Helios 1A an 1B were advanced French military surveillance satellites which were widely believed to have 1 meter resolution capability. The Missile and Space Directorate (DME) of the French armament agency (DGA) headed the overall $2 billion Helios program. Spacecraft and payload information was not readily available due to the secret nature of the program.

The Helios program was Europe's military optical reconnaissance system consisting of both a space and a ground segment, which commenced service in 1995, jointly funded by the French, Italian and Spanish governments. The Helios I optical observation satellites, launched in July 1995 and December 1999 respectively, could acquire high resolution images of any point on the globe, with daily revisit capability.

The spacecraft was 3-axis stabilized, nadir pointing. CNES operated a Helios ground station in Toulouse, France. The imaging system used 4096 pixel and 2048 pixel linear CCDs to provide 1 - 5 meter resolution images. The CCDs were produced by Thompson CSF. Tape recorders were manufactured by Schlumberger Industries.

Typical orbit: 675 km, sun-synchronous, 98.2 deg inclination. Mass: 2,537 kg (5,593 lb). Associated Launch Vehicle: Ariane 4.

• 1995 July 7 - Helios 1A - Launch Site: Kourou. Launch Vehicle: Ariane 4. Mass: 2,537 kg (5,593 lb). Perigee: 680 km (420 mi). Apogee: 682 km (423 mi). Inclination: 98.10 deg. Period: 98.40 min.

• 1999 December 3 - Helios 1B - Launch Site: Kourou. Launch Vehicle: Ariane 4. Mass: 2,750 kg (6,060 lb). Perigee: 680 km (420 mi). Apogee: 682 km (423 mi). Inclination: 98.20 deg. Period: 98.40 min.

  French optical military reconnaisance satellite based on Spot 4. Taken out of service in mid-October 2004, when the orbit of the satellite was lowered to 637 x 640 km, taking it out of the path of Helios 1A and the Helios 2A that would be launched in December 2004.

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