The Lagrangian points are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects (such as a satellite with respect to the Earth and Moon).
NEA (near earth asteroid) -> thrustarc-> stablemanifold-> target Lagrange point(SE [Sun Earth) L1/L2)
Why study SE (Sun Earth) L1/L2 first? Because if the NEA is in SE L1/L2 then it can be moved to EM (Earth Moon) L1/L2 through invariant manifolds (EM CR3BP)
If the final destination is a Lagrange point, low-thrust+ invariant manifolds might be more energy efficient than pure low-thrust. Thus, for a selected NEA, we might need smaller SEP (solar electric propulsion)
CR3BOP -The Circular Restricted 3-Body Problem describes the motion of a massless particle under the gravitational influence of two point masses m1 and m2, called primaries, in circular motion around their common centre of mass.
SE L1/L2: about 1.5 million km from the Earth
EM L1/L2: about 60,000 km from the Moon
1 AU: about 150 million km
1 LD: 384,403 km