The Galaxy 11, DUE to enter orbit in June 1998, will not only be the first HS-702 spacecraft bus to be built by Hughes Space and Communications , but it will also be the first geostationary-orbit (GEO) communications satellite to be launched from an offshore platform.
This space "first" involves the Boeing-led Sea Launch venture, a multi-national commercial-launch company. It is owned by Boeing Commercial Space of Seattle, with a 40% investment stake; Kvaerner of Oslo, Norway (20%); Russia's RSC-Energia of Moscow (25%) and the Ukrainian Yuznoye company in Dnepropetrovsk (15%). Boeing has reportedly invested $500 million in the venture.
Logical launch sites
The logic of Sea Launch is based on the inherent advantage of being able to launch from a mobile platform situated on the equator, as well as on projections of a satellite-manufacturing and launcher market worth $50 billion for the beginning of the next century.
Launching to an equatorial geostationary-transfer-orbit (GTO), which is the staging post by the satellite for a final burn to circularise the orbit at GEO), requires less energy because of the Earth's faster speed of rotation at the equator and the shorter route to GTO. This saves launch-propellant weight, which gives increased payload capability.
GEO launches from Baikonur, Kazakhstan; Cape Canaveral, Florida; Tanegashima, Japan; and Xichang, China are limited by their northerly locations, while the nearest operational base to the equator is the one used by Arianespace at Kourou, French Guiana.
With the bulk of the world's communications-satellite manufacturing taking place on the US West Coast - led by Hughes - the Sea Launch operation has been strategically based in the port of Long Beach, California.
Here, a semi-submersible launch platform, called the Odyssey, will undergo final preparation. The 131m-high vessel, which is being manufactured at the Rosenburg shipyard, in Stavanger, Norway, will be manned by 20 crew, and will house the kerosene and liquid-oxygen propellants for the Zenit launch booster being used in the project. Yuznoye will manufacture the first two stages of a Zenit 2 booster, which will be equipped with an RSC-Energia Block DM stage from the Proton D booster. The 61m-long Sea Launch vehicle will be called a Zenit 3SL. The Zenit 2 was first flown from the then-Soviet Union's Baikonur Cosmodrome in 1985. It has a launch record of 22 successes, five failures and one failure to reach correct orbit.
Command ship
The Odyssey will be supported by a command ship - manned by 250 crewmembers - which will serve as the control centre. After initial completion at the Govan shipyard, of Glasgow, Scotland, in the UK, the 198m-long ship will be taken to Russia this year to be prepared for service, and will arrive at Long Beach in early 1998. A completed rocket will be placed on the launch platform and shipped horizontally to the launch location, where it will be erected and fuelled ready for launch.
Customer spacecraft are to be processed in a special building at the 6.5Ha (16acre) Long Beach Sea Launch site and integrated on to the launcher before it is hauled aboard the platform's hangar.
Launches will take place from an equatorial site east of the Kiribati (Christmas) Islands, 1,600km south-east of Hawaii - a ten-day cruise from Long Beach - but the Odyssey could be moved to other locations, for example further north and nearer to the US coast, for possible launches into polar orbit for remote-sensing Earth-observation craft and potentially lucrative networks of mobile-communications satellites in low-Earth orbit (LEO).
As the Sea Launch vessel, it will be able to offer a GTO payload capability of 5,700kg, which compares with the maximum theoretical capability of Europe's Ariane 5 of 6,800kg for a single-satellite payload. Launches of Italian/ NASA/UK science satellites were made on Scout rockets into LEO from the Italian San Marco platform, off the coast of Kenya, between 1966 and 1988 and hundreds of missiles have been launched from sea-going vessels, mainly submarines.
Sea Launch is in the remarkable position of already having been booked for 15 launches. Hughes has reserved ten, starting with the Galaxy 11, and including three mobile-communications satellites being built for Inmarsat affiliate company ICO. Space Systems/Loral has booked five launches.
Source: Flight International
