The U.S. military shot down what U.S. officials called a Chinese surveillance balloon off the coast of South Carolina on Feb. 4, 2023. Officials said that the U.S. Navy planned to recover the debris, which is in shallow water.
The U.S. and Canada tracked the balloon as it crossed the Aleutian Islands, passed over Western Canada and entered U.S. airspace over Idaho. Officials of the U.S. Department of Defense confirmed on Feb. 2, 2023, that the military was tracking the balloon as it flew over the continental U.S. at an altitude of about 60,000 feet, including over Malmstrom Air Force Base in Montana. The base houses the 341st Missile Wing, which operates nuclear intercontinental ballistic missiles.
The next day, Chinese officials acknowledged that the balloon was theirs but denied it was intended for spying or meant to enter U.S. airspace. U.S. Secretary of State Antony Blinken said that the balloon's incursion led him to cancel his trip to Beijing. He had been scheduled to meet with Chinese Foreign Minister Qin Gang on Feb. 5 and 6.
Monitoring an adversary from a balloon dates back to 1794, when the French used a hot air balloon to track Austrian and Dutch troops in the Battle of Fleurus. We asked aerospace engineer Iain Boyd of the University of Colorado Boulder to explain how spy balloons work and why anyone would use one in the 21st century.
What is a spy balloon?
A spy balloon is literally a gas-filled balloon that is flying quite high in the sky, more or less where we fly commercial airplanes. It has some sophisticated cameras and imaging technology on it, and it's pointing all of those instruments down at the ground. It's collecting information through photography and other imaging of whatever is going on down on the ground below it.
Why would someone want to use a spy balloon instead of just using spy satellites?
Satellites are the preferred method of spying from overhead. Spy satellites are above us today, typically at one of two different types of orbit.
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The first is called low Earth orbit, and, as the name suggests, those satellites are relatively close to the ground. But they're still several hundred miles above us. For imaging and taking photographs, the closer you are to something, the more clearly you can see it, and this applies to spying as well. The satellites that are in low Earth orbit have the advantage that they're closer to the Earth so they're able to see things more clearly than satellites that are farther away.
The disadvantage these low Earth orbit satellites have is that they are continually moving around the Earth. It takes them about 90 minutes to do one orbit around the Earth. That turns out to be pretty fast in terms of taking clear photographs of what's going on below.
The second type of satellite orbit is called geosynchronous orbit, and that's much farther away. It has the disadvantage that it's harder to see things clearly when you're very, very far away. But they have the advantage of what we call persistence, allowing satellites to capture images continuously. In those orbits, you're essentially overlooking the exact same piece of ground on the Earth's surface all the time because the satellite moves in exactly the same way the earth rotates – it rotates at the exact same speed.
A balloon in some ways gets the best of those. These balloons are much, much closer to the ground than any of the satellites, so they can see even more clearly. And then, of course, balloons are moving, but they're moving relatively slowly, so they also have a degree of persistence. However, spying is not usually done these days with balloons because they are a relatively easy target and are not completely controllable.
What types of surveillance are spy balloons capable of?
I don't know what's on this particular spy balloon, but it's likely to be different kinds of cameras collecting different types of information.
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These days, imaging is conducted across different regions of the electromagnetic spectrum. Humans see in a certain range of this spectrum, the visible spectrum. And so if you have a camera and you take a photograph of your dog, that's a visible photograph. That's one of the things spy aircraft do. They take regular photographs, although they have very good zoom capabilities to be able to magnify what they're seeing quite a lot.
But you can also gather different kinds of information in other parts of the electromagnetic spectrum. Another fairly well-known one is infrared. If it's nighttime, a camera operating in the visible part of the spectrum is not going to show you anything. It's all going to be dark. But an infrared camera can pick up things from heat in the dark.
How do these balloons navigate?
Most of these balloons literally go where the wind blows. There can be a little bit of navigation, but there are certainly not people aboard them. They are at the mercy of whatever the weather is. They sometimes have guiding apparatus on them that change a balloon's altitude to catch winds going in particular directions. According to reports, U.S. officials said the Chinese surveillance balloon had propellers to help steer it. If this is confirmed, it means that its operator would have much more control over the path of the balloon.
What are the limits to a nation's airspace? At what altitude does it become space and anybody's right to be there?
There is an internationally accepted boundary called the Kármán Line at 62 miles (100 kilometers) altitude. This balloon is well below that, so it is absolutely, definitely in U.S. airspace.
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Which countries are known to be using spy balloons?
The Pentagon has had programs over the last few decades studying what can be done with balloons that couldn't be done in the past. Maybe they're bigger, maybe they can go higher in the atmosphere so they're more difficult to shoot down or disable. Maybe they could be more persistent.
The U.S. flew many balloons over the Soviet Union in the 1940s and 1950s, and those were eventually replaced by the high-altitude spy airplanes, the U-2s, and they were subsequently replaced by satellites.
I'm sure a number of countries around the world have periodically gone back to reevaluate: Are there other things we could do now with balloons that we couldn't do before? Do they close some gaps we have from satellites and airplanes?
What does that say about the nature of this balloon, which China confirmed is theirs?
China has complained for many years about the U.S. spying on China through satellites, through ships. And China is also well known for engaging in somewhat provocative behavior, like in the South China Sea, sailing close to other nations' boundaries and saber-rattling. I think it falls into that category.
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The balloon doesn't pose any real threat to the U.S. I think sometimes China is just experimenting to see how far they can push things. This isn't really very advanced technology. It's not serving any real military purpose. I think it's much more likely some kind of political message.
This article has been updated to include news that the balloon has been shot down by the U.S. military.
Sourdough is the oldest kind of leavened bread in recorded history, and people have been eating it for thousands of years. The components of creating a sourdough starter are very simple – flour and water. Mixing them produces a live culture where yeast and bacteria ferment the sugars in flour, making byproducts that give sourdough its characteristic taste and smell. They are also what make it rise in the absence of other leavening agents.
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My sourdough starter, affectionately deemed the “Fosters” starter, was passed down to me by my grandparents, who received it from my grandmother's college roommate. It has followed me throughout my academic career across the country, from undergrad in New Mexico to graduate school in Pennsylvania to postdoctoral work in Washington.
Currently, it resides in the Midwest, where I work at The Ohio State University as a senior research associate, collaborating with researchers to characterize samples in a wide variety of fields ranging from food science to material science.
As part of one of the microscopy courses I instruct at the university, I decided to take a closer look at the microbial community in my family's sourdough starter with the microscope I use in my day-to-day research.
Scanning electron microscopes
Scanning electron microscopy, or SEM, is a powerful tool that can image the surface of samples at the nanometer scale. For comparison, a human hair is between 10 to 150 micrometers, and SEM can observe features that are 10,000 times smaller.
Since SEM uses electrons instead of light for imaging, there are limitations to what can be imaged in the microscope. Samples must be electrically conductive and able to withstand the very low pressures in a vacuum. Low-pressure environments are generally unfavorable for microbes, since these conditions will cause the water in cells to evaporate, deforming their structure.
To prepare samples for SEM analysis, researchers use a method called critical point drying that carefully dries the sample to reduce unwanted artifacts and preserve fine details. The sample is then coated with a thin layer of iridium metal to make it conductive.
Exploring a sourdough starter
Since sourdough starters are created from wild yeast and bacteria in the flour, it creates a favorable environment for many types of microbes to flourish. There can be more than 20 different species of yeast and 50 different species of bacteria in a sourdough starter. The most robust become the dominant species.
You can visually observe the microbial complexity of sourdough starter by imaging the different components that vary in size and morphology, including yeast and bacteria. However, a full understanding of all the diversity present in the starter would require a complete gene sequencing.
The main component that gives the starter texture are starch grains from the flour. These grains, colored green in the image, are identifiable as relatively large globular structures approximately 8 micrometers in diameter.
Giving rise to the starter is the yeast, colored red. As the yeast grows, it ferments sugars from the starch grains and releases carbon dioxide bubbles and alcohol as byproducts that make the dough rise. Yeast generally falls in the range of 2 to 10 micrometers in size and are round to elongated in shape. There are two distinct yeast types visible in this image, one that is nearly round, at the bottom left, and another that is elongated, at the top right.
Bacteria, colored blue, metabolize sugars and release byproducts such as lactic acid and acetic acid. These byproducts act as a preservative and are what give the starter its distinctive sour smell and taste. In this image, bacteria have pill-like shapes that are approximately 2 micrometers in size.
Now, the next time you eat sourdough bread or sourdough waffles – try them, they're delicious! – you can visualize the rich array of microorganisms that give each piece its distinctive flavor.
With all the conspiracy theories floating around in 2020 when COVID-19 hit, I wanted to help my students learn to identify and deal with them. I was also concerned about political propaganda. And in my STEM-heavy school, I wanted to showcase what humanities scholars can do. So I created this class, which is distilled humanities for freshmen. Almost every student so far has been a science, technology, engineering and math major.
What does the course explore?
We start with a week called What Is Data? In Latin, “data” just means “things that are given.” Data can be in the form of measurements: “This bowlful of water weighs x.” But data can also mean “it reminds me of my grandma.” How can you tell when something could be meaningful, or whether it's just nonsense?
A later class that students find especially interesting is on apophenia, the tendency to see patterns where there aren't any, like the man in the Moon, or constellations of stars.
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Why is this course relevant now?
A fact is an interpretation of data. In physics class, you learn how to interpret physics data, find patterns, relate those patterns to other ones, and produce facts about them. If your argument hangs together logically, your interpretation can appear in the journal Nature Physics.
Humanities classes, however, prepare you to understand what facts are, period – whether they're based on biology or on the Bible, nutrition science or novels.
What's a critical lesson from the course?
One critical lesson is that many big conspiracy theories such as QAnon are about jumping to conclusions as quickly as possible. Being a good student and a good scholar means accepting that what you're examining might not be meaningful or might not indicate a pattern. What we're exploring here is how not to jump to conclusions. And this lesson applies as much to stuff in the real world as it does to lab work.
Without the kinds of critical thinking this course teaches, scientists can be susceptible to propaganda and unable to share their ideas effectively, whether it's in the media or to their colleagues, friends and family.
Students learn to look at the world with fresh, skeptical eyes. They learn to identify illogical arguments and rhetorical strong-arm tactics. In the Middle Ages, humanities – grammar, logic, rhetoric – prepared you to do science. What Is a Fact? is like that, helping students see how collecting data and being skeptical don't stop once you've left the lab. A questioning, open-minded attitude is an essential life skill.
Public opinion about EV crash safety often hinges on a few high-profile fire incidents. Those safety concerns are arguably misplaced, and the actual safety of EVs is more nuanced.
I've researched vehicle safety for more than two decades, focusing on the biomechanics of impact injuries in motor vehicle crashes. Here's my take on how well the current crop of EVs protects people:
The burning question
EVs and internal combustion vehicles undergo the same crash-testing procedures to evaluate their crashworthiness and occupant protection. These tests are conducted by the National Highway Safety Administration's New Car Assessment Program and the Insurance Institute for Highway Safety.
None of the Insurance Institute for Highway Safety crash tests of EVs have sparked any fires. New Car Assessment Program crash test reports yield comparable findings. While real-world data analysis on vehicle fires involving EVs is limited, it appears that media and social media scrutiny of EV fire hazard is blown out of proportion.
Weighty matters
What stands out about EV safety is that crash test results, field injury data and injury claims from the Insurance Institute for Highway Safety all reveal that EVs are superior to their internal combustion counterparts in protecting their occupants.
This EV advantage boils down to a blend of physics and cutting-edge technologies.
Thanks to their hefty battery packs positioned at the base of the car, EVs tend to carry considerably more weight and enjoy lower centers of gravity than conventional vehicles. This setup drastically reduces the likelihood of rollover accidents, which have a high rate of fatalities. Moreover, crash dynamics dictate that in a collision between two vehicles, the heavier one holds a distinct advantage because it doesn't slow down as abruptly, a factor strongly linked to occupant injury risks.
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On the technology side, most EVs represent newer models equipped with state-of-the-art safety systems, from advanced energy-absorbing materials to cutting-edge crash avoidance systems and upgraded seat-belt and air-bag setups. These features collectively bolster occupant protection.
Where risks do rise
Unfortunately, EVs also present numerous safety challenges.
While the inherent weightiness of EVs offers a natural advantage in protecting occupants, it also means that other vehicles bear the burden of absorbing more crash energy in collisions with heavier EVs. This dilemma is central to the concept of “crash compatibility,” a well-established field of safety research.
Consider a scenario in which a small sedan collides with a heavy truck. The occupants in the sedan always face higher injury risks. Crash compatibility studies measure vehicle “aggressivity” by the level of harm inflicted on other vehicles, and heavier models are almost always deemed more aggressive.
While EVs offer safety advancements for their own occupants, it's crucial to acknowledge and tackle the safety concerns they pose for others on the road.
I believe that technological advancements will serve as the primary catalyst for overcoming the safety hurdles faced by EVs. Lightweight materials, more powerful sensing technologies and safety algorithms, improved seat belts and better air bags will play pivotal roles in addressing these challenges.
Moreover, the tight connection between EVs and rapidly evolving computing capabilities is likely to foster the development of new safety technologies.