 EVALUATION OF LIQUID BRINE APPEARANCE AT EXOMARS ROVER'S CANDIDATE LANDING SITES.  B. Pal 1 and A. Kereszturi 2, 1 Eotvos Lorand University of Sciences H-1117, Bp., Pázmány P. s. 1/a. Hungary, 2 MTA Research Center for Astronomy and Earth Sciences (e-mail: paldeh@gmail.com).  Introduction: The possible appearance of low melting point liquid brines on Mars should be analyzed for future missions to identify methods and conditions to search for them and avoid uncertainties like at the Phoenix landing site [1]. Below the possibility of appearance for the four candidate ExoMars rover (EXM) landing sites are presented. Methods: Data came from the MGS TES Archive, and the Mars Climate Database [2] with its Web Interface, to collect surface pressure, temperature, water vapor vol. mixing ratio. These raw data was analyzed by a simple C based program of our own for periods when the temperature and water vapor content are both above threshold values. These eutectic temperature and water activity came from [3,4]. We performed an analysis on former and future Mars mission landing sites of how likely it is that liquid brine appears there, and which are the best periods for that. We worked with daytime max. and nighttime min. temperatures for the whole Martian year, and searched for ideal locations and periods, where there should be a higher possibility to find liquid water, which could be the key to understand the Martian environment and habitability better.   Fig. 1. Temperature and rel. humidity curves for Phoenix' landing site. Vertical blue bars show the ideal periods for brine appearance Results: Checking the temperature and relative humidity for the Phoenix landing site two periods were identified when Mg(ClO4)2 brines might appear (Fig 1.) in agreement with some observations [1]. For the four candidate EXM landing sites the situation in worse, and no such period is visible on the diagrams (Fig. 2.), although this is representative only for average conditions. Interesting possibility is specific slope exposures where the given location receives stronger insolation in early morning or late afternoon hours.  Figure 2. Daily temperature (red) and relative humidity (blue) curves for the Aram Dorsum EXM candidate landing site. These ideal periods are indicated in the Table 1. It is visible that there are some moderate differences between certain sites in the required temperature increase relatively to the average. Early morning periods at 6-7h requires 10-24 C increase, while evening/night periods varies more, occur between 20 and 3.5h and the required increase range between 8 and 16 C.  Table 1. Required temperature increase (+T) for different sites and local time (LMST) for brine appearance site / period (Ls) am LMST / +T pm LMST / +T Aram Dorsum (Ls=125) 7.5h / 24 C  20h / 10 C Aram Dorsum (Ls=235) 7h / 12 C  3.5 h / 12 C Hyspanis Vallis (Ls=125) 6h / 15 C 3h / 12 C Hyspanis Vallis (Ls=235) 6h / 15 C 3.5h / 10 C Mawrth Vallis (Ls=125) 7h / 10 C 23h / 8 C Mawrth Vallis (Ls=235) 7.5h / 18 C 23h / 16 C Oxia Planum (Ls=125) 6h / 12 C 3.5h / 12 C Oxia Planum (Ls=235) 7h / 16 C 3h / 10 C  Conclusions: The model based calculations suggest there are different specific periods and locations when/where the chance for brine appearance is the highest. During am periods slopes with eastward exposure might have elevated temperature relatively to the average, where the increase is supported by the low thermal inertia surface and weakly heat conducting rare atmosphere. In the future we implement solar insolation and slope exposure to the modeling to identify the accurate conditions for brine appearance that might help to focus targeted analysis of EXM rover. Acknowledgment: The OTKA PD 105970 is acknowledged. [1] Renno et al. 2009 JGR 114(C10)E00E03. [2] [Forget et al. 2011. EPSC-DPS 1568] [3] Gough et al. (2014) EPSL 393, 73-82. [4] Möhlmann and Thomsen (2011) Icarus 212, 123-130. 
