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SOHO Mission to Comets

Mission Type: Orbiter
Launch Vehicle: Atlas II-AS rocket (AC-121)
Launch Site: Cape Canaveral Air Station
NASA Center: Goddard Space Flight Center
Spacecraft Mass: 1850 kg at launch
Spacecraft Instruments:
1) CDS (Coronal Diagnostic Spectrometer)
2) CELIAS (Charge, Element, and Isotope Analysis System)
3) COSTEP (Comprehensive Suprathermal and Energetic Particle Analyzer)
4) EIT (Extreme ultraviolet Imaging Telescope)
5) ERNE (Energetic and Relativistic Nuclei and Electron experiment)
6) GOLF (Global Oscillations at Low Frequencies)
7) LASCO (Large Angle and Spectrometric Coronagraph)
8) MDI (Michelson Doppler Imager)
9) SUMER (Solar Ultraviolet Measurements of Emitted Radiation)
10) SWAN (Solar Wind Anisotropies)
11) UVCS (Ultraviolet Coronagraph Spectrometer)
12) VIRGO (Variability of Solar Irradiance and Gravity Oscillations)
Spacecraft Dimensions: Approximately 4.3 x 2.7 x 3.7 m (9.5 m with solar arrays deployed)
Total Cost: One thousand million Euros
ESA's SOHO Fact Sheet, 30 June 2003.

The European Space Agency (ESA)-sponsored Solar and Heliospheric Observatory (SOHO) carries twelve scientific instruments to study the solar atmosphere, helioseismology and solar wind. Information from the mission allows scientists to learn more about the sun's internal structure and dynamics, the chromosphere, the corona and solar particles.

The SOHO and Cluster missions, part of ESA's Solar Terrestrial Science Programme (STSP), are ESA's contributions to the Inter-Agency Solar Terrestrial Physics (IASTP) program. NASA contributed three instruments on SOHO as well as launch and flight operations support.

About two months after launch, on 14 February 1995, SOHO was placed at a distance of 1.5 million km from Earth at the L1 Libration Point. The spacecraft returned its first image on 19 December 1995 and was fully commissioned for operations by 16 April 1996.

SOHO finished its planned two-year study of the sun's atmosphere, surface, and interior in April 1998. Communications with the spacecraft were interrupted for four months beginning on 24 June 1998, but, after intensive search efforts, controllers managed to regain full control by 16 September.

Barring three instruments, the spacecraft was functional and was declared fully operational once again by mid-October 1998. SOHO's original lifetime was three years (to 1998), but ESA and NASA jointly decided to prolong the mission, enabling the spacecraft to compare the sun's behavior during low dark sunspot activity (1996) to the peak (around 2000).

The team -- and everyday people who just watch the website -- have also discovered dozens of comets, many of which are destroyed by the sun's powerful gravity and energy. One of SOHO's most important discoveries has been locating the origin of the fast solar wind at the corners of honeycomb-shaped magnetic fields surrounding the edges of large bubbling cells located near the sun's poles.

SOHO remains in its halo orbit, circling L1 once every six months.

Key Dates
2 Dec 1995:  Launch
Status: In flight
Fast Facts
SOHO Facts The team -- and everyday people who just watch the website -- have also discovered dozens of comets, many of which are destroyed by the sun's powerful gravity and energy.

SOHO carries twelve scientific instruments.

SOHO's original lifetime was three years (to 1998), but it is still going strong.
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Last Updated: 25 Jan 2011