In a few weeks, NASA controllers will deliberately crash their $ 330 million Dart robotic spacecraft into an asteroid. The half-ton probe will travel at more than four miles per second when it hits its target, Dimorphos, and will be destroyed.
The purpose of this scientific kamikaze mission is simple: space engineers want to learn how to deflect asteroids in case one is discovered on a collision course with Earth. Observations of Dart’s impact on Dimorphos’ orbit will provide crucial data on how spacecraft can protect Earth from the asteroid armageddon, they say.
‘We know that asteroids have hit us in the past,’ said Professor Alan Fitzsimmons, an astronomer at Queen’s University in Belfast. “These impacts are a natural process and will happen in the future. We would like to stop the worst of them.
“The problem is, we’ve never tested the technology needed to do that. This is the purpose of Dart, “said Fitzsimmons, a member of the science team for the Double Asteroid Redirection Test (Dart) mission. Launched last November, the probe is expected to reach its target in the early hours of September 27, BST. carefully tracking the asteroid’s path after the collision, scientists believe they will better understand how similar collisions could be used to deflect Earth-bound asteroids and comets.
“Dart’s target was carefully chosen,” said Jay Tate, director of the National Near Earth Objects Information Center in Knighton, Powys. “Dimorphos actually orbits another larger asteroid called Didymos, and the extent of the deflection caused by the crash will be easier to detect as the astronomers have carefully observed its path around the larger asteroid.”
Impacts from asteroids and comets have had major effects on life on Earth in the past. The best-known collision occurred 66 million years ago when a 10 km wide asteroid hit Chicxulub on Mexico’s Yucatán Peninsula. The collision created an explosion that had the energy of several billion atomic bombs and led to the destruction of 75% of all plant and animal species, including all terrestrial dinosaurs.
Since then, films like Don’t look up, Armageddon And Strong impact they depicted similar devastation triggered by asteroid or comet accidents in modern times. However, astronomers believe it is unlikely that we will experience such catastrophic impacts in real life in the near future.
“We know where the large asteroids are because we can see them with our current generation of telescopes and we know that none of the asteroids detected will come close to our planet for the next two hundred years or so. So we can rest easy in our beds on those, ”Fitzsimmons added.
“However, many of the smaller ones have yet to be detected and are still large enough to destroy entire cities and devastate large areas. We are mapping these smaller objects with increasing accuracy, but we will have to be prepared to act if we find one en route to Earth. Dart is the first step in making sure we have the right technology to tackle the threat. “
It’s a point made by NASA’s planetary defense officer Lindley Johnson, who stressed the importance of developing asteroid deflection technology as soon as possible. “We don’t want to be in a situation where an asteroid is headed for Earth and then we have to test this kind of capability.”
An example of the danger posed by small asteroids and comets is provided by the rocky object that penetrated the Earth’s atmosphere near the Russian city of Chelyabinsk on February 15, 2013. Thought to have a diameter of 20 meters, it exploded into the atmosphere, triggering a 400 kiloton explosion that injured more than 1,500 people.
“If that object had entered the atmosphere just 20km further north than it was, it would have caused much greater damage to the city,” Tate said. “We have been very lucky not to have suffered substantial losses from these things in living memory. We have to be aware that it will happen someday and be ready to do something about it ”.
Dart’s target, Dimorphos, is 160 meters in diameter and orbits its parent asteroid every 12 hours. Ten days before impact, the spacecraft will release an Italian-made probe the size of a bag, called LiciaCub, which is equipped with two cameras that have been given the Star Wars-inspired names of Luca and Leia. Images of the Dart asteroid impact will be recorded by Luke and Leia and transmitted to ground controllers.
Ground-based telescopes will then study the asteroid and pinpoint how its orbit has changed. “That way, we’ll get an idea of how easy it will be to deflect incoming asteroids or comets,” Tate said.
In addition, the European Space Agency will send a robotic spacecraft, Hera, in 2024 to Dimorphos to study the crater left by Dart and analyze its collision with the asteroid.
“Hitting Dimorphos won’t be easy,” said Fitzsimmons. “It is only 160 meters in diameter and the spacecraft will travel at four miles per second. Hitting the dead center of the asteroid, where the crash will have the most effect, will push Dart’s autonomous navigation devices to the limit.
“NASA engineers and scientists have done an amazing job and are confident it should definitely work. But you never know until you’ve done it, ”Fitzsimmons said.