A NASA spacecraft is stuffed with so much asteroid rubble that it’s jammed open and precious particles are drifting away in space.

The spacecraft Osiris-Rex briefly touched asteroid Bennu this week, NASA’s first attempt at such a mission.

The mission’s lead scientist, Dante Lauretta, said the operation collected far more material than expected – hundreds of grams – for taking back to Earth. However, the sample container on the end of the robot arm penetrated so deeply into the asteroid and with such force, that rocks got sucked in and wedged around the rim of the lid.

“We’re almost a victim of our own success here,” Lauretta said at a hastily arranged news conference.

Scientists were stunned – and then dismayed – on Thursday when they saw the pictures coming from Osiris-Rex following its successful touch-and-go at Bennu two days earlier.

• NASA scientists celebrate historic ‘touchdown’ on asteroid

A cloud of asteroid particles could be seen swirling around the spacecraft as it backed away from Bennu. The situation appeared to stabilise, according to Lauretta, once the robot arm was locked into place. But it was impossible to know exactly how much had already been lost

Lauretta said there is nothing flight controllers can do to clear the obstructions and prevent more bits of Bennu from escaping, other than to get the samples into their return capsule as soon as possible.

“Time is of the essence,” said Thomas Zurbuchen, chief of NASA’s science missions.

This is NASA’s first asteroid sample-return mission. Bennu was chosen because its carbon-rich material is believed to hold the preserved building blocks of our solar system. Getting pieces from this cosmic time capsule could help scientists better understand how the planets formed billions of years ago and how life originated on Earth.

Osiris-Rex will leave the vicinity of the asteroid in March – the earliest possible departure given the relative locations of Earth and Bennu. The samples won’t make it back until 2023, seven years after the spacecraft rocketed away from Cape Canaveral.

-AAP