In an unprecedented dress rehearsal for the day when an asteroid threatens Earth, a NASA spacecraft crashed into an asteroid at breakneck speed early on September 27 (India time). The $325 million project was the first attempt to move a natural object in space.
The Double Asteroid Redirection Test (DART), a vending machine-sized spacecraft that was launched in November, used novel navigational techniques created by the mission manager and spacecraft builder, Johns Hopkins University's Applied Physics Laboratory.
DART slammed into the harmless asteroid 9.6 million kilometres away at 22,500 kilometres per hour. Scientists anticipated that the collision would modify the asteroid's orbit, create a crater, and send streams of boulders and debris into space.
DART's radio communication quickly stopped, making the hit instantly apparent, but it will take days or perhaps weeks to assess how much the asteroid's path was altered. Only an hour before impact, DARTt's on-board camera, a crucial component of this clever navigation system, saw Dimorphos.
The target was Dimorphos, a 160-metre-tall asteroid. Greek meaning "twin". It is actually a moonlet of Didymos, a rapidly-spinning, five-times-larger asteroid that hurled debris off to create the smaller partner.
NASA watched as Dimorphos loomed larger and larger in the field of vision alongside its larger companion, with an image coming back to Earth every second.
"No, this is not a movie plot," NASA Administrator Bill Nelson tweeted earlier in the day. "We've all seen it on movies like Armageddon,' but the real-life stakes are high," he said in a prerecorded video.
Scientists insisted that DART would not be able to burst Dimorphos. The spacecraft only held 570 kg while the asteroid weighed 5 billion kg. That should be enough to reduce its 11-hour-and-55-minute orbit around Didymos, though.
According to NASA, much fewer than half of the projected 25,000 near-Earth objects in the lethal 140 metre range have been found. Less than 1% of the millions of smaller asteroids that have the potential to cause widespread damage are also known.
(With AP inputs)
