BOX B.1
Jupiter Europa Orbiter

Jupiter Europa Orbiter

images

Key Challenges

•   Radiation

–   Systems engineering for electronics vault repartitioning

–   “Fail operational” fault management to handle environment

•   Mass

–   Uncertainty in instrument and shielding mass

–   Low launch margin for this development phase

–   Overall sensitivity of system mass to changes

•   Power

–   System impacts of changing number and design of radioisotope power system units

–   Availability of plutonium-238

•   Instruments

–   Uncertainties in design of model payload

Science Objectives

•   Explore Europa to investigate its habitability

•   Key science issues addressed:

–   Characterizing the extent of the europan ocean and its relation to the deeper interior

–   Characterizing the ice shell and any subsurface water, including the nature of the surface-ice-ocean exchange

–   Determining global surface compositions and chemistry, especially related to habitability

–   Understanding the formation of surface geology, including sites of recent or current activity, and characterizing sites for future in situ exploration

–   Understanding Europa in the context of the Jupiter system

Key Parameters

•   Model Payload

–   Ocean: Laser Altimeter, Radio Science

–   Ice: Ice Penetrating Radar

–   Chemistry: Vis-IR Imaging Spectrometer, Ultraviolet Spectrometer, and Ion and Neutral Mass Spectrometer

–   Geology: Thermal Instrument, Narrow Angle Imager, Wide and Medium Angle Imager

–   Particles and Fields: Magnetometer, Particle and Plasma Instrument

•   Five Multi-Mission Radioisotope Thermoelectric Generators

•   Launch Mass: 4,745 kg

•   Launch Date: 2020 (on Atlas V 551)

•   Orbit: 100-200 km Europa Orbit + Jovian Tour

 

Ganymede orbiter. JEO would place a spacecraft equipped with remote sensing and radar investigations into a close orbit around Europa for a period of at least 1 year. Prior to insertion into Europa orbit, JEO would complete a 2-year tour of the jovian system using the Galilean satellites for gravity-assist flybys. Given the complex gravitational environments of the jovian system, the long-term stability of JEO’s orbit about Europa cannot be guaranteed. Therefore, to meet planetary protection requirements at the end of its mission, JEO would be either commanded to impact onto the surface of Europa in a controlled manner at a selected site, or ejected from Europa orbit and placed on a collision course with Jupiter. The combination of this controlled end-of-mission scenario, along with standard clean-assembly procedures, selective application of dry-heat microbial reduction, and the sterilizing effect of the jovian radiation environment, would allow JEO to meet planetary protection requirements. The integrated cost of these requirements, while not a primary driver of the mission budget, is nonetheless significant.

As of this writing, budget pressures have led to a descoping and replanning of JEO and probably of the entire EJSM program. Current studies are focused on developing less costly JEO mission concepts. Once those studies are complete and the budget picture is clarified, NASA will decide whether and how to proceed with Europa explora-



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement