Skynet (satellites)

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This article contains information regarding a satellite that is scheduled to launch in the next 13 hours. Details may change as the countdown and ascent progress. Launch details: Arianespace will use a Ariane 5ECA to launch Skynet 5C and Turksat 3A for the British Ministry of Defence and Turksat. Launch will occur from ELA-3 at the Guiana Space Centre, Kourou. Launch is scheduled for 12 June 2008 at 21:54 -22:39 UTC. See 2008 in spaceflight and the Spaceflight Portal for further details. edit this messagebox

Skynet is a family of military satellites, now operated by Paradigm Secure Communications on behalf of the UK Ministry of Defence, which provide strategic communication services to the three branches of the British Armed Forces and to NATO forces engaged on coalition tasks.

Contents 1 Models 1.1 Skynet 1 1.2 Skynet 2 1.3 Skynet 3 1.4 Skynet 4 1.5 Skynet 5 2 Security and safety 3 Satellite summary 4 See also 5 External links 6 References

[edit] Models

[edit] Skynet 1

There were two Skynet 1 satellites; the first, launched in November 1969, failed after less than a year of operation. The apogee kick motor on the second failed, leaving it in GTO.

[edit] Skynet 2

Following the failure of one of the Skynet 1 satellites, the timetable for the launch of the Skynet 2 system was delayed. When Skynet 2A was launched on 19 January 1974, the second stage of the Delta rocket failed, placing the satellite in an unusable orbit. Despite not being in the right place, the ground stations successfully located and tracked the missing satellite, and were able to use telemetry readings from the solar panels to determine its alignment. Based on this analysis it was decided to use the alignment thrusters to deorbit the unit, and it was destroyed when it re-entered the earth's atmosphere on 27 January.

Skynet 2B was successfully launched on 23 November 1974.

The Skynet 2 satellites were assembled and tested at the Marconi Space and Defence Systems establishment in Portsmouth, England, and were the first communication satellites built outside the US and USSR^[1]. The Skynet 2 system was very successful for its time, and remained in service for several years beyond the originally planned timeframe.

[edit] Skynet 3

Skynet 3 was abandoned in favour of the more advanced Skynet 4.

[edit] Skynet 4

Skynet 4 satellites have few similarities to the earlier generations. The cylindrical body of Skynet 1 and 2 was replaced by a large square body housing antennas with deployable solar-cell arrays. This marks the technological improvement from spin-stabilisation, used in earlier cylindrical satellites, to three-axis stabilisation using momentum wheels and reaction wheels controlling the satellite gyroscopically.

Skynet 4 were the first purely British built satellites, manufacture of 4A, 4B and 4C being carried out by British Aerospace Dynamics (BAe Dynamics). NATO adapted the design for the NATO IVA and IVB communication satellites, also manufactured by BAe Dynamics.

The improved Stage 2 satellites (4D, 4E and 4F) were built by Matra Marconi Space and Astrium to replace the earlier versions. Improvements included increased power and resistance to electronic jamming.

Skynet 4 provides SHF and UHF services using earth cover, wide area and spot beam coverage.

[edit] Skynet 5

Skynet 5 is the next generation of satellites, replacing the existing Skynet 4 Stage 2 system. It has been contracted via PFI to a partnership between Paradigm Secure Communications and EADS Astrium, a European spacecraft manufacturer. EADS Astrium will be responsible for the build and delivery of Skynet 5 satellites in orbit, whilst Paradigm will be responsible for provision of service to the MoD. Paradigm have also been contracted to provide communications services to NATO using spare capacity on the satellites.

The Skynet 5 satellite weighs about 4700 kilograms, has two solar panels each about fifteen metres long, and has a power budget of five kilowatts. It has four steerable transmission dishes, and a phased-array receiver designed to allow jamming signals to be cancelled out. They will also resist attempts to disrupt them with high-powered lasers [1].

The first of a constellation of three Skynet 5 vehicles was launched by a Ariane 5 rocket at 22:03 GMT on 11 March 2007, in a launch shared with the Indian INSAT 4B civil communications satellite, and entered full service on 10 May 2007. The launch was delayed from 10 March due to malfunction of a launch pad deluge system.^[2] Skynet 5A successully separated from its launch vehicle and Telemetry was acquired by its dedicated Control Centre approximately 40 minutes after launch.

The second Skynet 5 UK military communications satellite was launched at 22:06 GMT on 14 November 2007, from Kourou in French Guiana, aboard an Ariane 5ECA rocket. This launch was delayed from 9 November due to problems with the electronics on one of the Solid Rocket Boosters, and 12 November due to a fueling problem with the launch pad. At time of launch the Ariane 5 ECA launcher set a new record on this mission, orbiting a total payload of more than 8,700 kg.^[3]

The programme marks a change of approach in the UK from traditional defence procurement methods to a services-based contract which also includes provision of leased ground terminals, Reacher vehicles, the Satellite Communications Onboard Terminal (SCOT) for ships, and the associated baseband equipment.

Initially two Skynet 5 satellites were to be built, with insurance covering any launch loss; the MoD later decided to have a third satellite built in advance, and later still to have the third satellite launched to serve as an on-orbit spare.^[4]

[edit] Security and safety

In early 1999, Reuters reported that the Skynet system was breached by a group of hackers who issued blackmail threats against the MoD. Duncan Campbell reported that the wire reports were wrong.^[5]

[edit] Satellite summary

Summary

Model	Manufacturer	Launch date	Launch vehicle	Comments
Skynet 1
1A	Philco Ford	22 November 1969	Delta M
1B	Philco Ford	19 August 1970	Delta M	Apogee motor failure
Skynet 2
2A	Marconi Space Systems¹	19 January 1974	Delta 2000	Rocket guidance failure
2B	Marconi Space Systems	23 November 1974	Delta 2000
Skynet 4
4A	British Aerospace	1 January 1990	Titan 34D
4B	British Aerospace	11 December 1988	Ariane 44LP²
4C	British Aerospace	30 August 1990	Ariane 44LP
Skynet 4 Stage 2
4D	Matra Marconi Space³	10 January 1998	Delta 7000	Replaced 4B
4E	Matra Marconi Space	26 February 1998	Ariane 44L
4F	Astrium4	7 February 2001	Ariane 44L
Skynet 5
5A	EADS Astrium5	11 March 2007, 22:03 GMT	Ariane 5-ECA	Launched with Insat 4B
5B	EADS Astrium	14 November 2007	Ariane 5-ECA	Launched with Star One C1
5C	EADS Astrium	Postponed from 30 May 2008	Ariane 5-ECA	To be launched with Turksat 3A

Notes

1. With technical assistance from Philco Ford
2. Launched with Astra 1A, the first of the European Astra satellite constellation
3. Marconi Space Systems merged to form Matra Marconi Space in 1990. MMS acquired BAe Space Systems in 1994.
4. In 2000 MMS merged with DASA's space division to form Astrium.
5. BAE Systems sold its 25% share of Astrium, renamed EADS Astrium

[edit] See also

• Zircon (satellite)
• Skynet (fictional) - name coincidence for a sinister Aerospace Defense computer network in the Terminator movie series, which takes over the world.

[edit] External links

• www.skyrocket.de
• www.astronautix.com
• EADS Astrium - manufacturer
• BBC Article on March 2007 launch
• UK Skynet ground terminal locations
• Arianespace Launch Status & Schedule

[edit] References