NASA experts in planetary defence favour moving a potentially dangerous asteroid out of the path rather than blowing it up.
On Monday, a NASA spacecraft smashed an asteroid at breakneck speed in an unprecedented practise run for the day when a killer rock threatens Earth.
The spacecraft dubbed Dart collided with a harmless asteroid 7 million miles (11.3 million kilometres) distant, blasting into it at 14,000 mph (22,500 kph).
The collision was projected to create a crater, launch streams of boulders and soil into space, and, most critically, modify the asteroid’s orbit.
“We have impact!” Mission Control’s Elena Adams announced, jumping up and down and thrusting her arms skyward.
To capture the sight, telescopes around the world and in space were directed at the same point in the sky.
Though the hit was rapid — Dart’s radio communication abruptly stopped — it will take several months to establish how much the asteroid’s path was altered.
The $325 million effort was the first attempt to move an asteroid or other natural object in space.
“As far as we can tell, our first planetary defense test was a success,” Adams later told a news conference, the room filling with applause. “I think Earthlings should sleep better. Definitely, I will.”
NASA Administrator Bill Nelson reminded people earlier in the day via Twitter that, “No, this is not a movie plot.” He added in a prerecorded video: ”We’ve all seen it on movies like “Armageddon”, but the real-life stakes are high.”
Monday’s target is Dimorphos, a 525-foot (160-metre) asteroid. It’s a moonlet of Didymos, Greek meaning twin, a five-times-larger asteroid that hurled off the debris that formed the junior partner.
The pair has been orbiting the sun for ages without harming Earth, making them ideal candidates for save-the-world tests.
Dart, short for Double Asteroid Redirection Test, was launched last November and directed to its target using innovative technologies created by Johns Hopkins University’s Applied Physics Laboratory, the spacecraft manufacturer and mission manager.
Dart’s on-board camera, a critical component of this smart navigation system, detected Dimorphos less than an hour before impact. “Woo hoo!” screamed Adams, a Johns Hopkins mission systems engineer.
Adams and other ground controllers in Laurel, Maryland, watched with mounting excitement as Dimorphos loomed larger and larger in the field of view alongside its larger companion, with an image flashing back to Earth every second.
Dimorphos appeared alone in the photos within minutes; it resembled a large grey lemon, but with boulders and rubble on the surface. As the radio transmission concluded, the last image on the screen froze.
Flight controllers clapped, hugged, and shared high fives. After completing their job, the Dart crew moved straight into party mode. The spacecraft’s demise was met with little sadness.
“Normally, losing signal from a spacecraft is a very bad thing. But in this case, it was the ideal outcome,” said NASA programme scientist Tom Statler.
Carolyn Ernst of Johns Hopkins University said the spacecraft was clearly “kaput,” with remains likely in the new crater or cascading into space with the asteroid’s expelled material.
The impact should cut that time by ten minutes. Scientists remarked that the expected orbital shift of 1% may not appear to be significant. However, they emphasised that it would be a big adjustment over time.
Dart, according to scientists, would not shatter Dimorphos. In comparison to the asteroid’s 11 billion pounds, the spacecraft weighed only 1,260 pounds (570 kilogrammes) (5 billion kilograms). However, that should be enough to reduce its 11-hour, 55-minute orbit around Didymos.
“Now is when the science starts,” said NASA’s Lori Glaze, planetary science division director. “Now we’re going to see for real how effective we were.”
Given ample warning time, planetary security specialists favour pushing a threatening asteroid or comet out of the way rather than blowing it up and creating many bits that could rain down on Earth.
For large space rocks, many impactors or a combination of impactors and so-called gravity tractors, which are yet-to-be-invented machines that use their own gravity to drive an asteroid into a safer orbit, may be required.
“The dinosaurs didn’t have a space programme to assist them know what was coming, but we have,” NASA’s senior climate adviser Katherine Calvin said, alluding to the 66 million-year-old global extinction thought to have been caused by a huge asteroid strike, volcanic eruptions, or both.
Since its inception by astronauts and physicists 20 years ago, the non-profit B612 Foundation has advocated for impact tests like Dart to defend Earth against asteroid attacks.
Aside from Monday’s accomplishment, the world needs to do a better job of finding the numerous space rocks lying out there, cautioned the foundation’s executive director, former astronaut Ed Lu.
According to NASA, less than half of the estimated 25,000 near-Earth objects in the lethal 460-foot (140-metre) range have been identified. And only a fraction of the millions of smaller asteroids capable of causing widespread damage are known.
The National Science Foundation and the US Energy Department’s Vera Rubin Observatory, which is approaching completion in Chile, promises to transform the field of asteroid discovery, according to Lu.
Asteroid discovery and tracking “That remains the name of the game here. That is what must occur in order to protect the Earth,” he stated.