The GPS III satellites are expected to provide improved security against cyberthreats, as well as more accuracy for navigation.
SpaceX's recovery ship, Mr Steven is heading out into the ocean to attempt to catch at least one half of the expensive shell used to protect spacecraft during the early phases of launch. Iridium's Dnepr launch of two satellites was supposed to occur in 2015; GRACE-FO was to launch in 2017. The new rocket had its first successful launch May 11, when it carried Bangladesh's first geostationary communications satellite toward orbit.
Once the rocket launch and the payloads were deployed SpaceX did not try to recover the first stage of the rocket as it does for some launches.
Critics have questioned the safety of SpaceX's use of super-cooled rocket fuel that needs to be loaded right before takeoff - after astronauts are already on board.
Without access to Dnepr, Iridium and the German Research Center for Geosciences (GFZ) joined forces to book a single Falcon 9, splitting the cost between them.
The rocket roared off from a pad at Vandenberg Air Force Base at 12:47 p.m. and arced over the Pacific Ocean west of Los Angeles as it headed toward the South Pole.
In Gaza, Israel counts on army snipers over non-lethal arsenal
Her cousin and her neighbor were killed by Israeli troops during the protest, she said. Israel responded to its envoy's expulsion by expelling Turkey's Jerusalem consul.
NASA's Gravity Recovery and Climate Experiment Follow-on (GRACE-FO) is a follow up to the original GRACE mission, which launched on 17 March, 2002 and lasted far longer than the projected five year lifespan. Tuesday's mission was conducted with an outgoing Block 4 version. When complete, the Iridium NEXT constellation will include 75 satellites, with 66 being operational and nine spares.
For the first few days after launch, the lower, faster satellite will pull slowly ahead of the other until the two satellites are approximately 137 miles (220 kilometers) apart - the optimal separation distance for science operations. Iridium spent around $3 billion on Iridium Next, purchasing the satellites from Thales Alenia Space in Europe. Once in orbit, they'll be used to analyze Earth's water and ice content by detecting small changes in the planet's gravitation field.
If you want to watch the launch live you can do so via the YouTube window embedded above.
Because Earth isn't a perfectly uniform sphere, areas of space directly above land masses exert more pull than open water.
Once the Earth-facing satellite has put a safe distance between itself and its sibling, it will thrust back up into a higher orbit, so that one follows the other on the same trajectory. SpaceX appears to have been absolved from blame for this mishap, and certainly the first stage booster performed nominally during that mission.