Jovian Tour Design for Orbiter and Lander Missions to Europa

Europa is one of the most interesting targets for solar system exploration, as its ocean of liquid water could harbor life. Following the recommendation of the Planetary Decadal Survey, NASA commissioned a study for a flyby mission, an orbiter mission, and a lander mission. This paper presents the moon tours for the lander and orbiter concepts. The total delta v and radiation dose would be reduced by exploiting multi-body dynamics and avoiding phasing loops in the Ganymede-to- Europa transfer. Tour 11-O3, 12-L1 and 12-L4 are presented in details and their performaces compared to other tours from previous Europa mission studies

Jovian Tour Design for Orbiter and Lander Missions to Europa

This paper presents trajectory options for the lander and for the orbiter missions, while the trajectory design for the flyby option was presented in a previous work

An Overview of the Jupiter Europa Orbiter Concept's Europa Science Phase Orbit Design

Jupiter Europa Orbiter (JEO), the proposed NASA element of the proposed joint NASA-ESA Europa Jupiter System Mission (EJSM), could launch in February 2020 and conceivably arrive at Jupiter in December of 2025. The concept is to perform a multi-year study of Europa and the Jupiter system, including 30 months of Jupiter system science and a comprehensive Europa orbit phase of 9 months. This paper provides an overview of the JEO concept and describes the Europa Science phase orbit design and the related science priorities, model pay-load and operations scenarios needed to conduct the Europa Science phase. This overview is for planning and discussion purposes only

Evolutionary Computing for Low-thrust Navigation

The development of new mission concepts requires efficient methodologies to analyze, design and simulate the concepts before implementation. New mission concepts are increasingly considering the use of ion thrusters for fuel-efficient navigation in deep space. This paper presents parallel, evolutionary computing methods to design trajectories of spacecraft propelled by ion thrusters and to assess the trade-off between delivered payload mass and required flight time. The developed methods utilize a distributed computing environment in order to speed up computation, and use evolutionary algorithms to find globally Pareto-optimal solutions. The methods are coupled with two main traditional trajectory design approaches, which are called direct and indirect. In the direct approach, thrust control is discretized in either arc time or arc length, and the resulting discrete thrust vectors are optimized. In the indirect approach, a thrust control problem is transformed into a costate control problem, and the initial values of the costate vector are optimized. The developed methods are applied to two problems: 1) an orbit transfer around the Earth and 2) a transfer between two distance retrograde orbits around Europa, the closest to Jupiter of the icy Galilean moons. The optimal solutions found with the present methods are comparable to other state-of-the-art trajectory optimizers and to analytical approximations for optimal transfers, while the required computational time is several orders of magnitude shorter than other optimizers thanks to an intelligent design of control vector discretization, advanced algorithmic parameterization, and parallel computing

Searching for Subsurface Oceans on the Moons of Uranus Using Magnetic Induction

The icy moons of Uranus may contain subsurface oceans. Such oceans could be detected and characterized using measurements of magnetic fields induced by Uranus' time-varying magnetospheric field. Here we explore this possibility for Uranus's five major moons, with a focus on Ariel. We find that the magnetic field at each moon is dominated by the synodic frequency with amplitudes ranging from ∼4 nT at Oberon up to ∼300 nT at Miranda. If these bodies contain oceans with sufficient thicknesses (>∼3–40 km) and conductivities (>2 S m−1) even underlying relatively thick (∼50 km) ice shells, the induced surface fields should have amplitudes exceeding the typical ∼1 nT sensitivity of spacecraft magnetometry investigations. Furthermore, the magnetic field variations at the moons span periods ranging from 1 to 103 h. These could enable long-term measurements to separately constrain ocean and ice thicknesses and ocean salinity