Shulou(Shulou.com)11/24 Report--

Thanks to CTOnews.com netizens for the clue delivery of the holy Buddha! This article comes from the official account of Wechat: SF Chinese (ID:kexuejiaodian), author: SF

Humans don't have to worry about repeating the extinction of dinosaurs, because we are unlikely to be hit by asteroids more than a kilometer in diameter in the next 1000 years. What we need to worry about is small near-Earth objects such as smaller asteroids.

/ tr. by Colin Stewart (Colin Stuart)

Translation | pickup snow

Editor | Wen Jing

The original article is published in Science focus 2023.09.

A huge rock from space collided with the earth, we humans disappeared from the earth, and human civilization came to an end, just like when the dinosaurs were wiped out, this will be the ultimate cosmic disaster facing mankind. It is also the favorite background of many doomsday blockbusters. But this is just a fantasy plot.

A recent study shows that there are nearly 1000 known near-Earth asteroids more than a kilometer in diameter, and there is little chance that Earth will be hit by them over the next 1, 000 years. Previous studies have shown that 6600 million years ago, the asteroid that led to the extinction of dinosaurs was about 10 to 15 kilometers in diameter. Compared with it, these asteroids are much smaller, not to mention that they are unlikely to hit Earth.

We are not good at tracking comets and smaller asteroids. The new study was led by Oscar Fuentes-Mu Fuentes Munoz, an assistant researcher at the University of Colorado at Boulder. This study is a significant improvement over previous studies, which can only predict the next century.

Firebrand, an asteroid expert at Curtin University in Australia, said that there are some conditions attached to the assertion that "there is no danger of the Earth being hit within a thousand years." the most important thing we need to pay attention to is that it only applies to the large asteroids we know so far. " This argument doesn't apply to large asteroids that we haven't observed yet, "he said." it doesn't apply to comets, either, because we don't have a way to track comets in real time. "

This is important because many comets as big as asteroids fly in from outside the solar system, and they have never been to the solar system before. At present, we have no way to track them, except when comets are very close to us.

In addition, all asteroids less than one kilometer in diameter pose a potential threat to Earth. "at present, we are not good at tracking smaller celestial bodies." Brand said.

After all, the sky is vast, and these small asteroids are relatively small, and tracking them is like fishing for needles at the bottom of the sea. Even some asteroids reflect only 5% of the light the sun shines on their surface, making it more difficult to observe them.

Monitoring celestial bodies that pose a potential threat to Earth since smaller asteroids pose a potential threat to us, it is necessary to emphasize the possibility of accidental impacts. In March, 2023 DZ2, an asteroid 70 meters in diameter, passed between the Earth and the moon, and astronomers discovered it only a month in advance.

If it hits the earth, it may level a city. About two months later, an asteroid about the size of a truck, 2023 BU, skimmed about 3600 kilometers above the southern tip of South America. This height is roughly equivalent to the altitude of the communications satellite. We almost didn't even find it, and astronomers tracked its flight path only a week before it skimmed near Earth.

Such asteroids can wreak havoc without even hitting the surface of the earth. "Space rocks less than 50 meters in diameter could explode in the atmosphere and cause great damage to the area below," Brand said. " For example, in February 2013, a meteoroid about 15cm in diameter exploded over Chelyabinsk, Russia, injuring nearly 1500 people and damaging more than 7000 buildings at a total maintenance cost of about 240 million yuan.

Since then, astronomers have stepped up their search for asteroids. Last year, the NASA-funded Asteroid Land impact continuous warning system (ATLAS) became operational, the first tracking system to search the sky around the clock for near-Earth objects that could hit Earth. In May this year, the Simone Survey Telescope at the Vera Rubin Observatory in Chile was installed, a milestone in the field of celestial observation. Now, the Simone Survey Telescope is ready to connect with a 3.2-megapixel digital camera, the largest digital camera ever built, and the two will eventually form the large Integrated Survey Telescope (LSST).

Astronomers hope to start using LSST to observe the sky in October 2024. "this is a new way to observe asteroids, and it's very interesting." Brand said.

NASA hopes to launch a near-Earth object observation satellite in 2028 to observe tens of thousands of near-Earth objects less than 30 meters in diameter.

The disaster of an asteroid impact on Earth can be prevented, so what should we do if an asteroid is detected approaching? "asteroid impact is one of the few natural disasters that can be prevented by human beings." Fuentes Munoz and his colleagues point out in the new study.

In 2022, NASA made a major breakthrough in this field. At the time, NASA scientists successfully carried out a mission called the double asteroid redirection test (DART), in which a refrigerator-sized spacecraft crashed into Dimorphos, the smaller of the twin asteroid systems.

The collision successfully changed the orbit of "Demodus" around "Didymos" and shortened the operating cycle of "Demodus" by 32 minutes. However, the success criterion set by NASA for this mission is only to change the running cycle by 73 seconds, which shows that the mission has won a great victory.

Maybe in the future, we can crash an asteroid that is a threat to us out of its original orbit in a similar way. Human attempts to address the potential threat of smaller extraterrestrial bodies are making great strides in the right direction.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.