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Optically Stimulated Luminescence Dating (OSL)

Optically Stimulated Luminescence Dating (OSL)

The Optically Stimulated Luminescence Dating (OSL) technique determines the burial age of sedimentary deposits. This method utilizes he measurement of luminescence emitted by a sample at one wavelength during stimulation with light at a different wavelength. Dependent on the sample characteristics the emitted light is proportional to the dose accumulated since the last zeroing event (e.g. exposure to sunlight on the surface.

Up to now not a single dating technique has been developed for in-situ planetary exploration. The only information on the age of extraterrestrial planetary surfaces comes from the "crater-counting" method. This method has an inherent large error and low resolution and is completely inadequate for local geology. Luminescence dating has possibly the potential to open up a completely new discipline in planetary in-situ exploration. This assessment has a strategic value for the development of a new generation of in-situ instrumentation.

A laboratory model of the combined TL/OSL ready developed by Risø National Laboratory. (Image by courtesy of Risø National Laboratory).

Sedimentation processes on Mars are completely unexplored. However, remote observation gives a clear indication that aeolian and/or fluvial activity plays a major role in the transport of dust and formation of dust deposits. In addition, fluid phases may have contributed significantly to erosion and transport processes to form the Martian landscape. Dating of buried grains in sedimentary layers would give a crucial contribution to the understanding of surface forming processes and is essential for any further exploration of planet Mars.

It is therefore essential to develop a method, which can determine the chronology of sedimentary deposits. Such a technique must be incorporated into an instrument requiring low resources (mass, power, volume) and placed onto the surface of Mars. Since various sites on the Martian surface need to be visited, the instrument must be incorporated into a mobile surface rover having a soil penetration capability or a sample retrieval system.

The OSL method has been demonstrated its suitability in portable instruments during the fieldwork in sedimentary deposits on Earth. The Martian environment however differs considerably concerning environmental conditions and mineralogical composition of sedimentary deposits from Earth. A careful assessment of these aspects and the best suitable OSL technique itself is required prior a breadboard design.

The scope of the current activity is as follows:

  • To analyse, review and optimise the scientific requirements for a LD instruments appropriate to analyse the age of buried sedimentary soils below the Martian surface
  • To review and trade-off the best OSL techniques according the Martian surface mineralogy and geological setting
  • To set-up a measurement campaign on terrestrial analogue materials reflecting a known or assumed Martian mineralogy

This activity is carried out by Risø National Laboratory (Roskilde, Denmark) and University of Wales (Aberystwyth, UK).

Last Update: 1 September 2019
24-Jan-2022 17:39 UT

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