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The InSight lander, which operated from 2018 until its mission concluded in 2022, provided seismic data that helped scientists uncover this potential water reservoir. Located approximately 7.2 to 12.4 miles (11.5 to 20 km) below the surface, this water is trapped within fractured igneous rocks. At these depths, the temperature is warm enough to sustain liquid water, unlike the surface, where water would be frozen.
“Temperatures on present-day Mars become warm enough for stable liquid water near the top of mid-crust, and pores are expected to have closed at the bottom of the layer,” the study said.
Planetary scientist Vashan Wright from the University of California, San Diego, and lead author of the study, explained that the presence of liquid water deep within the Martian crust was determined by analysing the speed of seismic waves. These waves change speed based on the rock composition, presence of cracks, and what fills them.
The data indicates that a mid-crustal layer of cracked rocks filled with liquid water best explains both the seismic and gravity data collected by InSight. Wright noted, “If the InSight location is representative, extracting all the water from these fractures could fill a global ocean 1 to 2 kilometers deep.”
Implications for future Mars exploration
The discovery of such a vast underground water reservoir has significant implications for our understanding of Mars’ history and its potential to support life. More than 3 billion years ago, Mars was a warm and wet planet with rivers, lakes, and possibly oceans. This study suggests that instead of escaping into space, much of that ancient water seeped into the crust.
“Large volumes of liquid water transiently existed on the surface of Mars more than 3 billion years ago. Much of this water is hypothesized to have been sequestered in the subsurface or lost to space,” the study explains.
Planetary scientist Michael Manga from the University of California, Berkeley, a co-author of the study, explained that the water likely infiltrated from the surface, similar to Earth’s groundwater processes. This historical movement of water suggests that the Martian crust could have been water-rich from its early history.
The presence of subsurface water also holds promise for future human exploration. While Mars harbors ice at its poles, accessing this underground liquid water could be challenging due to its depth. Drilling to these depths is a formidable task, but researchers propose investigating regions like Cerberus Fossae, where geological activity might expel water to the surface.
Future exploration and the search for life
The findings from InSight’s data provide a tantalizing glimpse into the possibilities for life on Mars. While the existence of water doesn’t guarantee life, it creates environments that could potentially support microbial life.
The study, titled “Liquid water in the Martian mid-crust” was published in the journal Proceedings of the National Academy of Sciences and was authored by Matthias Morzfeld and Michael Manga and included contributions from researchers at the University of California, San Diego, and Berkeley.
