EXPERT REACTION: Huge reservoir of liquid water found under Mars' south pole
Our celestial red neighbour Mars has been giving us hints every so often about the presence of water on its otherwise barren wastelands; researchers from Italy finally cracked the planet's crusty shell and have found a massive reservoir of liquid water hiding underground. The team poked at the polar ice caps with radar and say they found a lake that stretches about 20 kilometres across, 1.5 kilometres deep. They add that the lake was likely able to stay liquid due to salts from Martian rocks dissolving into the water, coupled with the incredible pressure of the ice above.
Organisation/s: Istituto Nazionale di Astrofisica, Italy
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Associate Professor Bruce Schaefer Deputy Director of MU Planetary Research Centre, Earth and Planetary Sciences, at Macquarie University
This weeks announcement of liquid water beneath the Southern Polar ice caps on Mars in the journal Science this weeks ranks as one of the most exciting developments in planetary exploration in recent years.
Without liquid water, life as we are familiar with, cannot exist, and indeed NASAs whole search for life in the solar system has centred around finding liquid water. Until recently, only tantalising observations of liquid water on the Martian surface have been made, and these have been transient in nature.
The discovery of a large stable body of water (possibly as large as 20km) beneath the southern polar ice cap, changes fundamentally our understanding of past climates and the hydrosphere of Mars and greatly increases the range of potential habitats for life. Such lakes also occur beneath ice sheets on the Earth, notably beneath Antarctica and Greenland, where the melting point of water is reduced due to the pressure of ice above.
However, due to the very low temperatures on Mars, the Martian lake must be incredibly salty for water to remain liquid, even below the ice caps. So while there is now a whole new spectrum of potential habitats in which to search for life, the conditions are still incredibly hostile and much work still needs to be done.
Mr Warwick Holmes is the Executive Director of Space Engineering in the School of Aerospace, Mechanical and Mechatronic Engineering, at the University of Sydney
This is an incredible discovery by the researchers using the European Space Agency's MARSIS instrument onboard the Mars Express mission. The discovery of liquid water below the southern ice cap of Mars could provide us with the first evidence of life outside our own planet.
A similar situation has been discovered here on Earth, 4km below the ice of Antarctica, in Lake Vostok, where scientists have observed very primitive life in an area that is equally devoid of light and likely at similar temperatures. This bacterial life have been able to survive without the regular energy sources that we know are necessary to metabolize life on the surface of Earth using sunlight for example.
What we tend to think here on Earth is that if there is liquid water, there is a good chance for life. Lake Vostok is a great analogue for the slim possibility that basic lifeforms might exist deep under the surface of Mars in a similar liquid environment.
I predict future spacecraft mission to Mars and Engineers are going to be working very hard to design methods to sample this remote water source from this newly discovered subterranean Martian lake. This is currently our best, albeit slim chance of discovering life elsewhere in our Solar System until the more complex missions to Europa or Enceladus, the moons of Jupiter and Saturn we also believe have subterranean water sources.
This result is absolutely amazing - and something that is probably beyond everyone’s wildest expectations. For the first time we know that there is at least permanent body of liquid water on Mars (we’ve had evidence for temporary/transient liquid water for a little while now).
Why is this so exciting? Well, we know Mars was once warm and wet - and likely stayed that way for a very long time. The shift from ‘warm and wet’ to ‘frozen wasteland’ would have occurred very, very slowly, giving any life that got started on Mars plenty of time to adapt and to move with the water.
This lake, if it really is there, would be a prime place to look for life - after all, we have similar things on Earth (like the lakes buried beneath Antarctica), and life has been found to exist and thrive down there!
That doesn’t mean that there will be life there - but it does suggest that a lake on Mars would be a perfect place to look :)
This is a stunning result that suggests water on Mars is not a temporary trickle like previous discoveries but a persistent body of water that provides the conditions for life for extended periods of time.
The liquid water is not a lake that you would want to swim in, locked away 1.5 kilometres beneath the surface of the Martian South Pole the water would be a brine mixed with perchlorate salts.
It’s those salts that keep the water from freezing, familiar to anyone who can drive on ice-free roads in winter after the salt gritters have been at work.
The underground water might exist as a lake trapped beneath rock layers or mixed in with Martian soil to create a salty sludge, but either way at 20 kilometre across there is a lot of it.
There’s nothing special about this location other than the MARSIS radar on the Mars Express spacecraft is most sensitive to that region meaning there are likely similar water deposits below the ground all across Mars.
The ending of Total Recall where Arnold Schwarzenegger melts vast ice reserves just became less science fiction and more science fact.
As it is on Earth, so it is on Mars…
Aside from its rarefied atmosphere and lower gravity, Mars has many striking similarities with our own planet. Its axial tilt and day-length produce a climate that is a chilly analogue of Earth’s, with polar caps that mimic those of our own world’s. For more than three decades, planetary scientists have wondered whether that similarity extends to hidden lakes beneath the ice-caps, as we find under Earth's Antarctic ice-sheet.
Now, for the first time, we have compelling evidence of liquid water beneath Mars’ southern ice-cap. High-intensity radar reflections spotted in polar data from ESA’s orbiting Mars Express spacecraft can only come from a large body of liquid water near the base of the 1.5-km-thick ice-cap. It is probably kept liquid at its estimated temperature of -68C by dissolved mineral salts, whose presence on Mars is already known from surface landers.
This is a discovery of extraordinary significance, and is bound to heighten speculation about the presence of living organisms on the red planet. Caution needs to be exercised, however, as the concentration of salts needed to keep the water liquid could be fatal for any microbial life similar to Earth’s. With no immediate means of sampling the water, the jury remains out as to the possibility of the newly-discovered lake harbouring life. Watch this space!
This particular discovery of water on Mars simply reinforces work that over the past few years has identified water as the first resource to be "mined" in space.
Since United Launch Alliance put a price on delivering water in space in 2016, researchers, agencies and companies have focused on water, for support of life and chemical processes, and for conversion to hydrogen and oxygen for rocket fuel. That water could be sourced from asteroids, the moon, or Mars. Discovery of a large water supply on Mars confirms we're heading in the right direction.
Australia has taken a leadership position, with Prof Serkan Saydam and the group at UNSW's Australian Centre for Space Engineering Research [my centre] supporting twelve PhD students examining business cases, mining methods, earth analogues, asteroid selection, asteroid navigation and other resources (e.g. Platinum).
We will be hosting the fourth Off-Earth Mining Forum in Sydney in 2019.
Space Resource Utilisation is a key driver for much of the scientific research currently being undertaken by space agencies and commercial companies alike. Liquid and frozen water are key resources which can be used in-situ to produce fuel and provide life support for astronauts during deep space missions enabling reduced cost launches and space operations.
An increasing number of private commercial companies are investing in technology for Space Resource Utilisation to support Space Agency Deep Space Exploration Missions spurred on by and recent legal changes to US and Luxembourg domestic space legislation frameworks.
These frameworks provide private commercial companies within the USA and Luxembourg with the right to own materials which are recovered in-situ from solar system bodies such as the moon, planets, comets and asteroids. Confirmation of resources like liquid water will boost private and public investment in technology development and may catalyse higher levels of public-private investment in the space sector.
On July 25th, I will co-present a program called Boots on Mars, developed in collaboration with NASA Kennedy Space Center, Swampworks at the International Space University, Space Studies Program currently convening in the Netherlands.
This workshop will lead space industry professionals through an exercise to identify how NASA will overcome challenges to enabling in-situ resource utilization within potential Mars "Exploration Zones". The solutions identified within this workshop, will be used by NASA to inform ongoing planned Mars Science Missions similar to MARSIS for 2030’s and beyond.
The surface of Mars is an inhospitable place. With average temperatures of -60 C and an atmosphere around 100 times thinner than Earth, it is unlikely that liquid water persists on the surface. Given life (as we know it) requires water it is very unlikely any life could survive on the surface.
However, the recent finding by Orosei and colleagues published in Science, provides intriguing evidence for the presence of liquid water below the ice at the south pole on Mars. While the surface of Mars is inhospitable, there is the fascinating possibility that microbial life could survive and flourish in sub-glacial Martian waters.
There is evidence on Earth of substantial microbial life in the waters below the poles - and even microbes that can survive within ice veins. Whether similar scenarios are occurring on Mars remain to be experimentally established, but this finding of potential liquid water beneath the surface of Mars opens up fascinating areas of space exploration.
Aside from the advancement of human knowledge, this has the potential to impact on areas such as economics, theology, and ethics, as well as other philosophical issues that may ultimately define who we are.
Using a radar instrument (MARSIS) aboard a European Space Agency orbiter (Mars Express) an Italian group have discovered what may be a lake of liquid water under the south polar cap of Mars.
The lake is under 1.5km of ice and is about 20km wide. It is considered to be liquid rather than frozen because of the effects of the pressure of the overlying ice and the probability of it being a salty brine (both the pressure and the salts lower the melting point). This invites comparison with similar lakes under the ice caps of Earth.
For example, Lake Vostok in Antarctica is under 4km of ice and is 250km long. As with Lake Vostok the Martian lake (as yet unnamed) is a potential habitat for life. If life ever existed on Mars it is likely still to exist. It is possible that the lake is populated by Martian microbes.
NASA has been following the water on Mars (and in the solar system) for some time now.
Every time a body of liquid water is found it raises the prospect of discovering life.
We know Mars has had water on its surface in the past, but the wet atmosphere was lost largely through the lack of a magnetic field to prevent cosmic rays and solar wind from breaking up atmospheric molecules (including H2O).
This water might be the “smoking gun” of the oceans that have departed.
This is an amazing discovery from the Mars Express. There has been a long quest to find liquid water on Mars, as water is the key to life here on Earth which means that it is a great place to look for life on other planets.
For decades, we’ve been finding evidence of either ice or past flows. Now, we know that liquid water currently exists on Mars and just as subsurface lakes exist in Antarctica here on Earth, we now have that on Mars.
Every month, new discoveries are being made that is getting us closer to answering the fundamental question - does life exist somewhere beyond Earth.
Thinking further afield, in future explorations by humans of Mars it means that water can be used as a resource for those who may inhabit it.
To understand the history of Mars, we need to understand its water, particularly if we hope to know whether it could ever have supported life.
There's plenty of ice in the Martian polar caps, just like on Earth, but liquid water created the dry river and lake beds we see on the surface, and could possibly have contained organisms. So the discovery of liquid water under the Martian south pole is a landmark.
Even more importantly, though, the Italian team have shown that they can map out the water. So the next job is to see if there are more lakes like this, though 'lake' might be an optimistic term - the discovery team point out that it might be more like a layer of water-based sludge.
Their techniques aren't able to see if there are underground rivers connecting the lakes, as we think exist under the Antarctic ice sheet on Earth; that must be a future focus of research.
Water or sludge? Isolated lake or underground water system? Mars continues to surprise and intrigue us.
The potential discovery of liquid water under Mars’ southern ice cap is very exciting. Water and life on Earth are intimately linked, and perhaps there’s a very slim chance that life could exist in liquid water elsewhere in our Solar System.
A large body of liquid water on Mars could thus have huge implications, but there are good reasons for caution. This result relies on the interpretation of radar images taken with the Mars Express orbiter, and I’m sure the scientific community will debate alternative explanations of what Mars Express has observed in the coming months and years.
Gathering additional data will obviously be another crucial step for understanding what’s happening under the Martian ice.
This nice radar-based result is just the tip of the ice berg in the sense that we have only begun to scratch the surface of Mars with robotic arms and radar.
In the future we will find much more evidence for sub-surface liquid water on Mars. Then the issue becomes, would the potential life forms in this sub-surface water have access to enough energy to make a living?
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