Dear Kepler,

Ten years ago, you soared into space and slipped beyond Earth's gravitational grasp, leaving a wake of fire in Florida's nighttime sky. Twinkling above you were the stars you would mine for alien worlds. Below you spun a world on the verge of a scientific revolution.

You, Kepler, are one of the most transformative spacecraft humans have ever made. But you're gone now, and though we've both known for a few years that the end of your star-studded journey was drawing near, it still feels wrong.

For much of your time aloft, you seemed invincible: a planet-hunting probe that bravely competed in the cosmos’s most challenging staring contest, in which your unblinking eye caught the flickering light from hundreds of