The “sonic region” of the Sun corona remains extremely difficult to
observe with spatial resolution and sensitivity sufficient to understand
the fine scale phenomena that govern the quiescent solar corona, as well
as phenomena that lead to coronal mass ejections (CMEs), which influence
space weather. Improvement on this front requires eclipse-like
conditions over long observation times. The space-borne coronagraphs
flown so far provided a continuous coverage of the external parts of the
corona but their over-occulting system did not permit to analyse the
part of the white-light corona where the main coronal mass is
concentrated. The proposed PROBA-3 Coronagraph System, also known as
ASPIICS (Association of Spacecraft for Polarimetric and Imaging
Investigation of the Corona of the Sun), with its novel design, will be
the first space coronagraph to cover the range of radial distances
between similar to 1.08 and 3 solar radii where the magnetic field plays
a crucial role in the coronal dynamics, thus providing continuous
observational conditions very close to those during a total solar
eclipse.
PROBA-3 is first a mission devoted to the in-orbit demonstration of
precise formation flying techniques and technologies for future European
missions, which will fly ASPIICS as primary payload. The instrument is
distributed over two satellites flying in formation (approx. 150m apart)
to form a giant coronagraph capable of producing a nearly perfect
eclipse allowing observing the sun corona closer to the rim than ever
before.
The coronagraph instrument is developed by a large European consortium
including about 20 partners from 7 countries under the auspices of the
European Space Agency. This paper is reviewing the recent improvements
and design updates of the ASPIICS instrument as it is stepping into the
detailed design phase
