It was, literally, an amazing achievement. In the early hours of Tuesday, a NASA spacecraft collided with a small asteroid 11 million kilometers from Earth, and its exciting journey was captured by the camera, second by second, and broadcast to a global audience.
The purpose of the collision was to turn the rock called Demorphos – one of two halves of a binary system made up of two asteroids – into a narrower orbit around its larger partner, Didymus. The orbital adjustment has yet to be confirmed, but if successful it would prove, in principle at least, that humans have the knowledge to divert incoming asteroids toward us.
“What impressed and delighted me was that everything went well,” said Professor Alan Fitzsimmons, an astrophysicist at Queen’s University Belfast, who will now analyze collision images collected from telescopes in South Africa, Chile and Hawaii, and will take part in the mission A follow-up of the asteroid itself in 2027, carried out by the European Space Agency.
While it may take months to know if the transformation took seconds or minutes, Fitzsimmons says, “I’m more confident today than I was 24 hours ago that if there’s a small asteroid on a collision course with Earth, we can act on it.” .
So, the good news is that we can now clearly guard against the threat that wiped out the dinosaurs 66 million years ago. The unpleasant news is that humanity’s greatest existential dangers lie close to us.
Asteroids are rocky bodies, smaller than planets, that revolve around the sun “as opposed to comets made of ice, rocks and gas”. Most of the more than a million known samples are located in the main asteroid belt between Mars and Jupiter. The biggest concern are potentially dangerous asteroids, which are at least 140 meters wide and have orbits within 7.5 million kilometers of Earth — large and close enough to hit land, but small enough to avoid early detection. This made Demorphos the perfect target: the size is just right (160 metres), and too far away to pose a threat.
One of the reasons the DART was such a task that attracted public attention was its impressive display of technological audacity. While most spaceflights are designed to avoid catastrophic encounters with asteroids, planets, or space debris, engineering a deliberate destruction process between two accelerating bodies in the vast void of space required extreme precision.
The 570-kilogram Dart spacecraft, launched last year and guided by an autonomous navigation system, was traveling at six kilometers per second, or 14,000 miles per hour, and was designed to follow its target less than an hour before impact. Meanwhile, the center of the target “asteroid” was flying through space at more than twice that speed. It was astonishing to see the rocky surface of Demorphos in extremely sharp detail, as Dart crashed into it and ended its fate.
Dart was the first human attempt to intentionally move a celestial body. Its success doesn’t mean we can now play pool with space rocks, but it does indicate a viable line of planetary defense.
However, the comfort brought about by the ability to avoid asteroid catastrophe contrasts with our relatively optimistic approach to other threats. An asteroid catastrophe may occur once every million years, notes Lord Rees, Britain’s royal astronomer, co-founder of the Center for the Study of Existential Risk at the University of Cambridge, and author of If Science Saved Us. But “there are other big threats that could occur this century.”
While asteroid diversion technology is wise, Reis is more concerned about the misuse of biotechnology (particularly experiments that produce toxic viruses), artificial intelligence, pandemics, and nuclear aggression. He admits that his worst nightmare is a lone fanatic infiltrating a network: “Technology gives even small groups of people the power to cause a global catastrophe, like a virus, cyber attacks on power grids, or a breakdown in AI. Their village jerks Now a global scale.
When H.G. Wells summed up the dangers to civilization, he took into account the possibility of an “unexpectedly large mass of space rushing into us”. But also “some epidemics may appear at the present time (…) some drugs may appear, or a destructive madness that affects the minds of men.” Our ability to find our way out of an asteroid strike will be of little importance if we can’t rein in our destructive madness first.