This is a question in the area of extraterrestrial life. While life may be possible without it, space travel is probably impossible without metal. Metal is created in stars and heavy metals (above iron) are created in super novae.
In a German posting, someone mentioned that there are only very few stars outside of the galactic core which contain a lot of metal. There is little hope for life in the core itself but if metal is so rare outside the core, that surely limits the options for aliens to build civilizations.
My question: We can easily measure the amount of metal in a star by looking at its spectrum. Does that give a good indication of the metal distribution of dark bodies? Is there a theory about the relation between elements in the star and its planets?
I also read somewhere that there seem to be a lot of "free" planets (which don't orbit a sun). Does this also apply to them?