Launched by NASA (NASA), the aircraft named “Dart” (DART) ushered in the last moment of its life after 10 months of spaceflight-on September 26, in space 11 million kilometers away from the earth , The “Dart” with a total weight of 600 kilograms launched a suicide sprint towards the asteroid “Dimorphos” at a speed of 24,000 kilometers per hour.
Every move of the “dart” is monitored in real time by the Johns Hopkins University Applied Physics Laboratory. On the live feed, the Dart’s onboard camera captured second-by-second images of the asteroid Dimorph that grew larger and larger until it filled the live screen before the signal was lost.
This confirmed that the “Dart” aircraft had fallen into “Form II”. This is mankind’s first planetary defense exercise, designed to try to change the trajectory of asteroids to prevent the asteroid from hitting the earth and bringing about the end of the world.
”This is a ‘new age for humanity,’ an era in which we may have the ability to protect ourselves from a dangerous asteroid strike,” said Lori Glatz, director of NASA’s Planetary Science Division, shortly after the Dart impact. “It’s pretty remarkable, we’ve never had this capability before.”
Never before in human history, though, have we suffered a catastrophe from an asteroid impact. Is this “exercise” by NASA, which has been planned for 7 years and cost more than 2.3 billion yuan, too much to worry about?
The end of the world is always in “rehearsal”
According to NASA data, the earth is bombarded by dust and sand-sized particles from space more than 100 times a day; every two thousand years or so, the earth will be hit by a meteoroid the size of a football field; In 2000, the earth will encounter an impact from a celestial body large enough to destroy the earth’s civilization.
At present, many scientists believe that the extinction of the dinosaurs, the overlord of the prehistoric earth, was because an asteroid with a diameter of several kilometers hit the earth 65 million years ago. NASA revealed that at least four asteroids have recently threatened the earth at close range. One of them hit the earth in March this year and crashed in Greenland.
On September 26, 2022, the asteroid “Dimovos” hit by the spacecraft “Dart” (DART)
And on June 30, 1908, the most serious event of an alien celestial body hitting the earth in human history occurred. On that day, a fireball-shaped object with a diameter of 50 to 100 meters passed over Siberia, Russia, illuminating the entire sky. When the “fireball” touched the ground, a mushroom-shaped cloud of smoke appeared on the horizon. Immediately afterwards, the explosion occurred with a loud noise like thunder, and the sound of the explosion could be heard within a radius of 1,000 kilometers. The shock wave generated by this explosion not only shattered the glass windows hundreds of kilometers away, but also knocked down people hundreds of kilometers away-this power is equivalent to a magnitude 5.0 earthquake.
On June 30, 1908, the most serious event of an alien celestial body hitting the earth in human history occurred.
Not only that, the explosion also flattened the local virgin forest with more than 80 million trees in 2137 square kilometers. The scientific community refers to this event as the “Tunguska explosion”. Afterwards, scientists have concluded that the alien celestial body that caused the explosion was a rocky asteroid about the size of a 25-storey building, and the explosion power generated by its impact on the earth is equivalent to 10 megatons to 20 megatons of TNT explosives. It is more than 1,000 times more powerful than the atomic bomb dropped on Hiroshima in 1945.
105 years later, an event similar to the “Tunguska explosion” was staged over Chelyabinsk, Russia. On February 15, 2013, an asteroid the size of a five-story building rushed into the atmosphere over Chelyabinsk with a dazzling light, and sprinted towards the ground at a speed of 19 kilometers per second. place exploded.
At that time, the power of the explosion was equivalent to the energy of 440,000 tons of TNT explosives. The glass windows with a radius of 518 square kilometers were shattered by the shock wave, and some buildings were also damaged to varying degrees. According to official statistics, 1,491 people were injured by shattered glass and other things in the explosion. The event was the largest airborne explosion the Earth has experienced since the Tunguska explosion.
Russian Prime Minister Dmitry Medvedev said that the Chelyabinsk incident proved that the earth is vulnerable to meteorites and that it is necessary to establish a response system to protect the earth in similar events in the future.
Afterwards, NASA also established the Planetary Defense Coordination Office (PDCO) in 2016 to catalog potentially dangerous near-Earth objects, develop technologies to keep them away from Earth, and coordinate other agencies to work together to solve these problems.
Chelyabinsk, Russia, February 15, 2013, an asteroid sprints toward the ground
On February 15, 2013, asteroid fragments fell into a hole formed in Lake Chebarkul
Yekaterinburg, Russia, February 25, 2013. A local laboratory conducts research on meteorite fragments.
The sky and the earth net, prevent problems before they happen
In the field of planetary defense, the United States has always been at the forefront of the world. As early as 1998, NASA launched the Near-Earth Object Observation Program. In 2005, the U.S. Congress passed the NASA authorization law, requiring it to find 90% of near-Earth objects with a diameter of more than 140 meters within 15 years.
Today, among the nearly 20,000 near-Earth objects known to mankind, NASA has mastered more than 90% of them.
The “Dart” project has advanced planetary defense from the observation stage to the practice stage. Under the cooperation of NASA and the Johns Hopkins University Applied Physics Laboratory, on November 24, 2021, the “Dart” vehicle was launched from Vandenberg Air Force Base, California. According to the plan, it will be launched on September 26 this year. Crashed into the “two-shape”.
During the 10-month space cruise, the “Dart” can only rely on solar panels to supplement the energy needed for flight. In the 4 hours before the impact, the “Dart” is uncontrolled and completely autonomous. As long as there is an accident, the “Dart” project will be in vain.
The final destination of the “dart” was chosen as “two shapes”, which also went through multiple considerations. The main factor is that the “two-shape” has its own fixed orbit. Since the Dimorph is gravitationally bound to its parent star, Didymos, like the moon, it is unlikely that the Dart will accidentally send it on a collision course with Earth after it hits the Dimorph.
After the “Dart” completed its mission, scientists said that it would take about two months before they could determine whether the “two-shaped” asteroid had deviated from its orbit due to the impact of the “Dart”. “We’re looking forward to knowing what happens when a ‘dart’ hits a dimorph, but we’re more interested in knowing the What does that mean for possible future applications.”
At the same time, Nancy Chabot also said that the “Dart” collision was just a nudge, similar to “pushing a golf cart into the Great Pyramid”. However, there are still some key differences between Dart and defense against real asteroid impacts: First, the asteroids pre-selected by Dart for this mission do not themselves pose a risk of hitting the Earth. Secondly, the “dimorph” is part of a binary star system, and among the near-Earth asteroids, only about 1/6 are binary stars.
Faced with the threat of asteroids colliding with the earth, after years of research and exploration, scientists have proposed many methods, such as blowing them up with nuclear bombs, using the gravity of spacecraft to change their course, and using lasers to destroy them. Among those options, “Dart” can be said to be one of the simplest, that is, to hit those planets and change their original course.
Hearts save the “ball”
Although “Dart” is led by NASA and Johns Hopkins University Applied Physics Laboratory, scientists and engineers from other countries have also made great contributions to the success of the “Dart” project. In order to better grasp the situation of “Shape II”, under the coordination of NASA, dozens of telescopes around the world and in space are monitoring the trajectory of “Shape II” and “Dart”.
The “dart” collision was just a nudge, akin to “pushing a golf cart into the Great Pyramid”.
”Although ‘Dart’ is a test, international cooperation is necessary to complete it. So on the ‘Dart’ project, we have worked closely with colleagues in Europe and other parts of the world.” University of Arizona Lunar and Planetary Lab’s Alan Howell told the media.
After the “Dart” hits the “two-shaped” planet to complete the phased mission, the “Hera” mission of the European Space Agency (ESA) will play an extremely important role in the follow-up detection work. The European Space Agency has previously signed a contract worth 129.4 million euros with the German OHB Space Company. The project is mainly jointly funded by Germany and 15 European countries.
The funds will be used to build the space probe “Hera”. The design and integration of the “Hera” spacecraft will be completed by OHB. OHB will also work with space companies from 17 countries to assist ESA in its first planetary defense mission. If nothing else, the “Hera” spacecraft will be launched by an Ariane 6 rocket in October 2024. After two years in space, it is expected to arrive at Didymos in December 2026 and conduct close-up studies for at least six months.
In terms of exploration in the field of planetary defense, China, as a space power, has never been absent. In April this year, Wu Yanhua, deputy director of the China National Space Administration, revealed that China is preparing to build a near-Earth asteroid defense system. By the end of the “14th Five-Year Plan” (around 2025), China will try to approach an asteroid Observation, and the implementation of the nearest impact, in order to “change the orbit of the planet” technology experiment.
On July 21, 1969, Armstrong left a declaration of “one small step for man, one giant leap for mankind” on the moon. Now every small step of the “dart” in the sky will also be a big step for human beings to defend against planetary impacts and protect the earth.