esa-asteroide

This is why NASA is considering a gigantic space “shotgun”

To defend the Earth in the event that a threatening asteroid emerges by surprise, NASA is exploring the most direct track there is: obliterating it with great blows of space buckshot.

It’s no secret that stray asteroids pose a considerable threat to our civilization. The impact of a cosmic behemoth could wipe out much life on Earth. But NASA does not hear it that way; no question of letting humanity suffer the same disastrous fate as the dinosaurs, about 65 million years ago. And to be sure, it does not do things halfway: just take a look at its Pi -Terminal Defense for Humanity system to be convinced.

Many avenues have already been considered to protect the planet from such an event. The most promising of them are often based on the same concept: to send a means of propulsion to the celestial body in question, then to push it in order to deviate its trajectory in the hope that it passes a good distance from the Earth.

Several approaches, but no ideal solution

It’s an approach that several space agencies are exploring in conjunction with the Double Asteroid Redirection Test mission, or DART; for the occasion, they are going to play cosmic billiards with a 500 kg satellite. The latter will serve as a ram car, and will collide with the asteroid Dimorphos in the fall of 2022. The researchers thus hope to be able to study the mechanics of the point transfer of kinetic energy to determine whether or not this is a viable technique to save the Earth.

There is also another variant; instead of hitting the target violently, one can also imagine mooring to it delicately, then pushing it gradually using a means of propulsion. It is a far from obvious approach to implement in practice; but on paper, it is the ideal solution, because by far the most secure.

Indeed, there would not even necessarily be a need to send a gigantic vehicle; in the vacuum of space, even a very small engine is capable of slightly deflecting the trajectory of a gigantic object; these few degrees of difference can translate into a difference of several hundred thousand kilometers at the end of the race, which could save the Earth from a disastrous fate. But that means having several months ahead of us to organize the maneuver.

Time, a crucial parameter

And it is precisely this last point that worries NASA. Because despite industry-wide efforts to track down potentially dangerous asteroids, the cosmos is far too vast to do so comprehensively; there will necessarily remain many blind spots from where a threatening object could arise, likely to strike the Earth before humanity is able to react.

To be able to respond to this catastrophic scenario, moreover recently explored in the film Look Up with Leonardo DiCaprio, it is therefore also necessary to develop extreme emergency measures. In this context, it is necessary react quickly and strongly to avoid a scenario that could lead to thecomplete eradication of humanity. And that’s exactly the philosophy of the project by Philip Lubin, an engineer from the University of California at Santa Barbara.

With him, no question of doing in the lace. The principle of the Pi-Terminal Defense for Humanity is, moreover, extremely simple: it is essentially a huge space shotgun. This one would be able to catapult a charge similar to a buckshot; it would be made up of a multitude of metal rods, possibly lined with nuclear explosives. The goal: pulverize the intruder without further ado, and as quickly as possible!

According to NASA, this would respond to an imminent threat; the agency claims that it would even be possible to intercept a celestial body at a distance equivalent to that of the Moonthat is a few hours just before a potential impact with Earth. Our satellite would also be an ideal launch pad; the weak gravity and the absence of atmosphere would make it possible to dislocate the target with a largely higher precision.

A double-edged emergency solution

Of course, this poses another problem; instead of a massive asteroid, we would now be dealing with a shower of fragments that could be just as devastating. In the best-case scenario, the resulting fragments would be small enough to burn entirely upon atmospheric re-entry and would therefore not be hazardous.

But this is a hazardous forecast; a limit of which both Lubin and NASA are obviously well aware. “The effectiveness of this approach depends on the intercept time and the size of the asteroid”, explains the press release. Additionally, adverse consequences could occur even in the ideal scenario where none of the fragments hit the ground.

Indeed, it is not because a piece burns in the atmosphere that it disappears; the object remains subject to the laws of thermodynamics. It would therefore release a massive amount of energy in the atmosphere, with all the consequences that entails. But the engineer also defends the idea that at present it is the most reasonable last resort that we have today.

In practice, this approach would make it possible to effectively defend against asteroids several hundred meters in diameter.”, he insists. “That would virtually eliminate the threat of immediate mass destruction”. Moreover, compared to the other techniques proposed, this one has undeniable advantages; it is notably quite little expensive, and above all quite intuitive to develop and easy to test.

For these reasons, the project was selected by NASA as part of its Innovative Advanced Concepts program. It will therefore be explored in more detail; if this theoretical work proves conclusive, it could eventually end up being tested on a guinea pig far from Earth. Hopefully this will be enough if we ever find ourselves in this situation!

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