NASA’s Insight lander discovers huge underground reservoirs of water on Mars.

Graham writes ...

“When I consider your heavens, the work of your fingers,
the moon and the stars, which you have set in place, …”:  Psalm 8.

Credit: Unknown source.

As we have commented before on this blog page, Mars has not always been the arid desert that we see today. The confirmation of this view from data acquired by orbiting, imaging spacecraft is overwhelming, with clear evidence of water erosion and features such as river deltas and lakes. See for example, my blog post in February 2021 (just click on that date in the blog archive list on the right-hand side of this page), concerning the immanent adventures of NASA’s Perseverance rover as it set out to explore what was once a Martian lake bed. The second post in March 2021 looks more generally at the question of life elsewhere in the Universe.  Coming back to Mars however, we can ask 'where has all the water gone?'. The planet is small – about half the size of the Earth – and the consequence of this is that Mars’ gravity field was not strong enough to retain the atmosphere that it had more than 3 billion years ago when it was a ‘water world’. As the atmosphere slowly leaked away into space, the conditions were set for the surface water to evaporate rapidly (in geological terms).

Recently, a groundbreaking discovery has added a new layer of intrigue to Mars – the presence of liquid water deep beneath its surface. This finding, made possible through the detailed analysis of seismic data from NASA’s Insight lander, marks a significant milestone in our understanding of Mars and its potential to support life. The Insight lander, which touched down on Mars in 2018, was equipped with a seismometer that recorded vibrations from Mars quakes over four years. By carefully analysing these seismic waves, scientists were able to detect the presence of liquid water reservoirs located approximately 10 to 20 kilometres below the Martian crust – a process that is often used here on planet Earth to detect oil or water deposits underground. This discovery is particularly significant because it provides the first direct evidence of water on Mars, beyond that previously identified frozen in Mars’ ice caps. The amount of water discovered is staggering – enough to uniformly cover the planet’s surface to a depth of more than a kilometre. There is speculation that this underground water was there in Mars’ early history when surface water was plentiful, and that its underground location sustained it as the surface was transformed into an arid landscape.

An impression of the Insight lander on the Martian surface, with seismometer deployed. Credit: NASA.

So, why does all this matter? Well, as the astrobiologists will tell you (or any other biologist comes to that …), water is a crucial element for life as we know it. The presence of liquid water on Mars opens up new possibilities for the planet’s habitability. While the surface of Mars is a cold, arid desert, these underground reservoirs could potentially harbour microbial life. Moreover, any such underground life would likely to be quarantined from Earth-based life, so providing an uncontaminated environment to try to understand how life began (both on Mars and the Earth). It is also clearly a great resource for future missions with the objectives of exploring and possibly colonizing Mars - access to water would be vital for sustaining human life and supporting agricultural activities on the planet.

The assembly, integration and test of the Insight lander in a clean-room environment. Credit: NASA, Lockheed Martin Space.

The stowed configuration of the lander, about to be sealed into the entry capsule. The capsule entered the Martian atmosphere at about 5.5 km/sec. This was reduced to effectively zero in about 6.5 minutes, to achieve a successful soft landing. Credit: NASA, Lockheed Martin Space.

However, before we get carried away with all this, it is obvious that accessing these deep reservoirs poses significant challenges. The water is buried deep within the Martian crust, making it difficult to reach with current know-how. Future missions will need to take with them advanced drilling technology to tap into these resources. Additionally, the harsh conditions on Mars, including a global average temperature of -50 degrees Celsius, a harsh surface radiation environment (Mars has no protective magnetosphere) and surface dust that is potentially toxic to humans, present further challenges that need to be overcome!
 
If you would like to hear more on this, click here to hear the ‘5 Questions on’ podcast: ‘Huge reservoirs of water deep inside Mars’ (7 minutes), with the BBC’s science correspondent Victoria Gill talking with Michael Daventry.
 
Graham Swinerd
 
Southampton, UK
August 2024