Cosmic Grains on NASA Probe May Be Interstellar Dust
Seven microscopic grains of rock caught by the NASA Stardust probe may actually be interstellar dust, according to researchers.
The Stardust spacecraft returned from interstellar space in 2006, carrying seven microscopic particles that, upon closer examination, were shown to "have features consistent with an origin in the contemporary interstellar dust stream." These distinctive features allowed the researchers to distinguish them from the many particles on the spacecraft that were the result of debris.
Dr. Westphal of the University of California, Berkeley, said: "Our results are giving us the first glimpse of the complexity and diversity of interstellar dust particles." Judging from their analysis, interstellar particles are much more diverse in composition than previously believed. "It could easily have been that our answer when we did this project was to find that all interstellar dust particles are similar, and we are not finding that at all. They are all different from each other."
The interstellar medium, which can be found in the space between solar systems, consists of microscopic particles, gas, and cosmic rays. The interstellar dust was created in the beginnings of the solar system, before the Sun was born. The particles grew in the extremely high temperatures of the interior of other stars, and then cooled into microscopic rocks when they were expelled into interstellar space. As a result, interstellar dust can give scientists an enormous amount of insight into our early solar system. Having these particles available on Earth could lead to significant advancements in our knowledge of our solar system's origins.
"By analyzing interstellar dust, we can understand our own origins," said Westphal. "Just as people go to Africa to look for fossil hominids, say, 4.5 million years old, trying to understand the origins of humanity, we want to look at stuff that helped form the solar system 4.5 billion years ago."
Westphal also explained that the variety found in the particles' compositions indicates that each particle may have its own complex history: "[The particles] may have formed in one star and were then processed over tens of millions of years in the interstellar medium and mixed in with particles coming from other stars or even particles that formed in the interstellar medium in cold molecular clouds, so it's probably a mixture of lots of different things."