SpaceX is set to launch a new rideshare mission next month featuring two Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) satellites from a Nasa and German Research Center for Geosciences (GFZ) partnership, as well as five Iridium Communications satellites.

The mission is scheduled to be launched on-board a SpaceX Falcon 9 rocket on 19 May from Vandenberg Air Force Base (VAFB) in California, US.

It represents the second of four Iridium launches planned for this year.

As part of the mission, Falcon 9 will first deploy the twin GRACE-FO spacecraft, which will be followed by the five Iridium satellites that are part of the company’s NEXT constellation.

“Iridium’s network of six polar orbiting planes comprises a total of 66 satellites in an active constellation and nine in-orbit spares.”

Once launched, the Iridium-6/GRACE-FO mission will increase the total number of Iridium NEXT satellites in orbit to 55. The two remaining launches will include ten satellites each.

Shipping of the Iridium NEXT satellites to the launch site is expected to begin this week.

The GRACE-FO spacecraft have already arrived at Harris’ facility at VAFB and have been attached to their dispenser. They are being prepared for transfer to the SpaceX launch complex.

Iridium further noted that its all-new five NEXT satellites will be delivered to orbital plane six, which features 11 operational crosslinked satellites.

Iridium’s network of six polar orbiting planes comprises a total of 66 satellites in an active constellation and nine in-orbit spares.

To complete the network, the company aims to launch a total of 35 satellites to space within this year.

The NEXT satellite constellation features a total of 81 satellites, which are currently under construction, and six satellites serving as ground spares.