Scientists had been working on the various samples that crashed to earth before coming across mysterious black dust.
The small capsule made the 63,000-mile journey to Earth from the Osiris-Rex spacecraft this week.
It contained bits of rock from the menacing Bennu asteroid and landed in the Utah desert in the US.
Bennu has been described as the Solar System’s “most dangerous asteroid”, and has a one in 2,700 chance of colliding with Earth in the year 2182.
Experts hope that by analysing samples from it, they may be able to inform potential defence systems if it does begin to fly towards our planet.
When scientists opened the OSIRIS-REx science cannister at NASA’s Johnson Space Center in Houston on Tuesday, they found something they hadn’t anticipated.
The presence of an unidentified “black dust and debris” fell off the rock on opening, with researchers immediately halting their work.
A NASA spokesman explained: “Scientists and engineers removed the lid and saw black dust and debris on the surfaces of the avionics deck and TAGSAM. This dust will undergo a quick-look analysis to determine if it is in fact material from the asteroid Bennu.
“Ultimately, this speeds up the disassembly process. There is a very high level of focus from the team — the sample will be revealed with an amazing amount of precision to accommodate delicate hardware removal so as not to come into contact with the sample inside.”
NASA says it will hold a press conference in the next few weeks to share all its preliminary findings from the asteroid dust sample.
At just under 1,640ft (500m) across, Bennu is big enough to create a whopping three-mile (6km) crater on the Earth’s surface.
It would also generate enough energy to produce an arblast powerful enough to flatten buildings over hundreds of square kilometres, according to the Imperial College ‘Earth Impact’ programme.
Scientists already know that the top layer of Bennu is extremely soft given that the Osiris-Rex spacecraft sank 50cm into its surface before firing its rockets.
This spongey surface could in theory act like the crumble zone of a car — complicating attempts to nudge the asteroid out of harm’s way with something like a satellite.
While some of the material will be distributed to scientists around the world for intensive study, the bulk of the samples from Bennu will be preserved for future generations.
