Terminator orbits around the triple asteroid 2001-SN263 in application to the deep space mission ASTER

We search for stable orbits in the vicinity of the triple asteroid system, 2001-SN263, which will be target of the deep space mission ASTER, currently under study by the Brazilian space agency (AEB). Our numerical simulations include gravitational forces caused by the three bodies of 2001-SN263, higher-order terms of the primary’s gravity field, planetary perturbations and solar radiation pressure. Due to the low gravity of the triple system, the spacecraft’s motion becomes complex and the faint gravity forces of the secondaries are exceeded by radiation pressure from the Sun. However, we show that the so-called ”terminator orbits” within the asteroid system at distances between 6–10 km to the primary body can be found. A spacecraft parked in such orbit will stay within the system for several months without the need to adjust its trajectory. Additionally, these stable orbits will allow investigating the entire primary body including its poles as well as the two secondary bodies. We also show that a laser altimeter, which is part of ASTER’s primary payload, will benefit significantly from these terminator orbits.