Vision Photo courtesy of China
The near-Earth Object Telescope of the Purple Mountain Observatory that can observe asteroids. Photo courtesy of respondents
For different asteroids, the prevention methods are also different. For example, direct impact and blasting can be carried out in a pulsed manner, or progressive methods such as gravitational tugs, solar sails, and light pressure can be used to slowly change the asteroid’s orbit.
Zhao Haibin, researcher at the Purple Mountain Observatory, chief scientist of the Near-Earth Object Exploration and Solar System Astronomical Research Group
On March 22, a Burj Khalifa and two The double-sized asteroid 2001 FO32 had a close “meeting” with the earth-a safe and unpredictable flight over the earth. Although the probability of an asteroid hitting the earth is very small, the consequences once it hits the earth are unimaginable.
In 1994, the comet “Shoemaker-Levy 9” collided with Jupiter, the largest planet in the solar system. In more than 5 consecutive days, more than 20 comet fragments crashed into Jupiter, which is equivalent to the explosion of 2 billion atomic bombs over Jupiter in more than 5 days. The devastation can be imagined.
With the lessons learned, our scientists have launched close monitoring of near-Earth asteroids. The asteroid that “passed by” with the earth this time also provided astronomers with a valuable observation opportunity, enabling them to observe up close an asteroid that was formed at the beginning of the solar system.
Closely monitor dangerous near-Earth asteroids
Among the many small near-Earth objects (including asteroids, meteors, comets, etc.), there is a category Known as a potentially threatening celestial body. “Becoming a potentially threatening celestial body needs to meet two conditions: one is that the distance is close enough,To achieve the orbital distance with the earth is less than 0.05 astronomical units (about 7.5 million kilometers); second, the volume is large enough, the diameter must be greater than 140 meters. “Zhao Haibin, a researcher at the Purple Mountain Observatory and chief scientist of the Near-Earth Object Exploration and Solar System Astronomical Research Group, said in an interview with a reporter from Science and Technology Daily that if a near-Earth asteroid meets these two conditions at the same time, it is a potential threat to the earth.
In fact, the implicit meaning of potentially threatening celestial bodies is a threat to the earth as a whole. Zhao Haibin further explained that some small near-Earth asteroids can be very close to the earth but will not be Listed as potentially threatening celestial bodies because they are not enough to affect the entire Earth. Some of these smaller targets may enter within the distance of the earth and the moon or even within the orbit of a geostationary satellite. Even if they collide with the earth, the earth’s atmosphere can consume some of its material. It leaves only a few meteorites, so the threat posed by a single target is not that great, but because of the large number, the threat to the earth and human life cannot be underestimated.
Global A lot of data for monitoring and early warning of near-Earth objects comes from the United States, which depends on a large number of telescopes in the United States. In China, a Schmidt optical telescope with a clear aperture of 1.04 meters at the Purple Mountain Observatory can carry out monitoring and early warning of near-Earth asteroid Work, this astronomical equipment called “Near-Earth Object Telescope” is also the only telescope in the International Asteroid Monitoring Network that contributes data to China in a normal way.
“The NEO telescope has discovered more than 20 near-Earth asteroids, of which 5 near-Earth asteroids are potentially threatening celestial bodies. “Zhao Haibin told a reporter from Science and Technology Daily that although the number of domestic equipment is small and the site is relatively single, we are still working hard to provide China’s contribution.
Use different methods to guard against different “outside visitors”
If near-Earth asteroids pose a real threat to the survival of the earth, what should humans do?
Actually, monitoring and early warning of asteroids is not the ultimate goal, but to resolve the threat to the earthIt is the purpose, which is the so-called “asteroid defense.”
“The most direct defense method is to change the asteroid’s orbit.” Zhao Haibin’s solution is concise and concise, because the asteroid and the earth belong to the motion in the solar system. Celestial bodies are inevitably affected by the law of gravity in the solar system.
To make an asteroid change its orbit and not rush toward the earth, it is necessary to consider the asteroid’s size, speed, composition and mechanical properties and other related factors. It is also because of the many types of asteroids that the defense methods require careful and in-depth consideration.
In 2005, the United States carried out a space impact on a comet-the impactor released by the “Deep Impact” probe “hit” a distance of 431 million kilometers from the earth Comet “Temp One”. Zhao Haibin uses an example to analyze that this is an attempt by humans to defend against near-Earth asteroids. One of its intentions is to understand what operations are needed to change its orbit if a near-Earth object is about to hit the earth.
Zhao Haibin revealed that in the next few years, humans will conduct an impact test on an asteroid in a binary star system. By then, the asteroid in a binary star system may become the first one in the solar system. A celestial body whose orbit is changed by humans in a measurable way. And this impact experiment called the “Dart Project” will provide important data for humans to achieve near-Earth object defense.
“For different asteroids, the prevention methods are also different. For example, impulse methods can be used to directly impact, blast, or use gravitational tugboats and solar sails. Progressive methods such as light pressure and light pressure will slowly change the asteroid’s orbit.” Zhao Haibin introduced that both methods are currently in the process of research.
The value of studying asteroids is not only to resolve threats
There is no doubt that the primary value of studying asteroids is to resolve real threats, as mentioned above , Astronomers study the dynamic orbits and physical characteristics of asteroids, which can provide key data for mankind to prevent near-Earth asteroid impacts and to assess the hazards of impacts.
In addition, the study of asteroids also has very important scientific significance. Zhao Haibin said that, for example, regarding the source of life and water, near-Earth asteroids or near-Earth comets are the key objects of human suspicion. It is possible that they have brought the seeds of life and water to the earth, which requires scientists to study the water and water of the earth.The correlation of the composition of water between small celestial bodies, these studies are related to one of the ultimate human questions-where do we come from.
The asteroid itself has many mysteries to be solved. “It itself is the intermediate product of the evolution of the inner protoplanetary disk in the solar system to the planets.” Zhao Haibin further explained that there are planets, dwarf planets, asteroids, and of course some gas and dust in the solar system. In this system, asteroids are a kind of planetary “semi-finished products” in the planetary phase during the evolution of the solar nebula to planets. This provides very good clues for studying the evolution of planets and even the origin and evolution of the solar system. The study of asteroids has important supporting significance for exploring one of the ultimate scientific problems of cosmology-the evolution of the solar system.
It is worth mentioning that in the process of human beings finally going to space and using space resources, the resources of near-Earth asteroids are likely to be the first to be used by humans. “Especially some asteroids rich in rare metals, minerals and water resources are of great significance for future human use of space resources.” Zhao Haibin said.
(The original title is “Are Humans Ready to Face the Threat of Near-Earth Objects”)