PrelimDesignNEPmission - Preliminary Design of Nuclear...

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American Institute of Aeronautics and Astronautics 1 Preliminary Design of Nuclear Electric Propulsion Missions to the Outer Planets Chit Hong Yam, * T. Troy McConaghy, K. Joseph Chen * and James M. Longuski School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907-2023 Nuclear electric propulsion is expected to open new doors in deep space exploration. We study direct rendezvous missions to the outer planets which employ a constant-thrust, constant specific-impulse engine. We also consider how gravity assist can augment the capability of nuclear electric propulsion. We present numerical examples of gravity-assist missions to the outer planets, which use an engine similar to that of the Jupiter Icy Moons Orbiter. For example, in an Earth-Venus-Earth-Jupiter-Pluto mission, the spacecraft launches with a V of 2.2 km/s and rendezvous with Pluto in 10.5 years, with a propellant mass fraction of 50%. We demonstrate the benefit of using intermediate gravity-assist bodies (e.g. Venus, Earth and Mars) to decrease both mission duration and propellant cost. Nomenclature a 0 = initial acceleration of the spacecraft, mm/s 2 g = standard acceleration due to gravity, m/s 2 I sp = specific impulse, s m ± = propellant mass flow rate, mg/s m f = final spacecraft mass, kg m 0 = initial spacecraft mass, kg P = power, kW R J = radius of Jupiter T = engine thrust, N V = hyperbolic excess speed, km/s V = magnitude of a change in velocity, km/s η = overall engine efficiency I. Introduction N ambitious mission to Jupiter is being planned – the Jupiter Icy Moons Orbiter 1,2 (JIMO) mission. Although the details are uncertain, the JIMO spacecraft will be massive (as much as 20,000 kg after escape at Earth) and will use nuclear electric propulsion 3 (total engine power of about 100 kW) with a high specific impulse (about 6,000 s). The launch is expected in 2011. 1 Upon arrival at Jupiter, the spacecraft will spiral into orbit around Callisto, then Ganymede, and finally Europa – the Icy Moons of Jupiter. If such a potent propulsive system is built, then a natural question to ask is what other missions might be flown. In this paper we will focus not on the Jupiter Icy Moons Orbiter Mission, but instead on innovative missions to the outer planets that are made possible by this new propulsion technology. Our principal goal is to consider how a massive nuclear electric propulsion (NEP) engine, used in conjunction with gravity assists from the inner planets, can deliver a spacecraft to the outer planets (Jupiter, Saturn, Uranus, Neptune and Pluto). The technique of reaching the outer planets via gravity assists (but without electric propulsion) has been discussed for many decades beginning in the 1960’s with the pioneering work of Minovitch, 4,5 Flandro, 6 Deerwester, 7 and Niehoff.
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This note was uploaded on 01/15/2012 for the course AAE 490 taught by Professor Andrisani during the Fall '09 term at Purdue University-West Lafayette.

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PrelimDesignNEPmission - Preliminary Design of Nuclear...

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