Why NASA crashed a spacecraft into an asteroid

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  • Post last modified:September 27, 2022
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NASA clobber small, harmless asteroid millions of miles away in a first-of-its-kind, save-the-world experiment.

Dart – a catchier name than Double Asteroid Redirection Test – is essentially a small vending machine-sized battering ram. It faces certain destruction if it achieves its goal.
Dart weighs 570kg and carries only one instrument: a camera used for navigation, targeting, and documenting its demise.

Where did the spacecraft go?

Dart was on its way to a pair of asteroids seven million miles from Earth. Its prey was Dimorphos, the smaller offspring of Didymos (Greek for twin).

Dimorphos is about 525 feet (160 metres) across and orbits Didymos at a distance of less than a mile (1.2km).

NASA maintains that neither asteroid poses a threat to Earth now or in the future. That is why the pair was chosen.

The navigation system of the spacecraft was designed to distinguish between the two asteroids and, in the final 50 minutes, target the smaller one.

Why are scientists doing this?

The impact should be enough to push the asteroid into a slightly tighter orbit around its companion space rock, demonstrating that if a killer asteroid ever comes our way, we have a fighting chance of diverting it.

Cameras and telescopes will monitor the crash, but it will take months to determine whether it changed the orbit.

Observers will follow the pair of asteroids as they circle the sun to see if Dart changed Dimorphos’ orbit.

In 2024, a European spacecraft named Hera will retrace Dart’s journey to measure the impact results.

Although the intended nudge should change the moonlet’s position only slightly, that will add up to a major shift over time, according to Ms Chabot.

“So if you were going to do this for planetary defence, you would do it five, 10, 15, 20 years in advance in order for this technique to work,” she said.

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