Satellite operator Iridium announced today that five of its Iridium NEXT satellites will share a ride to space with two NASA satellites. The seven probes will launch on one of SpaceX’s Falcon 9 rockets in early 2018. It’s the eighth Falcon 9 launch that Iridium has contracted from SpaceX, and the first rideshare to space for the communications company. The NASA satellites going along for the ride are two GRACE-FO spacecraft — built with the GFZ German Research Center for Geosciences that will create maps of Earth’s gravity field.

"This is a very smart way to get additional Iridium NEXT satellites into orbit.”

"This is a very smart way to get additional Iridium NEXT satellites into orbit," Matt Desch, Iridium’s CEO, said in a statement. The company argues that the agreement “represents a particularly compelling economical solution.”

The launch will be part of Iridium’s plan to create a large constellation of telecommunications satellites in lower Earth orbit called Iridium NEXT. SpaceX is already under contract to launch 70 of the Iridium NEXT satellites across seven launches. The company’s Falcon 9 rocket launched the first 10 of these satellites in January, a mission that also marked SpaceX’s return to flight following its September launchpad explosion.

Iridium’s original goal was to launch 66 telecommunications satellites, along with 15 spares — six in orbit and nine on the ground. However, today’s announcement means that the company will increase the number of in-orbit spare satellites by three. That means there will be a total of 75 Iridium NEXT satellites in orbit by the time SpaceX is done launching them all.

This latest Falcon 9 is slated to take off from Vandenberg Air Force Base in California. The two NASA GRACE-FO satellites that will go up on this launch are successors to the space agency’s ongoing GRACE mission, which launched in 2002. Like the original mission, GRACE-FO will help track large-scale changes in how Earth’s mass is distributed. Knowing how our planet’s water, air, and other materials move around can help us understand natural processes like precipitation, floods, and tectonic shifts.