The sci-fi comedy "Walking to the Moon" produced by Happy Twist also put a serious question in front of the public - if the "uninvited guest" really hits the earth, how should humans respond?
Scientists have found that in the foreseeable future, there is basically no possibility of a "potentially threatening asteroid" colliding with the earth, but scientists still dare not be careless.
Because once the "dust" in the universe, the Earth, collides with another "dust", it may "cause unprecedented regional damage to human settlements."
In reality, on the "China Space Day" on April 24, 2022, the National Space Administration revealed that China will set up a near-Earth asteroid defense system to jointly deal with the threat of near-Earth asteroid impacts.
The power of science can make science fiction a reality.
How powerful was the asteroid hitting the Earth?
In "Lone on the Moon", the "Moon Shield Project" failed, and the earth was hit by the asteroid π.
After watching the film, Wei Ke, an associate researcher at the Institute of Atmospheric Physics, Chinese Academy of Sciences, pondered the question, how big should the asteroid π be in order for Duguyue to think that the earth was destroyed?
Judging by the global burning it caused, Weike concluded that "its size is estimated to be larger than the celestial body Chicxulub hit."
66 million years ago, an asteroid with a diameter of about 12 kilometers hit the earth, and the impact speed reached 100,000 kilometers per hour (about Mach 82, 28 kilometers per second), and the impact site was in the Yucatan Peninsula in Mexico. Near Cxulub, so this impact is also known as the Chicxulub impact, which ended the age of dinosaurs.
"Considering the smooth progress of the story, I estimate that the diameter of the asteroid π is about 10 to 15 kilometers." Wei Ke analyzed.
Under such an impact, the evolution of life on Earth and the state of the climate will be completely changed.
In the lifetime of the protagonists and their descendants, there will be no return to normal.
Earth's climate would also undergo dramatic changes, which Weike attributed to "dark world, dry and cold, sulfuric acid rain, hotter world."
In "A Lonely Moon", after being hit by the asteroid π, the earth becomes a dim planet, and the surviving humans can only live underground.
Li Jinxing, a researcher at the UCLA Research Institute, said that within a period of time when the giant meteorite hits, the smoke and dust will fill the entire earth's atmosphere and block the sunlight on the ground. "The ground atmosphere in the scene in the film cannot be breathed by the human body, and the entire planet changes Dark scenes are very likely to happen."
"A 10-kilometer-scale meteorite hits the earth, which will bring a devastating outcome." Li Ran, scientific advisor of "Lonely Moon" and a researcher of the Nebula Project of the National Astronomical Observatory of the Chinese Academy of Sciences, said that, as in the film, surviving humans need to live in a long period of time. Wearing equipment that can purify the air for a long time, "After the extinction of the dinosaurs, there were no large animals for a long time, which shows that the impact of meteorites hitting the earth on the natural environment is continuous."
In fact, even a ten-meter-level asteroid can cause great harm to human society.
On February 15, 2013, a meteor struck Chelyabinsk, Russia, injuring more than a thousand people.
NASA estimates that before entering the Earth's atmosphere, the asteroid was 17 meters in size, its mass was 10,000 tons, and the energy released by the explosion was about 500,000 tons of TNT explosive.
Is the "Moon Shield Plan" really feasible?
In 1967, Professor Sandov of the Massachusetts Institute of Technology proposed a design in his class: Assuming that the asteroid "Icarus" will hit the earth in 18 months, how to prevent a disaster?
The students designed the Saturn V rocket, the most powerful rocket under development at the time, to carry a 100-gigaton nuclear bomb to de-orbit or blast the asteroid.
Of course this is only on paper, even decades later.
In 2010, the National Academy of Sciences reported that specific defenses against nuclear explosions may require decades of research.
However, it is quite interesting that the method of using nuclear bombs to blow up incoming celestial bodies is quite favored by movie creators. The Hollywood disaster films "Doomsday", "Crash", and even "Lone on the Moon" envisaged similar methods.
The approach taken in "Lone on the Moon" is to use multiple large nuclear bombs "Moon Hammer" to directly destroy the meteorite, and choose the launch base on the moon.
Li Jinxing believes that it is feasible and realistic to use a nuclear bomb to smash an asteroid or make it deviate from the orbit of hitting the earth.
"If you smash the asteroid into many smaller pieces, then each piece hits the Earth with significantly less damage, and many of the smaller pieces burn directly in the atmosphere."
Some scientists have pointed out that this is a kind of "shredder-type thinking", which will make the future orbit of the debris more uncertain.
Li Ran thinks this view is justified, because after blowing up a large celestial body, it is difficult to directional control the movement trajectory of the fragments. In the movie, after the nuclear bomb bombs the asteroid π, the earth is faced with the impact of its fragments again. threat is the proof.
"There may also be collisions between these fragments, so the result of the nuclear bomb impact is uncontrollable. Unless the meteorite is very broken and blown evenly, this requires special design of the weapon, such as being able to penetrate deep into the Inside a huge celestial body, blow it up from the inside."
That is to say, the premise of the success of the plan in the film is that we can more accurately predict the changes after the meteorite is bombed, and how the orbit will deviate.
"This needs to be based on accurate detection of the shape and structure of the meteorite, accurate landing or bombardment of the target site, etc. If the meteorite is found late, it may be a mission that is not 100% ready. It's a big gamble." Li Jinxing said.
Li Ran also mentioned that in the film, when the asteroid π was discovered, there was only eight years left for human beings to prepare. When time is tight, destroying it with a nuclear bomb is a relatively quick way to operate. Of course, the premise is that Humans already have the ability to build a base on the moon.
According to current technology, the cost of establishing a lunar base is very high.
Around 1965, NASA spent $40 billion annually on the Apollo program and related programs, equivalent to 5% of the U.S. annual GDP, and they have not landed on the moon in the last 50 years.
"In the future, after the cost of launch, life support and many other aspects is greatly reduced, it is possible for humans to build a lunar base that can reside there." Li Jinxing said.
Attempts to resist "extraterrestrial visitors"
According to statistics from NASA's Jet Propulsion Laboratory, as of August 5, 2022, 850 near-Earth objects greater than 1 kilometer and 10,135 near-Earth objects greater than 140 meters have been discovered.
Among them, the ones that are considered to be likely to hit the earth are called "potentially threatening celestial bodies".
Among the Sentinel systems at NASA's Jet Propulsion Laboratory, the most threatening is (29075) 1950DA, which is estimated to have a diameter of more than 1 kilometer. hit the earth in the year.
But after correction for observation, the index quickly dropped to -2.05, which means the possibility of an impact is almost non-existent.
All in all, the risk of "extraterrestrial visitors" having a major impact seems small, at least in our lifetimes.
But for us on Earth, the consequences of being hit by something more than a few kilometers in diameter are extremely severe, so it would be wise to monitor the sky closely and figure out the climate processes involved, Weike said.
For the defense of near-Earth asteroids, the current thinking is still based on early detection, early prevention, and early planning.
As Li Ran said, "When it is found when it is far away from the earth, then we don't need to take very drastic measures."
There are many options for scientists to explore the defense against near-Earth asteroids hitting the earth.
They have envisioned using long-term forces to slowly change the asteroid's orbit, including kinetic or kinetic impact, powering meteorites, and ion thrusters.
"Many comets or meteorites are mainly composed of ice, and some scientists have imagined methods of heating them with rocket engines and lasers." Li Jinxing said.
But Zhu Jin, honorary curator of the Beijing Planetarium, said that scientists had some conceptual ideas, but they were far from practical applications.
"It is also because no asteroid with actual threat has been found yet." Zhu Jin introduced that the first accurate prediction of the asteroid hitting the earth was on October 6, 2008. Astronomers found that the asteroid 2008TC3 would hit the earth 19 hours later, and Issue a forecast.
As a result, the asteroid hit the uninhabited Nubian desert in Sudan as expected.
However, the asteroid is not large, only about 4 meters in diameter, and part of its wreckage is now on display at the Beijing Planetarium.
"At present, some countries have achieved very precise launch of the aircraft to an asteroid and landed. But how to make it deviated from its orbit is still in the stage of imagination." Li Ran specifically mentioned that in 2012, my country's After the Chang'e-2 satellite completed its scheduled exploration mission around the moon, it passed by the Tutatis asteroid numbered 4179 and took pictures of the asteroid.
This is also the first time in the world to achieve a close-range detection of the asteroid.
Beijing reporter Liu Changxin and Wang Shikun of Nanfang Daily