DART: Everything you need to know about NASA’s mission to deflect an asteroid


NASA says its DART spacecraft is on track to crash into an asteroid in the coming days. Speaking at a media briefing held at NASA Headquarters in Washington, the team behind the mission confirmed that all was going according to plan ahead of the impact, which is scheduled for just after midnight BST on 27 September. Here’s everything you need to know about the mission.

What is the aim of the DART mission?

DART, or Double Asteroid Redirection Test, is the first ever mission to attempt to redirect the path of an asteroid by crashing a spacecraft into it.

The mission is part of NASA’s planetary defence strategy and aims to build on our ability to model, predict and prepare for an asteroid that might provide a threat to Earth, should one be discovered.

It was launched on a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California on 23 November 2021 and is scheduled to make impact on 27 September 2022.

“It’s essentially a big science experiment to see if crashing a spacecraft into an asteroid is a good way to change its orbit around the Sun and potentially deflect an Earth-crossing asteroid away in the future should that happen, or rather when that happens,” said cosmochemist and author of Meteorite Dr Tim Gregory.

“It sounds impossible that something as lightweight as a spacecraft, even a spacecraft like DART, which weighs more than half a tonne, could possibly nudge something like an asteroid, which weighs millions of tonnes. But you don’t need to nudge an asteroid by very much for it to miss the Earth entirely. Just fractions of a degree, and you’ll miss the Earth by millions of miles.”

© NASA/Johns Hopkins APL

What asteroid will DART crash into?

DART’s target is a binary asteroid system made up of a larger asteroid named Didymos, which is Greek for ‘twin’, and a smaller companion asteroid named Dimorphos, which is Greek for ‘two forms’, that orbits it roughly every 12 hours. Didymos is around 780m across and Dimorphos is around 160m across.

“It’s important to stress that this particular asteroid system doesn’t pose a threat to the Earth. It was merely just chosen as a target for this science experiment, and it was chosen from a few different candidates based on its orbit around the Sun,” said Gregory.

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The spacecraft is going to target Dimorphos when it is around 11km from Earth. At the moment of impact, it is estimated to be travelling at around 6.6km/s.

What’s on board DART?

© NASA/Johns Hopkins APL/Ed Whitman

DART was designed and built by teams at Johns Hopkins Applied Physics Laboratory (APL) in Maryland, USA. The main structure is a cube roughly 1m across fitted with large, flexible solar arrays on opposite sides that stretch out around 8m each. It has a mass of around 610kg.

It is powered by NEXT–C, NASA’s Evolutionary Xenon Thruster–Commercial, an solar-powered ion propulsion system that produces thrust using xenon as fuel.

On board is a high resolution camera DRACO, or Didymos Reconnaissance and Asteroid Camera for Optical navigation. As well as being used to support navigation, the camera will also be used to measure the size and shape of the asteroid target to investigate the geology of the impact site. The images acquired by DRACO before the kinetic impact will be streamed back to Earth in real time.

In the final four hours before impact the SMART Nav, or Small-body Maneuvering Autonomous Real Time Navigation, will work alongside DRACO to autonomously maneuver the spacecraft into position for impact.

The spacecraft is also carrying a companion CubeSat named LICIACube (Light Italian CubeSat for Imaging of Asteroids) that was designed by the Agenzia Spaziale Italiana (ASI). LICIACube was deployed on 11 September during the spacecraft’s approach to Dimorphos and will capture images of the impact.

How can I watch DART crash into the asteroid?

If all goes to plan, DART will crash into Dimorphos at 00.14 BST on 27 September. NASA will be live streaming the event beginning at 23.00 BST on 26 September on NASA TV and YouTube.

What will happen after the collision?

Following the impact, the DART investigation team will compare the results of the spacecraft’s collision with Dimorphos via observations with ground-based telescopes with sophisticated computer simulations that they have already ran. This way they will be able to assess the efficacy of the kinetic impact and figure out the most effective way to employ it should any future planetary defence scenarios arise.

“The nature of doing any sort of science is sometimes you just don’t know what’s going to happen,” said Gregory.

“And with this mission being the first of its kind, I think the margin for success is very wide. And I guess, to paraphrase the Apollo astronauts, hopefully it will be a success, but it might be a very successful failure.”

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