The entry for Eärendil the Mariner at the Encyclopedia of Arda, a big Middle Earth site.
Eärendil was half-elf, half-mortal, and he sought to sail to the Undying Lands to beg the gods for help against Morgath (the dark lord). He eventually succeeded, but only after his wife Elwing brought him the Silmaril, by flying to him in the form of a white bird.
“He now sails the high airs with the Silmaril upon his brow, shining as the morning and evening star. ”
Tolkien purists stop reading here: It seems to me that Eärendil’s story is an excellent basis to build a Middle Earth/Star Trek (or maybe Star Wars? the mix might work better – or not) crossover game; He’s literally a mortal travelling in a flying ship to the distant world of the gods, using god-technology (what else would you call a Silmaril?) to signal them. The “War of Wrath” in which the Valar come to rescue their Elvish followers and kick Morgath’s butt (sorry) is a classic assault by an unimaginably advanced technological superpower.