1. Figures for Subsurface Hydrous Chlorides and Oxychlorine Salts (HyCOS)
as the Source Materials for Recurring Slope Lineae on Mars
Alian Wang1, Z. C. Ling2, Y. C. Yan1, Alfred S. McEwen3, Michael T. Mellon4, Michael D. Smith5, Bradley L. Jolliff1, James Head6
1Dept. Earth and Planetary Sciences and McDonnell Center for Space Sciences, Washington University in St. Louis, St. Louis, Missouri, 63130, USA;
2Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, , China;
3Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, 85721, USA;
4Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, 20723, USA;
5NASA Goddard Space Flight Center, Greenbelt, Maryland, 20771, USA;
6Dept. Earth, Environmental and Planetary Sciences, Brown University, Rhode Island, 02912, USA;

2. Deliquescence a. b. c. d. e. f. g. h. i.
Wang et al., 2017
Figure 1. Results of 270 T-RH driven deliquescence-dehydration-rehydration in experiment #1 . An experiment led to deliquescence was marked with orange colored spot; An experiment led to non-change or dehydration or rehydration was marked by a spot of other colors, whose phase identifications were marked and were made by using Raman spectroscopy. Note: the data of FeCl2·4H2O and KMgCl3·6H2O suggest some complicate phase transitions, thus were not included in Figure 4a.

3. Optical fiber feedthrough
Figure2. Experiment #3 set up
Sample cup
CaCl2
Dry ice (195K) beneath the red foam-cover a
CO2
H2O vapor supply b c
Dry ice
Raman objective d
Wang et al., 2017
Raman probe
Z stage
Electric Feedthrough
Rotation stage
Motor-hub
X stage
cold plate
Vacuum pump
& pressure meter
Laser Raman
Spectrometer
computer
PEACh
Optical fiber feedthrough
feedthrough
Quartz window
RH meter
Needle valve
Extra-dry CO2
water bath at 30 C
H2O
CO2 flow control
Extra dry CO2
mix
CO2 & H2O supply
T-sensor & control
Cooling system
LN2
Figure3. Laboratory set-up for Experiment #4
Wang et al., 2017

4. CaCl2·4H2O
MgCl2·6H2O
FeCl3·6H2O
AlCl3·6H2O a.
Fe3+-sulfates·9-20H2O
Mg-sulfates·7-6 H2O
Fe2+-sulfate·7H2O
Mg(ClO4)2·6H2O
Ca(ClO4)2·4H2O
NaClO4·H2O b.
Fe2+-sulfates·7H2O
Wang et al., 2017
Figure 4. Deliquescence phase boundaries of HyCOS compared with those of hydrous sulfates. The deliquescence phase boundary of each HyCOS was plotted through the middle space between two sets of RH values in T-RH field, where deliquescence was seen at the higher RH values but not seen at the lower RH values. The width of colored bar reflects the uncertainty of phase boundary in RH. Filled orange data points indicate occurrence of deliquescence. Unfilled points indicate non-change or dehydration, both against the deliquescence boundary at the lowest RH (e.g., CaCl2·4H2O for chlorides). Similar deliquescence boundaries for hydrous sulfates were drawn based on data in Figure S1, S2, S3 of supporting document.

5. Wang et al., 2017 a. MgCl2·6H2O b. CaCl2·4H2O c. FeCl3·6H2O
Deliquescence < 4
Deliquescence < 60
Deliquescence < 1
RSL surface
Salt-rich subsurface
a. MgCl2·6H2O
t30%
t100%
tcenter
Deliquescence < 50
Deliquescence < K
Deliquescence < 2 300K
b. CaCl2·4H2O
Deliquescence < 15
Deliquescence < 2 300K
Deliquescence < K
c. FeCl3·6H2O
Wang et al., 2017

6. Wang et al., 2017 d. AlCl3·6H2O e. Ca(ClO4)2·4H2O f. Mg(ClO4)2·6H2O
Deliquescence < 25
Deliquescence < 2 300K
Deliquescence < K
RSL surface
Salt-rich subsurface
d. AlCl3·6H2O
deliquescence
< K
deliquescence < K
deliquescence < 1 300K
e. Ca(ClO4)2·4H2O
Deliquescence < 30
Deliquescence < 100
Deliquescence < 3
f. Mg(ClO4)2·6H2O
t30%
t100%
tcenter
Wang et al., 2017

7. Figure 3. of Wang et al., 2017
Deliquescence
< 4 300K
< K
Salt-rich subsurface
RSL surface
g. NaClO4·H2O
t30%
t100%
tcenter
Wang et al., 2017
Figure 5. Time range observed from the macroscopic manifestation of deliquescence of a HyCOS, as the function of T and RH. A symbol (triangle, square, or diamond) marks the time when the full deliquescence (t100%) of tested amount of a HyCOS being reached. The low end of a downward bar from the symbol marks the time when > 30% of starting solid becoming liquid (t30%). The time ranges for deliquescence at different RHs are heavily overlapped. A black dotted line extrapolates through the center (tcenter) of observed time range t of a HyCOS to low temperature. A rectangle with solid red line marks the observed TRSL window. A rectangle with dotted red line marks the modeled T window of salt-rich subsurface [Mellon et al., 2004; Wang et al., 2013]. Purple stars mark the intersections of extrapolation line with the red rectangles, which suggest approximate time (tcenter(T) ) that a HyCOS to reach a macroscopic manifestation of deliquescence at a temperature.

8. a. Starting phase CaCl2
CaCl2.2H2O
CaCl2.4H2O +
CaCl2.6H2O
CaCl2.2H2O +
3800
3600
3400
3200
3000
Raman Shift (cm-1)
b. Starting phase MgCl2
MgCl2.xH2O
(x=2, 4, 6, 8, 12)
2800
3550
3500
1000
980
960
940
c. Starting phase NaClO4
NaClO4.xH2O
(x=1, 2, more)
3600
3400
3200
3000
Raman Shift (cm-1)
1040
1020
1000
980
960
d. Starting phase Ca(ClO4)2
Ca(ClO4)2 +
Ca(ClO4)2.xH2O
(x=2, 4)
940
920
3800
Mg(ClO4)2 +
Mg(ClO4)2.2H2O +
Mg(ClO4)2.6H2O
e. Starting phase Mg(ClO4)2
Figure 6. Evidences of HyCOS rehydration at 195 K. (a). Rehydration of CaCl2 at 195 K, revealed by the appearance of H2O Raman peaks (marked by dotted lines); (b) Rehydration of MgCl2 at 195K, revealed by the appearance of H2O Raman peaks; (c). Rehydration of NaClO4 at 195 K, revealed by the appearance of multiple H2O Raman peaks, and by a new Raman peak at 942 cm-1, in addition to 952 cm-1 peak of NaClO4 (both are ClO4 vibrational modes); (d). Rehydration of Ca(ClO4)2 at 195 K, revealed by the appearance of multiple H2O Raman peaks, and by a new Raman peak in cm-1; (e). Rehydration of Mg(ClO4)2 at 195 K, revealed by the appearance of multiple H2O Raman peaks, and by two new Raman peaks in cm-1.
Wang et al., 2017

9. 3800
3600
3400
3200
Raman Shift (cm-1)
Started as CaCl2
CaCl2·4H2O
(4 min 50 s)
a. CaCl2
1000
950
900
850
started as Ca(ClO4)2
Ca(ClO4)2 ·4H2O (14 min)
Ca(ClO4)2 ·2H2O (10 min)
b. Ca(ClO4)2
Wang et al., 2017
Figure 7. Evidence of extremely fast rehydration of chlorides and perchlorates measured at different T and RH in a Mars chamber in experiment #4. (a) rehydration of CaCl2 at 251 K, 23.6 %RH, and 16.4 mbar. The H2O peak (3445 cm-1) of CaCl2·2H2O appeared at 4 minutes 50 seconds after the starting of this experiment. (b). rehydration of Ca(ClO4)2 at 296 K, 4.8 %RH, and 19.7 mbar. The H2O peak (3491 cm-1) of Ca(ClO4)2 ·2H2O and the H2O peak (3550 cm-1) of Ca(ClO4)2·4H2O appeared at 10 and 14 minutes, respectively, after the starting of this experiment.