On Oct. 29, 1991, NASA's Galileo spacecraft flew past the asteroid Gaspra while traveling at roughly 18,000 miles per hour, capturing images of the small rocky body during the encounter. The flyby marked one of the first close-up looks at an asteroid by a spacecraft, giving scientists detailed views of a world that had previously been seen only as a distant point of light.
Galileo was on its way to Jupiter at the time, and the asteroid encounter was a scientific bonus along the route. Its cameras recorded Gaspra's irregular shape and surface features as the spacecraft passed at high speed, and the resulting pictures were among the first to show an asteroid in such detail.
The images helped researchers study the composition and history of asteroids, bodies that are remnants of the early solar system. Space.com's "On this day in space" series marks the anniversary of the event, recalling how the flyby expanded what planetary scientists could learn from small bodies in the asteroid belt.
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