Helium is the second-lightest element in the Universe
Helium is the second-lightest element in the Universe. Among helium's other uses include airships, air mixtures used in deep-sea diving, cooling nuclear reactors and infrared detectors, and in satellite and spacecraft equipment, and solar telescopes. NASA also uses massive amounts of helium to clean fuel from its rockets, and because the helium is so cheap, it makes no effort to recycle the gas. As the isotope helium-3, helium is also used in nuclear fusion research.