In the Netflix smash hit, a ‘planet destroyer’ comet is imminently heading towards Earth. Can something like this happen? Most importantly, would we have a chance to save ourselves?

In ‘Don’t Look Up’, Netflix’s latest smash hit, a pair of astronomers, made up of Kate Dibiasky (Jennifer Lawrence) and Randall Mindy (Leonardo DiCaprio), discover a comet coming from the outer reaches of the Solar System heading towards the Earth.

The rock, a ‘planet destroyer’ about 9 km long – similar in size to the one that wiped out the dinosaurs some 66 billion years ago – will impact in six months. Humanity will be annihilated, most of the species will become extinct and the catastrophe will have unimaginable dimensions. Scientists are desperate to communicate the threat to the world, but find inept politicians more concerned about their election results, media frivolous – Do aliens exist? Can that rockfall on my ex-wife’s house? They ask – and billionaire technocrats whose only goal is to become even more billionaires. Not to mention the significant percentage of deniers, conspirators, hoaxes and absurd memes.

Adam McKay’s comedy (watch out for ‘spoilers’ from here on) uses something as graphic as a comet slamming into Earth as an allegory for the danger that is really coming our way, climate change, and how we choose to ignore the warnings of scientists no matter how scary they are.

“I’m so bored,” snorts Chief of Staff Jason (Jonah Hill) at the White House when Dr. Mindy tries to explain why he’s sure what’s going to happen. The parody goes to the extreme in a morning television show in which the hosts, played by Cate Blanchett and Tyler Perry, laugh to life and death at the affair and treat Dibiasky, already desperate to be heard, as an unsympathetic wacko.

Not in a hundred years

With the advice of Amy Mainzer, professor of planetary science at the University of Arizona, the film also brings the issue of planetary defense to the fore, with the licenses (a few) of Hollywood. To begin with, “it would be extremely strange, practically impossible, for us to discover an object of that size with such a short reaction time. A body like this would have been seen much earlier”, says José María Madiedo, from the Institute of Astrophysics of Andalusia (IAA-CSIC).

NASA has a Planetary Defense Coordination Office (PDCO), in charge of searching for and characterizing “potentially dangerous” rocks, those whose orbits will reach less than 8 million km from Earth and with a size large enough (30 to 50 meters) as to cause significant damage. The organization, which by the way is mentioned in the film, issues warnings about the effects of potential impacts and studies strategies and technologies to mitigate them.

As explained by the US space agency, more than 95% of near-Earth asteroids of about 50 meters or larger have been discovered, tracked and cataloged. There is no chance that any of them will hit Earth during the next century. Similarly, it is extremely unlikely that any of the undiscovered objects of this size will do so. But the little ones are not a joke either. It is easier for them to go unnoticed. In 2013, an asteroid exploded over the Russian town of Chelyabinsk with a power of 500 kilotons, thirty times higher than the Hiroshima nuclear bomb. It caused minor injuries to almost 1,500 people and damage to buildings and constructions. It was barely 17 meters long and 10,000 tons in mass. The impact was the most intense since the Tunguska event, which also occurred in Siberia in 1908 and razed 2,000 square km of tundra. It did not leave an impact crater, and researchers believe it was the grazing passage of an asteroid, without actually impacting, or of a comet, made up of much more volatile material.

Nuclear bomb

In a theoretical exercise, assuming that we had the worst of luck and that a hypothetical comet coming from the Oort cloud or from some other place beyond Pluto decided to put us in its crosshairs in as short a time as six months, could we do something to save ourselves? “With today’s technology, practically nothing. It is a very short time to be able to react, design a strategy, get to the object and put it into practice ”, Madiedo acknowledges. “Apart from that, nowadays there is no protocol established at the international level in the face of such a threat,” he continues.

Nor does it seem that the first solution they opt for in ‘Don’t look up’, setting off a set of nuclear bombs against the comet to smash it to pieces in space, is the most convenient.

“That strategy, which is also the one that appears in the movie ‘Armageddon’, does not work. It is the least effective because it is not known how the rock will break. Some studies even indicate that the fragments could be grouped again due to the gravity of the object”, explains the astrophysicist. That is, we could continue to be hit by a giant or by a myriad of uncontrolled rocks.

Better a push

NASA is studying a different strategy with which it hopes to obtain better results. At the end of November, they launched the DART mission, whose objective is to impact Dimorphos, the moon of the asteroid Didymos, with the intention not of destroying it, but of giving it a ‘push’ that displaces it and deflects its trajectory. The spacecraft will reach its destination in autumn 2022 after a journey of 11 million kilometers. Dimorphos is not a threat. It is a test to see if the technique works in case we ever need it. “But a push is far less spectacular for Hollywood than nuclear explosions,” jokes Madiedo. And it takes time. In a critical, desperate situation, with a comet swooping down, “a nuclear explosion would probably not be ruled out.”

The largest potentially dangerous asteroid identified so far is 1999 JM8, 7 kilometers in diameter. “Due to its size, it could cause an event similar to the one that caused the extinction of the dinosaurs if it collided with Earth,” says Madiedo.

However, there is no danger of that happening in at least a hundred years. The next close encounter between our planet and this object will occur in 2075, but even then the asteroid will fly at a distance of just over 38 million kilometers.

As David Barrado, from the INTA-CSIC Astrobiology Center, points out in his book ‘Cosmic Dangers’, fortunately events like the one in Chelyabinsk have occurred in sparsely populated regions.

“The effect it could have on a large metropolis would be truly daunting, especially in the case of an asteroid similar to the one that produced the Tunguska event,” he writes.

“… To a large extent we are still exposed to cosmic chance. Only early warning and adequate investment in science and technology will allow us to have the necessary tools to subvert or mitigate this danger,” he concludes.

And let those who warn us of it be heard, be it an alien rock, a global pandemic or a climate change that, if not acted on soon, could crush us as inexorably as a comet fallen from the sky. It will not be because they have not warned us.

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