Helios

As early as 1978 France proposed an international monitoring agency employing satellites under the auspices of the United Nations. Failing to win support from either the US or the USSR, by 1981 France was studying the feasibility of deploying a national reconnaissance spacecraft called SAMRO and derived in large measures from the SPOT Earth observation satellite. The studies evolved into the present Helios program, whose maiden launch by an Ariane 40 booster was postponed from 1994 to 1995 due to disruption of the Ariane schedule following the launch failure of 24 January 1994 (References 1-7).

The $2 billion project is funded primarily by the French Delegation Generale pour l'Armement (DGA), Helios-1 is also being financially sponsored by Italy and Spain at a level of approximately 14% and 7%, respectively. Responsibility for the overall space system architecture has been delegated to CNES with Matra Marconi serving as the prime contractor. Major subcontractors include Aerospatiale, Alcatel Espace, Alenia, SEP, and Sodern (References 8-10).

Helios has a mass of about 2.5 metric-tons and operates in a sun-synchronous orbit at an altitude of 680 km and an inclination of 98 degrees. Outwardly, the spacecraft closely resembles SPOT 4 with a box-like bus and a five-segment solar array capable of generating 2.5 kW of electrical power. A 3-axis stabilization system and precision pointing accuracy supports the primary multi-spectral CCD imaging system with a resolution of one meter. In early 1994 Aerospatiale delivered the principal imaging payload to Matra Marconi, and, by the end of the year, final testing and integration were underway (References 11-12).

The main payload control facility for Helios is at Creil, France, whereas primary data reception sites are located in all three partner countries: Colmar, France; Lecce, Italy; and Maspalomas, Canary Islands (Spain). A tiered encryption scheme restricts images to only one or more of the Helios program states with France having the highest priority and widest data access. Images are also made available to the Western European Union, or possibly in the future to selected civilian customers on a commercial basis (References 13-15).

The launch of Helios 1A on 07 July 1995 was scheduled to be followed by Helios 1B in late 1996 or early 1997. This was a significant change in the original program which envisioned Helios 1B being held in reserve in the case of difficulties with Helios 1A, which has a design lifetime of four years or more. In part, this operational thinking was brought about by the demonstrated utility of space systems during the Persian Gulf War. However, subsequently this ambitious goal was abandoned, and planning for Helios 1B reverted to a scheduled 1999 launch. On 03 December 1999 the 123rd ARIANE launch (Flight 124) placed the HELIOS IB satellite into a polar sunsynchronous orbit using an ARIANE 40 launch vehicle (with no strap-on boosters). This was the 92nd ARIANE 4 launch and the 7th in the ARIANE 40 configuration. Helios IB sent back its first image the very next day, on 4 December 1999 at 13:20 (Paris time), when it passed within view of the image receiving centre at Colmar, north-east France, and the mobile theatre station deployed at Creil French air force base just outside Paris. This first image, a long strip of eastern France, showed that the satellite had been deployed nominally.

Helios-class satellites may also be sold to other nations if France can maintain control of the sale and use of the reconnaissance products (References 16-18).

A pair of Helios 2 spacecraft will be developed for missions beginning in 2003 with proved optical imagers (resolution perhaps down to 0.5 m), new infrared sensors for nightime reconnaissance, and expanded tape recorder capacities for storage of a greater number of photographs (up to 200) between downlink opportunities. During 1994, Germany was wooed to join the Helios 2 programas Spain and then Italy threatened to reduce their contributions. The price for German participation was leadership of the follow-on synthetic aperture radar reconnaissance satellite Horus (formerly known as Osiris) which could be launched as early as 2005.

Prime contractor :	CNES (centre national d'études spatiales)
Builder team :	Matra Marconi Space - Alcatel
User nations :	Co-operation : France (79%) - Italy (14%) - Spain (7%)
First launch :	July 7, 1995 by Ariane 4
Weight :	2,500 kg
Energy :	Solar generator supplying 2.2 kW
Specified useful life :	5 years
Orbit :	Circular, low altitude (around 700 km), sun synchronous
Ground facilities :	Encrypted control and programming of the satellite from France, image reception and processing in dedicated centres of the 3 co-operating countries
Payload :	Panchromatic, high resolution and wide-angle optical instruments, data storage on digital magnetic recorder, transmission to the ground by encrypted telemetry
Ground segment :	Dedicated Helios control center Two centers in each user nation (a main center and an image telemetry reception center) Field stations for image exploitation A theater station for France
Major operational capabilities :	Minimal delay for return to zone (less than 24 hours in general) Flexible and confidential programming Programmation, telemetry reception and image exploitation on the field using the Theatre Transportable Station
WEU interoperability :	Possible use of the Helios images at the Western European Union satellite centre in Torrejon, Spain
Planned inventory :	1 operational satellite in orbit since 1995 ; 2nd satellite to be launched at the end of 1999 ; Helios 2 program in progress (upgraded operational capabilities), first launch scheduled in 2003
Typical mission in former Yugoslavia :	High resolution optical images for mission preparation or Battle Damage Assessment (BDA)