International Space Agencies – Missions and Discoveries

NASA’s DART mission prepares for an asteroid Dimorphos collision


From UPSC perspective, the following things are important :

Prelims level : DART Mission, Didymos, Dimorphos

Mains level : Not Much


In the first-of-its kind NASA’s DART Mission is about to hit a small, harmless asteroid millions of miles away.

What is DART Mission?

  • The main aim of the mission is to test the newly developed technology that would allow a spacecraft to crash into an asteroid and change its course.
  • It is a suicide mission and the spacecraft will be completely destroyed.
  • The target of the spacecraft is a small moonlet called Dimorphos (Greek for “two forms”).
  • It is about 160-metre in diameter and the spacecraft is expected to collide when it is 11 million kilometres away from Earth.
  • Dimorphos orbits a larger asteroid named Didymos (Greek for “twin”) which has a diameter of 780 metres.

Why Dimorphos?

  • Didymos is a perfect system for the test mission because it is an eclipsing binary which means it has a moonlet that regularly orbits the asteroid.
  • It is observable when it passes in front of the main asteroid.
  • Earth-based telescopes can study this variation in brightness to understand how long it takes Dimorphos to orbit Didymos.

Collision course

  • At the time of impact, Didymos and Dimorphos will be relatively close to Earth – within 6.8 million miles (11 million kilometers).
  • The spacecraft will accelerate at about 24,140 kilometers per hour when it collides with Dimorphos.
  • It aims to crash into Dimorphos to change the asteroid’s motion in space.
  • This collision will be recorded by LICIACube, or Light Italian CubeSat for Imaging of Asteroids, a companion cube satellite provided by the Italian Space Agency.
  • Three minutes after impact, the CubeSat will fly by Dimorphos to capture images and video.

Why such mission?

  • Dimorphos was chosen for this mission because its size is relative to asteroids that could pose a threat to Earth.
  • The spacecraft is about 100 times smaller than Dimorphos, so it won’t obliterate the asteroid.
  • The fast impact will only change Dimorphos’ speed as it orbits Didymos by 1%, which doesn’t sound like a lot — but it will change the moon’s orbital period.


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