Near rectilinear orbits around the moon as operational orbit for the future deep space gateway

The aim of this paper is to revise the suitability of Near- Rectilinear Halo Orbits (NRHOs) as long-term destinations for a new crew-tended space station; referred here as Deep Space Gateway (DSG). NRHOs are a subset of the halo families characterized by promising stability properties. The document presents the formal definition and identification of NRHOs, as in the CR3BP model. Dynamical substitutes of the NRHOs are also refined in the Bi-Circular Model (BCM) by means of a multiple shooting method. Key features such as lunar south-pole coverage, station keeping requirements and accessibility of the orbit are then analysed. Several maintenance strategies based on three different underlying principles are considered and, finally, the accessibility of NRHOs from the Earth and polar Moon orbits is investigated

Opportunities for ballistic soft landing in binary asteroids

Remote sensing instrumentation onboard missions to asteroids is paramount to address many of the fundamental questions in modern planetary science. Yet in situ surface measurements provide the “ground truth” necessary to validate and enhance the science return of these missions. Nevertheless, because of the dynamical uncertainties associated with the environment near these objects, most missions spend long periods of times stationed afar. Small landers can be used much more daringly, however, and thus have already been identified as valuable assets for in situ exploration. This paper explores the potential for ballistic landing opportunities enabled by the natural dynamics found in binary asteroid systems. The dynamics near a binary asteroid are modeled by means of the circular restricted three-body problem, which provides a reasonable representation of a standard binary system. Natural landing trajectories are then sought that allow for a deployment from the exterior region and touchdown with minimum local-vertical velocity. The results show that, although landing on the main body of the system would require an effective landing system capable to dissipate excess of energy and avoid bouncing off the asteroid, the smaller companion offers the prospect of simple ballistic landing opportunities

Opportunities for ballistic soft landing in binary asteroids

Remote sensing instrumentation onboard missions to asteroids is paramount to address many of the fundamental questions in modern planetary science. Yet in situ surface measurements provide the “ground truth” necessary to validate and enhance the science return of these missions. Nevertheless, because of the dynamical uncertainties associated with the environment near these objects, most missions spend long periods of times stationed afar. Small landers can be used much more daringly, however, and thus have already been identified as valuable assets for in situ exploration. This paper explores the potential for ballistic landing opportunities enabled by the natural dynamics found in binary asteroid systems. The dynamics near a binary asteroid are modeled by means of the circular restricted three-body problem, which provides a reasonable representation of a standard binary system. Natural landing trajectories are then sought that allow for a deployment from the exterior region and touchdown with minimum local-vertical velocity. The results show that, although landing on the main body of the system would require an effective landing system capable to dissipate excess of energy and avoid bouncing off the asteroid, the smaller companion offers the prospect of simple ballistic landing opportunities

Asteroid belt multiple flyby options for M-Class Missions

Addressing many of the fundamental questions in modern planetary science, as well as in ESA’s cosmic vision, requires a comprehensive knowledge of our Solar System’s asteroid belt. This paper investigates potential opportunities for medium-class asteroid belt survey missions in the timeframe of 2029-2030. The study has been developed in support to CASTAway Asteroid Spectroscopic Survey mission proposal, which is to be submitted to the latest ESA’s medium size mission call. CASTAway envisages the launch of a small telescope with relatively straightforward (i.e. high TRL) remote sensing instrumentation to observe asteroids at a long-range (i.e. point source), but also at a short-range, resolving them at ~10 m resolution. This paper presents a challenging multi-objective optimization problem and discusses the feasibility of such a mission concept. A baseline trajectory is presented that meets both ESA’s medium size mission constraints and the science requirements. The trajectory loops through the asteroid belt during 7 years, visiting 10 objects of a wide range of characteristics, providing sufficient survey time to obtain compositional information for 10,000s of objects and the serendipitous discovery of also 10,000s of 10-m class asteroids. The methodology developed has enabled the exploration of the entire design space for a conservative Soyuz-launch performance, and has found a total of 200 different tour opportunities of the asteroid belt; all compliant with ESA’s 5th call for medium size missions

Semi-analytical perturbative approaches to third body resonant trajectories

In the framework of multi-body dynamics, successive encounters with a third body, even if well outside of its sphere of influence, can noticeably alter the trajectory of a spacecraft. Examples of these effects have already been exploited by past missions such as SMART-1, as well as are proposed to benefit future missions to Jupiter, Saturn or Neptune, and disposal strategies from Earth’s High Eccentric or Libration Point Orbits. This paper revises three totally different descriptions of the effects of the third body gravitational perturbation. These are the averaged dynamics of the classical third body perturbing function, the Öpik’s close encounter theory and the Keplerian map approach. The first two techniques have respectively been applied to the cases of a spacecraft either always remaining very far or occasionally experiencing extremely close approaches to the third body. However, the paper also seeks solutions for trajectories that undergo one or more close approaches at distances in the order of the sphere of influence of the third body. The paper attempts to gain insight into the accuracy of these different perturbative techniques into each of these scenarios, as compared with the motion in the Circular Restricted Three Body Problem

Combined low-thrust propulsion and invariant manifold trajectories to capture NEOs in the Sun-Earth circular restricted three-body problem

In this paper, a method to capture near-Earth objects (NEOs) incorporating low-thrust propulsion into the invariant manifolds technique is investigated. Assuming that a tugboat-spacecraft is in a rendez-vous condition with the candidate asteroid, the aim is to take the joint spacecraft-asteroid system to a selected periodic orbit of the Sun-Earth restricted three-body system: the orbit can be either a libration point periodic orbit (LPO) or a distant prograde periodic orbit (DPO) around the Earth. In detail, low-thrust propulsion is used to bring the joint spacecraft-asteroid system from the initial condition to a point belonging to the stable manifold associated to the final periodic orbit: from here onward, thanks to the intrinsic dynamics of the physical model adopted, the flight is purely ballistic. Dedicated guided and capture sets are introduced to exploit the combined use of low-thrust propulsion with stable manifolds trajectories, aiming at defining feasible first guess solutions. Then, an optimal control problem is formulated to refine and improve them. This approach enables a new class of missions, whose solutions are not obtainable neither through the patched-conics method nor through the classic invariant manifolds technique.Peer Reviewe

Hazardous near Earth asteroid mitigation campaign planning based on uncertain information on fundamental asteroid characteristics

Given a limited warning time, an asteroid impact mitigation campaign would hinge on uncertainty-based information consisting of remote observational data of the identified Earth-threatening object, general knowledge of near-Earth asteroids (NEAs), and engineering judgment Due to these ambiguities, the campaign credibility could be profoundly compromised. It is therefore imperative to comprehensively evaluate the inherent uncertainty in deflection and plan the campaign accordingly to ensure successful mitigation. This research demonstrates dual-deflection mitigation campaigns consisting of primary (instantaneous/quasi-instantaneous) and secondary (slow-push) deflection missions, where both deflection efficiency and campaign credibility are taken into account The results of the dual-deflection campaign analysis show that there are trade-offs between the competing aspects: the launch cost, mission duration, deflection distance, and the confidence in successful deflection. The design approach is found to be useful for multi-deflection campaign planning, allowing us to select the best possible combination of missions from a catalogue of campaign options, without compromising the campaign credibility.Peer Reviewe

Analysis of Ballistic Escape Opportunities via Multiple Lunar Swingbys for Fast and Flexible Missions

To escape the gravitational attraction of the Earth-Moon system and begin an interplanetary trajectory a spacecraft must first fly a hyperbolic escape orbit. To achieve so, interplanetary missions typically make use of medium-to-heavy launchers and dedicated injections, with the associated high cost. This therefore limits the possibility of developing low budget missions. However, the current democratization of space is enabling an increasing number of lower-cost proposals that need more efficient Earth escape routes. Performing gravity assist maneuvers with the Moon offers such an effective interplanetary gateway. This paper aims at studying feasible escape trajectory options compatible with the boundary conditions of the 2022 F-class mission call by the European Space Agency. However, the analysis is relevant for any mission capable of entering a trans-lunar transfer with the minimum energy to reach the Moon. To that end, it revises the state-of-the-art of ballistic escape trajectory design and then presents a streamline of solution refinement which begins on a patched-2BP, with Moon flybys modeled as a linked conic. This seed solution is subsequently refined into the CR3BP, which validates the simplified dynamical framework. The process continues with the Sun-Earth-Moon BCR4BP, which enables to study the influence of the Sun perturbation. The results prove the existence of different trajectory possibilities capable of reaching hyperbolic escape velocities of up to 1.5 km/s using two Moon gravity assists in less than 90 days

High-fidelity trajectory design to flyby near-Earth asteroids using Cubesats

Fast development of CubeSat technology now enables the first interplanetary missions. The potential application of CubeSats to flyby near-Earth asteroids is explored in this paper in consideration of CubeSats' limited propulsive capabilities and systems constraints. Low-energy asteroid flyby trajectories are designed assuming a CubeSat is initially parked around to the Sun-Earth Lagrange points. High-impulse and low-thrust trajectories with realistic thrusting models are computed first in the Circular Restricted Three-Body Problem (CR3BP), and then in a high-fidelity ephemeris model. Analysis in the ephemeris model is used to confirm that trajectories computed in the CR3BP model also exist in a more realistic dynamical model, and to verify the validity of the results obtained in CR3BP analysis. A catalogue of asteroid flyby opportunities between years 2019 and 2030 is provided, with 80¿m/s of available ¿V and departure from halo orbits around the first and second Sun-Earth Lagrange points (of similar size to those typically used by scientific missions). Results show that the CR3BP model can serve as an effective tool to identify reachable asteroids and can provide an initial estimation of the ¿V cost in the ephemeris model (with ±15¿m/s accuracy). An impulsive maneuver model can also provide an accurate estimation of the ¿V requirement for a CubeSat equipped with a high-impulse thruster (with 4¿m/s accuracy), even if its thrust magnitude is small and requires duty cycling; low-thrust ¿V requirements, however, may differ significantly from the impulsive results (±15¿m/s).Peer ReviewedPostprint (published version

Earth resonant gravity assists for asteroid retrieval missions

Asteroids and comets are of strategic importance for science in an effort to uncover the formation, evolution and composition of the Solar System. Near-Earth objects (NEOs) are of particular interest because of their accessibility from Earth, but also because of their speculated wealth of material resources. The possibility of retrieving entire NEOs from accessible heliocentric orbits and moving them into the Earth’s neighbourhood is today a credible possibility considered by NASA, within its Asteroid Initiative Framework, and examined in several recent scientific publications. This paper searches for asteroid retrieval trajectories that benefit from several resonant Earth encounters to decrease at each encounter the transfer ¿v cost. Particularly, the paper focuses on the Amor asteroid population, which have the encounters always occurring outside the Earth’s sphere of influence. Thus, the patched conic approximation is rendered essentially not applicable. Numerical exploration in the framework of the Circular Restricted Three Body Problem (CR3BP) becomes computationally expensive when combined with the sensitivities of multiple Earth encounters. Hence, this paper proposes a 3D extension of the energy kick function to rapidly assess all possible third-body effects into the asteroid’s trajectory. The osculating elements of the asteroid can be updated by means of Picard’s first iteration on each Keplerian element, where the perturbing forces of the third body (i.e., the Earth) are given by the Lagrange’s planetary equations. This allows a rapid scanning process of sequences of Earth encounters that may in turn allow a favourable perturbation to the asteroid orbital elements.Peer ReviewedPostprint (published version