Helios (spacecraft)
Prototype of the Helios spacecraft
|
|
| Operator | NASA / DFVLR |
|---|---|
| COSPAR ID |
Helios-A :1974-097A Helios-B :1976-003A |
| SATCAT no. |
Helios-A :7567 Helios-B :8582 |
| Website |
Helios-A : NASA Solarsystem Exploration page Helios-B : NASA Solarsystem Exploration page |
| Mission duration |
Helios-A: 10 years, 1 month and 2 days |
| Spacecraft properties | |
| Manufacturer | MBB |
| Launch mass | 370 kg (820 lb) |
| Power | 270W (solar array) |
| Start of mission | |
| Launch date |
Helios A: 07:11:01.5, December 10, 1974 Helios B: 05:34, January 15, 1976 |
| Rocket | Titan IIIE / Centaur |
| Launch site | Cape Canaveral AFS SLC-41 |
| End of mission | |
| Deactivated |
Helios-A: February 18, 1985 Helios-B: December 23, 1979 |
| Orbital parameters | |
| Reference system | Heliocentric |
| Eccentricity |
Helios-A: 0.5218 Helios-B: 0.5456 |
| Perihelion |
Helios-A: 0.31 AU Helios-B: 0.29 AU |
| Apohelion |
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 |
Helios-A: 10 years, 1 month and 2 days
Helios-A and Helios-B (also known as Helios 1 and Helios 2), are a pair of probes launched into heliocentric orbit for the purpose of studying solar processes. A joint venture of West Germany's space agency DFVLR (70% share) and NASA (30%), the probes were launched from Cape Canaveral, Florida, on Dec 10, 1974, and Jan 15, 1976, respectively. Built by Messerschmitt-Bölkow-Blohm as the main contractor, they were the first spaceprobes built outside the United States or Soviet Union.
The probes are notable for setting a maximum speed record among spacecraft at 252,792 km/h (157,078 mi/h or 43.63 mi/s or 70.22 km/s or 0.000234c). 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), closer than 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, and continued to send data up to 1985.
The probes are no longer functional but still remain in their elliptical orbits around the Sun.
The two Helios probes look very similar. They have a total mass of 370 kg (Helios 1) and 376.5 kg (Helios 2); the scientific payload, composed of eight instruments, is 73.2 kg on Helios 1 and 76.5 kg on Helios 2. The central body is a sixteen-sided prism 1.75 m in diameter and 0.55 meters high. Most of the equipment and instrumentation is mounted in this central body. Exceptions are the masts and antennas used in scientific experiments and small telescopes that measure the zodiacal light that emerge from the central body. Two conical solar panels extend above and below the central body, giving the assembly the appearance of a diabolo or spool of thread.
At launch the probe was 2.12 meters tall and reaches a maximum diameter of 2.77 meters. Once in orbit, a telecommunications antenna unfolded on top of the probe and increased the total height to 4.20 meters. Also deployed on orbit are two rigid booms carrying sensors and magnetometers, attached on both sides of the central body, and two flexible antennas used for the detection of radio waves, which extended perpendicular to the axis of the spacecraft for a design length of 16 metres each.
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