Worries have come up again! An unidentified object has appeared in the farmland of Saskatchewan, Canada, which may be space junk from outer space, and it may be space debris from the service module of the AX-3 Dragon manned spacecraft previously launched by the American company SPaceX.
Samantha Lawlor, a professor of astronomy at the University of Regina, Canada, said she was lucky to see the space junk because it fell into farmland, and it would be dangerous if it fell into densely populated urban areas such as downtown Regina or New York City.
From the footage, we can see that this piece of debris is black, and it is difficult to tell what it is from the picture alone, but it looks very similar to the space junk that fell into an Australian farm before.
Space junk falls frequently
In July 2022, a farm in New South Wales, Australia, also saw the appearance of multiple pieces of space junk, one of which reached a length of 3 meters and was stuck in the ground like a charred tree.
Brad Tucker, an astrophysicist at the Australian National University, examined the space junk at the site, and the numbers on the debris suggest that researchers believe they are likely to be part of the non-pressurized cargo bay of the American SpaceX Crew Dragon spacecraft. Subsequently, the Australian Aviation Authority also confirmed that the space junk was from the Crew Dragon spacecraft launched by SPaceX.
The situation in many places in southern New South Wales, Australia, said that a loud noise was heard at the time, and then the space debris began to be found one after another. The reason why you hear the loud noise is actually caused by the re-entry of space junk into the atmosphere. And the space junk that fell into the farm also showed obvious signs of burning, which was actually caused by re-entering the atmosphere.
Although it is known that these debris are space junk from outer space, experts still feel incredible about this situation, because such a situation is very rare, and space junk generally does not fall to the ground, but to the sea, because the ocean area is larger, and the probability of falling into the sea is higher. Of course, this is not absolute, no, there are also cases of space junk falling in Canada.
Such a situation is rare, but as humans launch spacecraft more frequently, the number of spacecraft operating in low-Earth orbit is increasing, and there are various spacecraft, satellites, probes, and some rocket wreckage, which generally end up returning to Earth.
In the process of returning to Earth, some debris still fell to the ground, and in March, a house in the United States was smashed through the discarded batteries of the International Space Station.
Here's what happened, on March 8, a resident's house in Naples, Florida, USA, was hit by an unidentified object falling from the sky, and the unknown object penetrated the house and broke through 2 floors. Fortunately, the unidentified object caused no harm to people.
Later, NASA also confirmed that the unidentified object that penetrated the 2nd floor was a discarded battery from the International Space Station. In March 2021, the International Space Station threw a 2.9-ton pallet into outer space containing 2.6 tons of discarded batteries.
The waste is not immediately re-entered into the atmosphere after being thrown into space, but continues to orbit the Earth. Because these discarded batteries have no power, they will continue to decline in speed and decay in orbital altitude before finally returning to Earth on March 8 this year.
Before this discarded battery returned to Earth, ESA issued a warning on March 7, and ESA said that on March 8, this group of discarded batteries would return to Earth.
The time of the return of this group of discarded batteries announced by ESA to the time of the house in Naples, Florida, USA is basically the same as the time when the house was broken down by an unknown object, and later NASA also confirmed that this unidentified metal object is indeed a discarded battery from the International Space Station.
Seeing that the International Space Station threw 2.6 tons of discarded batteries directly into outer space, many netizens may be worried, how can such a heavy waste be thrown into space at will? Such a heavy space junk falls, what if it hits someone?
It's normal to have such worries, 2.6 tons of waste is really heavy, but we don't need to worry too much. Because the Earth has a dense atmosphere, this is actually a good barrier, and when these discarded space junks return to the Earth, they must go through a process, which is to burn violently in the atmosphere.
Because the flight speed of this space junk is very fast, when it re-enters the atmosphere at a very fast speed, the aerodynamic heating effect is very strong, and the temperature will soar to one or two thousand ° C. Under such high temperatures, these space junk will basically turn into ashes, and only a small number of parts with strong heat resistance will not be directly burned, and may fall.
For example, the space junk that fell and smashed into a house in the United States on March 8 is very small, about 10 centimeters high, about 4 centimeters wide, and weighs about 0.7 kilograms. Due to its small size, it did not cause much damage when it was smashed down.
Will it hit someone?
On March 8, there were waste battery materials from the International Space Station that fell and smashed into houses, and now there is also space junk falling on the Canadian side, and some netizens may be worried that our earth is not safe.
From the history of human launch of satellites, probes, and spacecraft, in the past few decades, we have launched thousands of spacecraft into low earth orbit, and the number of known artificial flying objects has exceeded 20,000, and the number of these spacecraft is still growing rapidly.
Speaking of this question, I believe many netizens know that Musk's SPaceX company originally planned to launch 12,000 satellites to form the "Starlink" satellite network, and later they planned to launch another 30,000 satellites, if all the satellites are deployed in place, the number of Starlink satellites will reach 42,000.
In addition to Musk's Starlink satellites, other countries are also forming similar satellite networks, so the number of low-Earth orbit satellites will increase in the future. Most spacecraft are now designed with space junk in mind, so these spacecraft will have a controlled re-entry before the end of their mission, re-enter the Earth early, and then crash in a predetermined sea area.
For example, our Tianzhou cargo spacecraft, Russia's Progress cargo spacecraft, returned to Earth soon after the end of the mission, and then burned violently in the atmosphere.
Although we can now control some spacecraft to return to Earth at the right location and at the right time, and then fall into uninhabited areas, so as to avoid occupying limited orbital resources and avoiding spacecraft falling and hitting people in the event that the spacecraft gets out of control in the future, there are still many runaway spacecraft in low-earth orbit. There are spacecraft that have been flying for decades and have not yet returned to Earth.
For example, on April 10, 1974, the United States launched an "infrared calibrated balloon" (S73-7) satellite, which had problems entering orbit and then disappeared. Although it has disappeared, it was once found again in the 70s and 90s.
After a lapse of 25 years, in April this year, scientists discovered the trace of this satellite again. This means that the S73-7 satellite has been in low-earth orbit for 50 years and has not yet returned to Earth, and it will continue to occupy orbital resources. Eventually, the satellite will also return to Earth due to the decay of the orbital altitude.
Although these satellites will eventually return to Earth, and some may return to Earth in a state of loss of control, and we cannot control where they land, we don't need to worry too much.
Because there are many kinds of materials used in the manufacture of satellites and spacecraft, many of which are actually not heat-resistant, and when they return to the earth's atmosphere, they will burn violently in the atmosphere and turn into ashes, and only a small number of materials with strong heat resistance cannot be completely burned and fall off. However, such a situation usually does not hit people.
Because nearly 71% of the Earth's surface area is ocean, there is a high probability that this space junk will fall into the ocean. Moreover, the area of uninhabited land is also very large, such as deserts, Gobi deserts, alpine plateaus, etc., and the probability of these spacecraft wreckage falling into uninhabited areas is also very high, and the possibility of hitting people is still very small. Mankind has been in the space age for so long, and basically no news has been seen that space junk has hit people, so you don't need to worry too much.