Iridium set the launch date for its fifth mission carrying the NEXT satellites into orbit. The company and SpaceX expect a morning launch on 18 March 2018 to carry another 10 payloads into space, bringing the total in orbit to 50. The constellation needs 66 active in orbit to complete the new network.
The Iridium-5 mission will reuse the same SpaceX Falcon 9 first stage as the Iridium-3 launch in October 2017. This is the second reuse launch for Iridium and SpaceX continues to improve on that process, especially around the timing for refreshing the booster into service. That’s particularly good news for SpaceX as it sees the reuse as critical to its launch cost cutting efforts.
“We are entering the home stretch,” said Matt Desch, chief executive officer, at Iridium. “This is going to be a monumental year for us as we complete our constellation refresh. In addition to four launches, we will continue the testing and validation processes for our new specialty broadband service, Iridium CertusSM, and look forward to its commercial launch later this year. We consider 2017 to be a great success and anticipate this year to be even better.”
For Iridium the mission is also the beginning of what the company calls a “rapid-cadence launch schedule” to quickly complete the necessary launches for the new constellation. The first four launches averaged more than 16 weeks between events. Iridium now expects the final four launches to pace at approximately five week intervals, delivering the full complement of satellites into orbit by “mid-year.” Assuming the schedule holds that should be July for the final 10 satellites to go into orbit.
The spacing between launches one and two can be partially attributed to insurance requirements but the rest of the pacing is more on SpaceX and making sure that the rockets and range are available. Iridium and its manufacturing partner Thales Alenia Space produce the satellites well ahead of the launch schedule at this point.
Shifting to the faster launch cadence presents challenges for SpaceX and the operations team that integrates the new satellites into the active constellation. Those swaps come after the necessary testing confirms that the new satellites are operating nominally and generally occur without service interruption. SpaceX has shown it can handle the faster launch pacing. Presumably the Iridium team can as well.
It is worth noting that the full constellation of 66 satellites in orbit will not be realized until the Iridium-8 mission is successful. The Iridium-6 launch is a shared payload event, with five NEXT satellites and the twin satellites for the NASA/German Research Center for Geosciences (GFZ) Gravity Recovery and Climate Experiment Follow-On mission. Mission 7 will deliver another ten satellites to orbit, bringing the in-flight count to 65, one short of complete.
Aireon wins, too
One of the other big wins that the new Iridium NEXT constellation brings to orbit is the Aireon ADS-B aircraft tracking service. Even with only partial coverage of the globe the system is operating well and delivering significant data milestones with each test cycle. The company recently ran tests of its system against specially configured aircraft for the FAA and NAV Canada.
Those planes reduced the power output of their transmitters to 125 Watts from the normal 250 Watts and were still properly detected, even well out of the range of traditional ground-based ADS-B receivers. The company notes that it is receiving more than six billion aircraft positioning reports on a monthly basis with less than half the expected network operational.