A comparative reliability analysis of ballistic deployments on binary asteroids

Abstract

Small body missions can significantly benefit from deploying small landing systems onto the surface of the visited object. Despite the potential benefit that they may bring, deployments of landers in small body environments may entail significant mission design challenges. This paper thus addresses the potential of ballistic landing opportunities in binary asteroid moons from a mission design perspective, particularly focusing on reliability aspects of the trajectories. Two binaries that were previously identified as target bodies in several missions/proposals, Didymos and 1996 FG3, are considered in this paper. The dynamics near them are modelled by means of the Circular

Robust Trajectory Design for Ballistic Landings on Dimorphos

“…The investigation for ballistic landing trajectories specifically on the secondary of the Didymos system has seen an increase in interest in recent years for the contribution to the Hera mission, see e.g. [11] and [12].…”

“…Previous research (e.g. [8] and [12]) performed the trajectory design initially using only a nominal model of the system and only afterwards investigated the effect of uncertainties. In this work, these two analyses are combined to estimate the landing trajectory that has minimal touchdown velocity for a specific landing area, given all the uncertainties present in the system.…”

“…with no closed-loop control of the translational state during descent, are good options for the landing maneuver. The main drawback of ballistic landings are their sensitivity to errors in the deployment maneuver and uncertainties in the dynamical parameters [8]. Therefore, when designing ballistic landing trajectories, the impact of uncertainties needs to be taken into account.…”

“…large touchdown velocity and/or shallow impact angle). Other approaches involving bisection based methods to find minimum touchdown velocity landing trajectories for any landing location on the body have also been investigated in [8] and [14]. These methods give insight into what dynamically is the minimum touchdown velocity of a certain location, but it cannot consider any additional constraints on the trajectory itself.…”

Preliminary mission profile of Hera’s Milani CubeSat

“…ESA's Hera mission (Michel et al, 2018), the European component of the Asteroid Impact and Deflection Assessment (AIDA) international collaboration (Cheng et al, 2015), plans on deploying two CubeSats in the proximity of binary system 65803 Didymos, after arrival in 2027. The idea is supported by several SmallSat/CubeSat studies that have been performed in the past few years with reference to Hera (formerly known as AIM), to study the feasibility of deploying a small lander Lavagna, 2018, 2016;Lange et al, 2018;C ¸elik et al, 2019) and possibly CubeSats (Kohout et al, 2018;Lasagni Manghi et al, 2018;Perez et al, 2018) in the close proximity of Didymos. These were anticipated by detailed studies of the dynamical environment near binary asteroid systems (Tardivel and Scheeres, 2013;Tardivel, 2016;Ferrari et al, , 2014C ¸elik and Sánchez, 2017), some with direct application to the Didymos case study (Dell'Elce et al, 2017;Capannolo et al, 2019Capannolo et al, , 2016.…”