According to NASA, every 10,000 years there is a possibility that asteroids over 100 meters could reach Earth and cause great damage; therefore, the agency wants to be tested to be cautious.
For years, scientists have been preparing to face a distant threat, but one that could one day become real. They are asteroids that pass “close” to Earth and that, in theory, could collide with the planet.
NASA says that “an asteroid is not known to pose a risk of impact on Earth in the next 100 years”. From what is known so far, the most dangerous asteroid is the 2009FD, which has a less than 0.2% chance of reaching Earth in 2185.
But experts prefer to be cautious and be prepared for a real threat.
To this end, NASA, in collaboration with the European Space Agency (ESA), is preparing its first planetary defense mission, which will try to hit an asteroid to deflect its orbit.
The mission is called DART, which in English means dart, and in this case, they are the English initials for Double Asteroid Redirect Test.
This historic mission is planned for sometime between July and September 2022, and the target will be a newly appointed asteroid, Dimorphos.
Dimorphos means “two forms”, since it would be the first celestial body to have the shape of its orbit altered due to human intervention.
But what will the operation be like and what makes Dimorphos a perfect guinea pig to try this planetary defense technique?
The DART test mission will be the first attempt to deflect a space object using what experts call “kinetic impact”.
The operation will consist of launching the DART spacecraft to travel through space and deliberately collide with Dimorphos.
The idea is to make the impact change the trajectory of Dimorphos its trajectory – as when two billiard balls collide.
“What we want to do is change the object’s speed by maybe an inch per second,” explains astronomer Andy Rivkin, one of the mission leaders, on the DART portal.
“That’s not much,” he says, but thinking about Earth, that would be enough to deflect its course and prevent collisions.
Among all the options evaluated, NASA considers kinetic impact to be the “simplest and most technologically mature” method of defending Earth from asteroids.
How is the DART ship
The dart that plans to hit Dimorphos is a vessel that can travel 6.6 km per second.
It is equipped with solar panels that, when implanted, measure 8.5 meters in length each.
This illustration shows the Dimorphos-Didymos duo near the DART spacecraft
Inside, there will be a camera that will help to navigate in space and identify the target, in addition to choosing the best point of impact.
The probe will also carry a cubic satellite that will be disconnected a few days before the collision and will attempt to capture images of the moment of impact between DART and Dimorphos.
Why Dimorphos is the ideal target
The asteroid Dimorphos is part of a binary system, because it revolves around another asteroid called Didymos, which in Greek means twins.
Dimorphos has a diameter of 160 meters and is smaller than Didymos, which has a diameter of 780 meters.
The DART probe will hit Dimorphos almost from the front, shortening the time it takes this small asteroid to orbit Didymos for several minutes.
The plan in 2022 is that, with the impact, Earth’s telescopes can measure how much Dimorphos’ orbit has changed.
The idea of launching DART in the second half of 2022 is that, at that time, the Didymos system will be closer to Earth, at about 11 million kilometers, which will allow for better observations.
Simply put, Dimorphos will be the perfect target to assess the effectiveness of a ship like DART in diverting one celestial object from another.
Planetary defense programs aim to protect the Earth from the threat of nearby cosmic objects.
An asteroid is considered close to Earth when its orbit takes it about 50 million kilometers from our planet.
When the spacecraft collides with Dimorphos, telescopes can record the moment
Image: NASA / JOHNS HOPKINS APL
Although the vast majority of nearby objects that enter the Earth’s atmosphere disintegrate before reaching the surface, those larger than about 30 meters can cause damage if they manage to get through the atmosphere.
According to NASA, an object is considered potentially dangerous if it orbits 7.5 million km from Earth and is more than 140 km in diameter.
Every month, astronomers are able to detect several asteroids with a few meters in diameter that pass between the Earth and the Moon. Every day, the Earth’s atmosphere is also hit by meteoroids, which are small fragments of asteroids about one meter and cause bright trails that can be seen at night.
According to NASA, on average, every 10,000 years there is a possibility that asteroids over 100 meters could reach Earth and cause disasters or generate waves that flood coastal areas. So, for now there is nothing to worry about, but it is better to be prepared.