ELSI Planetary Workshop on Mars


Steve Squyres (Cornell University) Hidenori Genda (ELSI, Tokyo Tech) Martin-Torres & Maria-Paz Zorzano (Luleå University of Technology) Haruhisa Tabata (Univ. of Tokyo)

October 31, 2016

ELSI-2 104 ELSI Lounge



Speaker: Steve Squyres (Cornell University)

Title: Past, present, and future Mars exploration missions

---12am-1:30pm: Lunch beak---


Speaker: Hidenori Genda (ELSI, Tokyo Tech)

Title: Origin of Phobos and Deimos


Speaker: Martin-Torres & Maria-Paz Zorzano (Luleå University of Technology)

Title: Liquid water on Mars: from Curiosity data to HABIT and the ExoMars project

--Coffee beak--


Speaker: Haruhisa Tabata (Univ. of Tokyo)

Title: Stability of Martian surface water pH in response to atmospheric evolution


Discussion led by T. Usui (ELSI, Tokyo Tech)

Topic: Science targets & potential landing sites for future Martian lander/rover missions


Dinner @ mitsuru


Past, present, and future Mars exploration missions

Steve Squyres (Cornell University)

Mars has been a primary target of international exploration of Mars for decades. In this talk I will focus on past and ongoing NASA missions to the martian surface, and future Mars missions planned by NASA and JAXA.

NASA has conducted seven successful landed missions to Mars: Viking 1, Viking 2, Mars Pathfinder, Spirit, Opportunity, Phoenix, and Curiosity. The two Viking landers provided the first in-situ observations of the martian surface, and searched unsuccessfully for evidence of microbial life in martian soil. Mars Pathfinder was an engineering-focused mission that demonstrated airbag landing technology and six-wheeled rocker-bogey mobility, both of which were used subsequently on the Mars Exploration Rover project. The MER rover Spirit explored Mars for six years, and the rover Opportunity is still active today. Together the two have traversed more than 50 km, and have discovered substantial evidence for aqueous conditions potentially suitable for life. The rover Curiosity has been exploring Gale Crater for almost four years, and has discovered compelling evidence for formerly habitable conditions preserved in sedimentary rocks there, as well as tantalizing evidence for organic compounds.

Mars holds enormous potential for future exploration. Future NASA missions include the INSIGHT lander to investigate martian geophysics, and the Mars 2020 rover which will begin the process of returning carefully chosen samples from Mars. The martian moons Phobos and Deimos are also of particular interest. These objects are scientifically significant in their own right, and also probably host on their surfaces significant quantities of martian materials ejected by impact on the planet's surface.

Liquid water on Mars: from Curiosity data to HABIT and the ExoMars project

Javier Martin-Torres and Maria-Paz Zorzano (Luleå University of Technology)

The search for present life and habitability on Mars is conditioned by the availability of liquid water. It has recently been shown that liquid water is stable on Mars in the form of brines [Martín-Torres et al., Nature Geoscience, 2015]. Two other environmental conditions constrain the habitability of the near surface of Mars, the thermal range and the UV radiation dose [Rummel et al., Astrobiology, 2014].

In this presentation we will talk about these findings and about the instrument HABIT (HAbitability, Brine Irradiation and Temperature) that was recently selected to be part of the Surface Platform within the European Space Agency/Roscosmos ExoMars mission to Mars in 2020.

HABIT is dedicated to investigating the habitability on present day Mars by quantifying the availability of liquid water, the thermal ranges and UV doses. It includes the BOTTLE (Brine Observation Transition To Liquid Experiment) compartment to capture at nighttime atmospheric water by deliquescence of salts, and 3 environmental sensors devoted to monitoring the full diurnal and seasonal variations of the ground and air temperature, and the UV irradiance. These three sensors shall complement the existing environmental package of the spacecraft, which has Pressure and Relative Humidity sensors, providing a full equivalent to the existing REMS (Rover Environmental Monitoring Station), which is operating on Mars on board the Mars Science Laboratory (MSL) through more than 2.5 years. The 3 environmental sensors of HABIT will allow to constrain the habitability at the landing site in terms of metabolic and reproduction temperature, calculating the heat-flux and the UV biological dose, providing the Relative Humidity of the ground and air, to study the atmosphere/ surface water interchange, provide information about winds (which shall be useful also for the rover drilling and sampling operations), and about thermal inertia and subsurface thermal profile and hydration level complementing the studies of the other platform and rover instruments. It will also provide the concentration of the atmospheric trace gas ozone (complementing orbiter observations from NOMAD-TGO) and atmospheric UV opacity (providing continuous monitoring of the dust cycle). The BOTTLE unit is furthermore designed as an ISRU (In-situ Resource Utilization) demonstrator that shall quantify the amount of water (and derived products such as H2 and O2) available for future landed missions on Mars.

HABIT will provide environmental information that, because of its heritage from REMS which is operating on Mars since August 2012, will allow for extra-long term climate and atmospheric monitoring and will measure for the first time liquid water on Mars in a controlled way, while providing ISRU possibilities.


Martín-Torres et al., "Transient Liquid water and water activity at Gale crater on Mars", Nature Geoscience, doi:10.1038/ngeo2412, 2015.

Rummel et al. "A New Analysis of Mars ''Special Regions'': Findings of the Second MEPAG Special RegionsScience Analysis Group (SR-SAG2)", Astrobiology, Volume 14, Number 11, 2014.

Origin of Phobos and Deimos

Hidenori Genda (ELSI, Tokyo Tech)

Two small moons (Phobos and Deimos) are orbiting around Mars. Since they were discovered in 1877, their origin is still a mystery. I will review the leading hypotheses for the origin of Martian moons, that is, capture origin and impact origin. Especially, I will talk about our recent progress on the impact origin. Also I will discuss the science of Mars from the viewpoint of the origin of Martian moons and MMX mission.

Stability of Martian surface water pH in response to atmospheric evolution

Haruhisa Tabata (Univ. of Tokyo)

Chemical and mineralogical data of sedimentary rocks on Mars suggest that aqueous environment on Mars had experienced acidification from neutral (pH~7-9) to highly acidic pH (pH~2-4) at ~3.5 Ga. Hurowitz et al. (2010) proposed that this acidification may have been driven by photo-oxidation of ferrous iron in the surface water. Irradiations of UV light photo-oxidizes ferrous iron to ferric iron in association with H+ production, thus acidify the environment.

Although, Hurowitz et al. (2010) show that this mechanism could quantitatively explain the acidification of observed Meridiani mineralogical data, it still remains unsolved that: 1. How neutral pH water was sustained before 3.5 Ga, and 2. What the trigger for the acidification was.

However, if we consider wavelength dependence of iron photo-oxidation along with atmospheric evolution, we found that rapid acidification could be explained with slight decrease (~1 ppm) of atmospheric SO2. Which is in agreement with geological data suggesting declining volcanic activity after ~3.5Ga.

Yet, experimental data of iron photooxidation rate are heavily pH extrapolated in previous discussion, since data reported are limited in acidic pH range (pH 0.3-3.0). Therefore, to estimate the effect of iron photo-oxidation more quantitatively, we are working on the iron photo-oxidation experiment in neutral to alkaline pH and current status will be presented.