HOW’S THAT SPACE PROGRAM COMING ALONG? America’s Largest Asteroid Impact Left a Trail of Destruction Across the Eastern United States. “About 35 million years ago, an asteroid traveling nearly 144,000 mph (231,000 km/h) smashed into the Atlantic Ocean near the modern-day town of Cape Charles, Virginia. The space rock vaporized instantly, but its impact triggered a gargantuan tsunami, cast up a monsoon of shattered rocks and molten glass that spanned hundreds of miles and carved out the single largest crater in the United States — the so-called Chesapeake Bay impact structure.”