ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), is the primary payload of PROBA-3. It makes use of the formation flying technique to form a giant coronagraph capable of producing continuous observational conditions very close to those during a total solar eclipse, but without the effects of the Earth’s atmosphere. The coronagraph is distributed over the two satellites flying in formation at approximately 150 m apart. The so-called Coronagraph Satellite carries the telescope and the so-called Occulter Satellite carries the occulter disc. This novel design allows ASPIICS to cover the range of radial distances between about 1.097 and 3 solar radii from the solar centre (4.24 in the corners of the field of view). The field of view of ASPIICS and its excellent stray-light rejection (unprecedented in comparison with other coronagraphs) make it uniquely suited for studies of the solar corona, as it fills the crucial observational gap between the fields of view of low-corona EUV imagers and conventional space coronagraphs.
ASPIICS combines observations of the corona in both an unpolarised and polarized wide-band (536 nm – 566 nm passband, at half maximum), as well as in the Fe XIV line (530.4 nm), and with images of prominences in the He I D3 line (587.7 nm). The polarisation angles are 0, 60 and 120 degrees.
ASPIICS is intended to address two major solar physics science objectives:
1) to understand the physical processes that govern the quiescent solar corona,
2) to understand the physical processes that lead to coronal mass ejections (CMEs) and determine space weather.