In-situ measurements of solar energetic particles with the SupraThermal Electrons, Ions and Neutrals sensor onboard Solar Orbiter

The SupraThermal Electrons, Ions and Neutrals (STEIN) sensor is part of the Energetic Particle Detector (EPD) instrument suite onboard the upcoming Solar Orbiter mission. With a planned launch in early 2017, it will orbit the Sun with an perihelion as close as 0.28 AU. In the later phase of the mission Solar Orbiter will go to higher inclinations enabling observations of the polar regions of the Sun. STEIN provides low-energy measurements of electrons, ions and neutral particles from a few keV up to 100 keV. Its two anti-parallel telescope heads are aligned along the orbit averaged Parker spiral direction, and enable the detection of particle streams travelling sunwards and anti-sunwards along the heliospheric magnetic field. Each head includes several solid state detector (SSD) pixels and an electrostatic deflection system, which, in conjunction with the onboard magnetometer, allows to resolve pitch-angle distributions. We present the current development status as well as the expected performance of the sensor as part of EPD.