Some facts and figures about SOHO
Scientists from 62 institutes in 15 countries comprise the teams that provide and operate the instruments, with industries in 15 countries contributing to the spacecraft's construction.
Weighing 1.85 tons at launch, the European-built SOHO was launched by a NASA rocket on Dec. 2, 1995, and transferred to the vicinity of Lagrange Point 1, where it now hovers, approximately 1 million miles (1.5 million kilometers) from Earth.
The spacecraft was commissioned in April 1996 for a nominal operational life of two years, but this was later extended by five years -- until the end of March 2003.
Observations were severely interrupted twice, between June 25 and Nov. 5, 1998, and between Dec. 21, 1998 and Feb. 2, 1999. The first event was due to loss of contact and control. The second was attributed to gyroscope failure. In both cases NASA and ESA engineers, fully supported by SOHO's builder Matra Marconi, worked wonders to restore the spacecraft to full operations.
More than 30 eruptions called solar proton events have bombarded SOHO with energetic particles. The most severe, on July 14 and Nov. 9, 2000, temporarily blinded SOHO's instruments with particle "snow" and slightly impaired the efficiency of the spacecraft's power-generating solar panels.
More than 3,600 coronal mass ejections from the Sun have been observed by SOHO's Large Angle and Spectrometric Coronagraph (LASCO) instrument, making an average of two per day during SOHO's five years of observations.
SOHO is by far the most prolific discoverer of new comets in the entire history of astronomy. By mid April 2001 the number stood at 304, most of them being small comets that fall into the Sun. Amateur astronomers around the world examine SOHO's daily pictures -- via the Internet -- and have been first to spot more than 200 of the SOHO comets.
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