- Earth is regularly pelted with debris, some of it destructive.
- A spacecraft launched last week will test our ability to divert dangerous asteroids.
- It would be the first time we've altered the trajectory of a natural celestial body.
Most of what hits us is harmless. Meteorites don’t often cause damage, and they’re relatively rare compared with the thousands of tons of cosmic dust that rain down harmlessly every year. But then there are other forms of space rubble, like the 42 asteroids scientists recently rendered in unprecedented detail – a couple of which are longer than the Grand Canyon.
A spacecraft launched last week in the US is meant to help us prepare for something similar heading in our direction. If all goes to plan, it will crash into an asteroid 11 million kilometers away next September, knocking the rocky planetoid into a new orbit.
That should demonstrate our ability to nudge anything truly threatening off course. It would also mark the first time we’ve altered the movement of a natural celestial object.
NASA describes this Double Asteroid Redirection Test (DART) as a “planetary defense” exercise. The European Space Agency will follow with a 2024 launch to conduct a “crash scene investigation” of DART’s aftermath.
‘A lot more’ asteroids yet to be found
Still, best to prepare for the worst.
A few years ago, NASA announced that its catalog of known, near-Earth asteroids had topped 15,000. It added that none of them posed a risk of impact with Earth for the next century.
But NASA also said that while it located many of the bigger asteroids, there were still “a lot more” of the smaller but potentially hazardous type yet to be found.
Asteroids orbit the sun, and most exist between the orbits of Mars and Jupiter. Most meteorites are chunks broken off asteroids in that region, and meteors are asteroids or meteorites that burn up in Earth’s atmosphere – though the shockwaves they generate can do significant damage.
As many as 400 tracked, man-made objects enter Earth’s atmosphere every year. Some argue it might be prudent to curb the growing pool of man-made space junk that’s the source of these objects, as we better prepare for a disastrous collision with the natural variety.
And there is ample precedent for the natural variety.
Historical destruction from the heavens
66 million years ago, an asteroid believed to have been about 10 kilometers wide crashed into Earth. Its impact likely kicked up a metallic cloud of vaporized rock and dust that blocked out sunlight and triggered the extinction of three-quarters of life on the planet, including the dinosaurs.
More recently, a meteor either exploded or streaked over the Podkamennaya Tunguska River, in a remote part of Siberia, in June 1908 – killing wildlife and flattening an estimated 80 million trees across more than 2,000 square kilometers of forest.
Another unnerving encounter happened recently enough to be captured on video.
A small asteroid about the size of a six-story building entered Earth's atmosphere in February 2013 over Chelyabinsk, Russia, and triggered a blast above the planet's surface that was more powerful than the yield of some nuclear weapons.
More reading on asteroids and space missions
For more context, here are links to further reading from the World Economic Forum's Strategic Intelligence platform:
- One other result of the asteroid that landed 66 million years ago and wiped out the dinosaurs, according to this recent study: it may have prompted our early human ancestors to come down out of the trees. (Cornell University)
- The good news, according to this piece: asteroids are remnants of the early Solar System that could reveal secrets of Earth’s origin. The bad news: they could also bring an end to life on Earth. (The Conversation)
- About a month before DART another spacecraft was sent off to the never-before-explored, “very mysterious” Trojan asteroids. According to this piece, the mission was named after a prized fossil of one of the oldest-known human ancestors. (Nature)
- The spacecraft being catapulted at an asteroid as part of DART is “basically a box” a bit more than a meter wide, according to this piece, and it needs to make a direct hit on something the size of the Great Pyramid of Giza. (Wired)
- Little is known about the “quasi-satellite” asteroids that orbit the sun yet remain relatively close to Earth, but this recent paper suggests that one such Ferris-wheel-sized object may be the first confirmed asteroid to have splintered off our moon. (Science Daily)
- A “not-so-gentle nudge”: this piece has an infographic illustrating the DART mission’s trajectory, planned impact, and intended alteration of one asteroid’s orbit around a larger twin. (Nature)
- The UAE is already the first Arab state to have a Mars mission, and according to this piece it recently announced plans to land a spacecraft on an asteroid by 2033 – which would make it the fourth country ever to do so. (Al Monitor)