2 December 1995
Scientists ability to study the Sun, the star that sustains life o Earth, took a massive leap forward today with the launch of SOHO, a sophisticated state-of-the-art spacecraft built by the European Space Agency (ESA).
"Understanding how the Sun behaves is of crucial importance to all of us on Earth. It affects our everyday lives" said Roger Bonnet, Director of Science at ESA, who witnessed SOHO's spectacular nighttime launch from Cape Canaveral. "When SOHO begins work in four months time, scientists will, for the first time, be able to study this star 24 hours a day, 365 days a year".
The 12 instruments on SOHO will probe the Sun inside out, from the star's very centre to the solar wind that blasts its way through the solar system. It will even listen to sounds, like musical notes, deep within the star by recording their vibrations when they reach the surface.
SOHO was launched from Cape Canaveral Air Station, Florida, atop an Atlas IIAS rocket, at 09:08 CET on Saturday 2 December 1995. The 1.6 tonne observatory was released into its transfer orbit from the rocket's Centaur upper stage about two hours after launch. It will take four months for the satellite to reach its final position, a unique vantage point, located 1.5 million kilometres from Earth, where the gravitational pull of the Earth and Sun are equal. From here, the Lagrange point, SOHO will have an unobstructed view of the Sun all year round. SOHO's launch was delayed from 23 November because a flaw was discovered in a precision regulator, which throttles the power of the booster engine on the Atlas rocket. The system was replaced and retested before the launch.
SOHO is a project of international cooperation between ESA and NASA. The spacecraft was designed and built in Europe, NASA provided the launch and will operate the satellite from its Goddard Space Flight Center, Maryland. European scientists provided eight of the observatory's instruments and US scientists a further three. The spacecraft is part of the international Solar-Terrestrial Science Programme, the next member of which is Cluster, a flotilla of four spacecraft that will study how the Sun affects Earth and surrounding space. Cluster is scheduled for launch by Ariane 5 end of April 1996.