China has announced that it wants to develop a "space-ground" asteroid early-warning network, while providing few details on what it could look like. But recent papers and presentations to the United Nations provide clues as to what the country has in mind for planetary defense.

The China National Space Administration (CNSA) made the announcement on June 30 — International Asteroid Day — stating plans to construct a coordinated ground-and-space monitoring system for near-Earth asteroids. Li Mingtao, chief scientist at CNSA's Asteroid Monitoring and Early Warning Research Center, told state media that China is studying the feasibility of an asteroid defense system, with the ground-space monitoring network as its core.

"No asteroid has so far been identified that will definitely collide with Earth in the foreseeable future, but concerns over impact risks are not unfounded. Many near-Earth asteroids remain undetected," the state-run media outlet Xinhua quoted Li as saying in a report by Science and Technology Daily.

Li added that China will deploy multiple large-aperture optical telescopes at carefully chosen sites in order to be able to survey the sky, while adding a space-based monitoring constellation, free from atmospheric disruption and day-night constraints, with a particular focus on threats from the sunward direction, which are, from the ground, lost in the glare of the sun. The meteor that exploded over Chelyabinsk, Russia, in 2013, approached roughly from a sunward direction and was only detected once it entered the atmosphere.

Li told Science and Technology Daily that more than 40,000 near-Earth asteroids have been discovered so far, including over 95% of asteroids at least 1 kilometer (0.6 miles) wide, which are capable of causing a globally catastrophic impact. However, only around 45% of asteroids in the 140-meter (460-foot) class have been detected, which are large enough to devastate a small country.

The June 30 reports and CNSA statements were vague on what China's actual plans for its monitoring network may be. However, recent journal papers and a 2025 presentation to the U.N.'s Committee on the Peaceful Uses of Outer Space (COPUOS) give more detail on the country's thinking.

For example, a paper published in the Journal of Deep Space Exploration in June 2026, co-authored by Wu Weiren, chief designer of China's lunar exploration program and a leading voice on the country's asteroid defense plans, lays out the options under study.

For the space-based component, the paper names four candidate orbital positions for a monitoring network: the Sun-Earth L1 Lagrange point, an Earth-leading or trailing orbit, a Venus-like heliocentric orbit, and an Earth-companion distant retrograde orbit (DRO). The paper also describes ongoing research into each option's monitoring effectiveness.

A similar outline was found in a 2025 technical presentation to COPUOS by Chinese researcher Chen Yongcai. A "basic model" would consist of a single satellite at Sun-Earth L1, an orbit about 1.5 million kilometers (930,000 miles) inside that of Earth, paired with northern and southern ground stations. An "extended model" includes spacecraft in the three additional orbits stated in the Wu Weiren paper. The Venus-like option in particular closely tracks an earlier proposal known as CROWN, a constellation of small satellites in Venus-like orbits designed to survey the sunward sky and use its favorable geometry to track other populations of near-Earth asteroids.

The status and timelines of these plans are unclear, but they do indicate a clear interest in and commitment to planetary defense by China. The country's 15th Five-Year Plan, approved in March, states that an asteroid defense engineering project is under study, while China is developing a kinetic-impact and observation demonstration mission, similar to NASA's DART mission and the European Space Agency's (ESA) follow-on Hera project, which is scheduled to launch in 2027.

While China's apparent plans are not unique, they could augment global efforts. Anne Virkki, an asteroid researcher at the University of Helsinki who's familiar with international monitoring efforts, noted that NASA and ESA have plans to send missions to Sun-Earth L1 to search for asteroids in infrared light — NEO Surveyor and NEOMIR respectively.

"If China launches a similar mission, hopefully it has some capability that the other two do not, and that it shares the data internationally and not only for Chinese scientists," Virkki said.

Virkki noted that asteroids approaching from the sun's direction aren't physically unusual, but they are simply harder to track, which statistically makes them more likely to produce a surprise. She also pointed to the persistent, less-discussed gap in radar tracking capacity. That capacity took a serious hit with the 2020 collapse of the Arecibo Observatory in Puerto Rico, with no U.S. successor in the works.

China has discussed building its own radar capability, which Virkki said would be a welcome addition, provided the data is shared openly. China has built the "China Compound Eye" or Fuyan project near Chongqing in the country's southwest, which can be used for near-Earth asteroid monitoring. Wu's paper also notes ground-based radar in the proposal for asteroid monitoring.

"Hopefully, as China's planetary defense plans become more specific, we'll see telescopes and space telescopes that complement the existing or planned capabilities of other countries, rather than repeat redundantly, and contribute data openly and collaboratively," Virkki said. She noted that there are likely about 100,000 near-Earth asteroids that could cause significant local damage if they hit Earth, and we know the orbits of less than half of all such space rocks.

2029 will mark the International Year of Planetary Defense, when the infamous asteroid Apophis will fly past the Earth just within the orbit of geostationary satellites. "There is a lot of work left to do, and international collaboration is crucial," said Virkki.

How do you stop a large, threatening asteroid on its way to Earth? A new Chinese paper, investigating the issue, suggests a "pre-excavation detonation" could be the solution if there's enough warning time.

There may be millions of asteroids in our solar system, with a tiny percentage of them posing a possible, very tiny threat to our planet. NASA and many other entities keep an eye on the skies, and continue discovering new asteroids, but have found no imminent threats yet; Apophis, previously believed to be a small threat during its 2068 flyby of Earth, has now been ruled out as a problem for the foreseeable future.

But Earth has been smacked by space rocks in the past, with even the moderate-sized Chelyabinsk incident of 2013 causing reported property damage near its blast site in Russia. And as the researchers of a new paper point out, asteroids tens of meters in size and larger have been tracked flying safely, but closely, by Earth.

Assuming a theoretical space rock is on an imminent collision course and exceeds about 330 feet (100 meters) in size, simply blasting it (or even guiding it away) may not be a viable option, the researchers said in a peer-reviewed study in the journal Space: Science and Technology.

"Traditional kinetic impact, or long‑term force deflection methods, offer limited energy and cannot achieve effective deflection within short timeframes," the researchers said in a press release, adding they found few comprehensive analyses of how to do so. (NASA did successfully deflect an asteroid moonlet's orbit with the DART spacecraft in 2022, for example, but that was a unique test case in space.)

So the team, led by Xiaowei Wang from the China Academy of Launch Vehicle Technology, instead proposed using one of two "defense modes" for large incoming asteroids.

The first mode is a more simple impact detonation — simply put, smacking the asteroid's surface to create a shallow crater, in which a nuclear device is exploded. The other mode is a "pre-excavation detonation", or using a penetration device to create a deeper crater before exploding a nuclear warhead to "achieve deep detonation" in the interior of the asteroid.

The researchers' modeling included the energy of a launch vehicle, the velocity of the impact spacecraft, and changes to the velocity of the asteroid, in each of these two modes. The two modes were also tested against a "virtual threat asteroid database" assuming warning times of anywhere between one year and 20 years.

All in all, assuming enough time is available, it seems the deep-crater method wins out. "The flyby pre-excavation detonation mode, due to its ability to autonomously select the cratering location and achieve deep detonation, offers stronger energy coupling," the researchers wrote in the press release.

Such an impact could "destroy" asteroids that are roughly 330 feet (100 meters) or of that range, and push away asteroids of a size reaching about 0.6 miles (1 km) by imparting a velocity change of roughly 1 m/s in about 60 days.

While a shallow-crater mission could be launched more quickly, the researchers added, "the impact location is random, energy coupling is weak, and requirements for the nuclear device's impact resistance and detonation timing are extremely stringent."

Real-world missions would also have to take into account the composition of an asteroid (as a pile of rubble would likely require a different approach than a solid rock), whether the pathways of any pieces generated by an impact pose a threat, and how to safely get the nuclear warhead into space in the first place, among many other technical issues. The researchers did not raise these considerations in the press release.

They did, however, provide "recommended solutions" for when to use each of the two options. The shallow impact might be preferable "for emergency defense" on a huge asteroid if there is an extremely short warning time, because that mission is less complex. Otherwise, the "deep impact" would be the way to go.

When asteroids hurtle towards Earth in Hollywood films, astronauts often deploy nuclear warheads against them in order to save humanity. Now, scientists have found this strategy could actually help deflect an incoming cosmic impact — not by blowing an asteroid up with a nuke, but by exploding one more than a mile above its surface to shower it with X-ray radiation.

As the catastrophic end of the Age of Dinosaurs about 66 million years ago reveals, cosmic impacts can have disastrous effects for life on Earth. "Asteroids aren’t just history — they still impact the Earth today," Nathan Moore, a physicist at Sandia National Laboratories in Albuquerque, N.M., told Space.com. "Apophis, a near-Earth object about the size of the Olympic stadium, flew by Earth just last week."

In 2023, with the Double Asteroid Redirection Test (DART) mission, NASA showed it could potentially deflect a cosmic strike by crashing a spacecraft into the asteroid Dimorphos. Although scientists found the impact successfully altered the orbit of the approximately 525-foot-wide (160 meter) asteroid, the most dangerous asteroids are the size of mountains, and simply colliding a spacecraft against such giants would have minimal effect.

Hollywood movies such as "Armageddon" and "Deep Impact" have suggested using nukes to shatter incoming asteroids or comets. However, scientists have previously suggested that this might only break an asteroid into multiple fragments, changing a lethal bullet headed toward Earth into a deadly shotgun blast instead.

Now, Moore and his colleagues find that nuclear bombs could prevent devastating cosmic impacts if they explode well above the surface of the asteroid. They suggest the X-ray pulse from the outburst could vaporize rock off the asteroid's surface, resulting in a push that could steer a catastrophic strike away from Earth.

In a new study, the researchers employed the Z machine at Sandia National Laboratory, the most powerful laboratory source of radiation in the world. It generates powerful electric pulses, magnetic fields and X-rays to find out how materials react under high pressures and temperatures.

"At present, there is only one way to generate an intense enough X-ray burst to do an experiment like this, and that’s using the Z Machine," Moore said.

The scientists used electrical pulses from the Z machine to generate powerful magnetic fields. These in turn compressed argon gas to generate plasma, the same form of matter that makes up lightning and stars. This argon plasma produced the X-ray burst the researchers needed to simulate a similar one from a nuclear explosion.

"You have to concentrate a lot of power, about 80 trillion watts, into a very small space, the size of a pencil lead, and very quickly, about 100 billionths of second, to generate a hot enough argon plasma, several millions of degrees, to make a powerful enough X-ray burst to heat the asteroid material surface to tens of thousands of degrees to give it enough push," Moore said.

The scientists hung up a pair of targets in a vacuum, each 0.47 inches (12 millimeters) wide — one made of quartz, the other of fused silica. These materials are similar in composition to known asteroids.

Previous attempts to study various asteroid deflection strategies all held targets fixed in place, "which wasn't very realistic," Moore said. "After all, asteroids in outer space aren’t attached to anything. Besides, how would a mock asteroid accelerate realistically if it was anchored down?"

To overcome this problem, the researchers devised what they called "X-ray scissors." They hung the targets up using thin metal foil just 13 microns thick, or about one-eighth the thickness of an average human hair. This foil vaporized when the X-rays hit it, freeing the targets to accelerate naturally in space.

The X-ray pulses generated vapor plumes from each target and accelerated each one to about 155 mph (250 km/h), matching computational predictions.

"The ability to deflect miniature asteroids in a laboratory using the Z Machine is unlike anything else you can do anywhere else on Earth," Moore said.

Scaling these findings up to a 2.5-mile-wide (4 kilometer) asteroid, with a 1 megaton nuclear bomb exploding about 1.25 miles (2 km) from its surface, the researchers suggested the resulting push could help deflect dangerous asteroids away from Earth.

"For reference, a 4-km [2.5-mile] asteroid is predicted to be large enough to cause global devastation and possible disruption of civilization, according to the NASA Planetary Defense Strategy and Action Plan," Moore said.

Moore noted that asteroids come in a variety of compositions. "This new technique can be used to investigate the deflection response of different asteroid materials," he said. "Understanding how different asteroid materials vaporize and deflect will be critical for preparing for a planetary defense mission, should the need arise."

The scientists detailed their findings online Sept. 23 in the journal Nature Physics. 

Cathy Plesko, Ph.D., is a research scientist at Los Alamos National Laboratory in New Mexico. She contributed this article to Space.com's Expert Voices: Op-Ed & Insights.

In a couple of weeks, at the Planetary Defense Conference just outside of Washington, D. C., I'll be taking my turn at one of the highest-stakes role-playing games on the planet: an emergency response drill where astronomers, emergency management experts, planetary scientists (like me), meteoriticists, rocket scientists and other experts work together to practice our response if a large asteroid or comet were heading toward us. Like a fire drill, we practice our roles and test new technology and scientific data to see how it changes what we think the best response would be.  

Even though asteroids and comets large enough to be dangerous don't hit the Earth very often, they do hit at random, so there is a chance that an extinction-level event (like what happened to the dinosaurs) could happen to us. It would be like winning the worst lottery prize ever. So planning for a way to protect ourselves is important.

Related: Potentially Dangerous Asteroids (Images)

Fortunately, we're getting to the point where we can see these potentially hazardous objects coming and maybe even do something about it. Astronomers using Earth- and space-based telescopes have discovered almost 20,000 near-Earth objects so far, and the pace of discovery is speeding up. Like a new pair of glasses, future telescopes such as the upcoming NeoCam space telescope have the potential to show us hazards that we couldn't see before.

Once the telescopes reveal what an object is and where it's going, we can simulate its orbit for hundreds of years into the future. If that orbit crosses our planet's path at any point, the United Nations' International Asteroid Warning Network will notify member governments and serve as a clearinghouse for information about it.   

If the object has a chance of hitting Earth — say, one in a few thousand in the next 20 years — NASA's Space Missions Planning Group would coordinate among governments that are working on a defense plan so that everyone is on the same page when any action is required. A threatening object probably won't be kept a secret, because all the information about it will be published and the object will be visible to telescopes in many countries. 

Most objects are announced with estimated probabilities of impact similar to betting odds in Vegas. As more observations come in, the odds typically go to zero as we figure out that their orbit and Earth's don't actually cross. If, instead, data tells us that the object is more likely to hit than we thought, the Space Missions Planning Group would coordinate any space missions to go look at it up close or to push it off course or destroy it. 

Using science to answer the question, 'What if?'

As a research scientist at Los Alamos National Laboratory, I study what happens to the atmosphere and crust of a planet when an asteroid or comet hits and possible ways to stop that from happening. I use the supercomputers at Los Alamos, some of the fastest in the world, to run high-fidelity simulations to accurately model the physics of an impact. These simulations are constantly updated with cutting-edge data from NASA missions and Earth-bound laboratory experiments.  

I work on a team of scientists from national laboratories and NASA centers studying particular what-if scenarios, and report the results to the Planetary Defense Coordination Office. 

Our first what-if case study focused on asteroid Bennu, the target of the NASA OSIRIS-REx mission. Bennu is about as wide as the Empire State Building is tall, and weighs as much as 800 aircraft carriers. It approaches Earth once every six years, so astronomers can study it well and even use the Arecibo and Goldstone radio telescopes to make a 3D model of its shape. Fortunately, Bennu has only a one in 2,700 chance of hitting Earth, about 100 years from now. 

Related: OSIRIS-REx: NASA's Asteroid Sample-Return Mission in Pictures

We used computer models to study two ways of pushing Bennu off course so it wouldn't hit us: smashing it with a cannonball-like kinetic impactor or roasting one side by detonating a nuclear explosive device from a couple football fields away. We fed the best estimates of Bennu's shape, composition, mass and strength into our computer models and predicted what would happen in each scenario. Then we designed a spacecraft that could do the job. 

We learned that moving Bennu would be a big challenge if it was made of the type of rock that NASA meteoriticists hypothesize. We would need to launch that spacecraft 10 to 25 years before the predicted impact in order to push it off course. And we would need not just one, but a full fleet of kinetic cannonball impactors — more than we could currently launch in time. 

We published our predictions in a scientific journal last year, before OSIRIS-REx got to Bennu. For the Planetary Defense conference exercise, the OSIRIS-REx team is providing us with everything they are now learning by orbiting the asteroid. Soon, they'll use a robotic arm on the spacecraft to grab a sample and send it back to Earth for analysis. We'll feed that data into our models and rerun them to see what difference it makes. 

While we wait for OSIRIS-REx to send that space-rock sample back to Earth, we're studying another asteroid, Didymos B, or Didymoon, which is the smaller member of a binary asteroid system. NASA is designing the Double Asteroid Redirection Test, or DART mission, to test what really happens when we hit an asteroid with a kinetic cannonball impactor. They're targeting Didymoon to alter its orbit around another asteroid in the system, Didymos A, without changing either asteroid's orbit around the sun. That experiment will allow them to test the kinetic impactor deflection process without accidentally knocking Didymoon onto a collision course with Earth. 

I'm glad we're doing this research now, while we can take the time to carefully study the problem and triple-check our models without the pressure of a specific, potentially hazardous object coming at us. If we prepare well, then for the first time our species could prevent a major natural disaster. We can't yet push a hurricane off course, cork a volcano or lock an earthquake-prone fault, but in a few years, we could be ready to stop a comet in its tracks. 

• Asteroid Defense: Scanning the Sky for Threats From Space
• This Is NASA's New Plan to Detect and Destroy Asteroids Before They Hit Earth
• Asteroid Basics: A Space Rock Quiz

Follow us on Twitter @Spacedotcom or Facebook. 

Newspapers, news channels, radio programs and social media were on fire last month with reports of an asteroid that was discovered and going to pass close to Earth only twenty-one days later!

PHOTOS: This is Why Some Asteroids Act Like Comets

The asteroid, or as it turns out the extinct cometary nucleus, became known as "Spooky" -- officially 2015 TB145 -- when it transpired that its closest approach was on Halloween. What grabbed the attention of journalists was the lack of notice we received before the visitor rattled passed us at nearly 80,000 miles per hour (36,000 meters per second). The question on everyone's lips seems to be: why did we not find it earlier?

The simple and quick answer is that asteroids, and comets to a lesser degree, are pretty difficult to spot. Apart from the fact they are generally small, they are also usually quite dark too. In the case of our friend "Spooky," it is believed to be no larger than 600 meters across with an albedo (reflectivity) of 0.06. To put that into context, the albedo of a classroom blackboard is roughly the same. Now imagine a 600 meter-wide blackboard flying through space at 36,000 meters per second; by anyone's standard, that's going to be pretty tricky to detect.

Thankfully, there are organizations and armies of amateur astronomers around the world on the lookout for these unexpected visitors.

NEWS: Spooky Comet Gets Some Radar Love

There are at least seven observatory systems that are fully automated, scouring our skies every night on the lookout for rogue objects. LINEAR (Lincoln Near-Earth Asteroid Research program)and the Catalina Sky Survey are the most well known, chalking up thousands of near-Earth object discoveries and a whole host of comets. The rebooted NASA space telescope NEOWISE is also on the lookout in space, spotting these hard-to-see objects in infrared light.

The method that all of the automated systems, and indeed amateur astronomers, utilize to detect these dark near-Earth objects (or NEOs) is to analyse star fields for objects that should not be there. Then, once an object is discovered, it's a case of taking more observations as that object moves through the sky to calculate its orbit.

To understand this, imagine taking a photograph of a tennis ball as it flies through the air. A sharp picture will reveal its position accurately but will give you no clue as to its speed or direction. To do this, we need more pictures over a period of time. It is the same with a speeding asteroid; first you need to discover it and then observe it to work out its orbit. Once its orbital characteristics are known, its orbital path can be forecast, and astronomers can begin to calculate that object's level of risk.

PHOTOS: Top 10 Ways to Stop an Asteroid

Often the media gets wind of an asteroid discovery before its orbit is understood, or sometimes, as was the case with "Spooky," we simply don't get much notice -- regardless, 2015 TB145 flew safely past Earth at a distance of around 300,000 miles, just beyond the orbit of the moon.

There are now 13,280 known NEOs just like "Spooky," which are defined as objects that have entered Earth's orbital neighborhood and therefore put the Earth at risk of a collision some time in the future. But it is the NEOs that we don't know about that pose the real threat. As far as they are concerned, all we can do is keep our eyes peeled and hope that the biggest NEOs have already been discovered.

This article was provided by Discovery News.