Near Disasters in Space: Hubble Wears Glasses

A tiny problem can have huge consequences for a space mission. Sometimes a huge endeavor hinges on the smallest detail — three seconds' worth of fuel, an engineer's stubbornness, a speck of paint, or a 1.3-millimeter calibration. When surprise glitches revealed themselves after launch, it took massive efforts to save the missions that gave us a closer look at Mercury, a tour of the outer solar system, our only glimpse of Titan's surface, and an incredible view of the early universe. But even with hundreds of people putting in months of work, a few of these missions only succeeded by a razor-thin margin.