Readers wanted to know about asteroids, lithium batteries and more

Heat keepers

Long ago, molten iron could have erupted from metal asteroids in a process scientists refer to as ferrovolcanism, Lisa Grossman reported in “Metal asteroids may have once had iron-spewing volcanoes (SN: 5/11/19 & 5/25/19, p. 5). 

“In the cold vastness of space, how long are these rocks expected to keep their thermal energy?” asked online reader Bronze Condor.