Precursor missions to SolOSolar Orbiter (SolO) will be a satellite orbiting the sun whose key research objectives focus on questions of how space is created and controlled heliosphere from the sun. To help answer this question, he will study solar wind formation in the corona, solar transients and flares, and the solar dynamo. SolO is not the first satellite to focus on the sun, and its research will build on that of several highly successful missions in the past. These include, but are by no means limited to; the Solar and Heliospheric Observatory (SoHO), a joint ESA and NASA mission whose aim was to investigate the outer and inner layers of the sun and observe solar winds; the Transition Region and Coronal Explorer (TRACE), a NASA mission that took numerous photos of the photosphere and transition region; Ulysses, another ESA/NASA mission that studied, among other things, solar winds; and the Earth Solar Relations Observatory (STEREO), a mission to study coronal mass ejections. In this report we will examine these four missions and their contribution to the SolO mission.Solar and Heliospheric ObservatoryThe Solar and Heliospheric Observatory is an ongoing mission that, despite being plagued by problems, has been active for more than 16 years beyond its first 2 years . life span of one year. [1] First launched in 1995 as a joint mission of NASA and the European Space Agency, its main objective was to study the various layers of the sun and their contribution to solar winds and heliophysics in general. SoHO was equipped with an array of instruments including UV cameras, spectrographs and interferometers. Among these, one of the most active instruments has been the Michelson Doppler Imager (MDI). This imaging tool osci...... middle of paper ......SoHO environmentConclusionTo conclude, it is clear that each space mission must both build on the knowledge and experience gained from previous missions and learn from the difficulties and challenges posed by its predecessors, whether in establishing orbit, communications, or calamities like the one faced by SoHO. Solar Orbiter will use all available information from these four missions to succeed. References[1] http://sohowww.nascom.nasa.gov/about/docs/SOHO_Fact_Sheet.pdf Accessed on 02/27/2014[2 ] Fleck, Müller, Haugan, Duarte & Siili, 10 years of SoHO ESA Science Bulletin.[3] Solar Orbiter Definition Study Report, ESA, 2011.[4] http://trace.lmsal.com/Project/Mission/mission.htm TRACE mission description website. Accessed on 02/28/2014[5] http://trace.lmsal.com/POD/TRACEpodarchive24.html Accessed on 01/3/2014