The Planetary Terrestrial Analogues Library (PTAL) – An exclusive lithological selection of possible martian earth analogues

Abstract

The Planetary Terrestrial Analogues Library (PTAL) is a dedicated lithological collection that currently consists of 102 terrestrial rock samples selected to be possible Mars analogues. The ultimate goal is improving future remote mineralogical and petrological analysis on Mars and other planetary bodies based on selected analysis such as Near- Infrared Reflectance Spectroscopy (NIR), Raman spectroscopy, Laser Induced Breakdown Spectroscopy (LIBS) and X-ray diffraction (XRD).

Most international standards applied in the remote martian mineralogical and petrological analysis have so far been based on single, pure mineral analysis, with minimal interferences from other naturally occurring minerals. Here we present detailed lithological sample evaluations based on field appearance along with optical and XRD analysis of key terrestrial rock types. The detailed mineralogical and petrological descriptions give good basis for more complete lithological understanding. In combination with NIR, LIBS and Raman analysis of the very same samples PTAL aims at improving mineralogical and petrographical information from future rovers on Mars e.g. NASA's Mars2020-Perseverance and ESA and Roscosmos's ExoMars - Rosalind Franklin.

The PTAL sample collection covers exclusively collected volcanic, magmatic and various sedimentary rocks and regoliths from well-known locations all over the world. These samples have a general composition comparable to what is currently known from Mars. The strength of this sample collection is its origin as common whole rock samples, in which minerals occur in their natural settings. It thereby allows studying possible detection interferences and a comparison of the sensitivity of the different techniques. The collection, in addition, forms the base for various alteration studies to better understand and explain alteration and weathering conditions on Mars.

The complete results and sample preparations will be available to all scientists interested.