"Fireball" reappears in the American night sky?

I believe everyone still remembers that we have shared a topic before, that is, a roaring fireball appeared in the sky of the United States at about 8:00 a.m. on April 27, 2022. At first, scientists believed that the flying speed of this roaring fireball may reach an hourly speed. 55,000 miles, or 24,587 meters per second, which is at least twice the speed of Earth's second universe. Later, new research by scientists showed that the speed of the roaring fireball may not be as fast as previously predicted, about 35,000 miles per hour, or 15.6 kilometers per second. Although not as fast as predicted at the beginning, this speed is still quite astonishing, faster than the vast majority of human aircraft and spaceships.

Don't guess, this high-speed flying fireball is actually just a bolide, not an alien spacecraft. It also made a huge noise during the flight. It is said that its brightness is 10 times that of the moon. When it flew near the swampy terrain 55 kilometers north of the Concordia Parish settlement in Louisiana, it disintegrated into smaller pieces. Eventually, fragments of this roaring fireball crashed to the ground at 200-300 mph (320-480 km/h). Although it fell to the ground, it posed no threat to the ground due to its sharp drop in speed and disintegration into smaller fragments in the air.

Fireball reappears in American night sky

Not long after the last fireball, another roaring fireball appeared over the United States. What's going on? Could it be that the United States has been favored by these raging fireballs? In fact, there will be roaring fireballs in other areas, and this time the roaring fireballs in the United States are not the same as the roaring fireballs in the past few days. It is likely not a meteor or a meteorite, but a kind of aircraft.

On the evening of May 6, 2022, local time, an orange-red fireball flew over the state of Florida, USA. Many witnesses saw this scene and took many photos. From the photo, we can see that the tail of this raging fireball also has a long "tail". Although fireballs flew past in the United States a few days ago, and those fireballs flew past with huge noises, this time the fireballs did not make a huge noise.

Moreover, the fireball did not disintegrate when it flew past, so some people think that this should not be a naturally occurring small debris such as meteorites, comet fragments, asteroid fragments or meteors. Because these natural small fragments will burn violently after entering the atmosphere at high speed, the burning is the most violent in the front end area, and the burning situation at the end is relatively less violent, so these small fragments are prone to explosion when heated unevenly. , disintegration, etc., and then into a large number of small fragments, which eventually disappeared in the atmosphere.

This raging fireball that fell from the sky did not disintegrate or explode, basically ruling out the possibility of a small natural celestial body, and the biggest possibility was a spacecraft. Because the American manned Dragon spacecraft carried 4 astronauts back to Earth from the International Space Station at that time, the speed of the spacecraft at that time was almost close to the Earth's first cosmic speed of 7.9 kilometers per second, or 28,000 kilometers per hour. When the spacecraft re-enters the atmosphere at such a fast speed, under the action of aerodynamic heating, the surrounding temperature will reach as high as thousands of degrees Celsius, and it looks like a raging fireball from the outside.

Why are the astronauts in the spacecraft okay?

Whether it is the American manned Dragon spacecraft, the Russian Soyuz spacecraft, our Shenzhou manned spacecraft, or the space shuttle, there is one problem that cannot be avoided when returning to Earth, that is, it will burn violently in the atmosphere. This is because the earth has a dense atmosphere, and the speed of the spacecraft returning to the earth and re-entering the earth's atmosphere is quite fast. Under the action of the aerodynamic heating effect, it will inevitably heat up rapidly, and when the temperature reaches a certain level, it will burn. Such a situation also exists in planets with atmospheres such as Mars. Previously, the Perseverance rover, Curiosity rover, Zhurong rover and other probes also burned when they landed on Mars. Since the temperature outside the spacecraft is as high as several thousand degrees Celsius when it returns to Earth, why are the astronauts in the spacecraft okay?

From the structure of the spacecraft, we can see why. Under normal circumstances, the manned spacecraft mainly has three parts: the return cabin, the propulsion cabin, and the service cabin. The return cabin is the section that astronauts take when they return to the earth, while the propulsion cabin, service cabin and other cabin sections are generally directly abandoned in outer space. . Because the return capsule needs to bring the astronauts back to the earth safely, and during the process of returning to the earth, it will be burned at a high temperature of several thousand degrees Celsius. The general materials are unbearable, so the return capsule needs to undergo special treatment, such as in the The outside is coated with some ablative material or thermal insulation material to absorb this heat, thus protecting the return cabin from being burned by the high temperature. In addition, a complex life support system is required in the return cabin to protect the astronauts, such as maintaining a constant temperature and pressure environment in the return cabin, providing oxygen and absorbing carbon dioxide. After special treatment, although the temperature returned to the outside of the cabin was as high as thousands of degrees Celsius, the internal temperature did not exceed 30 degrees Celsius.

Some friends may find it strange that the spacecraft will burn violently when it returns to the earth when it also passes through the earth's atmosphere. Why not when it is launched? This starts with the speed of the spacecraft. When returning to Earth, the speed of the spacecraft is as high as several kilometers per second, and the aerodynamic heating effect caused by such a fast speed is unavoidable. When the spacecraft is launching, the speed starts from 0. As the height of the rocket and the spacecraft continues to rise, the speed will become faster and faster, but the air density will also decrease at high altitudes. Moreover, in the booster lift-off stage, the huge rocket and spacecraft combination is quite massive, and the acceleration will not be very fast, so the speed of the rocket and spacecraft combination will not be particularly fast in the early stage. Under such circumstances, the aerodynamic heating effect cannot make the rocket and spacecraft combination burn.