The Falcon 9 rocket lifted off from Vandenberg Air Force Base on California's central coast about 12:47 p.m. local time. The Block 5 rocket has more powerful engines, a stronger heat shield for the return trip through Earth's atmosphere and new retractable landing legs.
This first-stage booster has flown once before, a little more than four months ago when it launched the Zuma mission for the U.S. government-a satellite or spacecraft that was apparently lost in space after it failed to separate from the second stage of the Falcon 9 rocket.
At 2 minutes and 49 seconds into the flight, the first stage will separate and head for a watery grave and 23 seconds later the aluminium and carbon fiber fairing protecting the payload will peel off and head back to Earth for a hoped-for recovery.
While SpaceX has previously recovered and reused the Falcon 9 rocket's first stage, the company won't be recycling that piece of equipment from this launch.
SpaceX played the role of carpool driver on Tuesday, ferrying seven satellites into space. A 90 percent chance of good weather is forecast for the launch, but another launch window is available for tomorrow.
For the past several years, SpaceX has been developing the use of recycled rockets in order to cut launch costs and speed up flights. He billed it as one of the "largest tech upgrades in history", telling investors he expects the rest of the satellites to go up this year, "completing our Iridium NEXT constellation and starting on a well deserved [capital expenditures] holiday". Each Block 4 core will fly just two times as the company seeks to move all of its launches onto the newer Block 5 version of the rocket, which has slightly increased performance and numerous upgrades to optimize the first stage for reusability.
Groundwater, oceans, lakes, rivers and ice sheets will be monitored by the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO), a joint mission between the USA space agency and German Research Centre for Geosciences (GFZ).
NASA has spent $430 million on the mission, and Germany has spent about $91 million. Rather, "the instrument is really the two satellites together as a system" to detect changes in Earth's gravity, he said.
These variations in distance will be constantly recorded by the spacecraft, because each shift signals a change in mass on the planet underneath.
GRACE-FO will spend the next five years mapping Earth's gravity to study the effects of climate change around the world.