On July 4, 2005—yes, American Independence Day—the impactor hit. The timing was deliberate. NASA joked they were giving the comet “the fireworks it deserved.” When the impactor struck, scientists expected a nice, clean crater. Instead, the comet erupted like a shaken soda can. A massive plume of ice, dust, and organic compounds shot out, and the comet brightened five times over. The crater ended up being far larger than expected (150 meters wide), and the impact released energy equivalent to 4.5 tons of TNT.
It wasn’t enough to prevent a future impact, but it proved the principle: kinetic impactors work. That principle became the foundation for NASA’s (2022), which successfully slammed into the asteroid Dimorphos and shortened its orbit by 33 minutes. DART was Deep Impact’s spiritual sequel—and it worked perfectly. The Lost Probe and the Second Act Deep Impact’s flyby spacecraft continued observing Tempel 1 after the impact, then went into hibernation. NASA later woke it up for a bonus mission to comet Hartley 2 (2010), which turned out to be a “hyperactive” comet spewing cyanide gas and golf-ball-sized chunks of ice. Deep Impact
And it worked. The Deep Impact impactor carried a CD-ROM with 625,000 names of people who signed up online—including a young Elon Musk, a pre-fame Taylor Swift, and the director of the Deep Impact movie. Art met life, and both aimed for a comet. Instead, the comet erupted like a shaken soda can