Optimization of Return Trajectories for Orbital Transfer Vehicle between Earth and Moon

In this paper, optimum trajectories in Earth Transfer Orbit (ETO) for a lunar transportation system are proposed. This paper aims at improving the payload ratio of the reusable orbital transfer vehicle (OTV), which transports the payload from Low Earth Orbit (LEO) to Lunar Low Orbit (LLO) and returns to LEO. In ETO, we discuss ballistic flight using chemical propulsion, multi-impulse flight using electrical propulsion, and aero-assisted flight using aero-brake. The feasibility of the OTV is considered. 1. Nomenclature a = semimajor axis [km] dr a = radius direction component of thrust [km/s ] d a θ = argument direction component of thrust [km/s] dh a = normal direction of the orbit plane component of thrust [km/s] T a = thrust acceleration magnitude [km/s ] e = eccentricity [-] f = true anomaly [rad] h = altitude [km] sp I = specific impulse [sec] l = mean longitude [rad] M = mean anomaly [rad] n = mean motion [rad/s] p = semi-latus rectum [km] r = orbital radius [km] a r = altitude of apogee [km] p r = altitude of perigee [km] in Q = heating rate on stagnation point [W/m ] out Q = radiation energy [W/m ] e R = radius of the Earth [km] N R = radius of curvature of nose [m] max. T = temperature of stagnation point [K] f t = total flight time [sec] p t = orbital period [sec] w = argument of periapsis [rad] ε = emissivity [-] φ = in-plane thrust steering angle [rad] ρ = density of atmosphere [kg/m] σ = coefficient of Stefan-Boltzmann [W/(mK)] 2. Introduction The moon is recognized as an important destination for space science and exploration. To explore the moon efficiently, it is conceived that the special spacecraft is used in each segment such as LEO, Lunar/Earth Transfer Orbit (LTO/ETO), and LLO. For example, the OTV is the transportation spacecraft used in LTO/ETO. This paper aims at improving the payload ratio of the reusable OTV. The reusable OTV system is roughly composed of the payload module, the propulsion module, and the fuel cartridge. The payload module (included man) is separated from the OTV in LTO and is reached LLO by its single injection. The other modules (not included man) are returned to LEO through ETO. In this research, we focus on the optimization problem of return trajectories with small fuel consumption, because the return flight in ETO is not constrained the flight time and the safety compared to the flight in LTO. In ETO, we discuss ballistic https://ntrs.nasa.gov/search.jsp?R=20080012692 2017-08-27T23:08:06+00:00Z