Coordinated Universal Time, or U.T.C., the global reference for timekeeping, is beamed down to us from extremely precise atomic clocks aboard Global Positioning System (GPS) satellites. The time it takes for GPS signals to reach receivers is also used to calculate location for air, land and sea navigation. Owned and operated by the U.S. government, GPS is likely the least recognized, and least appreciated, part of our critical infrastructure. Indeed, most of our critical infrastructure would cease to function without it. And the satellites themselves could easily be taken out by hurtling space junk or the sun coughing up a fireball.
Source: International New York Times January 23, 2021 15:56 UTC