|Introduction to Solar Orbiter||Home|
The Sun's atmosphere and the heliosphere represent uniquely accessible domains of space, where fundamental physical processes common to solar, astrophysical and laboratory plasmas can be studied in detail and under conditions impossible to reproduce on Earth or to study from astronomical distances.
The results from missions such as Helios, Ulysses, Yohkoh, SOHO, and TRACE have enormously advanced our understanding of the solar corona, the associated solar wind and the three-dimensional heliosphere. However, we have reached the point where further in-situ measurements, now much closer to the Sun, together with high-resolution imaging and spectroscopy from a near-Sun and out-of-ecliptic perspective, promise to bring about major breakthroughs in solar and heliospheric physics.
The Solar Orbiter will, through a novel orbital design and its state-of the-art instruments, provide exactly the required observations.
The Solar Orbiter will for the first time
The scientific goals of the Solar Orbiter are
The underlying basic questions which are relevant to astrophysics in general are
In particular, we want
The near-Sun interplanetary measurements together with simultaneous remote sensing observations of the Sun will permit us to disentangle spatial and temporal variations during the co-rotational phases. They will allow us to understand the characteristics of the solar wind and energetic particles in close linkage with the plasma conditions in their source regions on the Sun. By approaching as close as 45 solar radii, the Solar Orbiter will view the solar atmosphere with unprecedented spatial resolution (35 km pixel size, equivalent to 0.05 arcsec from Earth). Over extended periods the Solar Orbiter will deliver images and data of the polar regions and the side of the Sun not visible from Earth.
The Solar Orbiter will achieve its wide-ranging aims with a suite of sophisticated instruments. Note that due to the Orbiters proximity to the Sun the instruments can be fairly small, compared to instrumentation required at the Earths orbit.
The payload includes two instrument packages, optimised to meet the solar and heliospheric science objectives:
The Solar Orbiter spacecraft benefits from technology developed for the Mercury Cornerstone mission. This allows such an ambitious mission to be carried out within the frame of an F mission.
Using solar electric propulsion (SEP) in conjunction with multiple planetary swing-by manoeuvres, it will take the Solar Orbiter only two years to reach a perihelion of 45 solar radii at an orbital period of 149 days. Within the nominal 5 year mission phase, the Solar Orbiter will perform several swing-by manoeuvres at Venus, in order to increase the inclination of the orbital plane to 30o with respect to the solar equator. During an extended mission phase of about two years the inclination will be further increased to 38°.
The spacecraft will be 3-axis stabilised and always Sun-pointed. Given the extreme thermal conditions at 45 solar radii (25 solar constants), the thermal design of the spacecraft has been considered in detail during the assessment study and viable solutions have been identified. Telemetry will be handled via X-band low-gain antennae, and by a 2-axis steerable Ka-band high-gain antenna.
The total mass of the Solar Orbiter is compatible with a Soyuz-Fregat launch from Baikonur.