Title:	Returning to Europa: can traces of surficial life be detected?
Authors:	Chela-Flores, J. Kumar, N.
Keywords:	Europa search for life biosignatures penetrators ion-traps biogeochemistry sulphur-reducing bacteria LAPLACE mission mass spectrometry
Issue Date:	Aug-2008
Publisher:	Cambridge University Press
Citation:	International Journal of Astrobiology, 2008, Vol.7, p263
Abstract:	There is at present a possibility for returning to Europa with LAPLACE, a mission to Europa and the Jupiter System for European Space Agency's Cosmic Vision Programme. The question of habitability by the identification of reliable bio-indicators is a major priority. We explain the options for approaching the question of selecting the right instrumentation for measuring the more abundant sulphur isotope, in spite of the fact that 32S is isobaric (same m/z) with 16O2. Two technologies are available for investigating the possible biogenicity of the surficial sulphur on the icy patches discovered by the Galileo mission. We argue that there is a need to use higher-order statistics in the data that are to be gathered with the instruments chosen for the payload (ion-traps for orbital measurements, or penetrators for surficial measurements). In particular, we argue in favour of data analysis taken from an orbital spacecraft that addresses fluctuations of the data retrieved, rather than the mean. For this purpose, we reconsider the significance of deviations of sulphur abundances relative to normal (meteoritic) values. In the present work, we consider the experimentally testable possibility of biogenically driven isotopic anomalies in the light of statistical data analysis. The fluctuation test that is being proposed in the context of future missions to Europa may well be appropriate to a laboratory experiment with sulphur-reducing bacteria with the corresponding isotopic fractionation.
Description:	Restricted Access. 12 months embargo for IRs.
URI:	http://hdl.handle.net/2289/3738
ISSN:	E-ISSN: 1475-3006 P-ISSN: 1473-5504
Alternative Location:	http://dx.doi.org/10.1017/S1473550408004242
Copyright:	2008 Cambridge University
Appears in Collections:	Research Papers (TP)

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