66 th International Astronautical Congress, Jerusalem, Israel. Copyright ©2015 by the International Astronautical Federation. All rights reserved. IAC-15-D4.3.9 Page 1 of 9 IAC-15-D4.3.9 TRAJECTORY OPPORTUNITIES TO ARJUNA-TYPE ASTEROIDS FOR ASTEROID MINING MISSIONS Scott Dorrington School of Mechanical and Manufacturing Engineering, University of New South Wales, and Australian Centre for Space Engineering Research, Australia, s.dorrington@unsw.edu.au Nathan Kinkaid School of Mechanical and Manufacturing Engineering, University of New South Wales, and Australian Centre for Space Engineering Research, Australia, n.kinkaid@unsw.edu.au John Olsen School of Mechanical and Manufacturing Engineering, University of New South Wales, Australia, j.olsen@unsw.edu.au This paper calculates the ΔV, stay-time and mission duration of trajectories to accessible asteroids, and uses them to compare the various asteroid mining approaches. The paper focuses on Arjuna-type asteroids, a class of near-Earth asteroids with very Earth-like orbits. Arjuna-type asteroids are inaccessible during most of their long synodic periods; however offer many low-ΔV launch opportunities over several years around times of opposition. Optimal launch dates and times of flight for the Earth- Asteroid and Asteroid-Earth trajectories are used to identify several classes of trajectory combinations with 1, 1.5, and 2-year durations. The Net Present Value method is used to develop figures of merit to assess the economic viability of each trajectory combination and mining approach over the duration of accessibility. I. INTRODUCTION Asteroid mining has been proposed as a means of reducing the cost of space exploration by creating a space-based infrastructure in Earth orbit. Asteroids have an abundance of mineral resources that could potentially be used to facilitate the refuelling and construction of spacecraft in Earth orbit [1, 2]. Several approaches to asteroid mining have been proposed including the retrieval of a whole asteroid, processing ore at the asteroid, and even the in-situ production of propellant from asteroid material for the return trajectory. In order to be viable, an asteroid mining mission would be required to return usable asteroid resources to Earth orbit at a lower cost than launching the same resources from Earth. Space missions are often designed to minimize the total mission delta-V (ΔV) – the cumulative change in velocity needed to transfer between trajectories throughout the mission. Asteroids accessible via short-duration and low-ΔV trajectories are ideal targets for asteroid mining missions. NASA has conducted several studies using these parameters to produce lists of potential asteroid targets: NASA’s Trajectory Browser [3], and Near-Earth Object Human Space Flight Accessible Targets Study (NHATS) [4]. While mission duration and ΔV are good indicators for initial screening of potential targets, in order to compare the available trajectories to find an optimal target and mission design, more appropriate parameters are needed. This paper will identify the classes of return trajectories available for a near-Earth asteroid, using figures of merit associated with economic analysis. II. NEAR-EARTH ASTEROIDS The asteroids that are most attractive for asteroid mining missions are near-Earth asteroids with low- eccentricity, low-inclination, and semi-major axis similar to that of the Earth. Arjuna-type asteroids are a sub-group of near-Earth asteroids that meet these requirements, having very Earth-like orbital parameters. Arjunas are considered co-orbital companions of the Earth, experiencing a 1:1 mean motion resonance [5]. There are several classes of co-orbital motion, distinguished by the long-term motion of their mean longitude (angular separation) relative to Earth. These classes include Horseshoe, Tadpole, Quasi-satellite, and Passing orbits (figure 1). Return trajectories to these asteroids are possible when they come within around 50 0 of the Earth. The mean longitude of Horseshoe and Tadpole orbits librate about 180 0 and ±60 0 respectively. As a result, they rarely come close enough to the Earth to become accessible. Quasi-satellites on the other hand, librate about 0 0 and experience multiple periodic close approaches to the Earth, offering many launch opportunities for return trajectories. Passing asteroids that are not trapped in any of these resonances