Properties of the Near-Sun Solar Wind

The solar wind is a hot, tenuous plasma that flows from the Sun into deep space. At the Earth, its interaction with our planet's magnetic field causes the aurora but can also damage satellites and disrupt communications and power grids. Although the solar wind can be sampled with a number of spacecraft, and we have ground based measurements of the Sun's surface and atmosphere, there is still much that we do not know about how the Sun creates the solar wind and how it evolves between its source and its arrival at the Earth.

In 2017, the European Space Agency will launch Solar Orbiter, which will travel closer to the Sun than ever before, within Mercury's orbit, to measure the solar wind in the inner solar system. Imperial are building the magnetic field instrument for Solar Orbiter.

In preparation for the launch of Solar Orbiter, it is planned to re-visit earlier measurements of the solar wind near the Sun, from the twin Helios spacecraft that were in operation in the 1970's and 1980's. These measurements are high quality, but advances in computer power in the last thirty years mean that they offer rich pickings for new discoveries. There is also more recent data from the Messenger spacecraft in orbit around Mercury.

We will be using Helios and Messenger data to study fundamental properties of the solar wind in the inner solar system: small scale solar wind structures; the interactions of different solar wind streams; and the development of shocks and turbulence.