Nasa prepares to launch spacecraft that will crash into asteroid and change its orbit in first ‘planetary defence’ test

Technique thought to be most technologically mature approach for mitigating a hazard

Nasa is preparing to launch its first-ever “planetary defence” mission to crash a spacecraft onto an asteroid to slightly change its course.

Engineers and scientists part of the American space agency’s Double Asteroid Redirection Test (Dart) team have filled the spacecraft with fuel, performed many of the final tests, and are running rehearsals as they approach the scheduled launch on 23 November, Nasa said on Thursday.

“Dart will be the first demonstration of the ‘kinetic impactor’ technique in which a spacecraft deliberately collides with a known asteroid at high speed to change the asteroid’s motion in space,” Lindley Johnson, Nasa’s planetary defence officer, said in a statement.

In the mission, the spacecraft is set to ram into the small moonlet asteroid Dimorphos — which orbits a larger companion asteroid called Didymos — at about 6km/s to slightly change its orbit.

Researchers then hope to use Earth-based telescopes to measure the effects of the impact on the asteroid system.

Didymos is nearly 780m in diameter, or about the height of the Burj Khalifa skyscraper in Dubai. Its moonlet Dimorphos is about 160m in diameter — about the size of the High Roller ferris wheel in Las Vegas.

At the planned time of impact, the asteroid system would be about 11 million km away from Earth.

“The last time Didymos was this close to Earth was in 2003; the next time will be in 2062,” Nasa said.

While neither space rock poses any threat to Earth, and no known asteroid of the size poses risk of collision with our planet “for at least the next century,” Nasa hopes to enhance the modelling and predictive capabilities of asteroid deflection with this exercise.

Nasa said that this would eventually help prepare for an actual threat if one ever arises in the future.

Currently, scientists build complex computer models of asteroid deflection based on mini-impacts they simulate in labs, but since asteroids are complicated bodies with a wide range of properties, internal structures, shapes and geologic features, Nasa felt it was necessary to carry out a real-world test.

“This technique is thought to be the most technologically mature approach for mitigating a potentially hazardous asteroid, and it will help planetary defence experts refine asteroid kinetic impactor computer models, giving insight into how we could deflect potentially dangerous near-Earth objects in the future,” Mr Johnson added.

“Though Dart ramming into Dimorphos means the end of the spacecraft, it’s just the start of the science,” Andy Rivkin, Dart investigation team lead at Johns Hopkins Applied Physics Laboratory, had said in January.

Over the last two years, Nasa engineers worked amid the Covid-19 pandemic following all health and safety protocols to build the Dart spacecraft from a collection of parts and outfitted it with different kinds of technologies it will need for the test mission.

These include the space agency’s NEXT-C ion propulsion system, which would improve performance and fuel efficiency for deep-space missions and a flat, slotted high-gain antenna for efficient communication between Earth and the spacecraft.

In early September, engineers installed the spacecraft’s only instrument, an on-board camera Draco, as well as its two roll-out solar arrays that each unfold to about 8.5m.

Since moving the spacecraft to its launch site at Vandenberg Space Force Base in California in early October, Nasa engineers have been preparing it for flight, testing the electrical system, different mechanisms, and wrapping the final parts in multilayer insulation blankets.

The Dart team has also been practicing the launch sequence from both the launch site as well as the mission operations centre at Johns Hopkins Applied Physics Laboratory in Maryland.

From 10 November, Nasa said its engineers would begin to link the spacecraft to its launch system, a SpaceX Falcon 9 rocket.

“Dart’s first launch opportunity is scheduled for November 23 at 10.20pm PST. If weather or other issues prevent a launch on the first night, the team will have an additional opportunity to launch the next day. If necessary, subsequent launch attempts can take place through February 2022,” the space agency noted.