Category: 7. Science

BEIJING — China’s first Mars sample-return mission, Tianwen 3, is scheduled for launch around 2028, with the goal of returning no less than 500 grams of Martian samples to Earth by around 2031, according to the mission’s chief scientist.

Hou Zengqian, an academician of the Chinese Academy of Sciences and chief scientist of the Tianwen 3 mission, together with his collaborators, recently published an article in Nature Astronomy, systematically outlining the overall plan and scientific objectives of the mission for the first time.

“The mission will be a critical step in China’s planetary exploration. We hope to provide the international community with an unprecedented opportunity to understand Mars,” Hou said.

The Tianwen 3 mission will involve two launches, and the spacecraft will take seven to eight months to reach Mars. It will operate on Mars for about one year and then return to Earth, with the entire process spanning over three years, according to Hou.

LIFE ON THE RED PLANET?

“We aim to unravel the mystery of whether life ever existed on Mars,” Hou said.

He introduced three primary scientific objectives for the Tianwen 3 mission: searching for potential signs of life on Mars, including biomarkers, fossils and archaea; studying the evolution of Mars’ habitability, such as changes in water, atmosphere and oceans; and investigating the geological structure and evolutionary history of Mars, from surface features to internal dynamics.

These three objectives are interconnected. The origination of life requires a habitable environment, the proliferation of life evolves in tandem with the environment, and habitability is closely linked to geological processes, Hou explained.

To address these objectives, nine research teams have been established, covering aspects such as life-related elements, environmental conditions and geology, in order to “enhance our understanding of this Earth-like planet in our solar system,” Hou said.

HOW WILL SAMPLES BE COLLECTED?

The mission’s engineering team has preliminarily designed three sampling methods: surface scooping, deep drilling and drone-assisted collection to ensure sample diversity and scientific value.

Tianwen 3 will not carry a Mars rover. Instead, it will use a drone to collect samples from locations within several hundred meters of the landing site, Hou said.

He noted that Tianwen-3 will be the first mission internationally to conduct 2-meter-deep drilling for sample collection on Mars.

Previously, NASA’s Perseverance rover collected shallow surface samples, and will rely on a follow-up mission to return them to Earth. In contrast, Tianwen 3 aims to accomplish both sampling and return in a single mission.

Hou emphasized that planetary protection is a major issue in deep space exploration, and that contamination control is a critical challenge that must be addressed. Strict measures are required to prevent the contamination of Mars by the spacecraft and the potential contamination of Earth’s biosphere by Martian samples.

China will adhere strictly to the planetary protection policies of the Committee on Space Research to safeguard Mars from terrestrial contamination and protect Earth from potential Martian life, ensuring authentic and reliable scientific results, Hou said.

The Tianwen 3 mission will establish a complete chain in the sample preservation process, from collection and sealing on Mars to transportation and analysis on Earth. Additionally, a high-security Mars sample laboratory will be constructed, featuring ultra-clean and biosafety areas, where returned samples will undergo strict sterilization, unsealing, processing and biological risk assessment, Hou said.

WHERE WILL SAMPLES BE SOURCED?

“The selection of the landing site on Mars is crucial, as it directly impacts the achievement of the mission’s scientific objectives. From an initial pool of over 80 candidate sites, we have narrowed it down to 19, and by the end of 2026, three final candidate sites will be selected,” Hou said.

This selection must balance engineering constraints and scientific priorities. Due to engineering limitations, the landing site must be located between latitudes of 17 degrees and 30 degrees north on Mars. Scientifically, the site should offer the highest potential to harbor and preserve traces of life, the scientist said.

This is akin to mineral exploration on Earth — it requires the establishment of theories and models to guide predictions, and to then search for a needle in the haystack.

Similarly, identifying a suitable landing site requires a study of the conditions needed for the emergence, proliferation and preservation of life, and the development of predictive models, Hou noted.

If there is or was life on Mars, it would be or have been the result of the interplay of multiple factors, such as liquid water, atmosphere, temperature, magnetic field and internal structure. An ideal landing site should meet the requirements for habitability and life development, Hou said.

OPEN COLLABORATION

China has adopted a fully open and collaborative approach to the Tianwen 3 mission, from the formulation of scientific goals and the development of payloads to the joint research it has conducted on returned samples.

“We aim to build a global platform for scientific collaboration through planetary exploration, advancing humanity’s shared scientific endeavors,” Hou said.

“During the scientific goal-setting phase, we hosted an international conference, inviting global experts to participate in the discussion. For payloads, China issued an international call for proposals. After the samples are returned, China will open access to international scientists, provided safety is ensured,” Hou said.

He added that some key technologies for the Tianwen 3 mission remain under development. The scientific team is leveraging Martian observational data to advance landing-site selection. Meanwhile, to achieve its primary scientific objectives, the team is intensifying full-chain research on the search for life on Mars.

The magnetosphere, formed by the Earth’s magnetic field, acts as a protective shield that deflects solar wind—the flow of charged particles constantly streaming from the Sun toward our planet. This magnetic barrier protects our atmosphere and the technology we increasingly depend on in the near-Earth space, such as communication satellites. However, the magnetosphere isn’t impenetrable, as a fundamental process called ‘magnetic reconnection’ can temporarily strip this barrier during intense solar wind and cause violent energy fluctuations in the near-Earth space. As human activity in this region increases, understanding and forecasting such space weather becomes critical.

A key to understanding these breaches lies in measuring what’s known as the ‘reconnection rate,’ which quantifies energy efficiency in magnetic reconnection processes. For decades, scientists have attempted to measure this rate using various methods, including spacecraft flying directly through reconnection zones and observations of solar flares by remote imaging. However, these traditional approaches provide only local snapshots of the magnetic reconnection process or are limited by specific, often unsteady conditions. Obtaining a comprehensive and consistent picture that bridges the gap between local and global reconnection rates remains a challenge.

Against this backdrop, a research team led by Associate Professor Yosuke Matsumoto from the Institute for Advanced Academic Research at Chiba University, Japan, is testing an innovative approach using soft X-ray imaging to measure the reconnection rates. The study, co-authored by Mr. Ryota Momose from Chiba University and Prof. Yoshizumi Miyoshi from Nagoya University, was made available online on June 23, 2025, and was published in Volume 52, Issue 12 of the journal Geophysical Research Letters on June 28, 2025.

Soft X-ray emission occurs through a charge exchange process between the heavy ions in the solar wind and the hydrogen neutral atoms originating from the Earth. In this study, the researchers propose leveraging the soft X-rays that are naturally emitted when solar wind particles interact with the boundaries of the magnetosphere to remotely measure reconnection rates across much larger regions than previously possible.

The team conducted advanced computer simulations on the Fugaku supercomputer, combining high-resolution global magnetohydrodynamic simulations of Earth’s magnetosphere with a model of soft X-ray emission. From the simulations, they analyzed how reconnection-related X-rays can be viewed from a satellite positioned at a lunar distance during intense solar wind conditions. This vantage point roughly matches that of an upcoming X-ray imaging satellite like GEO-X, which is scheduled for launch in the near future.

After analyzing the simulation results, the researchers found that the brightest X-ray emissions form distinct cusp-shaped patterns that directly reflect the magnetic field structure around reconnection zones. By measuring the opening angle of these bright regions, they calculated the global reconnection rate to have a value of 0.13, which closely matches theoretical predictions and previous laboratory measurements. Therefore, the results demonstrate that the geometry of bright X-ray features correlates with the reconnection rate, offering a new method to estimate this important parameter. “Imaging X-rays from the sun-facing magnetospheric boundary can now potentially quantify solar wind energy inflow into the magnetosphere, making X-rays a novel space weather diagnostic tool,” highlights Dr. Matsumoto.

By providing a new way to measure and understand magnetic reconnection, this research contributes directly to improving space weather forecasting. Being able to predict how solar activity influences the near-Earth space is vital for protecting astronauts and ensuring the reliability of communication systems and space missions, especially in the face of potentially devastating events like magnetic storms.

Notably, this study also has broader scientific implications for understanding magnetic reconnection in other contexts, as Dr. Matsumoto explains, “Magnetic reconnection is not only responsible for breaching Earth’s magnetic shield but is also the underlying process behind explosive events in plasma devices, the Sun, and black holes. Understanding this process is essential for advancing technologies like plasma confinement in fusion reactors and investigating the origin of high-energy cosmic rays.”

As humanity prepares for an era of space exploration and commercial space activities, this newly proposed method could pave the way to accurate space weather predictions, helping ensure the safety and success of our ventures beyond Earth’s atmosphere.

About Associate Professor Yosuke Matsumoto from Chiba University

Dr. Yosuke Matsumoto joined Chiba University in 2011. Since 2022, he has been serving as an Associate Professor at the Institute for Advanced Academic Research. He specializes in space and planetary science, as well as theoretical studies related to cosmic rays and astrophysics. He has published over 70 research papers on these topics and received multiple awards, including the NASA Group Achievement Award to the MAVEN Mission Team. He has professional memberships in multiple academic societies, including the Society of Geomagnetism and Earth, Planetary and Space Sciences.

The skies overhead are already teeming with satellites. But their orbiting numbers will skyrocket in the near future as the commercial and international space race takes off. Three projects alone — SpaceX’s Starlink, China’s Guowang megaconstellation, and Donald Trump’s proposed Golden Dome missile defense system — will launch tens of thousands of new satellites.

Today’s 12,000 satellites could, according to some estimates, grow to 60,000, or even 100,000 total satellites by 2030, as a space industry already worth hundreds of billions of dollars sees rapid growth.

This 21^st-century space race, while a boon for communications and Earth monitoring, is sending up a red flag with experts, who warn that the tech advances satellite may bring are linked to a growing number of Earth environmental impacts stretching from the industry’s supply chain here on Earth, into the upper atmosphere and out into space itself.

With countries initiating or expanding their space programs (including the U.S., EU, India, Japan, China, Russia, South Korea and the United Arab Emirates), and commercial efforts all in full swing, “we’re moving towards an industry that could cause a lot of damage to the environment if we don’t regulate it or understand it,” now, says Eloise Marais, an atmospheric chemist at University College London, U.K.

The industry’s toll stretches from its ground-based, energy-guzzling data centers, to metal-shedding rocket launches, to tons of orbiting space junk and debris regularly plummeting back to Earth. Among the risks are poorly understood space age atmospheric pollutants that could harm the ozone layer or worsen global warming.

These foreseen — and likely some still unforeseen — consequences are bringing calls for greater scrutiny of the space sector’s footprint, along with international regulation.

“The industry is developing a lot quicker than regulation can keep pace,” says Andrew Wilson, a lecturer in environmental management at Glasgow Caledonian University, U.K. “For that reason, what we’ve seen, historically speaking, is the space sector pretty much … do what it wants without much regard to the environment.”

From ground to sky

In 2019, when Samantha Lawler, associate professor of astronomy at the University of Regina, moved to a farm in Saskatchewan, Canada, she saw dark, starry skies for the first time in her life. “I could see the Milky Way from my back door,” she recalls.

But about then, the number of satellites began steadily increasing, mostly due to SpaceX’s Starlink megaconstellation. “How bad is this gonna make my sky look?” she wondered. She’s just one of many astronomers concerned about the impact of satellites impinging on the study and understanding of the cosmos.

When SpaceX satellite debris slammed to Earth near her home, she began looking deeper at the impact of the rapidly growing number of satellites. “I wrote a research paper about that,” she says. “And slowly realized how many more problems there are with having this many satellites in orbit beyond the light pollution.”

Those existing and potential harms include a space sector supply chain reliant on extracting numerous metals, critical minerals and other components used in rocket and satellite construction, along with prodigious industry water use. Energy-hungry data storage is also a space industry must-have, and is responsible for mostly overlooked but significant carbon emissions, according to Kevin Gaston, professor of biodiversity and conservation at the University of Exeter, U.K.

“Many of the conversations you have with people on the industry side, it’s all about the launches and … the immediate impacts of launch infrastructure and launches themselves,” says Gaston. “Almost no one’s been talking about the ground infrastructure data storage.”

A 2024 study estimates that data storage to support current Earth observation satellites produces annual carbon emissions equivalent to 41,000 London-to-Paris flights. That figure is set to grow.

Researchers also underline that spaceports and launches — putting payloads, various missions, and even tourists into space — remains a growth industry that has historically underrecognized terrestrial biodiversity concerns — perhaps beginning with Cape Kennedy’s role in the extinction of the dusky seaside sparrow (Ammospiza maritima nigrescens). In a 2024 paper, an international research team found that 60% of launch sites overlap with protected areas, especially in the tropics.

Fanhao Kong, an author on that study and a researcher at the University of Marburg, Germany, says concerns are numerous, ranging from pollution emitted during launches, contamination of water sources, and noise disruption.

“Biodiversity conservation is always the last consideration during the whole process,” she says. Her study highlighted how siting of spaceports predominantly on tropical coasts, along with the intrusive propulsion boost of launch vehicles, puts mangroves at particular risk.

Conservationists in Mexico recently raised alarm that debris from a failed SpaceX launch led to contamination of a beach used by endangered sea turtles. Campaigners in the U.S. have protested against spaceports in other locations due to concerns over local water pollution and potential harm to protected areas. Wilson notes there is very limited knowledge as to how spent payloads falling into the world’s oceans impact marine life.

Liftoff and burn up

In 2024, there was one rocket launch attempt every 36 hours. That comes to around 260 launches yearly, a statistic that will move ever higher in tandem with the space sector’s contribution to pollution and global climate change, say experts.

Depending on fuel type, rockets emit varied contaminants, including black carbon, reactive chlorine and reactive nitrogen oxides, which can help deplete the protective stratospheric ozone layer. Rockets also release water vapor in the upper atmosphere, which contributes to global warming.

“We know exactly how much of these particles are emitted. We know exactly what altitude they’re emitted at,” says Wilson. “The issue is we don’t really know what the overall impact would be on radiative forcing, and ozone destruction over a prolonged period of time.”

In a typical launch, most rocket exhaust is spread within the stratosphere (11-50 km; 7-31 miles) and mesosphere (50-80 km; 31-50 miles), the second and third of the five layers of Earth’s atmosphere.

“In the past, we’ve had too few rocket launches to see any appreciable impacts on ozone. There might be some localized ozone losses due to the rocket launches, but that rapidly heals,” says Laura Revell, an atmospheric scientist at the University of Canterbury, Aotearoa New Zealand. But with more and more countries and companies heading to space or launching satellites, that is likely to change fast.

Revell co-authored a recently published paper that assessed potential future impact on the ozone layer. Under a “conservative scenario” of around 900 launches per year by 2030 — where the current trajectory is headed — they found no significant ozone loss.

But, she says, that study modeled its research on rockets launched in 2019, so that doesn’t include newer vehicles like SpaceX’s mammoth Starship, the largest rocket currently under development. These giant launch vehicles and new fuel types could change that analysis.

A second modeled scenario estimated a far higher number of launches, totaling 2,040 annually also by 2030 — around a tenfold increase — resulting in a decrease in stratospheric protective ozone of around 0.29% globally, and 3.9% over Antarctica. That’s a rapid increase, but not beyond the realms of possibility, Revell says.

Experts are also increasingly concerned about the environmental impacts as a growing number of orbiting satellites burn up on reentry at the end of their lives. “10 years ago, the amount of satellites burning up was about a couple of tonnes per year,” says Minkwan Kim, an associate professor at the University of Southampton, U.K. “Now we have a couple of tonnes per day.”

The number of objects burning up on reentry will soon push past the natural levels of metals created my meteorites, according to his estimates.

Kim lays out several concerns regarding this increase: First, satellites when burning up release metal particles into the atmosphere, such as metal oxides, which could trigger chemical reactions that eat away at the ozone layer, causing harm to the protective layer vital to conditions needed for life on Earth.

Second, these metal oxides could act as an inadvertent geoengineering experiment. They’re a common ingredient in sunscreen for good reason, as they act as solar reflectors. “Imagine if we spray sunscreen at high altitude; it blocks the sunlight,” he says. “For the global warming response, it might be good, but we don’t know about the [other] consequences.”

Recent research published by the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder, U.S., estimates that satellite reentries could contribute enough alumina to the stratosphere to alter wind speeds and temperatures in the polar regions by 2040.

A third concern: Metal oxide pollutants could disrupt the functioning of satellites already in orbit. Particles deposited in the atmosphere could interfere with signals, meaning that more satellites may be needed to counteract this affect. “That means we have to launch more satellites, and then we have to burn more,” Kim says.

Analysts also worry the rapid rate of industry development will outpace the ability for researchers to keep up. “Even if we start the study now, by the time we have a credible assessment tool, there would be as many as 30,000 more satellites in orbit with similar increases in rate of [satellite] reentry vehicles by the time a comprehensive understanding of their effects could be written,” warns a 2024 NASA paper.

Space junk: A risk of ‘irreversible orbital pollution’

Just as thousands of tons of trash litter the Earth’s oceans and beaches, huge amounts of space junk now clutter our human endeavors in space.

According to the European Space Agency (ESA), the number of debris pieces larger than 1 centimeter (0.4 inches) in size — large enough to cause catastrophic damage to a satellite or spacecraft in a collision — is estimated at more than 1.2 million pieces. There are also more than 50,000 objects larger than 10 cm (4 in). As that number grows, fragments collide with each other, making even more fragments. In 2024, another 3,000 tracked objects were added to the total.

The ultimate concern is that space debris will collide with other debris and functioning satellites, creating more and more fragments, with the problem eventually spiraling out of control, unleashing the so-called Kessler Syndrome.

“A single [major] collision could trigger the Kessler Syndrome, a cascade of debris rendering key orbits unusable,” Walter Leal, chair of climate change management at the Hamburg University of Applied Sciences, Germany, wrote in an email. He cites the case of Iridium 33 and Cosmos 2251, two active satellites that collided in 2009, fragmenting into thousands of pieces.

If such a disaster happens, it could severely disrupt global communications, GPS, and other vital tools including climate monitoring, says Leal. “Megaconstellations (e.g., Starlink, OneWeb) exacerbate this [collision threat] by adding tens of thousands more satellites, increasing congestion.

“My major concerns regarding space debris center on its exponential growth and cascading risks,” he adds. “With millions of debris fragments now orbiting Earth — ranging from defunct satellites to paint flakes — even tiny objects travel at hypervelocity (7-8 km/s [or 4-5 miles per second]), posing catastrophic collision risks to active spacecraft like the ISS [International Space Station] or vital satellites.”

Many experts believe that collisions — even if they don’t reach the scale of the Kessler Syndrome — are inevitable. It’s an issue the space industry has become acutely aware of, with satellites now making tens of thousands of maneuvers annually to avoid collisions with one another and space junk.

The European Space Agency is addressing the space junk problem with its active debris removal program. By 2030, there will not be a single satellite launched by the ESA that has a risk of generating space debris in an uncontrolled way, says Andrea Vena, ESA’s chief climate and sustainability officer. Still, experts agree that a range of space junk cleanup solutions are urgently needed.

Space sustainability

The race for space is not set to end anytime soon. Satellite megaconstellations and grand visions for missile defense, colonizing the moon and Mars, are being proposed without clear plans for curtailing impacts here on Earth and in orbit.

“Through the commercialization of space, we’re seeing the cost per kilogram to launch go down and down,” says Wilson from Glasgow Caledonian University. “But we’re scaling up to a point that [space exploration] is becoming unsustainable.”

Wilson and others say that legislation and collaboration are vital at the national, international and global levels. A few past global agreements — primarily the Outer Space Treaty of 1966 — offer piecemeal preliminary guidance, but none fit today’s quickly evolving public-private space sector.

“We urgently need a UN-led treaty with standardized disposal protocols, liability clauses for incidents that create debris, and shared funding for cleanup missions,” writes Leal, adding that “urgent action is needed to prevent irreversible orbital pollution.”

Though the handling of space debris has become a hot topic, critics say legislation must go beyond what happens in orbit, and address growing environmental concerns related to the industry’s expansive footprint on the ground, where it is contributing to biodiversity loss, pollution and greenhouse gas emissions.

Kim believes the Montreal Protocol, an internationally binding treaty aimed at protecting the ozone layer, could act as a viable mechanism to regulate rocket and satellite burnup impacts. He notes that while further research funding is needed, action is essential due to already known potential harm. “All we need is to add one or two items [to the Montreal Protocol] related to spacecraft disposal,” he says.

That’s an issue the Montreal Protocol Scientific Assessment Panel is considering. “Our current understanding on the potential impacts on ozone from space activity is incomplete due to limited and uncertain knowledge of the resultant chemical and radiative changes in the stratosphere,” the panel wrote in a statement to Mongabay, adding it isn’t presently considering spacecraft monitoring or compliance within the protocol.

Experts like Wilson point to the upcoming European Union Space Act as an early regulatory front-runner, as it places sustainability at the forefront. He also believes voluntary standards, already in process by the commercial industry, will play a key role.

Vena at ESA, meanwhile, believes the future of space will follow circular economy principles, including careful assessment of materials used in spacecraft and satellite construction, prolonging vehicle lifespans, and ensuring safe, responsible disposal.

Wilson says the objective of his work and others isn’t to demonize or hamstring the industry, but to proactively support it to minimize harm. “The goal … is to say this is your footprint, and this is what you should be doing to reduce it, so that you’re becoming more efficient and more sustainable,” he says.

Banner image: NASA’s Artemis program plans to return humans to the moon, with the U.S. government agency working with SpaceX to develop the company’s Starship human landing system. Such explorations pose another unasked question: Who will be responsible for cleaning up space junk on the worlds that humanity explores? Image courtesy of NASA.

Citations:

Lawler, S., Boley, A., Rein, H., Fraser, W., Pike, R., Alexandersen, M., … Patterson, J. (2024). Light pollution from satellites: What’s coming and what astronomy research will be compromised. AAS/Division of Dynamical Astronomy Meeting, 55, 102.01. Retrieved from https://ui.adsabs.harvard.edu/abs/2024DDA….5510201L

Lawrence, A., Rawls, M. L., Jah, M., Boley, A., Di Vruno, F., Garrington, S., … McCaughrean, M. (2022). The case for space environmentalism. Nature Astronomy, 6(4), 428-435. doi:10.1038/s41550-022-01655-6

Kukreja, R., Oughton, E., & Linares, R. (2025). Greenhouse gas (GHG) emissions poised to rocket: Modeling the environmental impact of LEO satellite constellations. arXiv. doi:10.48550/arXiv.2504.15291

Anderson, K., Brewin, R. J., Mleczko, M. M., Mueller, M., Shutler, J. D., Wilkinson, R., … Gaston, K. J. (2024). The dark side of Earth observation. Nature Sustainability, 7(3), 224-227. doi:10.1038/s41893-023-01262-x

Ang, L. P., Kong, F., Hernández-Rodríguez, E., Liu, Q., Cerrejόn, C., Feldman, M. J., … Yin, X. (2024). Rocket launches threaten global biodiversity conservation. Communications Earth & Environment, 5(1). doi:10.1038/s43247-024-01963-x

Dallas, J. A., Raval, S., Alvarez Gaitan, J. P., Saydam, S., & Dempster, A. G. (2020). The environmental impact of emissions from space launches: A comprehensive review. Journal of Cleaner Production, 255, 120209. doi:10.1016/j.jclepro.2020.120209

Ryan, R. G., Marais, E. A., Balhatchet, C. J., & Eastham, S. D. (2022). Impact of rocket launch and space debris air pollutant emissions on stratospheric ozone and global climate. Earth’s Future, 10(6). doi:10.1029/2021EF002612

Revell, L. E., Bannister, M. T., Brown, T. F., Sukhodolov, T., Vattioni, S., Dykema, J., … Rozanov, E. (2025). Near-future rocket launches could slow ozone recovery. npj Climate and Atmospheric Science, 8(1). doi:10.1038/s41612-025-01098-6

Dominguez Calabuig, G. J., Wilson, A., Bi, S., Vasile, M., Sippel, M., & Tajmar, M. (2024). Environmental life cycle assessment of reusable launch vehicle fleets: Large climate impact driven by rocket exhaust emissions. Acta Astronautica, 221, 1-11. doi:10.1016/j.actaastro.2024.05.009

Sirieys, E., Gentgen, C., Jain, A., Milton, J., & De Weck, O. L. (2022). Space sustainability isn’t just about space debris: On the atmospheric impact of space launches. MIT Science Policy Review, 3. doi:10.38105/spr.whfig18hta

Boley, A. C., & Byers, M. (2021). Satellite mega-constellations create risks in Low Earth Orbit, the atmosphere and on Earth. Scientific Reports, 11(1). doi:10.1038/s41598-021-89909-7

Maloney, C. M., Portmann, R. W., Ross, M. N., & Rosenlof, K. H. (2025). Investigating the potential atmospheric accumulation and radiative impact of the coming increase in satellite reentry frequency. Journal of Geophysical Research: Atmospheres, 130(6). doi:10.1029/2024JD042442

Leal Filho, W., Abubakar, I. R., Hunt, J. D., & Dinis, M. A. (2025). Managing space debris: Risks, mitigation measures, and sustainability challenges. Sustainable Futures, 10, 100849. doi:10.1016/j.sftr.2025.100849

FEEDBACK: Use this form to send a message to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.

The Dead Sea is one of the most unique bodies of water on the planet. Sitting at the lowest point on Earth’s land surface, it’s known for its extreme salinity and incredible density. But there’s more happening beneath its surface than meets the eye.

Among the many unusual things scientists are learning about this hypersaline lake is the ongoing formation of what they call “salt giants” – massive underground salt deposits.

“These large deposits in Earth’s crust can be many, many kilometers horizontally, and they can be more than a kilometer thick in the vertical direction,” noted Eckart Meiburg, a professor of mechanical engineering at UC Santa Barbara..

“How were they generated? The Dead Sea is really the only place in the world where we can study the mechanism of these things today.”

Salt formation in the Dead Sea

While salt formations have been found under other seas – including the Red Sea and the Mediterranean – only the Dead Sea lets scientists observe them forming right now.

This gives researchers a rare chance to understand the actual physical processes behind these deposits, especially how their thickness changes across space and time.

A recent paper published by researchers at UC Santa Barbara and the Geological Survey of Israel explains how evaporation, water temperature, and salt saturation all combine to build these structures.

Because the Dead Sea is a terminal lake – one with no outlet – water can only leave by evaporation. As that water vanishes, salt stays behind, accumulating layer by layer.

This process has been going on for millennia, shrinking the lake and increasing salinity. The damming of the Jordan River, the lake’s main water source, has sped up this decline, with the lake now dropping by about one meter (three feet) per year.

Layers of salt and shifting temperatures

Temperature also plays a crucial role. The Dead Sea used to be what scientists call “meromictic,” with a stable layering of warm, less salty water on top and cooler, saltier water at the bottom.

“It used to be such that even in the winter when things cooled off, the top layer was still less dense than the bottom layer,” Meiburg explained. “And so as a result, there was a stratification in the salt.”

That changed in the early 1980s when water levels fell and surface salinity caught up to deeper levels.

Mixing between the layers began, turning the lake from meromictic to holomictic – meaning it now undergoes full mixing in the water column each year. Today, the Dead Sea stays stratified only during the warmer eight months of the year.

Salt snow in the summer

In 2019, scientists made a surprising discovery: halite crystals – or “salt snow” – were forming in the lake during the summer, not just in winter as expected.

Halite, or rock salt, forms when water can no longer dissolve salt due to high concentrations. Normally, this happens in the colder, deeper parts of the lake. But in summer, something unusual was happening.

The top layer of the lake grew even saltier due to evaporation. At the same time, its warm temperature allowed it to keep dissolving salt. This led to a special process known as “double diffusion.”

In this process, salty warm water from the top cools and sinks, while slightly less salty cool water below warms and rises. When the upper layer cools, the salt falls out, like underwater snowfall.

The constant shift in density and temperature, along with other factors like waves and currents, creates salt deposits in all kinds of shapes and sizes.

Unlike other shallow salt lakes where this happens mostly in dry seasons, the Dead Sea sees the most salt formation in winter. This year-round activity helps explain the birth of the salt giants.

A lesson from the distant past

The process happening in the Dead Sea today may also explain salt formations from long ago. Around 5.96 to 5.33 million years ago, the Mediterranean Sea dried up during what’s known as the Messinian Salinity Crisis.

“There was always some inflow from the North Atlantic into the Mediterranean through the Strait of Gibraltar,” Meiburg said. “But when tectonic motion closed off the Strait of Gibraltar, there couldn’t be any water inflow from the North Atlantic.”

The sea level dropped dramatically – up to 5 kilometers (about 3 miles) – due to evaporation, leaving behind thick salt crusts. These can still be found beneath parts of the Mediterranean. Later, the Strait of Gibraltar reopened, and the sea filled again.

Salt features of the Dead Sea

The Dead Sea continues to be full of surprises. Springs on its floor and varying salt flows create even more formations – including salt domes and chimneys.

Beyond learning how these features form, the study of the Dead Sea could have broader implications.

Watching how sediment moves on the newly exposed beaches may help scientists understand how coastlines in dry regions respond to sea level changes. It could also point to new ways to manage resources from such salty environments.

With its strange physics and active processes, the Dead Sea gives researchers a rare look at how massive salt deposits grow – one underwater snowflake at a time.

The full study was published in the journal Annual Review of Fluid Mechanics.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–

July 22 (UPI) — Scientists predicted that Tuesday will be a fraction of a second shorter than the average day as the Earth’s rotation is moving faster.

The international Earth Rotation and Reference System Service expects that Tuesday will be just 1.34 milliseconds shorter than the standard 24 hours.

“We’ve known about the rotation of the Earth being variable for about a hundred years,” said the former Director of Time at the United States Naval Observatory Dennis McCarthy. “This is just one of those little variations that comes along.”

The speed of the Earth’s rotation isn’t fixed. A 2023 study showed a day was approximately 19 hours in Earth’s early history.

July 5, 2024, was the shortest day ever, 1.65 milliseconds shorter than the usual 86,400 seconds, said MIT geophysicist Thomas Herring.

Scientists predicted that Aug. 5 could be the next day we will see a quicker rotation, 1.25 milliseconds shorter than usual.

“The cause of this acceleration is not explained,” a leading authority on Earth’s rotation at Moscow State University, Leonid Zotov, said. “Most scientists believe that it is something inside the Earth. Ocean and atmospheric models don’t explain this huge acceleration.”

WASHIGTON — Earth is spinning faster this summer, making the days marginally shorter and attracting the attention of scientists and timekeepers.

July 10 was the shortest day of the year so far, lasting 1.36 milliseconds less than 24 hours, according to data from the International Earth Rotation and Reference Systems Service and the US Naval Observatory, compiled by timeanddate.com. More exceptionally short days are coming on July 22 and August 5, currently predicted to be 1.34 and 1.25 milliseconds shorter than 24 hours, respectively.

The length of a day is the time it takes for the planet to complete one full rotation on its axis —24 hours or 86,400 seconds on average. But in reality, each rotation is slightly irregular due to a variety of factors, such as the gravitational pull of the moon, seasonal changes in the atmosphere and the influence of Earth’s liquid core. As a result, a full rotation usually takes slightly less or slightly more than 86,400 seconds — a discrepancy of just milliseconds that doesn’t have any obvious effect on everyday life.

However these discrepancies can, in the long run, affect computers, satellites and telecommunications, which is why even the smallest time deviations are tracked using atomic clocks, which were introduced in 1955. Some experts believe this could lead to a scenario similar to the Y2K problem, which threatened to bring modern civilization to a halt.

Atomic clocks count the oscillations of atoms held in a vacuum chamber within the clock itself to calculate 24 hours to the utmost degree of precision. We call the resulting time UTC, or Coordinated Universal Time, which is based on around 450 atomic clocks and is the global standard for timekeeping, as well as the time to which all our phones and computers are set.

Astronomers also keep track of Earth’s rotation — using satellites that check the position of the planet relative to fixed stars, for example — and can detect minute differences between the atomic clocks’ time and the amount of time it actually takes Earth to complete a full rotation. Last year, on July 5, 2024, Earth experienced the shortest day ever recorded since the advent of the atomic clock 65 years ago, at 1.66 milliseconds less than 24 hours.

“We’ve been on a trend toward slightly faster days since 1972,” said Duncan Agnew, a professor emeritus of geophysics at the Scripps Institution of Oceanography and a research geophysicist at the University of California, San Diego. “But there are fluctuations. It’s like watching the stock market, really. There are long-term trends, and then there are peaks and falls.”

In 1972, after decades of rotating relatively slowly, Earth’s spin had accumulated such a delay relative to atomic time that the International Earth Rotation and Reference Systems Service mandated the addition of a “leap second” to the UTC. This is similar to the leap year, which adds an extra day to February every four years to account for the discrepancy between the Gregorian calendar and the time it takes Earth to complete one orbit around the sun.

Since 1972, a total of 27 leap seconds have been added to the UTC, but the rate of addition has increasingly slowed, due to Earth speeding up; nine leap seconds were added throughout the 1970s while no new leap seconds have been added since 2016.

In 2022, the General Conference on Weights and Measures (CGPM) voted to retire the leap second by 2035, meaning we may never see another one added to the clocks. But if Earth keeps spinning faster for several more years, according to Agnew, eventually one second might need to be removed from the UTC. “There’s never been a negative leap second,” he said, “but the probability of having one between now and 2035 is about 40%.”

What is causing Earth to spin faster?

The shortest-term changes in Earth’s rotation, Agnew said, come from the moon and the tides, which make it spin slower when the satellite is over the equator and faster when it’s at higher or lower altitudes. This effect compounds with the fact that during the summer Earth naturally spins faster — the result of the atmosphere itself slowing down due to seasonal changes, such as the jet stream moving north or south; the laws of physics dictate that the overall angular momentum of Earth and its atmosphere must remain constant, so the rotation speed lost by the atmosphere is picked up by the planet itself. Similarly, for the past 50 years Earth’s liquid core has also been slowing down, with the solid Earth around it speeding up.

By looking at the combination of these effects, scientists can predict if an upcoming day could be particularly short. “These fluctuations have short-period correlations, which means that if Earth is speeding up on one day, it tends to be speeding up the next day, too,” said Judah Levine, a physicist and a fellow of the National Institute of Standards and Technology in the time and frequency division. “But that correlation disappears as you go to longer and longer intervals. And when you get to a year, the prediction becomes quite uncertain. In fact, the International Earth Rotation and Reference Systems Service doesn’t predict further in advance than a year.”

While one short day doesn’t make any difference, Levine said, the recent trend of shorter days is increasing the possibility of a negative leap second. “When the leap second system was defined in 1972, nobody ever really thought that the negative second would ever happen,” he noted. “It was just something that was put into the standard because you had to do it for completeness. Everybody assumed that only positive leap seconds would ever be needed, but now the shortening of the days makes (negative leap seconds) in danger of happening, so to speak.”

The prospect of a negative leap second raises concerns because there are still ongoing problems with positive leap seconds after 50 years, explained Levine. “There are still places that do it wrong or do it at the wrong time, or do it (with) the wrong number, and so on. And that’s with a positive leap second, which has been done over and over. There’s a much greater concern about the negative leap second, because it’s never been tested, never been tried.”

Because so many fundamental technologies systems rely on clocks and time to function, such as telecommunications, financial transactions, electric grids and GPS satellites just to name a few, the advent of the negative leap second is, according to Levine, somewhat akin to the Y2K problem — the moment at the turn of the last century when the world thought a kind of doomsday would ensue because computers might have been unable to negotiate the new date format, going from ’99’ to ’00.’

The role of melting ice

Climate change is also a contributing factor to the issue of the leap second, but in a surprising way. While global warming has had considerable negative impacts on Earth, when it comes to our timekeeping, it has served to counteract the forces that are speeding up Earth’s spin. A study published last year by Agnew in the journal Nature details how ice melting in Antarctica and Greenland is spreading over the oceans, slowing down Earth’s rotation — much like a skater spinning with their arms over their head, but spinning slower if the arms are tucked along the body.

“If that ice had not melted, if we had not had global warming, then we would already be having a leap negative leap second, or we would be very close to having it,” Agnew said. Meltwater from Greenland and Antarctica ice sheets has is responsible for a third of the global sea level rise since 1993, according to NASA.

The mass shift of this melting ice is not only causing changes in Earth’s rotation speed, but also in its rotation axis, according to research led by Benedikt Soja, an assistant professor at the department of civil, environmental and geomatic engineering of The Swiss Federal Institute of Technology in Zurich, Switzerland. If warming continues, its effect might become dominant. “By the end of this century, in a pessimistic scenario (in which humans continue to emit more greenhouse gases) the effect of climate change could surpass the effect of the moon, which has been really driving Earth’s rotation for the past few billions of years,” Soja said.

At the moment, potentially having more time to prepare for action is helpful, given the uncertainty of long-term predictions on Earth’s spinning behavior. “I think the (faster spinning) is still within reasonable boundaries, so it could be natural variability,” Soja said. “Maybe in a few years, we could see again a different situation, and long term, we could see the planet slowing down again. That would be my intuition, but you never know.” — CNN

A new study, published by a team of UBC Okanagan chemistry researchers, is creating a major rethink of how enzymes work. And how a quantum phenomenon helps an important enzyme control essential yet dangerous molecules.

Enzymes, also known as biocatalysts, are the tiny machines behind every process in living things, explains study co-author Hossein Khalilian, a doctoral student in the Irving K. Barber Faculty of Science ‘s Department of Chemistry. Enzymes make molecules that are crucial to life, while also breaking down molecules that are bad or unnecessary for us.

Radical enzymes represent an important class of biocatalysts that generate extremely unstable molecules-called free radicals-to enable a wide range of biochemical reactions. Free radicals are often negatively viewed, explains Khalilian. Uncontrolled ones contribute to serious conditions like cancer, autoimmune and neurodegenerative diseases. Yet, these molecules are essential for many biological functions and the body produces them as part of normal cellular functions.

The research, featured on the front cover of the Journal of the American Chemical Society , reveals that nature has developed a clever way to control these free radicals-using little-known quantum Coulombic interactions to manage them and prevent unwanted damage.

The researchers focused on an enzyme called viperin, which plays a role in the body’s immune response by producing and controlling highly reactive radicals that Khalilian describes as chemical loose cannons.

“While radicals can be useful, they can also cause serious damage if they’re not carefully controlled,” he says. “We’ve known for some time that viperin uses radicals to perform its function. But we didn’t expect to find quantum mechanical effects play such an important role in keeping that radical in check.”

Khalilian, who studies enzymes using computer modelling, explains that viperin is an antiviral enzyme activated as part of the immune response to many viruses. While running computer simulations to investigate viperin’s behaviour, he discovered that it uses a range of strategies, including previously unknown quantum Coulombic interactions, to get the radicals under control.

The Coulombic interaction is an electrostatic force between positive and negative charges, like the force that creates static electricity. The simulations reveal that the quantum version of these interactions is a key strategy employed by nature in radical enzymes to control the free radicals they use.

“This was something unexpected,” says Khalilian. “The radical was being gently held in place by Coulombic interactions to perform only the desired reaction. Like a magnetic tug, these forces are enough to stabilize the radical just long enough for the enzyme to do its job.”

Normally, he says, radicals like to move around or react with other things quickly, but in this case, something was keeping it still.

“These interactions are hard to see, and easy to overlook,” says Khalilian. “But it turns out it’s crucial. Without it, the radical would be too unstable to manage. It’s exciting because this is the first time quantum interactions have been shown to be this important in an enzyme. It gives us a new lens to look at biochemical reactions.”

This study provides evidence that the quantum Coulombic effect is likely a universal yet underappreciated feature of radical enzymes. The discovery could lead to new ways to design drugs, enzymes and catalysts.

The work doesn’t stop there, as principal investigator Dr. Gino DiLabio says ongoing studies are exploring whether this effect applies to other radical enzymes. If confirmed, it could reshape the traditional understanding of catalysis and boost advancements in biotechnology.

“Many modern medicines rely on reactions involving radicals,” Dr. DiLabio adds. “If we understand how nature controls them, we can also do it-perhaps more safely or effectively.”