The US is upgrading its 24 Global Positioning System (GPS) satellites in a bid to improve the accuracy of the technology and prevent outages.
Each of the existing 24 satellites will be replaced, the first of which was launched at the weekend, while the remaining six will be kept as spares.
"We know that the world relies on GPS," Colonel David B Goldstein, the upgrade's chief engineer, told the Los Angeles Times.
It is thought the new satellites will enable locations to be pinpointed to "within an arm's length, compared with a margin of error of 20 feet or more today".
The upgrade is expected to take ten years to complete and will be handled by engineers at the Los Angeles Air Force Base in El Segundo.
"This new system has the potential to deliver capabilities we haven't seen yet," Marco Caceres, senior space analyst for aerospace research firm Teal Group, added.
"Because GPS touches so many industries, it's hard to imagine what industry wouldn't be affected."
See also: 10 cool uses for satellites