![]() SOHO satellite | |||||||||||||||||||||||||||
Names | SOHO | ||||||||||||||||||||||||||
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Mission type | Solar observation | ||||||||||||||||||||||||||
Operator | ESA / NASA | ||||||||||||||||||||||||||
COSPAR ID | 1995-065A | ||||||||||||||||||||||||||
SATCAT no. | 23726 | ||||||||||||||||||||||||||
Website | sohowww.nascom.nasa.gov | ||||||||||||||||||||||||||
Mission duration | 2 years (planned) 28 years, 8 months and 20 days (in progress) | ||||||||||||||||||||||||||
Spacecraft properties | |||||||||||||||||||||||||||
Bus | SOHO | ||||||||||||||||||||||||||
Manufacturer | Matra Marconi Space | ||||||||||||||||||||||||||
Launch mass | 1,850 kg (4,080 lb) [1] | ||||||||||||||||||||||||||
Payload mass | 610 kg (1,340 lb) | ||||||||||||||||||||||||||
Dimensions | 4.3 × 2.7 × 3.7 m (14.1 × 8.9 × 12.1 ft) 9.5 m (31 ft) with solar arrays deployed | ||||||||||||||||||||||||||
Power | 1500 watts | ||||||||||||||||||||||||||
Start of mission | |||||||||||||||||||||||||||
Launch date | 2 December 1995, 08:08:01 UTC | ||||||||||||||||||||||||||
Rocket | Atlas IIAS (AC-121) | ||||||||||||||||||||||||||
Launch site | Cape Canaveral, LC-36B | ||||||||||||||||||||||||||
Contractor | Lockheed Martin | ||||||||||||||||||||||||||
Entered service | May 1996 | ||||||||||||||||||||||||||
Orbital parameters | |||||||||||||||||||||||||||
Reference system | Sun–Earth L1 orbit | ||||||||||||||||||||||||||
Regime | Halo orbit | ||||||||||||||||||||||||||
Perigee altitude | 206,448 km (128,281 mi) | ||||||||||||||||||||||||||
Apogee altitude | 668,672 km (415,494 mi) | ||||||||||||||||||||||||||
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![]() SOHO mission patch |
The Solar and Heliospheric Observatory (SOHO) is a European Space Agency (ESA) spacecraft built by a European industrial consortium led by Matra Marconi Space (now Airbus Defence and Space) that was launched on a Lockheed Martin Atlas IIAS launch vehicle on 2 December 1995, to study the Sun. It has also discovered over 5,000 comets.[2] It began normal operations in May 1996. It is a joint project between the European Space Agency (ESA) and NASA. SOHO was part of the International Solar Terrestrial Physics Program (ISTP). Originally planned as a two-year mission, SOHO continues to operate after over 25 years in space; the mission has been extended until the end of 2025, subject to review and confirmation by ESA's Science Programme Committee.[3]
In addition to its scientific mission, it is a main source of near-real-time solar data for space weather prediction. Along with Wind, Advanced Composition Explorer (ACE), and Deep Space Climate Observatory (DSCOVR), SOHO is one of four spacecraft in the vicinity of the Earth–Sun L1 point, a point of gravitational balance located approximately 0.99 astronomical unit (AU) from the Sun and 0.01 AU from the Earth. In addition to its scientific contributions, SOHO is distinguished by being the first three-axis-stabilized spacecraft to use its reaction wheels as a kind of virtual gyroscope; the technique was adopted after an on-board emergency in 1998 that nearly resulted in the loss of the spacecraft.