NASA and its methods to save the Earth from the impact of an asteroid

The DART mission of the United States space agency (NASA) to try to divert the trajectory of an asteroid with the impact of a spacecraft is currently lthe only way to defend the Earth of an object that is approached with current technology.

With this demonstration, «methods that could be used in the future will be added to our toolbox,» Lindley Johnson of NASA’s planetary defense office said in 2022.

Other proposed ideas include a «gravity tractor» o a mission to explode the hypothetical object with a nuclear weapon, Hollywood’s preferred method.

The DART mission of the United States space agency (NASA) to try to divert the trajectory of an asteroid with the impact of a spacecraft is for the moment the only way to defend the Earth.

Play billiards in space

This technique is what NASA experimented with in 2022. It consists of colliding with an asteroid with a ship, in order to «push» it slightly, and thus divert its trajectory. It’s a little like playing pool in space.

This first test made it possible to understand how the asteroid reacts and, therefore, to better calculate the force needed in the future.

The size of the ship used will depend on the size of the asteroid that threatens to collide with Earth.

If the threat of an asteroid impact on Earth were real, a mission would have to be launched one or two years in advance to confront a small asteroid.

If the threat of an asteroid impact on Earth were real, a mission would have to be launched with one or two years in advance to confront a small asteroid, or decades before the projected impact for objects hundreds of kilometers in diameter.

A larger object may require the impact of multiple spaceships.

If an object’s approach is detected years or decades before it hits Earth, a spacecraft could be sent to fly alongside it for long enough to deflect its trajectory with a gravitational pull on the part of the spacecraft, creating a «gravity tractor.»

«The virtue» of this method is its «completely good understanding,» because «we know how gravity works,» said Tom Statler, DART program scientist in a November briefing.

However, the mass of the spacecraft would be a limiting factor, and gravity pullers would be less effective for asteroids. more than 500 meters in diameter, which are precisely the ones that represent the greatest threat.

In a 2017 paper, NASA engineers proposed a way to overcome this drawback: make the spacecraft extract material from the asteroid to enhance its own mass and therefore gravity.

They also say it would be more effective to drill into the asteroid, bury the bomb and then detonate it, like in the movie «Armageddon,» starring Bruce Willis.

But none of these concepts have been proven and would take decades to build, test and launch.

Another option is launch nuclear bombs to redirect or destroy the asteroid.

«This may be the only effective strategy for the largest and most dangerous ‘planet killer’ asteroids (over a kilometer in diameter),» says a NASA paper on the topic, adding that the explosion could serve as a «last resort» in case other methods fail.

Blowing up a 200-meter asteroid would require a nuclear bomb 200 times more powerful than the one that exploded over Hiroshima in 1945.

But atomic weapons are controversial and They are prohibited for use in outer space.

Lori Glaze, director of NASA’s planetary science division, said in 2021 that the agency believed the best way to deploy the weapons would be at some distance from the asteroid to impart force to the object without making it explode into smaller pieces that could then multiply the threat to Earth.

A 2018 paper published in the «Journal of Experimental and Theoretical Physics» by Russian scientists analyzed the direct detonation scenario.

They built miniature models of asteroids and shot them with lasers. They showed that blowing up a 200-meter asteroid would require a bomb 200 times more powerful than the one that exploded over Hiroshima in 1945.

They also said that it would be more effective to drill into the asteroid, bury the bomb and then detonate itas in the film «Armageddon», the 1998 film, directed by Michael Bay and starring Bruce Willis.

GML