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Simulating thermal stress features on hot planetary surfaces in vacuum at high temperature facility in the PEL laboratory

Maturilli, Alessandro and Ferrari, Sabrina and Helbert, Jörn (2011) Simulating thermal stress features on hot planetary surfaces in vacuum at high temperature facility in the PEL laboratory. AGU 2011, 5-9 Dec 2011, San Francisco.

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Abstract

In the Planetary Emissivity Laboratory (PEL) at the Institute for Planetary Research of the German Aerospace Center (DLR) in Berlin, we set-up a simulation chamber for the spectroscopic investigation of minerals separates under Mercurial conditions. The chamber can be evacuated to 10-4 bar and the target samples heated to 700 K within few minutes, thanks to the innovative inductive heating system. While developing the protocol for the high temperature spectroscopy measurements we discovered interesting “morphologies” on the sample surfaces. The powders are poured into stainless steel cups of 50 mm internal diameter, 8 mm height and 3 mm depth, having a 5 mm thick base (thus leaving 3 mm free space for the minerals), and rim 1 mm thick. We selected several minerals of interest for Mercurial surface composition and for each of them we analyzed various grain size separates, to study the influence of grain dimensions to the process of thermal stressing. We observed that for the smaller grain size separate (0-25 µm) the thermal stress mainly induces large depressions and fractures, while on larger grain sizes (125-250 µm) small depressions and a cratered surface. Our current working hypothesis is that these features are mainly caused by thermal stress induced by a radiatively quickly cooling surface layer covering the much hotter bulk material. Further investigation is ongoing to understand the processes better. The observed morphologies exhibit surprising similarities to features observed at planetary scale size for example on Mercury and even on Venus. Especially the high resolution images provided currently from MESSENGER’S Mercury Dual Imaging System (MDIS) instrument has revealed plains dominated by polygonal fractures whose origin still have to be determined. Our laboratory analogue studies might in the future provide some insight into the processes creating those features

Document Type:Conference or Workshop Item (Poster)
Title:Simulating thermal stress features on hot planetary surfaces in vacuum at high temperature facility in the PEL laboratory
Authors:
AuthorsInstitution or Email of Authors
Maturilli, Alessandroalessandro.maturilli@dlr.de
Ferrari, SabrinaDipartimento di Geoscienze, Università degli studi di Padova, Italy
Helbert, Jörnjoern.helbert@dlr.de
Date:2011
Status:Published
Keywords:mercury, thermal stresses
Event Title:AGU 2011
Event Location:San Francisco
Event Type:international Conference
Event Dates:5-9 Dec 2011
Organizer:AGU
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):R - Vorhaben BepiColombo
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Terahertz and Infrared Sensors
Deposited By: Alessandro Maturilli
Deposited On:10 Jan 2012 12:48
Last Modified:10 Jan 2012 12:48

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