In a few weeks, NASA controllers will deliberately crash their $330 million Dart robot spacecraft into an asteroid. The half-ton probe will travel at over four miles per second when it hits its target, Dimorphos, and is destroyed.
The goal of this kamikaze science 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 spacecraft’s ability to 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 Belfast. “These impacts are a natural process and they will happen in the future. We would like to stop the worst of them.
“The problem is that we have never tested the technology that will be needed for this. That’s what Dart is all about,” said Fitzsimmons, a member of the science team for the Dart (Double Asteroid Redirection Test) mission. Launched last November, the probe is expected to reach its target in the early hours of September 27, BST. By carefully studying 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 is actually orbiting another larger asteroid called Didymos, and the extent of the deflection caused by the crash will be easier to detect as astronomers have carefully observed its path around the larger asteroid.”
Asteroid and comet impacts have had great 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 in Mexico’s Yucatán Peninsula. The collision created an explosion that had the energy of billions of atomic bombs and led to the destruction of 75% of all plant and animal species, including all terrestrial dinosaurs.
Since then, films such as Don’t look up, Armageddon and deep impact described similar devastation triggered by asteroid or comet crashes in modern times. However, astronomers believe it is unlikely that we will experience such catastrophic real-life impacts in the near future.
“We know where the big asteroids are because we can see them with our current generation of telescopes, and we know that none of the detected asteroids will approach our planet for the next two hundred years or so. So we can resting quietly in our beds about those,” Fitzsimmons added.
“However, many smaller objects have yet to be detected, and they are still large enough to destroy entire cities and devastate large areas. let’s find one that’s on its way to Earth. Dart is the first step to making sure we have the right technology to deal with the threat.
It’s a point backed by NASA 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 heading towards Earth and then has to test that kind of capability.”
An example of the danger posed by small asteroids and comets is provided by the rocky object that entered the Earth’s atmosphere near the Russian city of Chelyabinsk on February 15, 2013. It was thought to be 20 meters in diameter, it has exploded in the atmosphere, setting off a 400 kiloton explosion that injured more than 1,500 people.
“If this object had entered the atmosphere just 20 km further north than it did, it would have done much more damage to the city,” Tate said. “We were very lucky not to have suffered substantial losses from these things in living memory. We have to be aware that they will happen one day and be ready to do something about them.
Dart’s target, Dimorphos, measures 160 meters in diameter and orbits its parent asteroid every 12 hours. Ten days before impact, the spacecraft will launch a purse-sized Italian probe called LiciaCub, which is equipped with two cameras that received the star wars– names inspired by Luke and Leia. Footage of the Dart asteroid impact will be recorded by Luke and Leia and sent back to ground controllers.
Ground-based telescopes will then study the asteroid and determine how its orbit has changed. “That way we’ll get an idea of how easily it will be possible to deflect incoming asteroids or comets,” Tate said.
In addition, the European Space Agency should send a robot spacecraft, Hera, to Dimorphos in 2024 to study the crater left by Dart and analyze its collision with the asteroid.
“Hitting Dimorphos isn’t going to be easy,” Fitzsimmons said. “It’s only 160 meters in diameter and the spacecraft will be moving at four miles per second. Hitting the asteroid’s dead center – where the crash will have the most effect – will cause Dart’s autonomous navigation devices to their limit.
“NASA engineers and scientists have done a tremendous job and are confident that this should absolutely work. But you never really know until you do,” Fitzsimmons said.
NASA to crash a $330 million spacecraft into an asteroid to see if the impact can alter its trajectory