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ISS Science for Everyone

Science Objectives for Everyone
The main objective of the Selective Optical Diagnostics Instrument (SODI-DCMIX) is the measurement of the diffusion coefficients of selected ternary mixtures, taking advantage of the reduced gravity environment available on board the International Space Station (ISS). A combination of different and complementary techniques are used to characterize flight candidate samples among water-based and hydrocarbon mixtures. Experimental results from space experiments, performed in the Selectable Optical Diagnostic Instrument, are used to test thermodiffusion theories and develop physical and mathematical models for the estimation of (thermo)diffusion coefficients.
Science Results for Everyone
Tiny traffic! We can’t see them do it, though molecules in fluids and gases constantly move and collide. When temperature differences cause that movement – which is called the Soret effect – scientists can track it, by measuring changes in temperature and movement of mass, in the absence of gravity. This investigation went to space to measure mixtures of tetrahydronapthtalene (THN), isobutylbenzene (IBB), and n-dodecane (nC12). Researchers measured the separation of these chemicals, and calculated the numbers for the Soret effect for these chemicals. Because the Soret effect occurs in underground oil reservoirs, the results will help us better understand such reservoirs.

The following content was provided by Z Zaghir, Valentina Shevtsova, and is maintained in a database by the ISS Program Science Office.
Information provided courtesy of the Erasmus Experiment Archive.
Experiment Details


Principal Investigator(s)
Z Zaghir, Canada
Valentina Shevtsova, University of Brussels, Brussells, Belgium

H Bataller, France
A Bou-Ali, Spain
M Dejmek, Canada
Atsuki Komiya, Tohoku University, Katahira, Japan
W Köhler, Germany
Tatiana Lyubimova, Perm State University, Perm, Russia
Satoshi Matsumoto, Osaka City University, Osaka, Japan
A Mojtabi, France
I Ryzhkov, Russia
S Semenov, Russia
v Van Vaerenbergh, Belgium
S Wiegand, Belgium

European Space Agency (ESA), Noordwijk, Netherlands

Sponsoring Space Agency
European Space Agency (ESA)

Sponsoring Organization
Information Pending

Research Benefits
Earth Benefits, Scientific Discovery

ISS Expedition Duration
September 2013 - March 2014; March 2016 - April 2017; -

Expeditions Assigned

Previous Missions
Information Pending

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Experiment Description

Research Overview
The main purpose of SODI DCMIX is the measurement of diffusion coefficients of selected ternary mixtures taking advantage of the reduced gravity environment available on board the ISS. This work consists of three stages:
a) the determination of diffusion data requirements for petroleum reservoir models;
b) the simultaneous measurement of the Soret diffusion coefficients in binary and in tertiary systems;
c) the refinement of a multicomponent transport model applied to petroleum reservoir evaluation.

Fluids and gases are never at rest, even if they appear to be when viewed by the naked eye. But molecules are constantly moving and colliding even though there is no microscope powerful enough to see the phenomenon. Scientists are interested in observing and measuring these movements because they reveal important, practical information such as how heat spreads in a fluid and how quickly fluids mix.

Creating accurate models of how fluids heat is harder than it might seem. School physics classes can work out how long it would take to boil a liter of water, but what if the water were mixed with oil or a multitude of different liquids? Measuring liquid mixtures at rest is not always possible on Earth because heavier elements in a mixture will follow gravity and sink to the bottom.

A mixture on the International Space Station is free from the constraints of gravity, and will not separate. SODI-DCMIX exploits this fact to record temperatures of mixtures in space, using optical techniques to understand how molecules move in liquids. This experiment is a continuation from previous missions.

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Space Applications
This investigation is applied to new scientific knowledge, and not specifically to advances in space exploration.

Earth Applications
Understanding the fundamentals of thermodiffusion and thereby being able to predict its effects is of direct interest for example to oil companies that use computer simulations to model underground oil reservoirs and to optimize their exploitation.

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Operational Requirements and Protocols
Information Pending

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Decadal Survey Recommendations

Information Pending

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Results/More Information

SODI DCMIX studies the Soret effect.  The Soret effect is the movement of heat and mass that is caused by a difference in temperature.  This is different from convection, where hotter, less dense matter rises upward compared to cooler, denser material.  Gravity attracts denser matter more than less dense matter.  To measure the Soret effect, you have to measure the changes in heat and mass, while avoiding the effects of gravity.  That is why the SODI experiment is in space, on the ISS, to study the Soret effect.

Three chemicals, THN, IBB and nC12, were mixed and contained within cells, which were flown to ISS.  These three chemicals are similar to the chemicals that are found in oil reservoirs (Ahadi 2013).  From December 2011 to January 2012 they were studied as a part of the SODI investigation.

The first set of sample cells performed well. It was determined that a good design for controlling temperatures was achieved (Mialdun 2013). Another set of samples showed that the chemicals separated in the same way, in two separate attempts; because of this, the sessions could be repeated in a way that makes the data useful (Ahadi 2013).
During other sessions it was shown that THN separated towards the hotter side of the cell, while IBB and nC12 separated towards the cooler side.  By comparing the samples, the teams were able to find the number that measures the Soret effect for those chemicals (Ahadi 2015, Galand 2015, Mialdun 2015).

Understanding the Soret effect benefits us on Earth because it occurs in places like oil reservoirs, underneath the Earth’s surface.  The more we know about the Soret effect, the more we can learn about oil reservoirs (Ahadi 2013).

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Results Publications

    Mialdun A, Shevtsova V.  Temperature dependence of Soret and diffusion coefficients for toluene–cyclohexane mixture measured in convection-free environment. The Journal of Chemical Physics. 2015 December 14; 463(22): 224902. DOI: 10.1063/1.4936778. PMID: 26671399.

    Galand Q, Van Vaerenbergh S.  Contribution to the benchmark for ternary mixtures: Measurement of diffusion and Soret coefficients of ternary system tetrahydronaphtalene-isobutylbenzene-n-dodecane with mass fractions 80-10-10 at 25 °C. European Physical Journal E. 2015 April 27; 38(4): 10 pp. DOI: 10.1140/epje/i2015-15026-3.

    Ahadi A, Van Varenbergh S, Saghir MZ.  Measurement of the Soret coefficients for a ternary hydrocarbon mixture in low gravity environment. The Journal of Chemical Physics. 2013; 138(20): 204201. DOI: 10.1063/1.4802984. PMID: 23742467.

    Bou-Ali A, Ahadi A, de Mezquia DA, Galand Q, Gebhardt M, Khlybov OA, Kohler W, Larranaga M, Legros J, Lyubimova TP, Mialdun A, Ryzhkov II, Saghir MZ, Shevtsova V, Van Vaerenbergh S.  Benchmark values for the Soret, thermodiffusion and molecular diffusion coefficients of the ternary mixture tetralin+isobutylbenzene+n-dodecane with 0.8-0.1-0.1 mass fraction. European Physical Journal E. 2015; 38(30). DOI: 10.1140/epje/i2015-15030-7.

    Mialdun A, Legros J, Yasnou V, Sechenyh V, Shevtsova V.  Contribution to the benchmark for ternary mixtures: Measurement of the Soret, diffusion and thermodiffusion coefficients in the ternary mixture THN/IBB/nC12 with 0.8/0.1/0.1 mass fractions in ground and orbital laboratories. European Physical Journal E. 2015 April; 38(4): 112. DOI: 10.1140/epje/i2015-15027-2. PMID: 25916232.

    Mialdun A, Minetti C, Gaponenko YA, Shevtsova V, Dubois F.  Analysis of the thermal performance of SODI instrument for DCMIX configuration. Microgravity Science and Technology. 2013 February 6; 25(1): 83-94. DOI: 10.1007/s12217-012-9337-2.

    Ahadi A, Saghir MZ.  The microgravity DSC-DCMIX1 mission onboard ISS: Experiment description and results on the measurement of the Soret coefficients for isobutylbenzene, dodecane, tetralin ternary hydrocarbons mixtures. Experimental Thermal and Fluid Science. 2016 June; 74: 296-307. DOI: 10.1016/j.expthermflusci.2015.12.020.

    Jurado R, Gavalda J, Simon MJ, Pallares J, Laveron-Simavilla A, Ruiz X, Shevtsova V.  Some considerations on the vibrational environment of the DSC-DCMIX1 experiment onboard ISS. Acta Astronautica. 2016 October 6; epub: 31 pp. DOI: 10.1016/j.actaastro.2016.09.033.

    Ahadi A, Saghir MZ.  Determination of the glass wall effect in optical measurement of temperature in liquid using Mach–Zehnder interferometer. Applied Optics. 2015 May; 54(13): D74-D81. DOI: 10.1364/ao.54.000d74.

    Ahadi A, Saghir MZ.  Contribution to the benchmark for ternary mixtures: Transient analysis in microgravity conditions. European Physical Journal E. 2015 April 27; 38(4): 10 pp. DOI: 10.1140/epje/i2015-15025-4. PMID: 25916230.

    Khlybov OA, Ryzhkov II, Lyubimova TP.  Contribution to the benchmark for ternary mixtures: Measurement of diffusion and Soret coefficients in 1,2,3,4-tetrahydronaphthalene, isobutylbenzene, and dodecane onboard the ISS. European Physical Journal E. 2015 April 27; 38(4): 16 pp. DOI: 10.1140/epje/i2015-15029-0.

    Olle J, Dubert D, Gavalda J, Laveron-Simavilla A, Ruiz X, Shevtsova V.  Onsite vibrational characterization of DCMIX2/3 experiments. Acta Astronautica. 2017 November; 140: 409-419. DOI: 10.1016/j.actaastro.2017.09.007.

    Santos CI, Shevtsova V, Ribeiro CF.  Isothermal molecular diffusion in mixtures containing toluene, cyclohexane and methanol. European Physical Journal E. 2017 April; 40(4): 40. DOI: 10.1140/epje/i2017-11526-4. PMID: 28382586.

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Ground Based Results Publications

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ISS Patents

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Related Publications

    Ryzhkov II, Shevtsova V.  On the cross-diffusion and soret effect in multicomponent mixtures. Microgravity Science and Technology. 2009 January; 21(1-2): 37-40. DOI: 10.1007/s12217-008-9081-9.

    Ryzhkov II, Shevtsova V.  On thermal diffusion and convection in multicomponent mixtures with application to the thermogravitational column. Physics of Fluids. 2007; 19(2): 027101. DOI: 10.1063/1.2435619.

    Ahadi A, Saghir MZ.  New experimental method to measure pure and cross diffusion coefficients of transparent ternary mixtures using Mach–Zehnder interferometry. Optics and Lasers in Engineering. 2014 August; 59: 72-81. DOI: 10.1016/j.optlaseng.2014.03.009.

    Blanco P, Bou-Ali MM, Platten JK, de Mezquia DA, Madariaga JA, Santamaria C.  Thermodiffusion coefficients of binary and ternary hydrocarbon mixtures. The Journal of Chemical Physics. 2010; 132(11): 114506. DOI: 10.1063/1.3354114. PMID: 20331304.

    Koniger A, Wunderlich H, Kohler W.  Measurement of diffusion and thermal diffusion in ternary fluid mixtures using a two-color optical beam deflection technique. The Journal of Chemical Physics. 2010; 132(17): 174506. DOI: 10.1063/1.3421547. PMID: 20459173.

    Srinivasan S, Saghir MZ.  Experimental approaches to study thermodiffusion – A review. International Journal of Thermal Sciences. 2011 July; 50(7): 1125-1137. DOI: 10.1016/j.ijthermalsci.2011.02.022.

    Larabi MA, Mutschler D, Mojtabi A.  Thermal gravitational separation of ternary mixture n-dodecane/isobutylbenzene/tetralin components in a porous medium. The Journal of Chemical Physics. 2016 June 28; 144(24): 244902. DOI: 10.1063/1.4954244. PMID: 27369539.

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Related Websites

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NASA Image: ISS038E009255 - Mike Hopkins, Expedition 38 Flight Engineer (FE), preparing to install and activate the Selectable Optics Diagnostic Instrument (SODI) cell array two in the Microgravity Science Glovebox (MSG) for the Selectable Optics Diagnostic Instrument-Diffusion Coefficient in Mixtures 2 (SODI-DCMIX 2) experiment, in the U.S. Laboratory. SODI-DCMIX 2 is supporting research to determine diffusion coefficients in different petroleum field samples and refine petroleum reservoir models to help lead to more efficient extraction of oil resources. Photo taken during Expedition 38

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NASA Image: ISS049E002305 - View taken during Selectable Optics Diagnostic Instrument (SODI) DSC Hardware Setup the MSG Work Volume.

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NASA Image: ISS049E002308 - View taken during Selectable Optics Diagnostic Instrument (SODI) DSC Hardware Setup the MSG Work Volume.

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NASA Image: ISS049E002644 - NASA astronaut Kate Rubins works on Selectable Optical Diagnostics Instrument Experiment Diffusion Coefficient Mixture-3 (SODI) DCMix-3 Installation inside the station’s Microgravity Science Glovebox. The glovebox is one of the major dedicated science facilities inside the Destiny laboratory and provides a sealed environment for conducting science and technology experiments. The glovebox is particularly suited for handling hazardous materials when the crew is present.

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