ROADMAP - FROM LAB TO SPACE: EXPERIMENTAL SCATTERING MATRICES OF MARTIAN DUST ANALOGUES.
O. Muñoz, J. Martikainen, J.C. Gómez Martı́n, Instituto de Astrofı́sica de Andalucı́a, CSIC-IAA, Granada,
Spain. (olga@iaa.es), T. Jardiel, M. Peiteado, A.C. Caballero, Instituto de Cerámica y Vidrio, CSIC-ICV, Madrid,
Spain, G. Wurm, T. Becker, J. Teiser, University of Duisburg-Essen (UDE), Duisburg, DE, J. Merrison, K.
Rasmussen, A. Waza, Aarhus University (AU), Aarhus, DK, A. C. Vandaele, Y. Willame, L. Neary, F. Daerden, Z.
Filmon, A. Piccialli, L. Trompet, Royal Belgian Institute for Space Aeronomy, Brussels, BE.

We present experimental scattering matrix elements
as functions of the scattering angle of three Martian dust
analogue samples (JSC Mars 1, MMS2, and MGS1).
The measurements are performed at the IAA Cosmic
Dust Laboratory at a wavelength of 640 nm.

Introduction
Dust aerosol particles scatter and absorb solar radiation playing a key role in determining the thermal structure of Martian atmosphere. In the context of the EU
funded RoadMap project (http://roadmap.aeronomie.be)
we aim to generate an optically relevant Mars dust analogue as far as size and mineralogy is concerned. The
experimental study is motivated by the lack of satisfactory modelling approaches traditionally used to mimic
the role of mineral dust in the Martian atmosphere. A
major advantage of experimental measurements at visible wavelengths is that we can deal with real ensembles
of dust particles covering relatively broad size ranges
(including the resonance region). However, a systematic
study of the impact of different physical properties on
scattering of the sample under study remains extremely
challenging due to the difficulty in finding the appropriate samples. In RoadMap we use processing routines
imported from the field of functional, nano- and microceramics research for the synthesis of the dust analogues
with tailored properties.

Martian Analogue Samples
We are studying three Martian dust analogue samples:
JSC Mars 1 (Johnson Space Center regolith simulant
[Allen (1998)]; MMS-2 (Enhanced Mojave Mars 2 Simulant); and MGS-1 (Mars Global Simulant) [Cannon et
al. 2019]. Table 1 presents the mineral description for
the three analogue samples. Retrieved optical constants
in the UV-vis-NIR are presented by Martikainen et al.
This conference.
The bulk samples have been milled, sieved, and
subsequently dispersed for producing well-defined narrow size distributions spanning over a broad range in
the scattering size parameter domain, namely: ref f ∼
0.1µm; ref f ∼ 1µm; ref f ∼ 10 − 20µm. In this way

Table 1: Bulk major element chemistry for the JSC Mars-1
(JSC1), Enhanced Mojave Mars 2 (MMS-2), and Mars Global
(MGS-1) simulants.
Oxide
SiO2
T iO2
Al2 O3
Cr2 O3
F e2 O3
F eO
M nO
CaO
M gO
N a2 O
K2 O
P2 O5
SO3
Cl
SUM

JSC1
43.5
3.8
23.3
15.6
0.3
6.2
3.4
2.4
0.6
0.9
100

MMS-2
43.8
0.83
13.07
0.04
18.37
0.13
7.98
6.66
2.51
0.37
0.13
6.11
100

MGS-1
50.8
0.3
8.9
0.1
0.1
3.7
16.7
3.4
0.3
0.4
2.1
0.55
100

we will be able to disentangle size and composition effects on the scattering behaviour of our dust analogue
samples.
Experimental Scattering Matrices
The scattering matrices of our samples are measured
at the IAA COsmic DUst LABoratory (CODULAB)
located at the Instituto de Astrofı́sica de Andalucı́a,
Granada, Spain. For a detailed description of the experimental apparatus, calibration process, and data acquisition we refer to [Muñoz et al. (2010)]. As an example
in Fig.1 we present the measured scattering matrix for
the MMS2 at 640 nm.
All matrix elements (except F11 itself) are normalized to F11 , that is, we consider Fij /F11 , with i, j =1 to
4 with the exception of i = j =1. The values of F11 (θ)
are normalized so that they are equal to 1 at θ=30◦ .
The function F11 (θ), normalized in this way, is called
the phase function or scattering function. As shown in
Fig.1, the experimental phase function presents the typical behavior for irregular aerosols i.e. Strong forward
peak and flat dependence on the scattering angle at side-

Experimental scattering matrices of Martian dust analogues.

JSC reff=16.2µm; veff=0.34

0,3

1000
100

1
0,8

0,2

0,6

10
0,1

0,4

1
0

0,1

F11

0,01
0

30

60

-0,1
90 120 150 180 0

30

60

0,5

0
-0,5
F33/F11
0

30

60

0
-0,1
-0,2
-0,3
-0,4
90 120 150 180 0

Scattering Angle (deg)

0

90 120 150 180

0,5
0,4
0,3
0,2
0,1

1

-1

0,2

-F12/F11

F22/F11
0

30

60

90 120 150 180

1
0,5

0
-0,5
F44/F11

F34/F11

-1
30

60

90 120 150 180

Scattering Angle (deg)

0

30

60

90 120 150 180

Scattering Angle (deg)

Figure 1: Measured scattering matrix elements for the JSC sample ( ref f = 16.2µm : vef f = 0.34µm).

Experimental scattering matrices of Martian dust analogues.
and back-ward directions.
The experimental scattering matrices will be used
to check the validity of state-of-the-art numerical techniques based on simplified model particles to reproduce
the scattering behaviour of realistic poly-disperse irregular particles. We will present preliminary results based
on tri-axial ellipsoids and hexahedral particles.
Acknowledgements: This project has received funding from the European Union’s Horizon 2020 research
and innovation programme under grant agreement No
101004052.

References
[Allen (1998)] Allen, C. C., Morris, R. V., Jager, K. M.,
Golden, D. C., Lindstrom, D. J., Lindstrom, M. M.
and Lockwood, J. P. 1998. Lunar and Plnaetary Science Conference, 29.
[Cannon et al. (2019)] Cannon K. M., D. T. Britt, T. M.
Smith, R. F. Fritsche, Batcheldor, D. 2019. ICarus,
317, 470-478
[Muñoz et al. (2010)] Muñoz, O. Moreno, F., Guirado,
D., Ramos, J. L., López, A., Girela, F., Jerónimo,
J. M., Costillo, L. P., and Bustamante, I. 2010. JQSRT,
111, 187-196.