Watery graves: Should we be ditching big spacecraft over Earth’s oceans?

With increasing regularity, Earth’s oceans are the drop zones for incoming leftovers from space. 

For decades, Russian Progress resupply spacecraft loaded with tons of waste from the International Space Station (ISS) have been intentionally steered to reentries over the Pacific Ocean’s “spacecraft cemetery.” Similarly, Northop Grumman’s Cygnus cargo vehicles are filled with rubbish from the space station crew and ultimately ditched over the South Pacific.