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A Chinese rocket is falling back to Earth—but we don’t know where it will land

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A Chinese rocket is falling back to Earth—but we don't know where it will land


The probability that parts of the booster could hit populated land is admittedly quite low—it’s much more likely to land in the ocean somewhere. But that probability is not zero. Case in point: the CZ-5B booster’s debut last year for a mission on May 5, 2020. The same problem arose back then as well: the core booster ended up in an uncontrolled orbit before eventually reentering Earth’s atmosphere. Debris landed in villages across Ivory Coast. It was enough to elicit a notable rebuke from the NASA administrator at the time, Jim Bridenstine.

The same story is playing out this time, and we’re playing the same waiting game because of how difficult it is to predict when and where this thing will reenter. The first reason is the booster’s speed: it’s currently traveling at nearly 30,000 kilometers per hour, orbiting the planet about once every 90 minutes. The second reason has to do with the amount of drag the booster is experiencing. Although technically it’s in space, the booster is still interacting with the upper edges of the planet’s atmosphere.

That drag varies from day to day with changes in upper-atmosphere weather, solar activity, and other phenomena. In addition, the booster isn’t just zipping around smoothly and punching through the atmosphere cleanly—it’s tumbling, which creates even more unpredictable drag. 

Given those factors, we can establish a window for when and where we think the booster will reenter Earth’s atmosphere. But a change of even a couple of minutes can put its location thousands of miles away. “It can be difficult to model precisely, meaning we are left with some serious uncertainties when it comes to the space object’s reentry time,” says Thomas G. Roberts, an adjunct fellow at the CSIS Aerospace Security Project. 

This also depends on how well the structure of the booster holds up to heating caused by friction with the atmosphere. Some materials might hold up better than others, but drag will increase as the structure breaks up and melts. The flimsier the structure, the more it will break up, and the more drag will be produced, causing it to fall out of orbit more quickly. Some parts may hit the ground earlier or later than others.

By the morning of reentry, the estimate of when it will land should have narrowed to just a few hours. Several different groups around the world are tracking the booster, but most experts are following data provided by the US Space Force through its Space Track website. Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, hopes that by the morning of reentry, the timing window will have shrunk to just a couple of hour where the booster orbits Earth maybe two more times. By then we should have a sharper sense of the route those orbits are taking and what regions of the Earth may be at risk from a shower of debris.

The Space Force’s missile early warning systems will already be tracking the infrared flare from the disintegrating rocket when reentry starts, so it will know where the debris is headed. Civilians won’t know for a while, of course, because that data is sensitive—it will take a few hours to work through the bureaucracy before an update is made to the Space Track site. If the remnants of the booster have landed in a populated area, we might already know thanks to reports on social media.

In the 1970s, these were common hazards after missions. “Then people started to feel it wasn’t appropriate to have large chunks of metal falling out of the sky,” says McDowell. NASA’s 77-ton Skylab space station was something of a wake-up call—its widely watched uncontrolled deorbit in 1979 led to large debris hitting Western Australia. No one was hurt and there was no property damage, but the world was eager to avoid any similar risks of large spacecraft uncontrollably reentering the atmosphere (not a problem with smaller boosters, which just burn up safely).

As a result, after the core booster gets into orbit and separates from the secondary boosters and payload, many launch providers quickly do  a deorbit burn that brings it back into the atmosphere and sets it on a controlled crash course for the ocean, eliminating the risk it would pose if left in space. This can be accomplished with either a restartable engine or an added second engine designed for deorbit burns specifically. The remnants of these boosters are sent to a remote part of the ocean, such as the South Pacific Ocean Uninhabited Area, where other massive spacecraft like Russia’s former Mir space station have been dumped. 

Another approach which was, used during space shuttle missions and is currently used by large boosters like Europe’s Ariane 5, is to avoid putting the core stage in orbit entirely and simply switch it off a few seconds early while it’s still in Earth’s atmosphere. Smaller engines then fire to take the payload the short extra distance to space, while the core booster is dumped in the ocean.

None of these options are cheap, and they create some new risks (more engines mean more points of failure), but “it’s what everyone does, since they don’t want to create this type of debris risk,” says McDowell. “It’s been standard practice around the world to avoid leaving these boosters in orbit. The Chinese are an outlier of this.”

Why? “Space safety is just not China’s priority,” says Roberts. “With years of space launch operations under its belt, China is capable of avoiding this weekend’s outcome, but chose not to.” 

The past few years have seen a number of rocket bodies from Chinese launches that have been allowed to fall back to land, destroying buildings in villages and exposing people to toxic chemicals. “It’s no wonder that they would be willing to roll the dice on an uncontrolled atmospheric reentry, where the threat to populated areas pales in comparison,” says Roberts. “I find this behavior totally unacceptable, but not surprising.”

McDowell also points to what happened during the space shuttle Columbia disaster, when damage to the wing caused the spacecraft’s entry to become unstable and break apart. Nearly 38,500 kilograms of debris landed in Texas and Louisiana. Large chunks of the main engine ended up in a swamp—had it broken up a couple of minutes earlier, those parts could have hit a major city, slamming into skyscrapers in, say, Dallas. “I think people don’t appreciate how lucky we were that there weren’t casualties on the ground,” says McDowell. “We’ve been in these risky situations before and been lucky.” 

But you can’t always count on luck. The CZ-5B variant of the Long March 5B is slated for two more launches in 2022 to help build out the rest of the Chinese space station. There’s no indication yet whether China plans to change its blueprint for those missions. Perhaps that will depend on what happens this weekend.

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How Twitter’s “Teacher Li” became the central hub of China protest information

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How Twitter’s “Teacher Li” became the central hub of China protest information


It’s hard to describe the feeling that came after. It’s like everyone is coming to you and all kinds of information from all over the world is converging toward you and [people are] telling you: Hey, what’s happening here; hey, what’s happening there; do you know, this is what’s happening in Guangzhou; I’m in Wuhan, Wuhan is doing this; I’m in Beijing, and I’m following the big group and walking together. Suddenly all the real-time information is being submitted to me, and I don’t know how to describe that feeling. But there was also no time to think about it. 

My heart was beating very fast, and my hands and my brain were constantly switching between several software programs—because you know, you can’t save a video with Twitter’s web version. So I was constantly switching software, editing the video, exporting it, and then posting it on Twitter. [Editor’s note: Li adds subtitles, blocks out account information, and compiles shorter videos into one.] By the end, there was no time to edit the videos anymore. If someone shot and sent over a 12-second WeChat video, I would just use it as is. That’s it. 

I got the largest amount of [private messages] around 6:00 p.m. on Sunday night. At that time, there were many people on the street in five major cities in China: Beijing, Shanghai, Chengdu, Wuhan, and Guangzhou. So I basically was receiving a dozen private messages every second. In the end, I couldn’t even screen the information anymore. I saw it, I clicked on it, and if it was worth posting, I posted it.

People all over the country are telling me about their real-time situations. In order for more people not to be in danger, they went to the [protest] sites themselves and sent me what was going on there. Like, some followers were riding bikes near the presidential palace in Nanjing, taking pictures, and telling me about the situation in the city. And then they asked me to inform everyone to be cautious. I think that’s a really moving thing.

It’s like I have gradually become an anchor sitting in a TV studio, getting endless information from reporters on the scene all over the country. For example, on Monday in Hangzhou, there were five or six people updating me on the latest news simultaneously. But there was a break because all of them were fleeing when the police cleared the venue. 

On the importance of staying objective 

There are a lot of tweets that embellish the truth. From their point of view, they think it’s the right thing to do. They think you have to maximize the outrage so that there can be a revolt. But for me, I think we need reliable information. We need to know what’s really going on, and that’s the most important thing. If we were doing it for the emotion, then in the end I really would have been part of the “foreign influence,” right? 

But if there is a news account outside China that can record what’s happening objectively, in real time, and accurately, then people inside the Great Firewall won’t have doubts anymore. At this moment, in this quite extreme situation of a continuous news blackout, to be able to have an account that can keep posting news from all over the country at a speed of almost one tweet every few seconds is actually a morale boost for everyone. 

Chinese people grow up with patriotism, so they become shy or don’t dare to say something directly or oppose something directly. That’s why the crowd was singing the national anthem and waving the red flag, the national flag [during protests]. You have to understand that the Chinese people are patriotic. Even when they are demanding things [from the government], they do it with that sentiment. 

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Your microbiome ages as you do—and that’s a problem

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Your microbiome ages as you do—and that’s a problem


These ecosystems appear to change as we age—and these changes can potentially put us at increased risk of age-related diseases. So how can we best look after them as we get old? And could an A-grade ecosystem help fend off diseases and help us lead longer, healthier lives?

It’s a question I’ve been pondering this week, partly because I know a few people who have been put on antibiotics for winter infections. These drugs—lifesaving though they can be—can cause mass destruction of gut microbes, wiping out the good along with the bad. How might people who take them best restore a healthy ecosystem afterwards?

I also came across a recent study in which scientists looked at thousands of samples of people’s gut microbe populations to see how they change with age. The standard approach to working out what microbes are living in a person’s gut is to look at feces. The idea is that when we have a bowel movement, we shed plenty of gut bacteria. Scientists can find out which species and strains of bacteria are present to get an estimate of what’s in your intestines.

In this study, a team based at University College Cork in Ireland analyzed data that had already been collected from 21,000 samples of human feces. These had come from people all over the world, including Europe, North and South America, Asia, and Africa. Nineteen nationalities were represented. The samples were all from adults between 18 and 100. 

The authors of this study wanted to get a better handle on what makes for a “good” microbiome, especially as we get older. It has been difficult for microbiologists to work this out. We do know that some bacteria can produce compounds that are good for our guts. Some seem to aid digestion, for example, while others lower inflammation.
 
But when it comes to the ecosystem as a whole, things get more complicated. At the moment, the accepted wisdom is that variety seems to be a good thing—the more microbial diversity, the better. Some scientists believe that unique microbiomes also have benefits, and that a collection of microbes that differs from the norm can keep you healthy.
 
The team looked at how the microbiomes of younger people compared with those of older people, and how they appeared to change with age. The scientists also looked at how the microbial ecosystems varied with signs of unhealthy aging, such as cognitive decline, frailty, and inflammation.
 
They found that the microbiome does seem to change with age, and that, on the whole, the ecosystems in our guts do tend to become more unique—it looks as though we lose aspects of a general “core” microbiome and stray toward a more individual one.
 
But this isn’t necessarily a good thing. In fact, this uniqueness seems to be linked to unhealthy aging and the development of those age-related symptoms listed above, which we’d all rather stave off for as long as possible. And measuring diversity alone doesn’t tell us much about whether the bugs in our guts are helpful or not in this regard.
 
The findings back up what these researchers and others have seen before, challenging the notion that uniqueness is a good thing. Another team has come up with a good analogy, which is known as the Anna Karenina principle of the microbiome: “All happy microbiomes look alike; each unhappy microbiome is unhappy in its own way.”
 
Of course, the big question is: What can we do to maintain a happy microbiome? And will it actually help us stave off age-related diseases?
 
There’s plenty of evidence to suggest that, on the whole, a diet with plenty of fruit, vegetables, and fiber is good for the gut. A couple of years ago, researchers found that after 12 months on a Mediterranean diet—one rich in olive oil, nuts, legumes, and fish, as well as fruit and veg—older people saw changes in their microbiomes that might benefit their health. These changes have been linked to a lowered risk of developing frailty and cognitive decline.
 
But at the individual level, we can’t really be sure of the impact that changes to our diets will have. Probiotics are a good example; you can chug down millions of microbes, but that doesn’t mean that they’ll survive the journey to your gut. Even if they do get there, we don’t know if they’ll be able to form niches in the existing ecosystem, or if they might cause some kind of unwelcome disruption. Some microbial ecosystems might respond really well to fermented foods like sauerkraut and kimchi, while others might not.
 
I personally love kimchi and sauerkraut. If they do turn out to support my microbiome in a way that protects me against age-related diseases, then that’s just the icing on the less-microbiome-friendly cake.

To read more, check out these stories from the Tech Review archive:
 
At-home microbiome tests can tell you which bugs are in your poo, but not much more than that, as Emily Mullin found.
 
Industrial-scale fermentation is one of the technologies transforming the way we produce and prepare our food, according to these experts.
 
Can restricting your calorie intake help you live longer? It seems to work for monkeys, as Katherine Bourzac wrote in 2009. 
 
Adam Piore bravely tried caloric restriction himself to find out if it might help people, too. Teaser: even if you live longer on the diet, you will be miserable doing so. 

From around the web:

Would you pay $15,000 to save your cat’s life? More people are turning to expensive surgery to extend the lives of their pets. (The Atlantic)
 
The World Health Organization will now start using the term “mpox” in place of “monkeypox,” which will be phased out over the next year. (WHO)
 
After three years in prison, He Jiankui—the scientist behind the infamous “CRISPR babies”—is attempting a comeback. (STAT)
 
Tech that allows scientists to listen in on the natural world is revealing some truly amazing discoveries. Who knew that Amazonian sea turtles make more than 200 distinct sounds? And that they start making sounds before they even hatch? (The Guardian)
 
These recordings provide plenty of inspiration for musicians. Whale song is particularly popular. (The New Yorker)
 
Scientists are using tiny worms to diagnose pancreatic cancer. The test, launched in Japan, could be available in the US next year. (Reuters)

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The Download: circumventing China’s firewall, and using AI to invent new drugs

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The Download: circumventing China’s firewall, and using AI to invent new drugs


As protests against rigid covid control measures in China engulfed social media in the past week, one Twitter account has emerged as the central source of information: @李老师不是你老师 (“Teacher Li Is Not Your Teacher”). 

People everywhere in China have sent protest footage and real-time updates to the account through private messages, and it has posted them, with the sender’s identity hidden, on their behalf.

The man behind the account, Li, is a Chinese painter based in Italy, who requested to be identified only by his last name in light of the security risks. He’s been tirelessly posting footage around the clock to help people within China get information, and also to inform the wider world.

The work has been taking its toll—he’s received death threats, and police have visited his family back in China. But it also comes with a sense of liberation, Li told Zeyi Yang, our China reporter. Read the full story.

Biotech labs are using AI inspired by DALL-E to invent new drugs

The news: Text-to-image AI models like OpenAI’s DALL-E 2—programs trained to generate pictures of almost anything you ask for—have sent ripples through the creative industries. Now, two biotech labs are using this type of generative AI, known as a diffusion model, to conjure up designs for new types of protein never seen in nature.

Why it matters: Proteins are the fundamental building blocks of living systems. These protein generators can be directed to produce designs for proteins with specific properties, such as shape or size or function. In effect, this makes it possible to come up with new proteins to do particular jobs on demand. Researchers hope that this will eventually lead to the development of new and more effective drugs. Read the full story.

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