Fachbereich 14 - Geowissenschaften
Institut für Planetologie
Experimentelle Weltraumforschung

GENTNER - a Miniaturised Laser Instrument for Planetary in-situ Analysis

Planetary in-situ analysis is becoming one of the most important tools for exploring accessible celestial bodies. Chemical, mineralogical, structural, isotopic, and molecular information will provide stringent boundary conditions for the origin and evolution of these bodies and hence of the solar system. The past showed unprecedented examples of operating in-situ analysis instruments. Although their capabilities are re markable, these "first generation" instruments still suffered from constraints in terms of size, mass, and ope rations from the accommodating systems. While their operational scenario was more or less stationary, fu ture missions provide a high degree of mobility and call for new types of instrumentation. The overall goal of ExoMars, exobiologic research, requires advanced in-situ analytical tools to be characterized by

• short measurement duration: seconds instead of hours
• high sensitivity, high repetition rate, high reproducibility
• low mass, size, and resource needs
• high flexibility with respect to type, shape, and size of sample material
• robustness towards surface contamination like dust coverage

To "set the stage" for dedicated exobiology experiments - those to study in detail past or present forms of life - we propose an interdisciplinary instrument to determine rapidly and with relatively high sensitivity (down to 10 ppm) the concentrations of many elements in many Martian rocks, coarse fines and soil samples. At the same time the instrument will provide mineralogical information as well as information on possible organic components. This complementarity is essential to understand the results of de dicated exobiology experiments. The detection of the life-related elements H, C, N, O, P, S, and Fe and the investigation of their lateral and vertical distributions as well as their occurrences in the various Martian materials will be indicative of biologic activity. In addition, the almost complete knowledge of the ele mental inventory and the mineralogy is a pre requisite for under standing the geologic history of the visited sites, as well as of planet Mars as a whole. Finally, this versatile instrument is also excellently suited - in simplified versions - for missions to asteroids and comets.

The proposed novel instrument is a combination of

Laser-Plasma-Spectrometry (LIPS) and Raman-Spectroscopy.

This instrument is named GENTNER honouring the German physicist and cosmochemist Wolfgang Gentner (1906 - 1980).

GENTNER potentially meets the above requirements as demonstrated in a definition study carried out for the European Space Agency at research institutes and by industry in Germany. This new instrument greatly profits from synergetic effects - sharing e.g. the optical spectrometer, the lasers and onboard data re du cing facilities - as well as from recent developments in miniaturisation and from front-line laser research.

The basic GENTNER concept consists of one or more small, ultra-light-weight sensor heads mounted on an arm and/or near the tip of a drill, and the main mass components (pump laser, spec tro meter, computers etc.) installed on a rover. Optical fibres connect the sensor heads and the main components. Possibly it can be augmented by catho do luminescence (CL; for mineralogic aspects) or by laser induced fluorescence (LIF; for further "organic" aspects). An essential feature is the absence of sample preparation, a rather complex and risky operation in outer space.

GENTNER will perform hundreds of individual chemical and mineralogical ana lyses of all sample types within reach at all geologic sites visited. In addition, distant geologic units are accessible through the analysis of wind- and impact-transported individual coarse fines (~1 mm) samples. These analyses will not be obstructed by dust coverage since GENTNER allows for up to 2 mm depth profiling - a value of its own. At the same time GENTNER shall serve to grossly characterise samples prior to GC-MS and isotopic or microscopic studies in order to pre-select interesting samples for these experiments.

Although the individual components of GENTNER have already been studied to some extent in the laboratory, a dedicated la bo ra tory set-up of all components is required. Research on the interference of the techniques to be combined and on the optimisation of the components that also include effects of the Martian environment is needed. To build such a set-up and to develop in parallel critical flight components are the goals of the near future that, however, can only be pursued in frame of the Pasteur program.

Drittmittelgeber:

ESA

Beteiligte Wissenschaftler:

Elmar K. Jessberger, Ingrid Mann, Detlef Rost, Thomas Stephan, Iris Weber und das internationale GENTNER Team