  Coronal Mass Ejections (CMEs) and Corotating Interaction Regions (CIRs) are
major sources of magnetic storms on Earth and are therefore considered to be
the most dangerous space weather events. The Observatories of Solar Corona and
Active Regions (OSCAR) mission is designed to identify the 3D structure of
coronal loops and to study the trigger mechanisms of CMEs in solar Active
Regions (ARs) as well as their evolution and propagation processes in the inner
heliosphere. It also aims to provide monitoring and forecasting of
geo-effective CMEs and CIRs. OSCAR would contribute to significant advancements
in the field of solar physics, improvements of the current CME prediction
models, and provide data for reliable space weather forecasting. These
objectives are achieved by utilising two spacecraft with identical
instrumentation, located at a heliocentric orbital distance of 1~AU from the
Sun. The spacecraft will be separated by an angle of 68$^{\circ}$ to provide
optimum stereoscopic view of the solar corona. We study the feasibility of such
a mission and propose a preliminary design for OSCAR.
