Ariane’s first dual military satellite mission is a “go” for launch

The first Arianespace mission with a dual military satellite payload entered its final phase today as Flight 139 successfully passed its launch readiness review.

This review verified the readiness of the Ariane 4 launcher, and also validated the status of the Skynet 4F and Sicral spacecraft, the Guiana Space Center ground infrastructure and the downrange stations that will track the mission.

For Flight 139, the Sicral satellite is riding in the upper payload position, protected by the Ariane 4’s lightweight fairing. Skynet is installed below it, housed in the Ariane multiple payload deployment system.

Skynet 4F will be used by the U.K. Ministry of Defence for strategic and tactical communication services. It carries eight transponders: four SHF, two UHF and two in the S-band.

The satellite weighs 1,489 kg. (3,276 lb.) at liftoff and will have an eight-year lifetime at its final orbital position of 1 deg. West or 6 deg. East.

Italy’s Sicral is the country’s first military telecommunications will serve the Italian Defense Ministry. With a mass of 2,596 kg. (5,711 lb.) at liftoff, the spacecraft will have an operational lifetime of 10 years in its orbital location at 16.2 deg. East.

Sicral carries nine SHF, UHF and EHF transponders

Flight 139 is Arianespace’s second launch of 2001, and it will use an Ariane 44L version of the workhorse Ariane 4 family. The 44L version is equipped with four liquid strap-on boosters, and is the most powerful Ariane 4 configuration.