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Another Chinese rocket booster will crash to Earth Saturday. What’s the risk?

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The core stage of a Chinese Long March 5B rocket is set to tumble uncontrollably back to Earth next week, in a reentry that China is tracking closely and has said poses little risk. 

The roughly 25-ton (23 metric tons) rocket stage, which launched on July 24 to deliver the Wentian laboratory cabin module to China’s incomplete Tiangong space station, is predicted to reenter Earth’s atmosphere on July 30 at 7:24 p.m. ET, give or take 16 hours, according to researchers at The Aerospace Corporation’s Center for Orbital and Reentry Debris Studies (opens in new tab). 

Exactly where it will land is unknown, but the possible debris field includes the U.S., India, Australia, Africa, Brazil and Southeast Asia, according to The Aerospace Corporation (opens in new tab), a U.S. government-funded nonprofit research center based in California.

Related: NASA set to launch 2 rockets into the northern lights

The first stage of a rocket, its booster, is typically the bulkiest and most powerful section. Usually, the trajectories of rocket boosters are planned so they avoid orbit and plop harmlessly into the ocean or, if they do make it to orbit, perform a controlled reentry with a few bursts from their engines. But the Long March 5B booster engines cannot restart once they have stopped, dooming the booster to spiral around Earth before landing in an unpredictable location.

This is the third time in two years that China has disposed of its rockets in an uncontrolled manner. In the second instance, in May 2021, the rocket debris landed harmlessly in the Indian Ocean. But the first incident, in May 2020, caused metallic objects to reportedly rain down upon villages in the Ivory Coast, although there were no reported injuries. 

Due to their massive size, Long March 5B boosters can be especially risk-prone during uncontrolled reentry, meaning significant portions of their mass don’t burn up safely in the atmosphere. 

“The general rule of thumb is that 20% to 40% of the mass of a large object will reach the ground, but the exact number depends on the design of the object,” Marlon Sorge, a space debris expert at The Aerospace Corporation, said in an online Q&A (opens in new tab). “In this case, we would expect about five to nine metric tons [6 to 10 tons]. 

“Generally, for an upper stage, we see small and medium tanks survive more or less intact, and large engine components,” Sorge added. “The large tanks and the skin of this core stage are likely to come apart. We will also see lightweight items such as insulation fall out. The melting point of the materials used will make a difference in what remains.”

What’s the risk?

According to The Aerospace Corporation, as more than 88% of the world’s population is located under the rocket’s orbital footprint, some surviving debris could land in a populated area. But Muelhaupt said the odds of this debris harming someone range from 1 in 1,000 to 1 in 230 and the risk to a single individual is much lower — around 1 in 6 trillion to 1 in 10 trillion. For comparison, he added, the likelihood of being struck by lightning is roughly 80,000 times greater. The internationally accepted casualty risk threshold for the uncontrolled reentry of rockets is 1 in 10,000, according to a 2019 report issued by the U.S. Government Orbital Debris Mitigation Standard Practices.

Despite the relatively low risk of damage to people or property, China’s decision to launch rockets without options for controlled reentry has drawn some stern admonishments from U.S. space experts.

“Spacefaring nations must minimize the risks to people and property on Earth of reentries of space objects and maximize transparency regarding those operations,” NASA Administrator Bill Nelson wrote in a statement (opens in new tab) after the 2021 Long March 5B crash landing. “It is clear that China is failing to meet responsible standards regarding their space debris.” 

“Why are we worried? Well, it did cause property damage the last time [in 2020], and people are having to do preparation as a result,” Ted Muelhaupt, a space expert and consultant with The Aerospace Corporation, said during a news conference. “This is not needed. We have the technology to not have this problem.”

China has dismissed these concerns as “shameless hype.” In 2021, Hua Chunying, then-spokesperson for the Chinese Ministry of Foreign Affairs, accused Western reporting of bias and “textbook-style double standards” in its coverage of China’s falling rockets. For instance, in March 2021, debris from a falling SpaceX rocket smashed into a farm in Washington state, an event she claims Western news outlets covered positively and with the use of “romantic words.” 

According to Article VII of the 1967 Outer Space Treaty, of which all the major spacefaring nations  — including China — are parties, any country that sends an object into space is internationally liable for the damage it may cause to another party when it comes crashing back to Earth. If this were to happen, the incident would be processed in a claims commission or handled through diplomatic channels — such as in 1978, when the malfunctioning Soviet satellite Kosmos 954 crashed into western Canada, spraying a roughly 370-mile-long (600 kilometers) path with debris from its broken onboard nuclear reactor.

Christopher Newman, a professor of space law and policy at Northumbria University in London, said all of the major launch nations will have parts of space objects that return to Earth in an uncontrolled manner, but establishing an international consensus on how to deal with them is difficult given current geopolitical tensions. 

“This is a problem that needs an international solution, especially as objects such as rocket bodies are three times more likely to impact on cities in the ‘Global South,'” Newman told Live Science. “Yet we only have to look at the attitude of countries to space tracking and space situational awareness, as well as the debris problem in Earth orbit, to see that the international community is not yet motivated to try and solve this issue. 

“As a lawyer, it is clear to me that momentum for change only comes when there is some form of disaster or tragedy — and by then it is often too late,” he said. “The warnings are there for all users of space; the question is whether they will take action now to deal with them.” 

Originally published on Live Science.



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Ancient Rocks Hold Clues to How Earth Avoided a Mars-Like Fate

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A depiction of Earth, first without an inner core; second, with an inner core beginning to grow, around 550 million years ago; third, with an outermost and innermost inner core, around 450 million years ago. University of Rochester researchers used paleomagnetism to determine these two key dates in the history of the inner core, which they believe restored the planet’s magnetic field just before the explosion of life on Earth. Credit: University of Rochester illustration / Michael Osadciw

New paleomagnetic research suggests Earth’s solid inner core formed 550 million years ago and restored our planet’s magnetic field.

Swirling liquid iron in the Earth’s outer core, located approximately 1,800 miles beneath our feet, generates our planet’s protective magnetic field, called the magnetosphere. Although this magnetic field is invisible, it is vital for life on Earth’s surface. That’s because the magnetosphere shields the planet from solar wind—streams of radiation from the sun.

However, about 565 million years ago, the magnetic field’s strength dropped to 10 percent of its strength today. Then, mysteriously, the magnetic field bounced back, regaining its strength just before the Cambrian explosion of multicellular life on Earth.

What caused the magnetosphere to bounce back?

This rejuvenation happened within a few tens of millions of years according to new research from scientists at the University of Rochester. This is very rapid on geological timescales and coincided with the formation of Earth’s solid inner core, suggesting that the core is likely a direct cause.

“The inner core is tremendously important,” says John Tarduno, the William R. Kenan, Jr., Professor of Geophysics in the Department of Earth and Environmental Sciences and dean of research for Arts, Sciences & Engineering at Rochester. “Right before the inner core started to grow, the magnetic field was at the point of collapse, but as soon as the inner core started to grow, the field was regenerated.”

In the paper, published on July 19, 2022, in the journal Nature Communications, the scientists determined several key dates in the inner core’s history, including a more precise estimate of its age. The research provides new clues about the history and future evolution of Earth and how it became a habitable planet, as well as the evolution of other planets in the solar system.

Earth’s layers and structure.

Unlocking information in ancient rocks

Earth is made up of layers: the crust, where life exists; the mantle, Earth’s thickest layer; the molten outer core; and the solid inner core, which is, in turn, composed of an outermost inner core and an innermost inner core.

Earth’s magnetic field is generated in its outer core. Swirling liquid iron there causes electric currents, driving a phenomenon called the geodynamo that produces the magnetic field.

Because of the magnetic field’s relationship to Earth’s core, scientists have been attempting for decades to ascertain how Earth’s magnetic field and core have changed throughout our planet’s history. They cannot directly measure the magnetic field due to the location and extreme temperatures of materials in the core. Fortunately, minerals that rise to Earth’s surface contain tiny magnetic particles that lock in the direction and intensity of the magnetic field at the time the minerals cool and solidify from their molten state.

To better constrain the age and growth of the inner core, Tarduno and his team used a CO2 laser and the lab’s superconducting quantum interference device (SQUID) magnetometer to analyze feldspar crystals from the rock anorthosite. These crystals have minute magnetic needles within them that are “perfect magnetic recorders,” Tarduno says.

By studying the magnetism locked in ancient crystals—a field known as paleomagnetism—the researchers determined two new important dates in the history of the inner core:

  • 550 million years ago: the time at which the magnetic field began to renew rapidly after a near collapse 15 million years before that. The researchers attribute the rapid renewal of the magnetic field to the formation of a solid inner core that recharged the molten outer core and restored the magnetic field’s strength.
  • 450 million years ago: the time at which the growing inner core’s structure changed, marking the boundary between the innermost and outermost inner core. These changes in the inner core coincide with changes around the same time in the structure of the overlying mantel, due to plate tectonics on the surface.

“Because we constrained the inner core’s age more accurately, we could explore the fact that the present-day inner core is actually composed of two parts,” Tarduno says. “Plate tectonic movements on Earth’s surface indirectly affected the inner core, and the history of these movements is imprinted deep within Earth in the inner core’s structure.”

Avoiding a Mars-like fate

A better understanding of the dynamics and growth of the inner core and the magnetic field has important implications, not only in uncovering Earth’s past and predicting its future, but in unraveling the ways in which other planets might form magnetic shields and sustain the conditions necessary to harbor life.

Researchers believe that

“This research really highlights the need to have something like a growing inner core that sustains a magnetic field over the entire lifetime—many billions of years—of a planet.”

Reference: “Early Cambrian renewal of the geodynamo and the origin of inner core structure” by Tinghong Zhou, John A. Tarduno, Francis Nimmo, Rory D. Cottrell, Richard K. Bono, Mauricio Ibanez-Mejia, Wentao Huang, Matt Hamilton, Kenneth Kodama, Aleksey V. Smirnov, Ben Crummins and Frank Padgett III, 19 July 2022,



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Building-size asteroids are barreling toward Earth

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Two skyscraper-size asteroids are zooming toward Earth this weekend, with one making its closest approach on Friday (July 29) and the second whizzing by on Saturday (July 30).

The first asteroid, dubbed 2016 CZ31, will fly by around 7 p.m. ET (23:00 GMT) on Friday, whizzing at an estimated 34,560 mph (55,618 km/h, according to NASA.

Astronomers estimate that the asteroid measures about 400 feet (122 meters) across at its widest point, making it about as wide as a 40-story building is tall. The asteroid will safely miss our planet, passing about 1,740,000 miles (2,800,000 kilometers) out from Earth — or more than seven times the average distance between Earth and the moon. According to NASA, this space rock makes close approaches to Earth every few years, with the next one scheduled for January 2028.

Related: Why are asteroids and comets such weird shapes?

On Saturday, a second, ever larger asteroid will skim past our planet, albeit at a greater distance from Earth. That asteroid, named 2013 CU83, measures approximately 600 feet (183 m) across at its widest visible point, and will pass by about 4,320,000 miles (6,960,000 km) from Earth, or about 18 times the average distance between Earth and the moon.

This colossal space rock will be traveling at 13,153 mph (21,168 km/h) when it nears Earth at 7:37 p.m. ET (23:37 GMT).

Both of these close encounters are significantly further afield than the asteroid 2022 NF, which came within 56,000 miles (90,000 km) — or about 23% the average distance between Earth and the moon — on July 7.

NASA and other space agencies closely monitor thousands of near-Earth objects like these. Even if an asteroid’s trajectory puts it millions of miles from our planet, there is an extremely slim chance that the asteroid’s orbit could shift slightly after interacting with the gravity of a larger object, such as a planet; even such a tiny shift could potentially put an asteroid on a collision course with Earth on a future flyby.

As such, space agencies take planetary defense very seriously. In November 2021, NASA launched an asteroid-deflecting spacecraft called the Double Asteroid Redirection Test (DART), which will slam directly into the 525-foot-wide (160 m) asteroid Dimorphos in autumn 2022. The collision won’t destroy the asteroid, but it may change the space rock’s orbital path slightly, Live Science previously reported. The mission will help test the viability of asteroid deflection, should some future asteroid pose an imminent danger to our planet.

Originally published on Live Science.

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An uncontrolled Chinese rocket booster will fall to Earth this weekend

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Sometime this weekend, a massive booster from a Chinese rocket will begin an uncontrolled fall back to Earth from space — and because of its considerable size and weight, parts of it may survive the descent through our planet’s atmosphere and hit the ground. The chances of the rocket hitting anyone and killing them are exceedingly rare, but a similar falling Chinese rocket last year sparked major concern worldwide, which means this rocket will probably do the same.

The booster is part of a Long March 5B rocket, which launched on July 24th, sending a new module into orbit for China’s growing Tiangong space station. After the giant rocket reaches space, it sheds a fairly massive part of itself: its core booster. This booster sticks around in orbit, lapping the planet before eventually falling back to Earth. Since the rocket part is more than 100 feet long and more than 22 tons in weight, it’s possible that up to 9 tons’ worth of material could survive the fall.

Space trackers are doing their best to predict exactly when and where the Long March 5B booster will come down. The situation closely mimics that of last year’s global scare over an uncontrolled Chinese rocket that fell back to Earth, as well as a similar uncontrolled reentry in 2020. Both of those instances also involved a core booster from China’s Long March 5B, which does not have the capability of disposing of itself in a controlled manner. Fortunately, last year, the rocket came down in the sparsely populated Indian Ocean, but in 2020, that falling rocket did dump debris off of the Ivory Coast, sending metal pipes and other objects into villages without causing any injuries.

Still, the risk to the average human from this year’s rocket is so low that it should not keep anyone up at night. In fact, for any one person on Earth, there are six chances in 10 trillion that a part of this rocket will hit you and cause some kind of casualty or injury, according to the Aerospace Corporation, a nonprofit that does space research and development, as well as provide technical guidance on spaceflight. But, the fact that space trackers have to continue to deal with this kind of issue without knowing when and where the rocket will come down is frustrating.

“Why are we worried? Well, it did cause property damage the last time, and people are having to do preparation as a result,” Ted Muelhaupt, a space traffic expert and consultant with the Aerospace Corporations’ corporate chief engineer’s office, said during a presser about the rocket. “Furthermore, this is not needed. We have the technology to not have this problem.”

In the United States and Europe, the rule for space operators is that if there is going to be some kind of uncontrolled reentry of space debris into Earth’s atmosphere, there must be a lower than 1 in 10,000 chance that the falling object will cause some kind of casualty, or injury, on the ground. It’s a particularly high bar to clear, which is why US and European missions have to be vigilant about how they dispose of the rockets they send into space. “Basically, once you’re done delivering your payload, you turn your rocket around, fire the engine, and drive it back into the ocean somewhere, usually someplace where there’s no population,” Marlon Sorge, a space debris expert and technical fellow with the Aerospace Corporation, said. “You do that, and you have pretty much mitigated the risk right there.”

Controlled disposal is something that most launch providers throughout the world do already. SpaceX and the United Launch Alliance, for instance, purposefully deposit parts of their rockets over the ocean after they launch to space. Plus, the core of SpaceX’s Falcon 9 rocket is famous for actually flying back to Earth and landing upright — either on a drone ship or landing pad — following its flights. The core booster of the Long March 5B doesn’t have that capability. Once it launches into orbit, the engines on the rocket core can’t really reignite. “They’re designed for a single burn,” Jonathan McDowell, an astrophysicist at the Harvard Center for Astrophysics and space tracking expert, tells The Verge. “And so this thing just burns once and then switches off, and it’s dead.” Then we just have to wait for it to fall back to Earth as its orbit decays over time.

The Aerospace Corporation estimates that there is between a 1 in 1,000 and 1 in 230 risk of a casualty from the falling Long March 5B booster. That’s 10 times above the 1 in 10,000 threshold, which is why there is heightened vigilance around this specific case. And whenever China pulls a stunt like this, the US isn’t particularly happy about it. “Spacefaring nations must minimize the risks to people and property on Earth of reentries of space objects and maximize transparency regarding those operations,” NASA administrator Bill Nelson said when the 2021 Long March 5B fell. “It is clear that China is failing to meet responsible standards regarding their space debris.”

China seemingly took note of the criticism. During this most recent launch, one Chinese official during the CGTN launch livestream mentioned that they had made improvements to dispose of the booster after launch. “The last segment, or the core segment, once it [enters] into the orbit, it also [works] as a spacecraft,” Xu Yansong, former director for international cooperation at the China National Space Administration, said during the livestream. “So we’ll have to bring it back safely and in a controlled manner. So one of the first missions was unable to do that, but later on, we improve our technologies. And so what we call the passivation of the last stage has been conducted, so we can safely bring back the last fuselage.”

However, it does not seem like anything has changed since the last scare. In fact, the European Union’s Space Surveillance and Tracking network has found that the booster is tumbling through space, indicating there is no control over the object. So we’ll be going through the whole process of predicting where it will come down all over again. As of now, the European Union, the US Space Force, and the Aerospace Corporation’s best guesses of when it will come down is sometime late Saturday night or early Sunday morning. As for where it will come down, it’ll be somewhere between 41.5 degrees North and 41.5 degrees South. That means about 1 billion who live north and south of those lines have zero risk. (Boston and parts of Tasmania — congratulations, you’re right outside the zone.) But 88 percent of the human population lives within that range, according to the Aerospace Corporation.

Predictions will get more precise with each passing day as we get closer to Sunday, and the Aerospace Corporation is continually updating its predictions here. The European Union is keeping track as well, as is the Space Force. As for what to expect when the rocket comes down? Based on past experience, the debris could spread over an area hundreds of miles in length along the rocket’s orbital track. Some pieces, depending on their size and weight, may hit the ground slowly, while others might hit the ground fast, at speeds that could reach hundreds of miles per hour. Ultimately, it’s a guessing game, and we may not know much about this event until the rocket actually comes down. “The history of reentering things has been a history of continuing surprise,” says McDowell. “How much actually does survive reentry? Sometimes more survived than you might have initially expected.”

But even though there is slightly more risk than usual with this falling rocket, it’s important to keep things in perspective. “The risk to any given individual in any given year from getting conked in the head by a piece of space debris is one in 100 billion,” Muelhaupt said. “You’re 80,000 times more likely to get hit by lightning than you are by space debris. But this doesn’t mean that this is a good thing to do.”

So enjoy this new round of falling rocket uncertainty. Once it’s over, we’ll probably have to do it all again. There’s another Long March 5B launch tentatively scheduled for this fall.



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China says closely tracking rocket debris hurtling towards Earth | Space News

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Beijing says uncontrolled re-entry of rocket debris poses little risk to anyone on the ground.

Remnants of a large Chinese rocket are expected to streak through the atmosphere this weekend in an uncontrolled re-entry that Beijing says it is closely tracking but poses little risk to anyone on Earth.

The Long March 5B rocket blasted off Sunday to deliver a laboratory module to the new Chinese space station under construction in orbit, marking the third flight of China’s most powerful rocket since its maiden launch in 2020.

As occurred during its first two flights, the rocket’s entire main-core stage – which is 100 feet (30 metres) long and weighs 22 tonnes (48,500 pounds) – has already reached low orbit and is expected to tumble back towards Earth once atmospheric friction drags it downward, according to American experts.

Ultimately, the rocket body will disintegrate as it plunges through the atmosphere but is large enough that numerous chunks will likely survive a fiery re-entry to rain debris over an area some 2,000km (1,240 miles) long by about 70km (44 miles) wide, independent US-based analysts said on Wednesday.

The probable location of the debris field is impossible to pinpoint in advance, though experts will be able to narrow the potential impact zone closer to re-entry in the days ahead.

The latest available tracking data projects re-entry will occur at about 00:24 GMT on Sunday, plus or minus 16 hours, according to the Aerospace Corp, a government-funded nonprofit research centre near Los Angeles.

Risk ‘fairly low’

The overall risk to people and property on the ground is fairly low, given that 75 percent of Earth’s surface in the potential path of debris is water, desert or jungle, Aerospace analyst Ted Muelhaupt told reporters in a news briefing.

Nevertheless, the possibility exists for pieces of the rocket to come down over a populated area, as they did in May 2020 when fragments of another Chinese Long March 5B landed on the Ivory Coast, damaging several buildings in that West African nation, though no injuries were reported, Muelhaupt said.

By contrast, he said, the United States and most other spacefaring nations generally go to the added expense of designing their rockets to avoid large, uncontrolled re-entries – an imperative largely observed since large chunks of the NASA space station Skylab fell from orbit in 1979 and landed in Australia.

Overall, the odds of someone being injured or killed this weekend from falling rocket chunks range from one-in-1,000 to one-in-230, well above the internationally accepted casualty risk threshold of one-in-10,000, he told reporters.

But the risk posed to any single individual is far lower, on the order of six chances per 10 trillion. By comparison, he said, the odds of being struck by lightning are about 80,000 times greater.

Chinese foreign ministry spokesman Zhao Lijian said the probability of debris causing harm to aviation or to people and property on the ground was very low. He said most components of the rocket would be destroyed on re-entry.

Last year, NASA and others accused China of being opaque after the Beijing government kept silent about the estimated debris trajectory or the re-entry window of its last Long March rocket flight in May 2021.

Debris from that flight ended up landing harmlessly in the Indian Ocean.

A few hours after Zhao spoke on Wednesday, the China Manned Space Agency (CMSA) gave the approximate position of its latest rocket in a rare public statement. As of 4pm (08:00 GMT), the agency said the rocket was circling the globe in an elliptical orbit that was 263.2km (163.5 miles) high at its farthest point and 176.6km (109.7 miles) high at its nearest.

No estimated re-entry details were given by CMSA on Wednesday.

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Debris from China space rocket could fall to Earth in next few days

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In this photo released by Xinhua News Agency, the Long March 5B Y3 carrier rocket, carrying Wentian lab module blasts off from the Wenchang Space Launch Center in Wenchang in southern China’s Hainan Province Sunday, July 24 (AP)

Debris from a Chinese rocket is set to crash to Earth some time over the next few days, with the potential for wreckage to land across a wide swathe of the globe. Part of a Long March 5B rocket China launched on July 24 will make an uncontrolled reentry around July 31, according to the Aerospace Corp, a nonprofit based in California, that gets US funding.
The possible debris field includes much of the US, as well as Africa, Australia, Brazil, India and Southeast Asia, according to Aerospace’s predictions. Concern over the re-entry and the impact it could have is being dismissed by China, however, with state-backed media saying the warnings are just “sour grapes” from people resentful of the country’s development as a space power.
“The US is running out of ways to stop China’s development in the aerospace sector, so smears and defamation became the only things left for it,” Global Times newspaper reported, citing an expert.
The descent of the booster, which weighs 23 metric tonnes, would be part of what critics say is a series of uncontrolled crashes that highlights the risks of China’s escalating space race with the US. “Due to the uncontrolled nature of its descent, there is a non-zero probability of the surviving debris landing in a populated area – over 88% of the world’s population lives under the re-entry’s potential debris footprint,” Aerospace said on Tuesday. In May 2021, pieces of another Long March rocket landed in the Indian Ocean, prompting concern that the Chinese space agency had lost control of it. “It is clear that China is failing to meet responsible standards regarding space debris,” Nasa administrator Bill Nelson had said.
China is closely following the reentry of the booster from this week’s launch, foreign ministry spokesman Zhao Lijian said in Beijing on Wednesday. “It is customary for international practice for rockets’ upper stages to burn up in the Earth’s atmosphere on reentry,” said Zhao. “Right from the research and development stage of the space engineering programme, it is designed with consideration for debris mitigation and return from orbit.” Bloomberg

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First Mars samples set to land on Earth in 2033

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As Perseverance investigates the site of an ancient lake that existed billions of years ago, it’s collecting rocks and soil. This material is of interest because it could contain evidence of past microscopic organisms that would reveal whether life ever existed on Mars. Scientists will have the chance to use some of the most sophisticated instruments around the world to study these precious samples.

The ambitious Mars Sample Return program involves collaboration between the two agencies to retrieve 30 samples from the red planet. Multiple missions will launch to Mars later this decade to safely pick up and bring the samples back.

The program is nearing the end of its conceptual design phase, and NASA has completed its system requirements review. The review has led to changes that will reduce the complexity of future missions and increase probability of success, according to NASA officials.

“The conceptual design phase is when every facet of a mission plan gets put under a microscope,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate, in a statement. “There are some significant and advantageous changes to the plan, which can be directly attributed to Perseverance’s recent successes at Jezero and the amazing performance of our Mars helicopter.”

Initially, the plan was to launch a fetch rover along with a Sample Retrieval Lander in the mid-2020s. Once released on the Martian surface, the fetch rover would have retrieved samples from where Perseverance has stashed them on the Martian surface.

Now, Perseverance will be the primary transport vehicle to carry samples to the lander. The rover’s latest health and life expectancy assessment shows that it should still be in prime condition to deliver the samples itself in 2030. Perseverance will back up to the lander, and the lander’s robotic arm will transfer the samples.

The Sample Retrieval Lander will carry two sample recovery helicopters, similar in style to the Ingenuity helicopter currently on Mars — rather than a fetch rover.

“Recent operations of the Ingenuity helicopter on Mars, which has completed 29 flights — 24 more than originally planned — have shown us the usefulness of potential rotorcraft of Mars,” said Jeff Gramling, director of the Mars Sample Return Program.

Engineers have been impressed with Ingenuity’s performance. The helicopter has survived more than a year beyond its expected life span. In the event that Perseverance can’t return the samples to the lander, the little choppers will be able to fly away from the lander, use arms to retrieve the samples and bring them back.

The two sample return helicopters will be similar in size to Ingenuity but will be a little bit heavier. The landing legs will come equipped with small mobility wheels to allow it to travel on the ground as well as fly, and each chopper will have a little arm that can grab sample tubes, said Richard Cook, Mars Sample Return program manager at NASA’s Jet Propulsion Laboratory in Pasadena, California.

If Perseverance’s health remains the same over the next eight years and it doesn’t need any help in returning samples to the lander, the choppers could observe and capture images of the process.

Getting samples back to Earth

The Sample Retrieval Lander also carries the Mars Ascent Vehicle — the first rocket that will ever launch from the Martian surface, with the samples tucked safely inside. The spacecraft is currently set to launch from Mars in 2031.

A separate mission will launch from Earth in the mid-2020s, called the Earth Return Orbiter, to rendezvous with the Mars Ascent Vehicle.

Onboard the Earth Return Orbiter is the Capture/Containment and Return System, which will collect the container of samples from the Mars Ascent Vehicle while both vehicles are in orbit around Mars.

The Earth Return Orbiter will then head back to our world. Once the spacecraft is close to Earth, it will release the Earth Entry Vehicle that contains the cache of samples, and that spacecraft will touchdown on Earth in 2033.

Previously, the agency said the samples could return to Earth by 2031, but the planned launch dates for the orbiter in fall 2027 and the lander in summer 2028 have created the new arrival date.

Engineers are currently testing robotic components for the campaign at NASA and ESA centers. The Mars Sample Return program will move into the preliminary design phase in October, which will last for about a year. The design phase will result in technology development as well as engineering prototypes for the main components.

“ESA is continuing at full speed the development of both the Earth Return Orbiter that will make the historic round-trip from Earth to Mars and back again; and the Sample Transfer Arm that will robotically place the sample tubes aboard the Orbiting Sample Container before its launch from the surface of the Red Planet,” said David Parker, ESA director of human and robotic exploration, in a statement.

Diverse samples

The Perseverance rover has collected 11 rock core samples so far. The samples represent “an amazing suite of materials,” said Meenakshi Wadhwa, principal scientist for Mars Sample Return and director of Arizona State University’s School of Earth and Space Exploration.

“The latest one, in fact, is a fine-grained sedimentary rock that has the greatest potential for preserving biosignatures, potentially, and so we have a diversity of materials already in the bag, so to speak, and really excited about the potential for bringing these back,” Wadhwa said.

“Working together on historic endeavors like Mars Sample Return not only provides invaluable data about our place in the universe but brings us closer together right here on Earth,” Zurbuchen said.

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China’s 21-ton rocket booster will fall down to Earth after space station launch

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The 23-ton Long March 5B rocket which carried the Wentian laboratory module, took off from Hainan Island at 2:22 p.m. local time Sunday, July 24, and the module successfully docked with China’s orbital outpost.
Its job completed, the rocket has gone into an uncontrolled descent toward Earth’s atmosphere and it’s not clear where it will land. The uncontrolled descent marks the third time that the country has been accused of not properly handling space debris from its rocket stage.
“It’s a 20-tonne metal object. Although it will break up as it enters the atmosphere, numerous pieces — some of them quite large — will reach the surface,” said Michael Byers, a professor at the University of British Columbia and author of a recent study on the risk of casualties from space debris.
Space debris poses an extremely minimal risk to humans, Byers explained, but it’s possible that larger parts could cause damage if it lands in inhabited regions. Byers said that due to the increase in space junk, those small chances are becoming more likely, especially in the global south, according to the research published in the Nature Astronomy journal, with rocket bodies being approximately three times more likely to land at the latitudes of Jakarta, Dhaka and Lagos than those of New York, Beijing or Moscow.

“This risk is entirely avoidable since technologies and mission designs now exist that can provide controlled reentries (usually into remote areas of oceans) instead of uncontrolled and therefore entire random ones,” he said via email.

Holger Krag, the head of the European Space Agency’s Space Debris Office, said international best practice was to conduct a controlled reentry, targeting a remote part of the ocean, whenever the casualty risk is too high.

He added that the re-entry zone for the rocket was geographically limited to between the latitudes of 41 degrees south and 41 degrees north of the equator.

The US Space Command said it will track the Chinese rocket’s fall back to Earth, according to a spokesperson.

Based on varying atmospheric conditions, the exact entry point of rocket stage into Earth’s atmosphere “cannot be pinpointed until within hours of its reentry,” the spokesperson said, but it is estimated to reenter the Earth’s atmosphere around August 1.

The 18th Space Defense Squadron, part of the US military that tracks reentries, will also provide daily updates on its location.

CNN has reached out to the China Manned Space Agency for comment.

Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics, said that space debris weighing more than 2.2 tons is typically brought down to a specific location on its first orbit of Earth.

“The point is that things that big are normally not put in orbit without an active control system,”he said.

With “no active control system, and no re-startable engine to boost it back down to Earth… it just tumbles along in orbit and eventually burns up due to friction with the atmosphere,” McDowell told CNN.

China was heavily criticized last year for its handling of space debris after it launched another module on a similar rocket. Its remnants plunged into the Indian Ocean near the Maldives 10 days after the launch.

NASA said China failed to “meet responsible standards.”

“Spacefaring nations must minimize the risks to people and property on Earth of re-entries of space objects and maximize transparency regarding those operations,” said NASA Administrator Bill Nelson at the time.

China responded to criticisms by blaming the US for “hyping up fears” over the rocket reentry and accused US scientists and NASA of “acting against their conscience” and being “anti-intellectual.”
In 2020, a Chinese rocket core — which weighed nearly 20 tons — made an uncontrolled re-entry into Earth’s atmosphere, passing directly over Los Angeles and Central Park in New York City before eventually diving into the Atlantic Ocean.

Space junk such as old satellites reenter the Earth’s atmosphere on a daily basis, although most of it goes unnoticed because it burns up long before it can hit the ground.

It’s only larger space debris — such as spacecraft and rocket parts — that pose a very small risk to humans and infrastructure on the ground.

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How did Earth avoid a Mars-like fate? Ancient rocks hold clues

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A depiction of Earth, first without an inner core; second, with an inner core beginning to grow, around 550 million years ago; third, with an outermost and innermost inner core, around 450 million years ago. University of Rochester researchers used paleomagnetism to determine these two key dates in the history of the inner core, which they believe restored the planet’s magnetic field just before the explosion of life on Earth. Credit: University of Rochester / Michael Osadciw

Approximately 1,800 miles beneath our feet, swirling liquid iron in the Earth’s outer core generates our planet’s protective magnetic field. This magnetic field is invisible but is vital for life on Earth’s surface because it shields the planet from solar wind—streams of radiation from the sun.

About 565 million years ago, however, the magnetic field’s strength decreased to 10 percent of its strength today. Then, mysteriously, the field bounced back, regaining its strength just before the Cambrian explosion of multicellular life on Earth.

What caused the magnetic field to bounce back?

According to new research from scientists at the University of Rochester, this rejuvenation happened within a few tens of millions of years—rapid on geological timescales—and coincided with the formation of Earth’s solid inner core, suggesting that the core is likely a direct cause.

“The inner core is tremendously important,” says John Tarduno, the William R. Kenan, Jr., Professor of Geophysics in the Department of Earth and Environmental Sciences and dean of research for Arts, Sciences & Engineering at Rochester. “Right before the inner core started to grow, the magnetic field was at the point of collapse, but as soon as the inner core started to grow, the field was regenerated.”

In the paper, published in Nature Communications, the researchers determined several key dates in the inner core’s history, including a more precise estimate for its age. The research provides clues about the history and future evolution of Earth and how it became a habitable planet, as well as the evolution of other planets in the solar system.

Unlocking information in ancient rocks

Earth is composed of layers: the crust, where life is situated; the mantle, Earth’s thickest layer; the molten outer core; and the solid inner core, which is in turn composed of an outermost inner core and an innermost inner core.

Earth’s magnetic field is generated in its outer core, where swirling liquid iron causes electric currents, driving a phenomenon called the geodynamo that produces the magnetic field.

Because of the magnetic field’s relationship to Earth’s core, scientists have been trying for decades to determine how Earth’s magnetic field and core have changed throughout our planet’s history. They cannot directly measure the magnetic field due to the location and extreme temperatures of materials in the core. Fortunately, minerals that rise to Earth’s surface contain tiny magnetic particles that lock in the direction and intensity of the magnetic field at the time the minerals cool from their molten state.

To better constrain the age and growth of the inner core, Tarduno and his team used a CO2 laser and the lab’s superconducting quantum interference device (SQUID) magnetometer to analyze feldspar crystals from the rock anorthosite. These crystals have minute magnetic needles within them that are “perfect magnetic recorders,” Tarduno says.

By studying the magnetism locked in ancient crystals—a field known as paleomagnetism—the researchers determined two new important dates in the history of the inner core:

  • 550 million years ago: the time at which the magnetic field began to renew rapidly after a near collapse 15 million years before that. The researchers attribute the rapid renewal of the magnetic field to the formation of a solid inner core that recharged the molten outer core and restored the magnetic field’s strength.
  • 450 million years ago: the time at which the growing inner core’s structure changed, marking the boundary between the innermost and outermost inner core. These changes in the inner core coincide with changes around the same time in the structure of the overlying mantel, due to plate tectonics on the surface.

“Because we constrained the inner core’s age more accurately, we could explore the fact that the present-day inner core is actually composed of two parts,” Tarduno says. “Plate tectonic movements on Earth’s surface indirectly affected the inner core, and the history of these movements is imprinted deep within Earth in the inner core’s structure.”

Avoiding a Mars-like fate

Better understanding the dynamics and growth of the inner core and the magnetic field has important implications, not only in uncovering Earth’s past and predicting its future, but in unraveling the ways in which other planets might form magnetic shields and sustain the conditions necessary to harbor life.

Researchers believe that Mars, for example, once had a magnetic field, but the field dissipated, leaving the planet vulnerable to solar wind and the surface without oceans. While it is unclear whether the absence of a magnetic field would have caused Earth to meet the same fate, “Earth certainly would’ve lost much more water if Earth’s magnetic field had not been regenerated,” Tarduno says. “The planet would be much drier and very different than the planet today.”

In terms of planetary evolution, then, the research emphasizes the importance of a magnetic shield and a mechanism to sustain it, he says.

“This research really highlights the need to have something like a growing inner core that sustains a magnetic field over the entire lifetime—many billions of years—of a planet.”

New research provides evidence of strong early magnetic field around Earth

More information:
Tinghong Zhou et al, Early Cambrian renewal of the geodynamo and the origin of inner core structure, Nature Communications (2022). DOI: 10.1038/s41467-022-31677-7
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China wants to defend the Earth from asteroids using the moon

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China’s “Planetary Defense System” has been catching momentum recently, with Beijing researchers now planning to utilize the moon to protect Earth from asteroid strikes that could potentially wipe out a city or human civilization, according to scientists involved in the project.

Two optical telescopes would be built on the moon’s south and north poles to survey the space around them for any threats that may have slipped through the ground-based early warning network, especially those approaching from the blind side facing the sun.

The new project entails putting three guardian satellites carrying loads of fuel and kinetic weapons into the moon’s orbit around the Earth, Wu Weiren, chief designer of the Chinese Lunar Exploration Program, said in a paper published in the Chinese peer-reviewed journal Scientia Sinica Informationis.

According to the planned project, when the system detects a celestial body with the potential to cause severe damage, it sends one or all of the guardian satellites to intercept the asteroid within a short timeframe, as short as a week, faster than what any large rocket launched from Earth could achieve, according to the team.

“It will have the ability to intercept incoming asteroids from all directions, and can form a defense circle about twice the distance between the moon and Earth – about 800,000km in diameter,” Wu and his colleagues said.

“It will have the ability to intercept incoming asteroids from all directions, and can form a defense circle about twice the distance between the moon and Earth – about 800,000km in diameter.”

Wu and his research team

China’s currently developing Earth Defense System consists of giant radars and telescopes in an attempt to manage an extinction event such as the one that wiped out the dinosaurs about 65 million years ago.

Planetary surveillance

But before breaking ground on the moon, China would first launch satellites into the moon’s orbit to test their latest surveillance, tracking and interception technologies.

These satellites could, potentially, be used to defend China’s national security by having the telescopes and sensors pointed toward the Earth, the researchers suggested.

They “have the ability to monitor the geosynchronous orbit,” a high-altitude belt hosting many communications and military satellites, they said in the paper.

The Earth-defending satellites could help China keep a close eye on other countries’ satellites “and improve the ability to protect high-value space assets”.

A growing space power

China has become a growing space power, putting ever-increasing effort in recent years to improve its capabilities in space. So far, China has launched new satellites, landed probes on the moon and explored its dark side, and even constructed its own space station.

Nasa administrator Bill Nelson said earlier this month he was concerned about the possibility China would take over the moon, though Beijing has denied this and dismissed these claims.



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