The spacecraft that Nasa deliberately crashed into an asteroid last month succeeded in nudging the rocky moonlet out of its natural orbit in a world first, the space agency claims.
“This is a watershed moment for planetary defence and a watershed moment for humanity,” Nasa chief Bill Nelson said on Tuesday.
Findings of telescope observations unveiled at a Nasa news briefing showed that the test flight of the DART spacecraft on September 26 achieved its primary goal: changing the direction of an asteroid through sheer kinetic force.
The $330 million [£296 million] Dart mission, which was seven years in development, also marked the world’s first test of a planetary defence system designed to prevent a potential doomsday meteorite collision with Earth.
The target of the Dart flight was an egg-shaped asteroid named Dimorphos, roughly the size of a football stadium, orbiting a parent asteroid about five times bigger called Didymos once every 11 hours, 55 minutes.
The aim was to fly the Dart impactor vehicle - no bigger than a vending machine - directly into Dimorphos at about 14,000 miles per hour (22,531 kph), creating enough force to shift the moonlet’s orbital track closer to its larger companion.
Comparison of pre and post impact astronomical measurements of the Dimorphos orbit around Didymos showed a 32-minute shortening of its trajectory, proving the exercise as a viable technique to deflect an asteroid from a collision course with Earth, if such an asteroid were ever discovered.
APL scientists had predicted that the Dart impact would shorten the orbital path of Dimorphos by at least 10 minutes but said they would have considered a change as little as 73 seconds a success.
Neither of the two asteroids involved in the test, nor Dart, short for Double Asteroid Redirection Test, posed any threat to Earth, Nasa scientists said.
But the mission did prompt renewed calls for space laws to be updated around space debris and liability.
While the mission has been widely accepted as necessary and valuable for the protection of mankind, one senior space lawyer said it highlights the need for an update to archiac space law surrounding space debris.
Rachael O’Grady, partner in the international arbitration practice at Mayer Brown, told the Standard: ““Even though what happened is a great thing and should be encouraged…it is dangerous from a legal perspective because the more and more that happens in space...without updating the rules… the harder it’s going to be to find a set of rules people are happy to agree to.”
She did admit that it is very unlikely that the collision between the Dart spacecraft and Dimorphos asteroid would cause damage to another nation’s satellite or spacecraft.
But she said it raises questions about increasing near-collisions already happening in Earth’s orbit which is “littered” with space debris.
“If it was closer to Earth it would be extremely likely a collision would occur because of the congestion,” Ms O’Grady said.
