The Helios I and Helios II space probes were a series of probes launched into heliocentric orbit for the purpose of studying solar processes. A joint venture of the Federal Republic of Germany (West Germany) and NASA, the probes where launched from the John F. Kennedy Space Center at Cape Canaveral, Florida, on Dec. 10, 1974, and Jan. 15, 1976, respectively.

The probes are notable for having set in the mid-1970's a maximum speed record among spacecraft at 252,792 km/h (about 70km/s), also roughly 0.0002 times the speed of light. . Helios 2 flew three million kilometers closer to the Sun than Helios 1, achieving perihelion on 17 April 1976 at a record distance of 0.29 AU (or 43.432 million kilometers), slightly inside the orbit of Mercury. Helios 2 was sent into orbit 13 months after the launch of Helios 1. The Helios space probes completed their primary missions by the early 1980s, but they continued to send data up to 1985. The probes are no longer functional but still remain in their elliptical orbit around the Sun.

The name Helios has also been used for a NASA experimental aircraft, the Helios Prototype, and for a series of French military photo-reconnaissance satellites, Helios 1B and Helios 2A.

References

1. http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Helios_02&Display=ReadMore

External links

• Helios 1 - NSSDC Master Catalog
• Helios 2 - NSSDC Master Catalog
• Helios 1 Mission Profile by NASA's Solar System Exploration
• Helios 2 Mission Profile by NASA's Solar System Exploration
• Titan/Centaur D-1T TC-2, Helios A, Flight Data Report