"Mars ‘96 consisted of an orbiter, two landers, and two soil penetrators that were to reach the planet in September 1997. The rocket carring Mars 96 lifted off successfully, but as it entered orbit the rocket’s fourth stage ignited prematurely and sent the probe into a wild tumble. It crashed into the ocean somewhere between the Chilean coast and Easter Island. The spacecraft sank, carrying with it 270 grams of plutonium-238."
Chronology of Mars Exploration That’s a bit scary…
