A Science Strategy for the Exploration of Europa (1999) / Chapter Skim
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3 Strategy for the Post-Galileo Exploration of Europa
3 Strategy for the Post-Galileo Exploration of Europa
Pages 31-40
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From page 31... ...
Characterizations on a wide range of scales are required not only to enable a more complete understanding of Europa's complex history, but also to provide critical information for potential landing operations, such as site selection and the global and regional scientific context in which to understand lander results. Galileo results suggest that the general geology of Europa can be characterized with imaging data of a few hundred meters per pixel covering a substantial fraction of the surface (note that as indicated in Table 3.1, only a very small fraction of the surface was imaged at this resolution during GEM)
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From page 32... ...
Flybys of Europa during the nominal Galileo mission and GEM will yield information on the lowest-degree and lowest-order spherical harmonic contributions to the gravity field. The degree-two gravity field has been used to infer the moment of inertia of Europa and its layered internal structure.)
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From page 33... ...
Radio tracking of the orbiting spacecraft could measure periodic changes in the gravitational field. The detection of the periodic variations in the gravitational field of the larger mass redistribution that would occur if Europa has an ocean would also readily determine if indeed there was an ocean.
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From page 34... ...
hich an ocean might be ~ ~ O detectable by an orbiting radar system.7 Of course, the actual performance may be better or worse depending on the true temperature and chemical composition of the icy shell. CHARACTERIZATION OF DEEP INTERIOR STRUCTURE AND DYNAMICAL PROCESSES Measurements of the topography, gravity field, and magnetic field of Europa will aid efforts to characterize Europa's deep internal structure and dynamics.
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From page 35... ...
It is more likely that many geochemical properties of the europan environment will have to be characterized before the probability of the origin and development of life there can be sensibly assessed. Among the properties of interest are the presence and concentrations of chemicals that might serve as nutrients or as poisons, the energy sources available that might support life, the present and past redox states, organic materials that might be residues from living organisms or prebiotic processes, or the characteristic times for physical processes, both in sequence and duration.
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From page 36... ...
Neutral and ion mass spectrometers with a resolution of 1 emu will be required. Such instruments have a long history of successful use on sounding rockets, Earth orbiters, and planetary spacecraft such as the Pioneer Venus orbiter; a neutral mass spectrometer is currently on its way to Mars aboard Japan's Nozomi spacecraft.
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From page 37... ...
As a precursor to detailed study, certain geological and geophysical properties of the ice need to be characterized to provide context for interpretation of geochemical properties of the ice and the possibility of life. Lateral and vertical temperature profiles and the rate of interior heating, if known, would constrain models of the interior composition of the aqueous outer shell and the distribution of heat-producing, radioactive elements below that crust, which in turn
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From page 38... ...
Measurements of concentration ratios of a few well-chosen elements in the material would provide general information about the rocky mantle, including probable abundances of elements such as potassium and phosphorus that are essential for life on Earth. Isotopic properties of the material can constrain time scales for a variety of events, including europan igneous differentiation and ice movement.
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From page 39... ...
This enables precipitation of hydrated oxyhydroxides of Fe3+, which in turn scavenge the ocean of many trace ions. Measurements of the pH of europan ocean water, together with the other geochemical measurements, would reveal much about the water-rock chemical reactions and the likely composition of the rock.
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From page 40... ...
Hibbits, P.D. Martin, and the Galileo Team, "Candidate Surface Materials of the Icy Galilean Satellites That Might Be Distinguished by the Galileo SSI Camera," abstract, 29th Lunar and Planetary Science Conference, Lunar and Planetary Institute, Houston, Texas, 1998.
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