On September 15, 2017, scientists deliberately flew a 5,700-kilogram, 3.26 billion dollar spacecraft into Saturn's atmosphere and watched it burn up in about 45 seconds, all to protect potentially habitable moons from Earth microbes. This deep dive tells the nearly 20-year saga of Cassini-Huygens, a joint NASA, European Space Agency, and Italian Space Agency mission that survived 1990s budget cuts, two attempts by Congress to cancel it, and lawsuits over the 32.7 kilograms of plutonium-238 that powered it.

We cover why solar panels could not work 1.4 billion kilometers from the sun, the seven-year pinball route past Venus, Earth, and Jupiter, and the near-catastrophic Doppler shift flaw in the Huygens receiver that engineers fixed by rewriting Cassini's orbits rather than its hardware. Then come the discoveries: methane lakes and rivers on  ...