Asteroid hits the earth, and is one of the biggest threats to human survival and development on the earth.
In the history of the earth, there have been many species extinction events caused by asteroid impacts. An asteroid with a diameter of ten kilometers can cause supervolcanic eruptions to the earth, tsunami and other devastating disaster events. In the solar system, there are countless asteroids of all sizes. There are nearly 100,000 asteroid belts of just between the orbits of Mars and Jupiter.
1994, a comet named Sumerk-Levi 9 hit Jupiter. Its diameter is only 1.5 kilometers, but the energy released by the impact reached 40 trillion tons of TNT equivalent . is equivalent to the power of 3 billion Hiroshima atomic bombs . If it hits the earth, even if humans are not completely extinct, they will be knocked back to the Stone Age at once. Tens of thousands of years of civilization development is destroyed. Therefore, responding to and preventing the threats brought by asteroids is an important event that all mankind cannot slack off.
Can humans cope with asteroids?
NASA's DART spacecraft previously hit a distant asteroid Dimorphos at hypersonic speed. Its goal is to change the orbit of the asteroid, to verify the possibility of protecting the earth from asteroid attacks in this way, This is also the first time that humans have tried to change the movement of celestial bodies in the universe.
As early as 2012, NASA began planning the DART mission, and European Space Agency also participated in the project. The impact target is an asteroid with a diameter of 160 meters. belongs to a dual asteroid system , which orbits the larger planet "Didymos".
They will not crash into the earth. According to orbital calculations, this binary star system will pass by at 111 million kilometers from the earth. It is precisely because they are far away from the earth, even if the experiment fails, it will not pose a threat to the earth, so they are selected as targets.
In December 2021, DART flew into space on a rocket of SpaceX. Under NASA's flight command, it completed most of the range. In July, it used its own reconnaissance and optical navigation asteroid camera to capture 243 images of the target system. Through these images, ground researchers completed the precise positioning of the target planet . In the following month, the team conducted three trajectory correction simulations, further reducing the error amplitude of the spacecraft's impact orbit.
In the last few hours of the DART space journey, ground personnel handed over control to the autonomous airborne navigation system on the spacecraft. During , the Tianlong camera on DART recorded and transmitted back to the Earth at a speed of 1 frame per second. It was monitored in real time by the Mission Operation Center of the Applied Physics Laboratory of Johns Hopkins University and broadcast live at NASA Space Administration outside Washington, DC.
In addition, DART also carries the LICIACube satellite, it has broken away from the parent 11 days before the impact, and will observe the impact process 1,000 kilometers away from the impact point, and study the impact craters at close range.
Because the impact target Dimorphos is very small and has a diameter of only 170 meters, it was seen in the distance one hour before the impact. and the size of a pixel on the sensor. As DART gradually approaches, Dimorphos begins to grow bigger and bigger until the live broadcast screen of NASA is covered, and the signal is interrupted, which means that DART successfully crashes into Dimorphos.
If the impact of DART achieves the expected effect, Dimorphos' orbit around Didymos will be offset by 1%. scientists do not know the texture of Dimorphos in advance. To know how the impact result is, , and to wait for the data sent back by LICIACube, it will take pictures of the entire asteroid, and the entire process will take about weeks to several months.
This is not NASA's first space impact experiment. As early as 2005, NASA used the Deep Impact Small Spacecraft to install Comet Stamp 1. However, this impact was not to change its orbit , but to understand the composition structure of the comet, so the significance of this mission is completely different.
When the data is transmitted back, scientists can calculate the specific parameters required to knock the asteroid out of orbit, so that in the future, they can use impact to save humans.
impact is just the last step to eradicate the threat. Before this, early warning of asteroid threats must be made, that is, dangers will be discovered several months or even years before impacting the earth. has the ability to prepare and deal with in a timely manner. If the asteroid is already very close to the earth, it is probably impossible to escape the disaster with the current technological level of human beings.
In addition, this response method can only be used for planets with smaller mass and volume. If the size of the planet reaches more than several kilometers, the method will be useless and can only sit and wait for death. In order to avoid this situation, a large number of scientists are trying to create conditions for interstellar immigration to .
Although humans have not discovered traces of life in outer space, this does not mean that there is no planet suitable for human survival in the universe. In fact, according to scientists' exploration of the universe, has discovered 54 planets suitable for human habitation in the outer plane. have a slightly larger mass than the earth, and have an ecological environment similar to the earth, and some may even be more perfect than the earth.
The only problem we have to face is how to get there
Those livable planets are close to dozens of light years, and the far ones have reached hundreds or even thousands of light years. Judging from the current technological level of humans, may have become extinct on spacecraft and have not yet reached the target planet. can only develop continuously in times of peace, and there is still a long way to go.
