NASA astronaut Gregory H. Johnson and his pal Steve Robinson were flying a T-38 today over the gulf and noticed this weird scene: the space shuttle cruising on board a barge. "Not something you see every day," he says. Indeed!

The shuttle is the Explorer, the full shuttle replica that was installed Kennedy Space Center Visitor Complex, in Florida. Explorer—which obviously never flew to space—has been replaced by Atlantis. Explorer is now en route to the Johnson Space Center in Houston, Texas. [Twitter via Dvice]