MOSCOW, August 15 (RIA Novosti) - Scientists say seven microscopic grains of interstellar dust brought to Earth by NASA’s spacecraft Stardust appear to have originated from outside our solar system, the journal Science reported earlier this week.
The specks were thoroughly analyzed by a team of more than 30,000 researches called “dusters”.
The particles have been examined with powerful x-rays and the results show that the grains contain crystalline minerals. Astronomical measurements had indicated that cosmic rays whipping around the galaxy destroy most crystals.
Three small particles contain sulfide, but others are sulfur-free—a hint, Science says, that Stardust may have sampled two different populations of interstellar dust.
The researchers now plan to measure the abundance of oxygen isotopes within the grains. If they differ from the Sun’s, the discrepancy would confirm that the dust comes from outside the solar system.
The gathered dust is considered young by cosmic standards: less than 50 million to 100 million years old, the life expectancy of interstellar dust.
The Stardust spacecraft was launched in 1999 to collect samples of Comet Wild-2 and in 2006 it parachuted them back to Earth for laboratory analysis.
An international team of scientists then began the examination of the returned particles to find out if the specks were indeed ancient building blocks of the solar system, however, the nature and origin of the particles turned out to be surprisingly unexpected.