Boron Boron Boron is a chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in the Solar system and in the Earth's crust. Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. These are mined industrially as evaporites, such as borax and kernite. The largest known boron deposits are in Turkey, the largest producer of boron minerals. Elemental boron is a metalloid that is found in small amounts in meteoroids but chemically uncombined boron
Application of silicon-germanium thermoelectrics in space exploration Application of silicon-germanium thermoelectrics in space exploration Silicon-germanium (SiGe) thermoelectrics have been used for converting heat into power in spacecraft designed for deep-space NASA missions since 1976. This material is used in the radioisotope thermoelectric generators (RTGs) that power "Voyager 1", "Voyager 2", "Galileo", "Ulysses", "Cassini", and "New Horizons" spacecraft. SiGe thermoelectric material converts enough radiated heat into electrical power to fully meet the power demands of each spacecraft. The properties of the material and the remaining components of the RTG contribute towards the efficiency of this thermoelectric conversion. Heavily doped semiconductors, such as silicon-germanium (SiGe) thermoelectric couples (also called