SpaceX launches satellites for NASA, Iridium in 'rideshare' mission

LOS ANGELES - US private space firm SpaceX launched two new Earth-observing satellites for NASA and five commercial communications satellites for Iridium on a used Falcon 9 rocket in a ride-share mission on Tuesday.

The unique rideshare mission blasted off from Space Launch Complex 4E (SLC-4E) at Vandenberg Air Force Base, the state of California, at 12:47 pm PDT (1947 GMT).

This Iridium-6/GRACE-FO Mission first deployed the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) satellites approximately 11 minutes and 30 seconds after launch.

"The twin #GRACEFO satellites have deployed from the @SpaceX Falcon 9 rocket. We await our first communication from #GRACEFO via our communications station at McMurdo, Antarctica," NASA tweeted after launch.

The joint project between the US National Aeronautics and Space Administration (NASA) and the GFZ German Research Center for Geosciences (GFZ) GRACE-FO mission will continue GRACE's 15-year legacy of tracking the movement of Earth's mass. As its twin satellites fly over areas of higher and lower mass, the distance between them changes slightly due to gravitational forces.

The GRACE-FO mission is expected to last at least five years, but requires both satellites in healthy condition to collect useful data, according to NASA.

Tuesday's launch also carried to orbit five more satellites for Iridium Communications' second-generation Iridium-NEXT constellation, joining 50 such spacecraft already in operation.

"Successful deployment of 5 @IridiumComm NEXT satellites to low-Earth orbit confirmed," SpaceX confirmed after about one hour and 12 minutes after the liftoff.

The Iridium Next communications satellites that SpaceX is launching with GRACE-FO are the latest in a series for Iridium Communications to build up that company's satellite constellation.