- If Mars nonetheless has any liquid water, it could possibly be discovered deep underground in aquifers utilizing the seismoelectric methodology, say researchers at Penn State College.
- Seismic waves from marsquakes would transfer by water, creating distinctive electromagnetic alerts.
- Future probes might use the identical approach to check the subsurface oceans of moons like Europa and Enceladus.
Discovering underground water by marsquakes
Scientists say Mars as soon as had oceans, however at present its floor is principally bone-dry. Nevertheless, Mars would possibly nonetheless have liquid water deep underground in aquifers. On June 17, 2024, researchers at Penn State College in Pennsylvania said it could be doable to search out such aquifers by listening to marsquakes, Mars’ model of earthquakes. The quakes would produce sure electromagnetic alerts when shifting by the water deep beneath the floor.
The researchers published their peer-reviewed findings in JGR Planets on Might 5, 2024.
Water on Mars could also be deep underground
Mars is chilly and very dry on its floor at present, principally a planet-wide desert. However scientists have recommended there would possibly nonetheless be some aquifers of liquid water far beneath the floor the place it’s hotter. If that’s the case, it’s possible too deep for conventional strategies like ground-penetrating radar to search out it. Orbiting spacecraft utilizing radar have discovered intensive ice deposits on Mars, nevertheless.
So, how might we discover the water, if it’s there? The Penn State researchers stated we might hearken to marsquakes. When quakes move by our bodies of liquid water, they produce electromagnetic alerts. By analyzing marsquake information, scientists might detect subsurface aquifers, in the event that they exist.
Nolan Roth is the examine’s lead creator within the Division of Geosciences at Penn State. He said:
The scientific neighborhood has theories that Mars used to have oceans and that, over the course of its historical past, all that water went away. However there’s proof that some water is trapped someplace within the subsurface. We simply haven’t been capable of finding it. The concept is, if we are able to discover these electromagnetic alerts, then we discover water on Mars.
Listening to marsquakes to search out water on Mars
The researchers stated as an alternative of an everyday ground-penetrating radar, they counsel utilizing the seismoelectrical method. It’s a more recent approach, nonetheless below improvement, to non-invasively characterize Earth’s subsurface. Sensors positioned on the floor can detect the electromagnetic alerts produced when seismic waves from an earthquake move by liquid water. Variations in how rocks and water transfer from the seismic waves produce distinct electromagnetic fields. When an aquifer is discovered, the info from these sensors reveal an aquifer’s depth, quantity, location and chemical composition. A future rover or lander might use this method on Mars, as Roth noted:
If we hearken to the marsquakes which might be shifting by the subsurface, in the event that they move by water, they’ll create these fantastic, distinctive alerts of electromagnetic fields. These alerts could be diagnostic of present, modern-day water on Mars.
The truth is, it could be even simpler to do on Mars than on Earth. That’s as a result of water in Earth’s subsurface isn’t restricted to only aquifers. This different water can create completely different electromagnetic alerts. So, to search out aquifers, scientists must filter out this different “background noise”. However on Mars, there isn’t any different liquid water within the floor, nearer to the floor. This implies any alerts of aquifers could be cleaner and extra distinct. Co-author Tieyuan Zhu at Penn State said:
On Mars, the place the near-surface is definitely desiccated, no such separation is required. In distinction to how seismoelectric alerts usually seem on Earth, Mars’ floor naturally removes the noise and exposes helpful information that permit us to characterize a number of aquifer properties.
So, if a future Mars mission used this seismoelectrical approach, then it needs to be pretty simple to search out aquifers, in the event that they exist.
Modeling the Martian subsurface
To check simply how effectively the approach would work on Mars, the researchers created a pc mannequin of the subsurface. They then added aquifers to the mannequin. The outcomes indicated the approach ought to be capable of discover deeply buried aquifers on Mars. The truth is, it might reveal how thick or skinny they’re, their salinity (quantity of dissolved salt they comprise) and different bodily properties. Roth stated:
If we are able to perceive the alerts, we are able to return and characterize the aquifers themselves. And that will give us extra constraints than we’ve ever had earlier than for understanding water on Mars at present and the way it has modified during the last 4 billion years. And that will be an enormous step forward.
What about InSight?
NASA’s InSight lander, which landed in 2018 and ended its mission in 2022, detected many marsquakes with its seismometer. It additionally mapped the subsurface. However there have been limitations. Any aquifers would in all probability be too deep to detect with its devices, and seismometers can have issues distinguishing between water, fuel and rock. It additionally had a magnetometer although, which measures magnetic fields. If scientists mixed the info from the magnetometer and seismometer, it might doubtlessly reveal seismoelectric alerts. That may in all probability require extra research again on Earth, and a devoted seismoelectrical instrument on a future Mars mission would nonetheless be preferable.
Ocean moons
The identical approach is also used elsewhere; for instance, on ocean moons. A landed probe on Europa or Enceladus might then measure how thick (deep) the moons’ oceans are. Zhu said:
This shouldn’t be restricted to Mars, the approach has potential, for instance, to measure the thickness of icy oceans on a moon of Jupiter. The message we need to give the neighborhood is there’s this promising bodily phenomenon – which obtained much less consideration prior to now – which will have nice potential for planetary geophysics.
This might assist scientists decide simply how habitable these oceans is likely to be. However as an alternative of being buried deep in a rocky subsurface, these oceans are lined by a crust of water ice.
In 2018, the Mars Express orbiter discovered the primary proof for possible lakes of salty liquid water beneath the ice cap on the planet’s South Pole. Different research, nevertheless, cast doubt on that interpretation of the radar information. But others have supported it. The controversy continues.
Backside line: Is there nonetheless any liquid water on Mars? A brand new examine suggests scientists might discover aquifers deep beneath the floor by listening to marsquakes.
Source: Characterizing Liquid Water in Deep Martian Aquifers: A Seismo-Electric Approach
Read more: Marsquakes reveal red planet’s deep secrets
Read more: Liquid water on Mars beneath polar ice?
