A football-field sized asteroid came close to hitting Earth in July, though NASA scientists spotted it 24 hours before the close call, according to internal agency documents obtained by BuzzFeed News.
The asteroid, 2019 OK, was estimated 187-427 feet wide, according to NASA, and is the largest asteroid to pass this close to Earth in quite a number of years. It missed Earth by 45,000 miles, less than one-fifth the distance to the Moon.
"Because there may be media coverage tomorrow, I'm alerting you that in about 30 [minutes] a 57-130 meter-sized asteroid will pass Earth at only 0.19 lunar distances (48,000 miles)," Lindley Johnson, NASA's planetary defense officer, wrote in a July 24 email. "2019 OK was spotted about 24 hours ago."
The object, "slipped through a whole series of our capture nets," Paul Chodas of NASA's Jet Propulsion Laboratory wrote to his colleagues two days after the flyby in late July, describing what he called the "sneaky" space rock. "I wonder how many times this situation has happened without the asteroid being discovered at all."
The emails indicate NASA's asteroid detection needs improvement.
"This one did sneak up on us and it is an interesting story on the limitations of our current survey network," Johnson wrote in a July 26 email.