  HelioSwarm (HS) is a NASA Medium-Class Explorer mission of the Heliophysics
Division designed to explore the dynamic three-dimensional mechanisms
controlling the physics of plasma turbulence, a ubiquitous process occurring in
the heliosphere and in plasmas throughout the universe. This will be
accomplished by making simultaneous measurements at nine spacecraft with
separations spanning magnetohydrodynamic and sub-ion spatial scales in a
variety of near-Earth plasmas. In this paper, we describe the scientific
background for the HS investigation, the mission goals and objectives, the
observatory reference trajectory and instrumentation implementation before the
start of Phase B. Through multipoint, multiscale measurements, HS promises to
reveal how energy is transferred across scales and boundaries in plasmas
throughout the universe.
