Planetary Terrestrial Analogues Library (PTAL)

A new and exciting era of planetary space exploration started in 2000 with a plethora of in-situ and orbital missions in operation at terrestrial planets and small Solar System bodies. The characterisation of the surface of these planetary objects is one of the major goals of space exploration. In order to support these operations, reduction and analyses of the space mission data, the PTAL (Planetary Terrestrial Analogues Library) project aims to build and exploit a multi-instrument spectral data base and joint spectral interpretation tools.

Logo: PTAL project
Logo: The PTAL project

About the project

Both the understanding of alteration pathways and coordinated analyses of the surface of Mars from orbital and landed platforms with new and well-characterised spectral data will allow unprecedented interpretations of the climatic and environmental evolution for materials detected at new landing sites using our well-defined experimental parameter space for deriving conditions and evolution of environment and climate at Mars. Defining and characterising the ingredients for habitability at yet another planet will broaden our conception on the origin and evolution of life on our own planet, and prepare future investigations of forthcoming space missions in which several project members are highly involved.

We will determine mineral alteration pathways for natural and artificial terrestrial analogue materials under well-defined and controlled experimental conditions. The impact of varying environmental conditions will be tested to better constrain the geochemical aspect of habitable conditions on Mars, the prime target of this project. All natural and artificial rock samples and their alteration products will be characterised for the spectral library with commercial and dedicated spacecraft instrumentation (NIR, RAMAN, LIBS) under laboratory conditions, and where possible on in-situ field campaigns.


The main objective of the project is to build and exploit the spectral library Planetary Terrestrial Analogues Library (PTAL) for the characterisation of the mineralogical and geological evolution of terrestrial planets and small Solar System bodies. This aim will be achieved by conducting the following four tasks:

  1. Performing laboratory experiments under controlled conditions and documenting rock alteration of field-collected planetary (often Martian) analogue materials, so that the impact of varying of environmental conditions (e.g., gas pressure, temperature, pH-value) can be quantified. We will be able to characterise and define the geochemical aspect of habitable conditions on Mars, which is the prime target of this investigation.
  2. Characterising of rocks and their alteration/weathering products as input for the spectral library with standard commercial and dedicated spacecraft instrumentation (NIR, RAMAN, LIBS, XRD) under laboratory conditions and where possible on in-situ field campaigns at Earth analogue sites.
  3. Performing coordinated analyses of the Martian surface from both orbital and landed platforms with new spectral data.
  4. Developing a data base, which will allow users to jointly interpret laboratory results and newly gathered in-situ or remote sensing data using the instruments (LIBS, NIR, RAMAN) on board of current and future space missions (e.g., Hayabusa-2, Curiosity, ExoMars, Mars2020).


Comparing with Earth’s conditions and our understanding, driven by the still limited knowledge of the origin of life on Earth, results in a list of numerous requirements for favourable conditions for past and present habitability and development of biological signature hosting materials: (1) properties of available water like salinity, pH, and temperature; (2) the energy of water in the environment (e.g., quiet vs. energetic), which has implications for the stabilisation of microbial communities; (3) availability of raw materials necessary for life including the so-called CHNOPS elements and a source of electron donors, presence of mineral suites of mixed valence states for redox energy; (4) proximity to a paleo-surface to enable photosynthesis; (5) radiogenic elements for radiolysis; (6) protection from radiation like that provided by a planetary magnetic dipole field; (7) and the rate of burial, for example, in a lacustrine setting, which has implications for the viability and stability of microbial communities. Thus, we search for places in the Solar System for which such conditions comply or did comply in the past with the preserved geological record or current environmental state.

The variety of aqueous minerals identified to date are a testimony to a complex past water history and the alteration of crust-forming minerals on Mars, since these minerals span a wide range of geochemical environments. Their study in localised regions, or globally with a statistical approach, has furthermore revealed variations in time and space. A correlation with morphological features indicates that it is possible to decipher their original environments, based on the knowledge we gathered about Earth environments. Despite this diversity, some key minerals on Mars have not been detected yet, or have not been satisfactorily characterised. Future landing missions with the adequate measurements proposed here, are paramount to achieve this.

The alteration of rocks on Earth and Mars is driven by geochemical, mechanical and sometimes biological processes. On Earth, these processes can be tested and evaluated under laboratory conditions, as well as in nature, while for Mars and other planetary bodies we mainly rely on remotely detected mineral distributions and the interpretation of surface morphology to yield insight in the geological and climatic evolution of Mars or the respective planetary body. Merging these two very different lines of investigation is the goal of the PTAL project.


WP1 - Laboratory Experiments, Field Analog Site Studies: 

This WP led by University of Oslo (UiO) combines field campaigns to collect a variety of fresh and altered samples providing a broad spectral database for the natural and artificial primary lithologies and weathering products from Earth. In addition, selected samples will be reacted to further understand the formation of alteration phases at strictly controlled conditions in laboratory experiments.

WP2 - Spectral characterisation of laboratory and field samples

This WP is led by University Paris Sud (UPSud), and will provide the spectral characterisation of the natural and artificial mineral samples with the individual instruments (located at UPSud/IAS, IRAP, and UVA), either prototype or flight spare, deployed on the different active and future landers, and individual procedures to allow the full scientific exploitation of the spectra.

WP3 - Spectral characterisation of planetary surfaces from orbital and landed platforms

PTAL is to build a multi-instrument spectral database of natural and experimentally produced minerals. The base for this library is collected and observed within WP1 and WP2, while the actual library is set up in WP4. WP3 shall allow the team to make use of the new spectral information and apply them to space-based measurements of ongoing lander and orbital missions as well as missions, which will deliver data during the course of the project. The main goal of this WP is to produce jointly a high number of scientific publications based on European and international space data. We will try to address the aqueous history of Mars specifically, and the detection of alteration minerals specifically, and deriving tentatively periods of habitability, conditions for developing precursors of life.

WP4 - Spectral Library of IR, Raman and LIBS

The WP is led by the University of Valladolid (UVA). The main aim of the database is to allow the use of spectra stored for purposes related with comparison, identification, quantification and spectral calculation when spectroscopic instruments IR, Raman and LIBS operate in planetary missions and/or analysing materials in the field or in the laboratory. The spectra need to be classified in close correlation with the samples from which they were obtained.

WP5 - Management and Dissemination

This WP is led by the University of Oslo (UiO) as coordinator and main contact point for the European Commission.


This project is financed through the European Research Council in the H2020-COMPET-2015 programme.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 687302.

The project period is from 01.01.2016 - 31.12.2020.


Published May 13, 2016 10:58 PM - Last modified Oct. 5, 2016 2:20 PM