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Japan launches huge Inmarsat-6 F1 communications satellite into orbit

A huge, highly advanced commercial communications satellite just took to the skies.

The Inmarsat-6 F1 satellite launched atop a Mitsubishi Heavy Industries H-2A rocket on Wednesday (Dec. 22) from Japan's Tanegashima Space Center at 10:32 a.m. EST (1532 GMT).

The 12,060-pound (5,470 kilograms) Inmarsat-6 F1 is the first of two "I-6" spacecraft that London-based company Inmarsat plans to loft to geostationary orbit, about 22,240 miles (35,790 kilometers) above our planet. 

A Mitsubishi Heavy Industries H-2A rocket launches the Inmarsat-6 F1 communications satellite from Tanegashima Space Center in Japan on Dec. 22, 2021.

A Mitsubishi Heavy Industries H-2A rocket launches the Inmarsat-6 F1 communications satellite from Tanegashima Space Center in Japan on Dec. 22, 2021. (Image credit: MHI)

The I-6 pair "are the largest and most sophisticated commercial communications satellites ever launched," Inmarsat representatives wrote in a fact sheet (opens in new tab). "Inmarsat's first dual-payload satellites, the I-6s feature both L-band (ELERA) and Ka-band (Global Xpress) payloads."

The Inmarsat-6 F1 communications is seen during thermal vacuum testing in preparation for its December 2021 launch.  (Image credit: Inmarsat)

The I-6 satellites will be compatible with existing terminals for Inmarsat's already-operational ELERA and Global Xpress networks, company representatives said.

The H-2A is Japan's primary medium-lift launcher. The expendable rocket has sent many prominent payloads skyward over the years, including Japan's Hayabusa2 asteroid sample-return mission (in 2014) and the United Arab Emirates' Hope Mars orbiter (in 2020).

Wednesday's launch had originally been targeted for Tuesday (Dec. 21), but concerns about possible bad weather caused a one-day delay.

Editor's note: This story was updated at 12:30 p.m. EST on Dec. 22 with news of successful liftoff.

Mike Wall is the author of "Out There (opens in new tab)" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall (opens in new tab). Follow us on Twitter @Spacedotcom (opens in new tab) or on Facebook (opens in new tab)

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Michael Wall is a Senior Space Writer with Space.com (opens in new tab) and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.