The Geophysical Detection Of Subsurface Water On Mars

Until now we have only scratched the surface of Mars, while any liquid water on Mars is most likely deep underground. NASA/Hubble image

Pasadena - Oct. 16, 2000
The search for subsurface water has become a primary focus of Mars exploration. Its abundance and distribution (both as ground ice and groundwater) have important implications for understanding the geologic, hydrologic, and climatic evolution of the planet, the potential origin and continued survival of life, and the accessibility of a critical in situ resource for sustaining future human explorers.

For these reasons, a principal goal of the Mars science, astrobiology, and human exploration programs is to determine the three-dimensional distribution and state of subsurface H2O, at a resolution sufficient to permit reaching any desired volatile target by drilling.

The three targets most often discussed are groundwater, massive deposits of near-surface ground ice (associated with the ponded discharge of the outflow channels or the relic of a former ocean), and ice-saturated frozen ground.

Although the belief that Mars is water-rich is supported by a wide variety of geologic evidence, our ignorance about the heterogeneous nature and thermal evolution of the planet's crust effectively precludes geomorphic or theoretical attempts to quantitatively assess the current geographic and subsurface vertical distribution of ground ice and groundwater.

For this reason, any exploration activity (such as deep drilling) whose success is contingent on the assumed presence of subsurface water must be preceded by a comprehensive high-resolution geophysical survey capable of assessing whether local reservoirs of water and ice actually exist.

Terrestrial experience has demonstrated that the accurate interpretation of such data is likely to require the application of multiple geophysical techniques [e.g., see the summary of the Mars Deep Water Sounding Workshop, held at NASA Ames in January 1998].

In recognition of the high-priority and cross-discipline importance of this issue, a week-long conference on the geophysical detection of subsurface water (addressing both Earth and Mars) is planned for August 6-10, 2001, at the Lunar and Planetary Institute in Houston, Texas.

The purpose of this meeting is to:

Clarify the reasons why a global geophysical reconnaissance for water on Mars is needed.

Identify the types of investigations (orbital, global surface network, and high-resolution local) best suited for determining both the state and three-dimensional distribution of subsurface water.

Assess the diagnostic limitations and potential environmental complications associated with such investigations.

Determine what other areas of Mars science would benefit from the acquisition of this proposed suite of geophysical data.

Given the enormous base of experience that already exists in these areas within the terrestrial research and exploration communities, the participation of terrestrial scientists will be actively encouraged.

MARSDAILY

Exploring the Canyons and Cliffs of Mars

Camron Park - July 11, 2000
In the first three installments of this series, I described the current theories now being offered to explain Surveyor's remarkable discovery of what looks very much like recent eruptions of liquid groundwater onto Mars' surface -- and in the coldest, most unlikely parts of the planet imaginable. There are at least five theories bouncing around at the moment (in two of which the stuff erupting isn't even water, but carbon dioxide).

SPACE.WIRE