PARIS — Mobile satellite services provider Iridium Communications will upgrade the existing Iridium satellite constellation’s dedicated Earth station for the U.S. Defense Department under a contract valued at up to $47 million over five years, Iridium announced Oct. 31.

Under the contract, McLean, Va.-based Iridium, which generates between 20 and 25 percent of its annual revenue from the Defense Department, will provide hardware, software and integration services to assure that the Hawaii facility is compatible with Iridium’s second-generation constellation, called Iridium Next.

Iridium is spending about $3 billion on Iridium Next, which like the current constellation features 66 satellites, plus six in-orbit spares, in low Earth orbit, with intersatellite links permitting calls and data messages to be loaded onto one satellite, passed to others and then downlinked to the Hawaii ground station. Launches of the Iridium Next satellites are scheduled to begin in 2015.

The gateway station upgrade contract is with the Defense Information Systems Agency, or DISA, and is structured as a single one-year commitment with up to four one-year options. The $47 million value assumes all four option years are exercised.

Peter B. de Selding was the Paris Bureau Chief for SpaceNews.