On April 19, 2021, Pan-STARRS, a wide-field astronomical telescope in Hawaii, discovered a near-Earth asteroid, provisionally designated 2021PDC, with a Turin index of 7 based on a trajectory tracked over several days, which is very likely to collide with Earth in a few months! The asteroid is between 35 and 700 meters in diameter, and once it hits the Earth, it will cause regional disasters!
Within a few days, all the world's optical and infrared telescopes were aimed at the asteroid, neat (near-Earth asteroid tracking) After nearly a week of tracking and orbit simulations, confirmed that the asteroid will hit the Earth on October 19, 2021, and the impact point is located in possible North Africa or Europe!
On June 30, 2021, after more than two months of observations and orbital simulations, scientists have determined that the asteroid will hit Earth 100%, and supercomputer orbital simulations show that the probability of an impact in Europe is extremely high.
How to avoid impact? NASA and the temporary planetary defense team are discussing whether to use nuclear bomb blasting to change its orbit or directly destroy it, the diameter of the 2021 PDC is between 35 meters and 700 meters, and the effect of nuclear bomb bombardment in space is not good, and scientists are worried that it will be blown into several pieces and pose a greater risk to the earth.
October 14, 2021, 5 days before the impact, 2021 PDC is still 6.4 million kilometers away from the earth, small telescopes can already see, the early warning radar on the earth has been able to detect its presence, the good news is that the size is smaller than originally expected, the bad news is that the impact probability is more than 99.999%, the impact point is confirmed in Europe at the junction of Germany, the Czech Republic, Austria, Slovenia and Croatia ...
<h1 class="pgc-h-arrow-right" Data-track="6" how many defense methods are there > asteroid impact? </h1>
The above is a simulation of an asteroid impact between NASA and ESA in 2021, but the end result is that we have no way to change the trajectory of the 2021 PDC, which means that it will drive straight into under human surveillance and eventually crash into Europe, resulting in a regional disaster!
The reason is simple, because the interval between the discovery of the asteroid and the impact is only 183 days, exactly half a year, and the reason for the failure is that after accurately determining the orbit and impact probability, there is not enough time to send the spacecraft or nuclear bomb to the asteroid to destroy it!
How many ways are there to change the orbit of an asteroid?
Destroying the asteroid is of course the best, but our purpose is not to let the asteroid hit the earth, so the most labor-saving way is to change the asteroid's orbit, so that it can rub shoulders with the earth, generally there are the following ways to make the asteroid change the orbit:
1. Install an engine on the asteroid to accelerate the asteroid so that its orbit crosses the Earth's trajectory
2. The emission of artificial objects to hit the asteroid, the energy and material ejection generated change the asteroid orbit
3. Launch a detector to form an array that reflects sunlight, irradiate the asteroid to produce a material eruption and change the orbit
4. The laser illuminates the asteroid, causing its surface material to erupt, producing a dynamic effect to change the orbit
5. Color the asteroid to absorb thermal radiation eruptions to change orbit
6. Directly launch the probe to drag the asteroid and change the orbit
7. Launch a probe to change the orbit of an asteroid with a gravitational drag effect
There are many methods, but one thing must be pointed out that asteroids are often more than one million tons, and the rocket engines of modern humans, even the most powerful Saturn V F1 rocket for the moon landing of the year, are only 680 tons, and the thrust weight is one part per million, which is also pushed to the Year of the Monkey. And more than 3,000 tons of fuel burned out in a few minutes, even crazier than the water pipe rupture and leakage, this asteroid is hundreds of millions of kilometers away, how to send it is also a big problem!
Therefore, it is necessary to intervene in the orbit of this asteroid in advance a few years or even more than a decade ago, so that under the slight influence of many years, it is possible to gradually accumulate and eventually make the asteroid change its orbit and rub the earth without any danger!
In addition, it takes several months to prepare for the launch of a probe, and the launched probe is still at the second cosmic velocity level (the asteroid orbits the sun, and must be at the second cosmic speed or above to catch up with the asteroid), so NASA and ESA will determine that the months are completely insufficient.
What if you changed your orbit and hit Earth?
Another problem that scientists worry about is that the asteroid orbit is very difficult to predict, and even the exact orbit after a few months is not necessarily accurate, because the asteroid has a very complex radiation dynamic effect, one is the light pressure, the other is exposed to the light radiation itself there is an ejector, and the asteroid is irregular and still in motion (irregular rotation), the ejection is also random, so this dynamic effect can not even be calculated by the quantum computer!
This leads to another question, since the asteroid's orbit is unpredictable, is it really 100% going to hit Earth? What if scientists intervene early and instead crash into Earth?
Why doesn't a nuclear bombing work?
In Hollywood's asteroid impact blockbusters, nuclear bombing is undoubtedly the most exciting part, but in fact, there is some truth in the need for oil workers to drill holes in the asteroid and explode deep into the asteroid's interior in "Apocalypse", because there is no air in space, the shock wave effect does not exist, and the only energy and light radiation and the dynamic effect of blowing up the asteroid material change the orbit is very limited.
Another conundrum is how to get to such a distant location, the existing nuclear bombs are designed to bombard targets on Earth, to bomb the asteroid, you must use a rocket that launches the planetary probe, and in the end it may bombard the asteroid unscathed!
Maybe design a space "ground-drilling warhead", such as a three-point warhead hitting the same point in turn, drilling into the interior explosion! In order to maximize the bombing effect, but in the end it is possible to explode into a "scattered bomb" and fly to the earth, bombing the earth into a sieve!