Nasa to crash spacecraft deliberately into asteroid

Space agency seeking to test technology that could be used to deflect rocks from hitting Earth in the future

A spacecraft operated by the US space agency Nasa is deliberately to smash into an asteroid in a test of a technique that may in the future be used to protect the Earth.

The spacecraft will, in the early hours of Tuesday in Ireland, seek to adjust the course of the asteroid in space.

Nasa’s double asteroid re-direction test (Dart) is a $300 million (€310 million) mission launched in November 2021 in the first test of technology that could be used in the future to deflect an object in space on a trajectory towards Earth from hitting the planet.

The target for the test is called Dimorphos and is about 11 million km from Earth. It is about 150m wide and orbits another larger asteroid. The spacecraft is designed to hit Dimorphos at about 22,000km per hour and adjust its course as a result.


At present Dimorphos completes an orbit around the larger asteroid, known as Didymos, every 11 hours 55 minutes.

If the test works as planned the spacecraft should, by crashing into Dimorphos, change its course and make it take it less time in future to travel around the nearby larger asteroid – potentially by about ten minutes.

The magnitude of the change will depend on the structure and composition of Dimorphos – whether it is a solid mass or rocks held together by gravity.

A separate nearby spacecraft will monitor and capture images of the impact as the Dart mission crashes into Dimorphos.

Space telescopes such as Hubble and James Webb will also seek to assess the impact as will instruments on Earth.

Prof Alan Fitzsimmons of Queen’s University in Belfast said the Dart mission “will give us our first proof that we have the technology to prevent a small asteroid hitting Earth”.

Prof Fitzsimmons, who is a member of the Dart investigation team, said the mission and a planned follow-up test should provide a much better idea about “how to protect ourselves against a catastrophic impact”.

In 2005 the US Congress mandated Nasa to find, by 2020, 90 per cent of near-Earth asteroids that were sufficiently large to destroy a city if they hit the planet. These are considered to be those close to 125m or wider in diameter. However the task remains only half completed.

The collision between the spacecraft and Dimorphos is scheduled to take place at 12.14am Irish time on Tuesday.

Martin Wall

Martin Wall

Martin Wall is Washington Correspondent of The Irish Times. He was previously industry correspondent