Small asteroids enter the atmosphere several times a day. Sometimes the night sky lights up. We also know that large asteroids hit Earth occasionally, because they happened in the past.
But how can we prevent an asteroid collision that could really hurt us?
There are millions of asteroids in the solar system of different sizes. space agencies NASA and the European Space Agency say Tracks all known asteroids that could pose a threat to us.
They are trying to predict where asteroids will be located in the future, and whether any of them have a chance of hitting Earth.
It could lead to more than 50,000 deaths and injuries
These are greater than 140 meters wide. An asteroid of this size could cause more than 50,000 deaths and injuries, according to a source Study in the magazine Geophysical Research Letters that simulates the impacts of asteroids in places all over the Earth.
Fortunately, there are no known steroids that pose any particular danger for the next 100 years, according to NASA.
But there are dark numbers. It can be difficult to detect these asteroids. NASA estimates that they have detected only about 40 percent of asteroids at 140 meters and above.
Small change has big consequences
So what happens if an asteroid is discovered that has a high chance of hitting us? Now a method will be tested for the first time: the DART spacecraft will be pointed directly at an asteroid.
This is just a test. The asteroid that will collide does not pose any danger to Earth.
The plan is to change the asteroid’s orbit to see if the method works.
The change of course may be slight, but it will change enough, for example, to skip the ground long after the collision itself.
The target in this test is a fragment of a double asteroid – the small Demorphos at 165 meters orbiting the much larger Didymos asteroid at an altitude of about 800 metres, like a small moon.
The plan is to sacrifice the DART probe by hitting it directly at Dimorphos. This will happen in October 2022, and the probe will be launched on November 24.
The sifting is fully automatic. The probe will find and collide with Dimorphos itself. Then it goes quickly.
73 seconds shorter cycle means success
The probe then travels at a speed of more than 23,000 kilometers per hour. The probe weighs about 560 kilograms, and it will hit the asteroid with great force.
It is as if a fully loaded truck weighing 60 tons must reach more than 2,000 kilometers per hour, and then crash into a wall.
But scientists don’t know exactly what will happen when the probe hits, because they aren’t sure how to make Dimorphos. This is one of the reasons for making this attempt.
Even if the probe collides with great force, it will still slow down a mound of rock more than 160 meters in diameter. It is the size of the Great Pyramid of Giza. According to the ESA.
Researchers estimate that the asteroid will go a little slower after the crash.
But this may be enough to affect the path around Didymus. If Demorphos slows down a bit, it will make the orbit around the large asteroid smaller. Thus, Demorphos will spend less time traveling around Didymus after the collision.
For the test to be successful, the cycle must be 73 seconds shorter than today’s 12-hour Dimorphos cycle, According to this study on the DART task.
Those who lead the DART task believe they can reduce the cycle by up to ten minutes, According to National Geographic.
But no one knows for sure what will happen.
Can’t be sure how the asteroid was put together
We don’t know for sure how asteroids are built, because we haven’t visited enough of them, Stephanie Werner tells forskning.no. She is a geologist and researcher in fields including planet formation at the University of Oslo.
Dimorphos can be a loose collection of rocks and gravel. The asteroids visited by the space probes appear to be covered with sand, pebbles, and large boulders.
Werner describes an impact as a sandbag collision, if it is built this way. Alternatively, the asteroid may be more solid on the inside.
This will affect how quickly the Demorphos impact will change. But researchers cannot be sure of this in advance.
There is a small satellite called LICIACube in flight, and it will be separated from the DART probe before impact. Thus, it can photograph and measure what was ejected from the asteroid after the crash.
Werner believes that this is one of the most interesting things from a scientific point of view, as it may bring more knowledge about asteroids.
The value of this experience is also related to how well they measure the impact of the avalanche, Werner believes. It is difficult to make detailed measurements of such a small asteroid. Collisions with both radar and telescopes must be monitored, but the outcome must also be further investigated.
One follow-up mission will be sent in 2024. The European Space Agency (ESA) is responsible for the Hera probe, which will travel to the double asteroid.
There he will take accurate measurements and document the results of the DART test. The idea is that the results of this experiment will become a defense technology for the planet that can be replicated if the need arises. According to the ESA website.
Many others canceled quests
DART is a successor to several other proposed space missions that will test different ways to alter the course of a potentially dangerous asteroid.
This is the most violent method, says Stephanie Werner.
– There have been many proposed methods, such as parachutes or small engines connected to the asteroid.
She says many of the methods have been investigated and modeled, but no one else has become so yet. Asteroid redirect mission is an example A high-profile mission canceled in 2017.
One proposal here was for the satellite to pick up a large boulder from the surface of an asteroid, which would then be lifted into space.
This rock can act as a kind of gravity rope that pulls the large asteroid below. This may be enough to change the orbit of the asteroid, but the mission has been postponed until now.
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