Seven tiny specks of dust can clarify the origin of the solar system
The Stardust project is one of the longest and most complex science in the world. Back in 1999, a small Stardust spacecraft was sent into space. Its name reflects the main purpose for which the probe was launched: to collect samples of interstellar dust, and deliver the collected to Earth. The first mission of the device was to approach the comet Wild 2 and collect samples of matter in its tail.
After the comet, the probe continued its mission, and successfully collected cosmic dust samples. It is clear that the dust was not collected in a paper bag: an airgel collector was used to collect samples of the substance, when microparticles were left intact. According to scientists, these microparticles are the oldest trace of the evolution of our solar system and the galaxy as a whole. The study of interstellar dust samples can also clarify how the formation of the solar system, the nucleation of stars, and many other questions went.
Stardust collected dust until 2006, the device traveled a path of 3 billion kilometers. Stardust then walked close to Earth, dropping a capsule with trapped dust (the capsule fell in Utah). During the fall, the collector itself was not damaged, but the airgel was inside, so the scientists had to solve the problem of working with the damaged surface of the airgel. This problem has been resolved successfully.
This is how the collector looks (diameter - about 30 centimeters)
After that, scientists began to scan individual sections of the airgel, and the scanning was carried out in layers, starting from the surface of the gel, and ending with the "bottom" of the cell. After scanning, it turned out that in the hands of scientists - more than 700 thousand series of images of each site (the number of individual photographs exceeded several million). The work on the study of interstellar matter was complicated, since not only dust was recorded in the photographs, but also airgel damage.
In general, scientists had a lot of work to do, which they could not handle in the foreseeable future. Therefore, it was decided to involve the public in the work. For this purpose, the Stardust @ home project was organized, where, after initial preparation, any interested person could begin work on the detection of samples of interstellar matter.
Traces of penetration of particles into the airgel
Only now, in 2014, the preliminary results of all this gigantic work were published (work is still ongoing, only 77 airgel plates were checked, 55 remained). The project involved more than 30 thousand volunteers, in addition to scientists from NASA. If anything was found that the volunteer suspected of the sample being searched for, the photo was tagged. After that, the scientists carefully studied the photograph, followed by the study of the sample, which was photographed. To study the sample, a scanning x-ray microscope was used to obtain information on the chemical composition of the sample. Volunteers, by the way, called each other "Dusters". Out of 30 thousand people, 714 voluntary participants in the project are already mentioned in scientific publications related to the Stardust project.
After a careful study of all the materials, it turned out that most of the samples were microscopic particles of the apparatus itself, knocked out of the shell by micrometeorites (if these objects can be called that, of course, they are very small) that collided with the apparatus within the solar system. These particles are easy to detect, since they have a lot of aluminum, the Stardust shell is made of this metal. Traces of gas formed during the collision of particles with the solar panels of the probe were also found in the particles.
At the moment, only 7 samples have been discovered, which scientists, with a high probability, consider this to be interstellar matter. The size of the particles is a maximum of 2 microns (0.002 mm), which is 2% of the thickness of a human hair. Nevertheless, scientists hope that such samples will also be able to clarify the stages of the formation of the solar system. In addition, in the future, as scientists hope, the remaining samples will provide additional material for research. Now they are examining already found samples.