SOHO (Solar and Heliospheric Observatory) is a collaboration between ESA and NASA. It is located near L1 Lagrange point in space and is studying the Sun. It was launched 2nd December, 1995 on an Atlas IIAS.
SOHO spacecraft. Image credit: NASA / ESA
The SOHO spacecraft was built in Europe by prime contractor Matra Marconi Space (now EADS Astrium) under overall management by ESA. It carries European and American Instruments with international participation.
The twelve instruments on board SOHO were provided by European and American scientists. Nine of the international instrument consortia are led by European Principal Investigators, three by Principal Investigators from the USA.
SOHO spacecraft is not in Earth orbit. It is located near L1 Lagrange Point.
SOHO is a project of international collaboration between ESA and NASA to study the Sun from its deep core to the outer corona and the solar wind.
NASA was responsible for the launch and for mission operations. Large radio dishes around the world which form NASA’s Deep Space Network are used for data downlink and commanding. Mission control is based at Goddard Space Flight Center in Maryland.
Artist’s impression of SOHO with the Sun
SOHO has provided information about the Sun, from its interior, through the hot and dynamic atmosphere, to the solar wind and its interaction with the interstellar medium.
They include the following:
– Revealing the first images ever of a star’s convection zone (its turbulent outer shell) and of the structure of sunspots below the surface.
– Providing the most detailed and precise measurements of the temperature structure, the interior rotation and gas flows in the solar interior.
– Measuring the acceleration of the slow and fast solar wind.
– Identifying the source regions and acceleration mechanism of the fast solar wind in the magnetically “open” regions at the Sun’s poles.
– Discovering new dynamic solar phenomena such as coronal waves and solar tornadoes.
As of April 2013, SOHO has discovered over 2400 comets.
The observatory was meant to operate till 1998, but has continued successfully.
In November 2012, a mission extension lasting until December 2014 was approved.