Multiple-spacecraft transfers to Sun-Earth distant retrograde orbits for asteroid detection missions

As demonstrated by the meteorite fall in Chelyabinsk, Russia, in February 2013, also asteroids with a diameter smaller than 40 m can enter the Earth’s atmosphere and cause a local damage on ground. For such small Potentially Hazardous Asteroids (PHAs) a short warning would be sufficient to have a protection plan in place on ground. However, small asteroids are difficult to be detected from ground, especially if they approach the Earth from the Sun direction, such as the Chelyabinsk object. For this reason, a multi-spacecraft mission was proposed to monitor PHAs from a telescope base orbiting on Distant Retrograde Orbits of the Sun – Earth system. This space-based system would allow increasing the warning time of asteroids incoming from the Sun
direction. In this article a trade-off analysis is performed on the DRO and constellation size based on some measures of the detection capabilities. Moreover, the transfer to selected DROs from a Low Earth Orbit is designed to minimise the total Δv and time to build the constellation.