similar views were advanced by retired CIA officer Tyler Drumheller, who in 2006 wrote that he had sources at the time who "collectively provided incontrovertible evidence that the [South African] apartheid government had in fact tested a nuclear bomb in the South Atlantic in 1979, and that they had developed a delivery system with assistance from the Israelis."

a dodecahedron-shaped satellite in a clean room; and an illustration of the same satellite in orbit above earth

The Vela-5A & B satellites in a cleanroom at Los Alamos National Laboratory (left); and an illustration of one of the satellites in orbit above Earth (right). (Image credit: Los Alamos National Laboratory)

What remains unknown?

Scientists revisit the mystery

While we still don't know if the South Atlantic Flash was a nuclear test, several scientists have reexamined the available evidence within the last decade, and what they found has lent further weight to the idea that the Vela incident had involved a detonation of some kind.

Among the most significant assessments, a 2017 study by Christopher Wright and Lars-Erik De Geer combined modern research into interplanetary dust and hypervelocity impacts with revelations from recently declassified documents, as well as publicly available information that had been previously overlooked.

Their conclusion: while no model was presented for the tenuous "meteoroid" theory advanced by the May 1980 scientific panel, the double flash observed by the Vela satellite in 1979 was indeed "consistent with a nuclear explosion, albeit detected by an aged satellite for which background modulation was abnormal and/or commenced earlier," adding that additional radionuclide and hydroacoustic evidence existed which supported the conclusion "that the Vela Incident was a nuclear weapon test explosion."

Wright and De Geer weren't alone either. A 2022 study examined data collected by NASA's Nimbus-7 satellite just 16 minutes and 44 seconds after the double flash over the South Atlantic, which suggested a disturbance in the ozone layer that appeared to be consistent with a blast-generated shock wave.

an illustration of a hexagonal satellite with two wing-like solar panels in orbit above earth

Artist's concept of a Nimbus spacecraft in orbit over Earth. (Image credit: NASA)

Still, some of the original members of the 1980 scientific panel have defended its work amid the more recent scientific studies. Richard Mueller, who served as the panel's youngest member at the time, defended the group's conclusions in a November 2019 oral history conference, maintaining that the chances the Vela incident had involved a nuclear event were "as close to zero as it gets."

This determination, Mueller argued, was made despite early interpretations by many panelists that a nuclear event had seemed most likely. Wright and De Geer, both of whom attended the 2019 oral history conference, were among the participants that pushed back on Mueller's views.

Who was responsible?

Amid the mounting evidence over the last several decades suggesting the Vela incident was indeed a nuclear test, debate continues over who was most likely to have been responsible.

Although suspicions have long centered on a cooperative — and secret — strategic effort between apartheid-era South Africa and Israel, publicly available evidence remains lacking, and a fair amount of information in declassified documents that could point to this possibility remains redacted.

a dodecahedron-shaped satellite in orbit above earth

An illustration of two Vela satellites separating in orbit. (Image credit: Los Alamos National Laboratory)

The mystery remains

Thus, after more than four decades, questions continue to linger over the famous Vela incident, including what nations might have been involved in such a test if it occurred. Despite that uncertainty, one thing does seem evident: information conveyed in unredacted portions of declassified records, combined with modern scientific analyses, increasingly point to the likelihood that the strange "South Atlantic Flash" in 1979 was anything but natural.

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Is Russia's rival to Starlink failing? Here's what we know.

Russia's attempt to replicate SpaceX's Starlink satellite network seems to be moving as slowly as the front lines in eastern Ukraine.

The Rassvet program, often billed as Russia's answer to Starlink, started launching its first operational satellites earlier this year. Two launches, one in March and a second in July, have delivered 32 Rassvet satellites to low-Earth orbit, some 10 percent of the roughly 300 Rassvet spacecraft Russia aims to put into orbit by the end of next year to provide connectivity for military and civilian users. The company in charge of Rassvet, Bureau 1440, wants to deploy 924 satellites by 2035.

But none of the 32 satellites launched so far have reached the 500-mile (800-kilometer) orbit they were designed to operate in. The rockets that launched the first two batches of Rassvets released the satellites much closer to Earth, and the satellites were expected to use their own plasma engines to raise their orbits over the next few months.

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More Starlink satellites and two big launches for China

Rocket launches this week On Tuesday, Aug. 18, Chinese aerospace firm LandSpace is targeting 7:35 p.m. EDT for the second flight of its Zhuque-3 rocket from the Jiuquan Satellite Launch Center in China, according to tracking from Next Spaceflight. The launch was scrubbed last week after a Long March 7A rocket exploded hours before Zhuque-3’sContinue reading "More Starlink satellites and two big launches for China"

The post More Starlink satellites and two big launches for China appeared first on Astronomy Magazine.

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Starlink Satellites Reveal a Hidden Atmosphere 300 Miles Above Earth

Modern Space Telecommunications Satellite Orbiting EarthSatellites designed to provide internet service are now serving an unexpected second purpose: helping scientists map the nearly invisible atmosphere at the edge of space. Researchers at Kyoto University have used orbital changes from about 1,200 Starlink satellites to map Earth’s thermosphere, a thin and difficult-to-observe region of the upper atmosphere. Their analysis produced the [...]
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Exploring 'very low Earth orbit': The world's 1st air-breathing satellite thruster could soon get a test run

A new way to move around Earth's outer atmosphere could soon get a field test.

The Spanish company Kreios Space plans to launch into orbit the world's first satellite that uses scooped-up air to push it forward, the company announced on Tuesday (Aug. 4).

The technology Kreios Space has been developing is called air-breathing electric propulsion (ABEP). It relies on air sourced from Earth's atmosphere, which is then heated up, ionized and expelled to generate thrust.

Diagram showing the different types of orbit around Earth.

Diagram showing the different types of orbit around Earth. (Image credit: ESA)

This method will allow satellites in very low Earth orbit (VLEO) — the region from roughly 60 miles to 250 miles (100 to 400 kilometers) above our planet — to counteract atmospheric drag without the aid of liquid fuel.

"Kreios is building the satellites that make sustained operations in very low Earth orbit possible," Kreios Space CEO Adrián Senar said in the Aug. 4 announcement.

"By enabling satellites to fly lower, longer and more efficiently, we are enabling higher-resolution Earth observation, much better satellite communications, more responsive and accurate missions and a more sustainable orbital infrastructure," he continued.

Kreios Space chose Lithuanian-based Kongsberg NanoAvionics to provide the satellite bus that will carry the ABEP system into orbit for the test run.

"Kreios is tackling one of the most demanding operating environments in space, and this mission joins a very short list of European VLEO initiatives," Kongsberg NanoAvionics CEO Atle Wøllo said in the same statement.

"Our engineering team has worked closely with Kreios to configure the MP42 satellite bus to the mission's specific requirements and support the integration of Kreios' technology," he added.

Kreios Space did not give a target launch date for the mission in Tuesday's statement, saying that the company will launch it "at a time when interest in and development of VLEO technologies has accelerated." But the company's website identifies 2027 as a notional target for its first space mission.

A new, very low frontier

Satellites in low Earth orbit (LEO) — altitudes of roughly 100 miles to 1,200 miles (160 to 2,000 km) — generally don't need constant propulsion. Usually, a small boost from traditional thrusters here and there is enough to keep a LEO satellite on the right track. To power the thrusters, these satellites usually have some form of fuel built in.

VLEO works differently. It's low enough that there's still some atmosphere present, which generates drag on spacecraft. If you want a satellite to move around VLEO, it'll need to employ propulsion most or all of the time to counteract that drag. Any fuel that the satellite brings with it therefore won't last long.

So, if satellites are going to operate in VLEO, it would be very helpful to have a method of propulsion that doesn't require traditional fuel — a method like ABEP.

Satellites in VLEO have a few advantages over those operating in LEO, like sharper imagery thanks to the closer vantage point. One of the biggest advantages is that VLEO is much less crowded. There are thousands of satellites in LEO — most of them SpaceX's Starlink broadband spacecraft — and the number is growing all the time. But VLEO has plenty of room.

If ABEP technology works and companies start outfitting satellites with this new propulsion method, then we might start seeing satellites operate quite close to Earth, zooming through the atmosphere and using the air around it to stay on course.

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