Preparatory study: Accessing asteroids on horseshoe orbits

There is a handful number of particular asteroids on "Horseshoe Orbits". Eventually, some of them would run close to L1 or L2 points, from where a spacecraft may fly along the horseshoe orbits with infinitesimally small departure/return ΔV. So, if the flight period becomes long but still admissible, those asteroids might be interesting targets for exploration or capture missions. Yet, from the synodic period point of view, they appear hardly accessible and not practical. The paper investigates a qualitative approach to reach potential targets on horseshoe orbits thanks to zero-velocity curves, and discuss the possibility of application to known objects.