Tim Furniss/RAF OAKHANGER
Matra Marconi Space (MMS) of Stevenage, UK, is completing production of the first of three uprated Skynet 4 UK-dedicated military-communications satellites, which are to be launched on a Boeing Delta booster from Cape Canaveral in January 1998.
The Skynet 4D will be followed by crafts E and F on Ariane 4 boosters in September 1998 and September 1999, by which time the original Skynet 4A-C satellites, the first of which was launched in 1988, will all have been replaced. The MMS in-orbit delivery contact for the D, E and F craft is worth $520 million.
The Skynets provide secure military and tactical communications for the UK Ministry of Defence and military services, using large fixed terminals in the UK and transportable Earth terminals from small troop manpacks to equipment on submarines, naval vessels and aircraft. MMS manufactures a range of these terminals as well as fixed ones for ground stations.
The enhanced Skynet 4 D-F series incorporate steerable antennas for SHF spot beams, increased power, improved anti-jamming capability and a fully tunable UHF system for increased flexibility.
GEOSYNCHRONOUS ORBIT
The 4D, which will replace the Skynet 4B at 53¹E in geosynchronous orbit (GEO) was the first in the series to be launched, in 1988 by an Ariane 4. The 4B will then be placed into a "graveyard" orbit. The Skynet 4A - originally to have been deployed on the Space Shuttle - was launched by a Titan 3 and placed at 34¹W in GEO, while the Skynet 4C flew aboard another Ariane and is located at 1¹W.
MMS says the Skynet 4s "proved their worth in the Gulf War - the first high-technology 'satellite war' - and are providing an essential link to the peacekeeping troops in Bosnia".
The satellites - and the two, almost identical, MMS-built NATO communications satellites - are operated and controlled by the Royal Air Force's Logistics Command's No 1001 Signals Unit, whose Space Operations Squadron is based at RAF Oakhanger, Hampshire.
Oakhanger is a " key location" for the operation and management of the UK Military Satellite Communications System, and is home to half of the 1001 Signals Unit, which provides voice, telegraph, facsimile, data and imagery services to military users, as well as supporting "non-military government agencies", says the RAF. The Signals unit was formed in June 1968 and moved to Oakhanger in February 1969.
A two-man command team constantly monitors and controls the health of each spacecraft, and the night shift is the busiest, says Flt Lt Ian Poyner, one of the centre's RAF engineering-officer spacecraft controllers. The Skynet's geosynchronous orbit is inclined by 3¹, so that the spacecraft move cyclically 6¹ (or 4,416km) north and south daily. They also move in an east-west direction 0.2¹ (or 147km) monthly.
Despite the considerable autonomy on board spacecraft today, "there is still a need to provide highly skilled engineering controllers who can 'fly' the spacecraft when required", says Oakhanger station commander Wg Cdr Rick Kiralfy. The ageing Skynet 4B is a "graceful old lady", says Kiralfy, and requires major care. Its solar arrays have been distorted to a slight angle and it is running out of orbital attitude-control-system propellant.
Oakhanger also houses one of the three satellite ground stations (SGS) which provide strategic and tactical communications services from the satellites. The SGS at Oakhanger includes two14m-diameter dishes. Siemens Plessey provides the turnkey facilities under two contracts together worth $160 million. Oakhanger also provides telemetry and data transmissions for US military satellites, and Space Shuttle voice links for NASA.
These sites are connected by military and commercial communications links for the transfer of traffic and control information. The satellite-network control centres provide the interface between users of fixed and deployed terminals using UK military satellites.
EFFICENCY DRIVE
The MoD's cost-cutting and efficiency drive has seen private enterprise introduced to Oakhanger and 1001 Signals Unit. The support contractor Assessment Services (Facilities Management) employs about 40% of the personnel for RAF Oakhanger and 1001 Signals Unit, providing engineering, logistics, administrative and computer support, resulting in "a 20% annual saving".
The governments of the UK, France and Germany are now preparing for the first steps towards the joint Trimilsatcom system by issuing invitations to tender to the MMS and Alcatel Espace-led consortia to conduct a Phase B project-definition study.
The Trimilsatcom programme is due to reach a Phase C/D stage in 1999/2000. The $2.6 billion system would replace the Skynet 4 fleet and French Syracuse transponders on the national Telecom 2 communications satellites and provide Germany with its first dedicated military communications system. The UK Government is still also considering its own option of a dedicated fleet of Skynet 5 satellites, which may be procured conventionally or operated privately from the Ministry of Defence.
Source: Flight International
