  Coronal mass ejections (CMEs) and solar energetic particles (SEPs) are two
phenomena that can cause severe space weather effects throughout the
heliosphere. The evolution of CMEs, especially in terms of their magnetic
structure, and the configuration of the interplanetary magnetic field (IMF)
that influences the transport of SEPs are currently areas of active research.
These two aspects are not necessarily independent of each other, especially
during solar maximum when multiple eruptive events can occur close in time.
Accordingly, we present the analysis of a CME that erupted on 2012 May 11
(SOL2012-05-11) and an SEP event following an eruption that took place on 2012
May 17 (SOL2012-05-17). After observing the May 11 CME using remote-sensing
data from three viewpoints, we evaluate its propagation through interplanetary
space using several models. Then, we analyse in-situ measurements from five
predicted impact locations (Venus, Earth, the Spitzer Space Telescope, the Mars
Science Laboratory en route to Mars, and Mars) in order to search for CME
signatures. We find that all in-situ locations detect signatures of an SEP
event, which we trace back to the May 17 eruption. These findings suggest that
the May 11 CME provided a direct magnetic connectivity for the efficient
transport of SEPs. We discuss the space weather implications of CME evolution,
regarding in particular its magnetic structure, and CME-driven IMF
preconditioning that facilitates SEP transport. Finally, this work remarks the
importance of using data from multiple spacecraft, even those that do not
include space weather research as their primary objective.
