Artist’s illustration of the Inmarsat 6 F2 communications satellite with solar arrays and its L-band antenna deployed in orbit. Credit: Inmarsat
A large European-built communications satellite owned by London-based Inmarsat is set to ride a SpaceX Falcon 9 rocket into orbit Friday night from Cape Canaveral, kicking off a mission to connect ships and airplanes across the Atlantic Ocean and the U.S. East Coast through 2040.
With a wingspan as wide as a Boeing 767 jetliner and a body the size of a double-decker bus, the Inmarsat 6 F2 spacecraft will be parked in geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the Earth, using a dual-band communications payload provide in-flight WiFi on aircraft, broadband services to ships, and connectivity for U.S. military and other government users.
“It is one of the world’s largest spacecraft in terms of weight and power, but inside of it, I think the thing that makes it unique is all the signal processing that goes on,” said Peter Hadinger, Inmarsat’s chief technology officer.
“It’s an incredibly advanced signal processor that’s capable of forming beams on the Earth and moving them around in real-time, creating channels as we need them, moving the spacecraft’s power to where it’s required on the face of the Earth,” Hadinger told Spaceflight Now in a pre-launch interview. “And that makes it a very capable spacecraft because we can take all the spacecraft’s energy and put it where it’s needed on a moment-by-moment basis.”
Inmarsat 6 F2 is the twin of another satellite, Inmarsat 6 F1, that launched in December 2021 on a Japanese H-2A rocket. Both Inmarsat 6 satellites were built by Airbus, use electric propulsion for their in-orbit maneuvers, and host L-band and Ka-band communications payloads targeted at different segments in the mobile communications market.
The satellite has 20 steerable wideband Ka-band beams to provide broadband connectivity to airplane passengers and ships at sea, along with an umbrella-like L-band reflector that will open to a diameter of 30 feet (9 meters) in space.
The L-band payload is tailored for lower-bandwidth applications, such as maritime search and rescue, ship and asset tracking, and supply chain management. Inmarsat’s most recent fleet of L-band communications satellites was the Inmarsat 4 series launched between 2005 and 2013, and the two Inmarsat 6 satellites will replace them. Each Inmarsat 6 satellite provides 50% more L-band communications capacity than the entire four-spacecraft Inmarsat 4 fleet.
The Inmarsat 5 satellites, providing Ka-band connectivity through the company’s Global Xpress service, launched between 2013 and 2019.
SpaceX’s Falcon 9 rocket is set to take off from Space Launch Complex 40 at Cape Canaveral Space Force Station with the Inmarsat 6 F2 spacecraft at 10:59 p.m. EST Friday (0359 GMT Saturday). SpaceX has an 89-minute launch window to get the mission off the ground Friday night, or else wait for another day.
Forecasters predict a 75% chance of good weather for liftoff during the late-night launch window. The 229-foot-tall (70-meter) Falcon 9 rocket will head east from Florida’s Space Coast, with its reusable first stage booster aiming to land on a drone ship a few hundred miles downrange in the Atlantic Ocean. The upper stage will fire its engine two times to inject Inmarsat 6 F2 into an elongated geostationary transfer orbit ranging in altitude between 155 miles and 21,561 miles (250-by-34,700 kilometers).
Separation of the 12,048-pound (5,465-kilogram) spacecraft from the Falcon 9 rocket is scheduled around 32 minutes into the mission.
The I6 F2 spacecraft will check in with ground controllers a few minutes later, then begin a series of health checks and a partial deployment of its power-generating solar arrays. Once the satellite’s thrusters move its orbit safely above the atmosphere, ground teams will send commands to a full deployment of the solar arrays and the unfurling of the 30-foot L-band antenna reflector next week.
Then the satellite will continue reshaping its orbit using the electric propulsion system, which is lighter and more efficient than conventional liquid-fueled maneuvering rockets. The plasma thrusters are positioned on the ends of articulating robotic arms, providing precise pointing as the satellite circularizes its orbit and moves from an inclination of 27 degrees — the drop-off orbit SpaceX will reach with the Falcon 9 — to a position directly over the equator.
The two Inmarsat 6 satellites will extend Inmarsat’s narrowband L-band services, used around the world in maritime operations, until around 2040. Inmarsat is planning to launch additional Ka-band satellites in the next few years, including two Ka-band instruments on satellites in a high-inclination orbit to extend broadband coverage over the Arctic. The Arctic mission is slated to launch late this year on another SpaceX rocket from California.
The Inmarsat 6 F2 spacecraft encapsulated inside the payload fairing of a SpaceX Falcon 9 rocket at Cape Canaveral. Credit: Inmarsat
The I6 F2 satellite should reach its operational position in geostationary orbit in September. The electric propulsion system is lower-thrust than conventional liquid-fueled orbit-raising engines, but is also more efficient and less massive, meaning satellite manufacturers can outfit their spacecraft with more communications capacity.
That is the case with the Inmarsat 6 satellites. I6 F1 is about to enter operational service over the Indian Ocean in the next couple of months, and will provide services across a region spanning from Africa to Asia. I6 F2 should be ready for the start of commercial services by the end of this year, according to Hadinger.
“The real important thing is that it adds a tremendous amount of new capability to all those narrowband devices, whether they’re handheld phones, or emergency communication devices that couple along with our wideband services for redundancy,” Hadinger said.
The L-band payload is good for all-weather communications, which is useful in maritime safety. The L-band service can also support commercial drones for disaster response and medical delivers, asset tracking and internet of things applications, and autonomous transportation. The Ka-band payload will be capable of higher-speed connectivity, such as internet services, at speeds of tens or hundreds of megabits per second.
“This spacecraft will be over the Atlantic, and the hotspots that it fills will probably be initially along the East Coast of the United States,” Hadinger said of the I6 F2 mission.
The new Inmarsat satellites, including I6 F2, are crucial for the company’s plans to maintain its market position as constellations of low Earth orbit satellites, like SpaceX’s Starlink fleet and OneWeb’s network, begin operational service to provide broadband internet connectivity. Starlink and OneWeb’s business strategies include serving consumers on land, in the air, and at sea.
Inmarsat was established in 1979 to develop a network of satellites to provide a communications lifeline for maritime safety and distress messages. The maritime safety mission is still part of Inmarsat’s network, but the company has evolved to provide a broader menu of communications services.
“Inmarsat is focused exclusively on mobility,” Hadinger said. “We do not serve residential consumers and fixed businesses so much. Our focus is on the maritime industry, the aviation industry, and governments, with a little bit of portable land requirements thrown in.
“But the majority of things we do are on the move, and that really causes us to focus on frequency bands and satellites which allow us to communicate with small antennas because if you’re going to be on the move, you need to have an antenna that’s buried in the skin of an aircraft or which is on a ship, and these things are rolling and rocking on the way,” Hadinger said. “So all of this has to be tracked and handed off from beam to beam and from satellite to satellite as the user moves around the world.”
Inmarsat plans to launch the Arctic Satellite Broadband Mission later this year, in partnership with Norway and the U.S. Space Force. Then Inmarsat’s GX 7, GX 8, and GX 9 satellites — the next spacecraft to augment the company’s Ka-band network — will launch in late 2024 or early 2025, Hadinger said.
“The I6 spacecraft will be joined by a further five major scale satellites by 2025,” said Rajeev Suri, CEO of Inmarsat. “Each of these has the capability to deliver focused connectivity over a larger region and come with certainty — in resilience, in robustness, in service quality — that is unique to Inmarsat.”