Accessibility assessment and trajectory design for multiple Near-Earth-asteroids exploration using stand-alone CubeSats

Continuous breakthrough of related technologies enables stand-alone interplanetary CubeSats, requiring primary propulsion systems for orbit maneuvering and trajectory control, to be applied in deep space missions. The application of stand-alone interplanetary CubeSats to explore multiple Near-Earth asteroids (NEAs) is investigated in this paper. Indirect and direct transfer trajectories to rendezvous with NEAs are designed assuming CubeSats are firstly parked on the Sun-Earth Halo orbits. To select candidate target asteroids that CubeSats could potentially reach, two assessment methods of the accessibility of NEAs are proposed based on the characteristic of the Sun-Earth Circular Restricted Three-Body Problem (CRTBP). Compared to the traditional methods, the two methods derive analytical expressions of the velocity increments of the transfer trajectories, which can simplify the accessibility assessments. By applying the assessment methods, the list of asteroids, ranked with respect to the accessibility of NEAs between the years 2020 and 2031, is produced. Then the transfer trajectories from the Sun-Earth Halo orbits to asteroids are calculated by numerical optimization method in the CRTBP model. It can be found that the two methods could serve as the effective tools to assess the accessibility of asteroids and the accuracy of the assessment methods of indirect transfer and direct transfer are ±0.02 km/s and ±0.1 km/s, respectively.