since hydrogen and oxygen are not metals - by far the bulk of weight launched into space, I will have to go with iron.

__________________
"I will do my best to understand and explain the universe from big to small without invoking miracles, unrepeatable events, or divine intervention. In place of those things I will use observations, mathematics, and science."


-Cross
My travel blog

Some of my Astrophotography


Those that lack education have a hard time understanding its value. - Cross