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Helios (spacecraft)
Pair of sun-orbiting probes launched in 1974-76 by the American and West German space agencies / From Wikipedia, the free encyclopedia
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This article is about the solar orbiting spacecraft. For the NASA experimental aircraft, see Helios Prototype. For French military photo-reconnaissance satellites, see Helios 1B and Helios 2 (satellite).
Helios-A and Helios-B (after launch renamed Helios 1 and Helios 2) are a pair of probes that were launched into heliocentric orbit to study solar processes. As a joint venture between German Aerospace Center (DLR) and NASA, the probes were launched from Cape Canaveral Air Force Station, Florida, on December 10, 1974, and January 15, 1976, respectively.
![]() | This article includes a list of general references, but it lacks sufficient corresponding inline citations. (August 2022) |
Quick Facts Mission type, Operator ...
![]() Prototype of the Helios spacecraft | |
Mission type | Solar observation |
---|---|
Operator | |
COSPAR ID | Helios-A: 1974-097A Helios-B: 1976-003A |
SATCAT no. | Helios-A: 7567 Helios-B: 8582 |
Website | Helios-A: Helios-B: |
Mission duration | Helios-A: 10 years, 1 month, 2 days Helios-B: 3 years, 5 months, 2 days |
Spacecraft properties | |
Manufacturer | MBB |
Launch mass | Helios-A: 371.2 kg (818 lb) Helios-B: 374 kg (825 lb) |
Power | 270 watts (solar array) |
Start of mission | |
Launch date | Helios-A: December 10, 1974, 07:11:01 (1974-12-10UTC07:11:01) UTC[1] Helios-B: January 15, 1976, 05:34:00 (1976-01-15UTC05:34) UTC[2] |
Rocket | Titan IIIE / Centaur |
Launch site | Cape Canaveral SLC-41 |
Entered service | Helios-A: January 16, 1975 Helios-B: July 21, 1976 |
End of mission | |
Deactivated | Helios-A: February 18, 1985 (1985-02-19) Helios-B: December 23, 1979 |
Last contact | Helios-A: February 10, 1986 Helios-B: March 3, 1980 |
Orbital parameters | |
Reference system | Heliocentric |
Eccentricity | Helios-A: 0.5218 Helios-B: 0.5456 |
Perihelion altitude | Helios-A: 0.31 AU Helios-B: 0.29 AU |
Aphelion altitude | Helios-A: 0.99 AU Helios-B: 0.98 AU |
Inclination | Helios-A: 0.02° Helios-B: 0° |
Period | Helios-A: 190.15 days Helios-B: 185.6 days |
Epoch | Helios-A: January 15, 1975, 19:00 UTC[1] Helios-B: July 20, 1976, 20:00 UTC[2] |
Close
The Helios project set a maximum speed record for spacecraft of 252,792 km/h (157,078 mph; 70,220 m/s).[3] Helios-B performed the closest flyby of the Sun of any spacecraft until that time. The probes are no longer functional, but as of 2024 remain in elliptical orbits around the Sun.