NASA sent a probe in 1999 to chase a comet named Wild-2. During that time, the Stardust probe worked on another task worthy of its name. Stardust had a tray opened for 195 days to capture interstellar dust particles. The particles are also called interstellar dust motes and contain elements supporting life, such as carbon, nitrogen and oxygen.
Astronomers work on finding new ways to identify potentially habitable planets with the available technology. Recently, scientists discovered that companion planets might foster life as they cool slower.
Stardust managed to meet Wild-2 in 2004. Two years later, the probe sent a sample container to Earth. After initial analysis, scientists reached the conclusion that seven dust motes have their origins outside of the solar system.
“By analyzing interstellar dust, we can understand our own origins,” said lead study author Andrew Westphal, a planetary scientist at the University of California at Berkeley. “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.”
Interstellar dust motes identified after thousands of volunteers joined forces with scientists
Identifying the seven dust motes was no easy task. Numerous volunteers helped the researchers establish which particles are valuable. The volunteers looked at around one million digital images of microscopic impacts made on a substance placed on Stardust’s tray.
The seven pieces of interstellar dust are more diverse in shape and content than presumed. The dust motes are very small, measuring about 4 microns, with two of them being larger than the rest. The specks contain olivine, a magnesium-iron-silicate mineral. It may indicate that they originate in disks around other stars.
Bringing samples back on Earth has many advantages. The equipment on Earth is much more complex for now than the instruments attached to space probes. To have a first look at the interstellar dust motes, researchers used some of the most powerful microscopes on the planet.
Interstellar dust motes roam around the Earth as well. However, the seven particles sent home by Stardust are young, with a lifespan of only 50 to 100 million years. This means that they are samples of our contemporary galaxy.
After an initial analysis, researchers agreed that we do not possess the adequate technology to properly analyze the sample without destroying it. So they decided is should be stored until a better moment arises.