Tim Furniss/London
A LOCKHEED MARTIN Titan 4/Centaur is scheduled to launch a Block 1 Military Strategic and Tactical Relay (Milstar) satellite into geostationary orbit (GEO) from Cape Canaveral, Florida, in November. That this second Block 1 spacecraft is also the last - and late - serves to illustrate the controversial nature of the Milstar programme, although four Block 2 spacecraft are scheduled to be launched later.
When it was conceived in 1981, as a $40 billion-plus programme, it was intended to serve as a nuclear-hardened, all-service, system to ensure that the USA had a survivable worldwide communications capability in the event of a nuclear war.
In 1984, while President Reagan was describing the Soviet Union as "the Evil Empire", he gave the Milstar programme the highest national priority, and also launched the Strategic Defense Initiative, or "Star Wars". The end of the Cold War changed all that. The Milstar became a Cold War relic and was threatened with cancellation. A bitter inter-service and congressional battle then ensued.
To rescue the programme, the function of the Milstar spacecraft was changed in mid-programme. The role of the satellites was changed from strategic to tactical communications, complementing the existing operational US Air Force defence space-communications system (DSCS) and US Navy ultra-high-frequency (UHF) communications satellites. The craft were to retain many of the unique and superior features of the original design, but with less nuclear shielding.
The 4,600kg Milstar spacecraft, built by Lockheed Martin, are the first to allow all three armed services to communicate with each other on the same network, equipped with systems to establish automatically, maintain and reconfigure voice and data networks in real time.
A QUESTION OF PAYLOADS
The original TRW-built low-data-rate (LDR) payload has 192 channels, with a total capacity of 0.5Mbits and a maximum 2,400 bits/s data rate. The LDR payload was originally to have been used to relay emergency messages to initiate a nuclear counterstrike, but is now used for telex and voice communications.
The Milstars work at extremely high frequency (EHF), as well as at UHF and SHF, using frequency hopping to avoid interference and interception and to eliminate the requirement for extensive ground networks. They are described as the most sophisticated and secure communications satellites ever developed.
The end of the Cold War was not the only factor to give the programme trouble: it was also grossly over-budget and already late. With each satellite costing about $5 million, the US Congress threatened to cancel the programme in 1990. The Congress had the behind-the-scenes support of the Milstar operator, the USAF, which preferred funds to be directed elsewhere. The USN, as the main beneficiary of the satellites' more tactical communications role, continued to push hard for the survival of the programme, and for control over it.
As originally conceived, 20 Milstars were to have been built, but this was reduced to eight new-role spacecraft, with six being flown in GEO and two in polar orbit. Congressional pressure then reduced this further, to just six spacecraft, equipped only with the original TRW-built LDR payload, and with no polar orbiters.
The programme was amended again in 1992 with four of the remaining six craft to be modified to become new Milstar 2 satellites to meet their new roles more realistically. One of the three, Milstar Block 1s already built was to be modified as a Milstar 2 and three new craft commissioned. Lockheed Martin was awarded a contract to produce the modified Block 1 craft and the first new Milstar 2.
The Milstar 2s will be equipped with an additional medium-data-rate (MDR) payload built by Hughes Aircraft. The MDR will provide 32 channels with a a much greater, 1.5 Mbits/s, data rate to provide voice, data, image and other intelligence-data communications.
The two original Block 1s are equipped only with the LDR. The first Milstar Block 1 satellite was launched as the Development Flight Satellite 1 (DFS) on 7 February 1994, amid still-lingering doubts about the programme's exclusivity and future. There is still a need for the DSCS and UHF satellites. The UHF satellites are already equipped with EHF payloads, and this is an option for later DSCS craft.
Nonetheless, the Milstar Block 1s will provide a far superior "instant-access" service to US forces which, had it been available, could have improved operations considerably during Operation Desert Storm in 1991. Then, manoeuvres had to be planned according to the communications support available at the time. The first Milstar 1 has been operating well in 90°W geostationary orbit.
The DFS 2 will be placed over the Atlantic Ocean, while the first will eventually be moved over the Pacific. The spacecraft can be manoeuvred to different orbital slots as required. The first Milstar 2 satellite will not begin operating until 1998. Three further, Titan 4 Milstar launches, will be completed by 2001. The final $1.3 billion contract for the two remaining satellites was awarded to Lockheed Martin in 1995.
The Milstars have survived. The programme, which was awarded a $647 million budget in 1995, will now cost an estimated $4 billion. The USAF is still in the driving seat, operating the Milstars from Falcon AFB, Colorado. Lighter and cheaper Milstar 3/EHF versions, have even been proposed for launch, starting in 2003.
Source: Flight International