Historic NASA asteroid deflection mission has Irish input

The first test of NASA’s asteroid-deflection technology – DART – took place early this morning, and a Queen’s University Belfast scientist was part of a global team assessing whether it was successful, or not.


The aim of DART (Double Asteroid Deflection Test) is to shift a 160-metre-wide asteroid called Dimorphos off course by slamming a space probe into its surface. If the plan works, it will demonstrate that it’s possible to deflect similar-sized asteroids from colliding with Earth.

Professor Alan Fitzsimmons, an astronomer at the School of Mathematics and Physics at Queen’s University Belfast is an expert on asteroids and comets. Speaking in advance of the mission, Fitzsimmons said that, along with colleagues around the world, will be observing DART through several ground and space-based telescopes.

“We will be observing the dust and rocks and everything else that’s thrown up by the impact,” says Fitzsimmons. “We will make as many measurements as possible over the coming nights to find out exactly what has happened,” he says.

The probe slammed into Dimorphos – a moonlet of its parent asteroid Didymos – some 11 million km from Earth, at four miles per second. The probe was destroyed in the collision. Astronomers were able to quickly determine whether the asteroid was deflected by the collision.

As well as the telescopes on the ground and in near space, the collision was observed by a small CubeSat called LICIACube designed by the Italian Space Agency. The CubeSat flew past Dimorphos three minutes after the impact and took images of the effect that it had.

Fitzsimons works on ATLAS, the Asteroid Terrestrial-Impact Last Alert System, funded by NASA. This is a robotic astronomical survey, which acts as an early warning system for detecting smaller near-Earth objects – about the size of Dimorphos – a few weeks before they impact Earth.

The giant asteroids that threaten all life on Earth should they collide with our planet, are extremely rare, and don’t currently pose a threat says Fitzsimmons. “The ‘dinosaur killers’ are about 10km across and are so bright that we see them easily in our telescopes,” says Fitzsimons. “We’ve found all of them and they are not coming near us.”

There are about 1,000 smaller asteroids, says Fitzsimmons – about 1km in width – that can disrupt global weather, by filling the atmosphere with dust, or destroying cities or small countries like Ireland should they fall directly on them. “So far, we’ve found over 900 of these,” he says.

The real asteroid threat, he says, is from those less than 1km in width.

The Dimorphos asteroid, which is 160m wide – and is similar in size in the colosseum in Rome – is in this small, but still dangerous category and was selected by NASA for DART, because it is precisely the type of asteroid that may represent the most significant threat to the Earth.

“Our main concern at the small objects that aren’t going to cause global effects but would certainly give you a bad day if they landed within a few hundred kilometres of you,” says Fitzsimmons.

Astronomers have only found a small fraction of asteroids the size of Dimorphos, which they believe exist. The impact of even very small asteroids can be significant, and that’s why DART is so important.

The Chelyabinsk air burst explosion over the Urals on 15 February 2013, for example, released about 30 times as much energy as the atomic bomb on Hiroshima – produced by an asteroid that was just 20m wide.

“There’s been commentary in the media about the amount of money that DART is costing but compared to the costs of what would happen if we let one of these things land is insignificant,” says Fitzsimons.

In 2024, a follow up mission of the European Space Agency, called Hera, will conduct a detailed follow up survey of the collision site.

An Irish company, Innalabs, in Dublin, is providing a gyroscope that will orientates the Hera spacecraft and facilitates its navigation systems.

“Innalabs will provide the main gyroscope that tells the (Hera) satellite whether it is turning left or right,” says Alberto Torasso, Vice President of Space Programs at InnaLabs.

The gyroscope will also make sure – by orientating Hera correctly in space – that images taken of the collision site are not blurred.