Zürcher Nachrichten - NASA defense test kicked asteroid off course -- and changed its orbit around the sun

The experiment pushed the moonlet asteroid Dimorphos into a smaller, faster route around its sibling Didymos -- and according to new research out Friday, it also pushed the pair into a slightly different orbit around the Sun.

The test on Dimorphos was never based on any actual threat to our planet.

But the successful experiment and additional analysis offers a solid data point to mount a defense if any such eventual threat is detected, researchers said.

"This study marks a notable step forward in our ability to prevent future asteroid impacts on Earth," the team of international researchers wrote in their new paper published in the journal Science Advances.

Their observations detailed in the paper showed that the Double Asteroid Redirection Test (DART) in 2022 marked "the first time a human-made object has measurably altered the path of a celestial body around the Sun," NASA said in a statement.

Rahil Makadia, the study's lead author, told AFP his team tracked stellar occultations -- the moment when an asteroid passes in front of a star, causing a brief dimming for less than a second -- to obtain hyper-precise measurements of the asteroid's position, speed and shape.

- Tiny change, significant deflection -

Obtaining this data is no small feat. The team relied on volunteer astronomers from around the globe, who recorded 22 of these stellar occultations.

Using that data along with years of additional observations, Makadia said the team was able to measure Didymos's orbit around the sun with precision.

"We were able to measure what this change was exactly," he said, and make computations that could assist with future "planetary defense efforts."

The orbital change was miniscule -- just 0.15 seconds.

But it's enough to make a difference, scientists say.

"This is a tiny change to the orbit, but given enough time, even a tiny change can grow to a significant deflection," said Thomas Statler, lead scientist for solar system small bodies at NASA Headquarters in Washington, in a statement.

"The team's amazingly precise measurement again validates kinetic impact as a technique for defending Earth against asteroid hazards and shows how a binary asteroid might be deflected by impacting just one member of the pair."

N.Fischer--NZN