|Posted: 2011-December-24 at 11:50pm | IP Logged
I'm with Klankster and his rocket scientist source. More likely it's from a low-orbit satellite or booster that's reentered, or one of Russia's that never made it to orbit. The shuttle didn't usually leave anything in orbit. The solid boosters were reusable, and the external tank shouldn't have had too many small tanks attached to it. One site I read speculated that it was a propellant tank from a spy satellite.
Wherever it came from, it's definitely a gas tank from a satellite, and not some of the more exotic ideas a few commenters have posted on other sites.