Could specks from space be alien visitors?

Turns out – there may be itsy-bitsy aliens among us.

Scientists say seven microscopic particles collected by Nasa’s comet-chasing spacecraft Stardust appear to have originated outside our solar system. If confirmed, this would be the world’s first sampling of contemporary interstellar dust.

The dust collectors were exposed to space in the early 2000s and returned to Earth in 2006. Since then, dozens of scientists worldwide led by physicist Andrew Westphal of the University of California, Berkeley, have hunted for specks and analysed the “precious” grains found.

This is unbelievably tiny! The largest interstellar dust track found in the Stardust aerogel collectors was this 35 micron-long hole produced by a 3 picogram speck of dust that was probably travelling so fast that it vaporised upon impact (UC Berkeley/Andrew Westphal)

The team was assisted by 30,000 citizen-scientists, known as “dusters”, who scanned more than one million images in search of elusive tracks made by incoming particles.

“These are the most challenging objects we will ever have in the lab for study, and it is a triumph that we have made as much progress in their analysis as we have,” said Michael Zolensky, curator of the Stardust laboratory at Nasa’s Johnson Space Centre in Houston and co-author of the Science paper.

Westphal says the suspected interstellar particles are surprisingly diverse. Some are fluffy like snowflakes.

Nasa’s Stardust spacecraft which collected comet and interstellar dust in 2004 (Nasa)

Stardust was launched in 1999 and returned to Earth on Jan. 15, 2006, at the Utah Test and Training Range, 80 miles west of Salt Lake City. The Stardust Sample Return Canister was transported to a curatorial facility at Johnson where the Stardust collectors remain preserved and protected for scientific study.

The findings were published Thursday in the journal Science.