One day in late September, a box-shaped spacecraft weighing about half a ton will crash into an asteroid seven million miles from Earth at a speed of 15,000 miles per hour in an attempt to launch it. into a new orbit.
This suicide mission by a boat the size of a golf cart is not just a self-indulgent imagined experiment NASA scientists with money to burn.
The very future of humanity may hinge on its success because the $ 330 million (£ 269 million) Double Asteroid Redirection Test (DART, for short) could provide the answer to a problem that has worried astronomers for centuries: what to do. when an asteroid is on a collision course with our planet.
“This is a mission for planet Earth – all the peoples of Earth – because we would all be threatened,” said NASA administrator Bill Nelson, who added that Dart has “turned science fiction into science facts.”
The DART mission will reach its final stage later this year, when the object reaches the asteroid Dimorphos
Since the 1980s, when scientists first realized that the six-mile-wide Chicxulub Crater off Mexico’s Yucatan Peninsula had been left behind by an asteroid whose impact had triggered the mass destruction of all non-dinosaurs. aviaries, Hollywood has clung to the potential for success of seeking a plot.
Films like Armageddon, Deep Impact and, more recently, Don’t Look Up, have all made millions at the box office playing on our fear of an extinction-level event triggered by an asteroid killing the planet.
And, according to NASA, such fears are not out of place. It has classified some 28,000 asteroids as “close to Earth” objects and its scientists believe there could be thousands large enough to cause catastrophic damage if they hit Earth.
The nearly 200 impact craters that have been found around the world so far are testament to the fact that the Earth has been rocked quite a bit by asteroids over the millennia.
Pictured is the SpaceX Falcon 9 rocket that carried DART off the planet when it launched in November 2021.
The role of the DART mission is to test the effectiveness of an asteroid deflection method that involves a “kinetic impactor”, in this case a spacecraft traveling at more than four miles per second.
NASA hopes to establish that if you hit an asteroid or comet strong enough while it’s far enough away from Earth, you can move it off course so it never hits us.
Launched in June last year aboard one of Elon Musk’s SpaceX Falcon 9 rockets from an airbase in California, Dart will target a tiny “moon”, or small moon, just 530 feet wide called Dimorphos, orbiting the largest asteroid Didymos, a rock 2,560 feet in diameter.
Neither is on a collision course with Earth and they have been chosen because even if Dimorphos is successfully deflected, there is no risk of it coming close to us.
Once in the Didymos system, it will hit the moonlet head-on, powered by its electric propulsion system powered by 28-foot long solar panels.
The more asteroid material that is shattered by Dimorphos by the impact, the more it will be moved off course.
Scientists expect the impact will send the small asteroid into a tighter orbit around the larger one. The spaceship, meanwhile, will be destroyed.
All this will be recorded by a small Italian-built satellite carried on DART, which will be released days before the spacecraft hits the asteroid, so that the aftermath of the collision can be recorded.
Meanwhile, an on-board camera will transmit images of the moment of impact.
Scientists will also be able to track what happens with the telescope from Earth and, four years later, from another satellite, Hera, which will be launched in 2024 by the European Space Agency.
The spacecraft was powered using two Roll Out Solar Arrays (ROSA), which provide it with solar energy
It makes a lot of sense to find a way to deal with an oncoming asteroid since, unlike other natural threats like earthquakes and volcanoes, we can see one arrive years later.
And experts generally believe it’s a question of when, not if, the earth will have to deal with one next.
As we have seen, Hollywood held true long ago that asteroids were worthy of being treated by disaster films.
Inevitably, the methods they devised to avoid the imminent destruction of the world were rather more dramatic than the DART.
In the 1998 film Armageddon, a team of rugged deep-sea oil drillers led by Bruce Willis are sent into space to tackle a Texas-sized asteroid that is expected to hit Earth, wiping out all life, in 18 days.
An advanced version of the Space Shuttle lands them on the rock where they detonate a nuclear bomb, splitting the asteroid into two halves that both fly safely over the planet.
The plot is not entirely ridiculous: NASA has in fact trained astronauts on how they could actually land and walk on an asteroid, recreating the conditions of near-zero gravity on the seabed off the coast of Florida.
Possible scenarios that have been proposed for an asteroid landing could include a mission to collect rock samples – asteroids are known to sometimes contain rare elements – or to install rocket engines on its surface which could then be ignited to alter them. the trajectory.
But when it comes to blasting an asteroid, scientists believe that even if it were possible (and after eons of being tossed around in space, they are extremely resilient), the gravitational pull of its core would actually force the rock back together.
When he arrives in Dimoprhos, he will crash headlong into the asteroid in an attempt to divert its course
An alternative that scientists believe could work would be to detonate a nuclear bomb or missile near the asteroid, but the use of nuclear weapons in space is prohibited by international law, so for the moment it is very unlikely to test this thesis. risky.
Another theory is that the gravity exerted by a nearby spacecraft – what is known as a “gravity tractor” – may be enough to push the asteroid on a new course.
However, aside from the wisdom of risking everything on Bruce Willis, perhaps the main reason Armageddon was so unrealistic was its timing.
According to Nancy Chabot, a project scientist for DART, a spacecraft could not be launched at the last minute to save Earth.
“This is something you do five, ten, 15, 20 years ahead: gently push the asteroid so that it gleefully navigates its way and doesn’t impact Earth,” he said.
Dimorphos orbits a larger asteroid called Didymos and was chosen because even if something goes wrong it is not in danger of being on a collision course with Earth.
It’s okay if you have enough notice.
While nearly all of the largest “near-Earth” asteroids have already been located and none are likely to hit us within the next century at least, of the estimated 28,000 out there that are at least 460 feet wide, only 10,000 have been identified.
And even the smallest of these is big enough to wreak havoc on a small US state.
Scientists continually photograph space in search of new asteroids, using computers to detect any signs of motion, such as when something passes in front of a distant star.
However, smaller asteroids glow dimmer and must get close enough to Earth before they are noticed.
A mountain-sized asteroid known as 1998 OR2 flew over Earth in what NASA called a “close approach” – actually, 3.9 million miles away – two years ago.
Future plans could see astronauts themselves land on asteroids to collect rock samples or attempt to deviate their course by installing rocket engines on objects.
In 1999, the world observing space was horrified when a previously undetected “city killer” asteroid, up to 427 feet wide, arrived within 45,000 miles of Earth, less than a fifth of the distance from the Moon.
Michael Brown, an Australian astronomer, said it “would have exploded like a very large nuclear weapon” if it hit the planet.
Smaller space rocks, known as meteors, generally burn in the Earth’s atmosphere, visible as so-called shooting stars.
In 2013, a previously undetected meteor, about 66 feet wide, crashed over the Russian city of Chelyabinsk, releasing up to 30 times more energy than the Hiroshima atomic bomb.
Some scientists claim that it burned for a short time so fiercely that it was brighter than the sun.
Earth has not been hit by a large meteorite since the Tunguska event of 1908, when one estimated to be up to 250 feet wide mercifully landed in an uninhabited region of Siberia.
It destroyed 80 million trees and left charred reindeer carcasses over an area twice the size of Los Angeles.
If he had arrived four hours later, he would have destroyed St. Petersburg.
Every year, the 30th anniversary of the accident in Siberia is marked by Asteroid Day.
Its co-founders – who include the late Stephen Hawking and Queen guitarist and astrophysicist Brian May – aim to raise awareness of the asteroid threat and what can be done to protect Earth.
A small spacecraft called the DART could provide a push in the right direction.