With its form of a 26-sides-polyeder, STARDUST represents an enlarged three-dimensional bronze replica of a “pre-solar grain” that is so far only known and accessible through a two-dimensional electron micrograph. The chemical composition of the granule reveals that it is a hard “space mineral” of extraterrestrial origin. The original grain consists of silicon and nitrogen as silicon nitride (Si3N4) and comes from a meteorite, although it would require additional isotopic analysis to determine whether it is indeed pre-solar. It is a silicon nitride grain chemically separated from the Sahara 97166 meteorite. Sahara 97166 is a so-called enstatite chondrite, forming a rare class of primitive meteorites. Meteorite Sahara 97166 was found in the Sahara in 1997, hence the name. Stardusts, or “pre-solar grains,” are tiny particles of matter either derived from primitive meteorites or collected as Interplanetary Dust Particles (IDP) during space missions. Their isotopic compositions show that they are extraterrestrial and this applies without exception to grains containing silicon carbide (SiC). The pre-solar origin of grains consisting of silicon nitride (Si3N4), on the other hand, can only be identified by isotopic analysis.
The indentation in the stardust is the only concave shape on this object, which indicates that minerals like to use other minerals for their own growth, following a certain matrix or lattice order.
The “indentation” in the stardust polyeder represents the negative form of another mineral that was removed in the process of dissolution (chemical analysis). If we want to go even further back in the history of the paradigmatic “space mineral” shown, we have to realize that it, representative of its “species”, initially only “grows” in two dimensions; only after a certain phase (much later) does it go into the third dimension. The reason for this is that the structures of the crystals can only be ordered step by step – following a matrix or a lattice.
Scientific background and acknowledgments
1. Peter Hoppe (Group Leader, Particle Chemistry Department, Max Planck Institute for Chemistry [https://www.mpic.de]) granted the artist rights to use the images of the grain.
2. Joachim Huth (Max Planck Institute for Chemistry, Mainz) provided the artist with valuable insights and explanations during numerous stimulating conversations. (At the MPI for Chemistry, J. Huth has been responsible for a series of images, including those originating from the Hubble Space Telescope and NASA’s “Stardust” mission [1999–2006].) In this context, the dust grains condensed in the winds of the planetary nebula NGC 6751 were fetched, which were eventually incorporated back into the matter of a new star system, such as the Sun. “NanoSIMS” (a spatially high-resolution secondary ion mass spectrometer) has been in operation at the Max Planck Institute for Chemistry in Mainz since 2001 and is the only device in Germany to date that can detect presolar dust grains smaller than 0.3 μm , allows.
3. Dr. rer. nat. Astrid Besmehn, a mineralogist at the Central Institute for Engineering, Electronics and Analytics (ZEA), confirmed and supplemented the scientific data provided by Hoppe and Huth regarding the selected extraterrestrial grain used by the artist to create the three-dimensional model. Dr. Besmehn’s analyses of comparable grains helped shed light on their extraterrestrial or presolar origin.
