Taking a fresh look at Mars
LAST week, during Science Week here in Australia, there was much discussion about water. Indeed, the topic this year was Deep Blue: innovation for the future of our oceans.
As the wording suggests, the water being discussed was mainly the water found on Earth, and at the Queen Victoria Museum we had a number of live streamed presentations about the topic. These included guest speakers Christelle Auguste of the Australian Maritime College and Dr Beth Fulton of the CSIRO.
Included in our presentations was information on what is known about water other than on Earth, including the water in comets and asteroids, subsurface oceans on some of the Moons in our Solar System, and the detection of water on planets orbiting stars other than our Sun.
On the subject of water on other celestial bodies, Mars once again had an important mention. For a long time, we have known about the existence of water on Mars, with a wealth of information about Martian water having come from many of the spacecraft sent to the Red Planet.
Among other studies, the Mars Odyssey spacecraft, in orbit around Mars, returned evidence many years ago that there is subsurface water ice there, even at latitudes well away from the Martian poles. The Phoenix lander, which touched down at a Martian latitude of 68 degrees north, detected water ice directly.
Conditions on Mars do not allow liquid water to be stable on the surface today, but we have seen evidence of liquid water in the past. Close examination of surface material has shown substances that were affected by liquid water, and spacecraft images taken from orbit have shown features that appear to have been carved out by running water. That has pointed to Mars being warmer and wetter in its distant past.
Now, however, there is a new theory about the history of the Red Planet. Writing in Nature Geoscience recently, researchers Anna Gelofre, A. Mark Jellinek and Gordon Osinski suggest that networks of valleys on Mars may have been carved out by liquid water underneath huge glaciers.
Although glaciers on Earth have the appearance of being slowly moving ‘rivers’ of ice, it is possible for liquid water to be underneath the ice. A location at which this has been discovered is Devon Island, the largest uninhabited island on
Earth. Devon Island is in far northern Canada, to the west of Greenland. Researchers have discovered that there is a lake beneath the ice, where the temperature does not exceed -10.5C. The reason that water there does not freeze is that it is hypersaline water, meaning that it is very, very salty, which lowers its freezing point.
The same situation may have existed on Mars.
Liquid water underneath ancient Martian glaciers may have carved out the valley networks that have been clearly seen in images sent back by the many spacecraft orbiting Mars.
The fact that this may have been the case on Mars long ago leads to the questioning of whether the planet was actually warmer then, because liquid water underneath the glaciers need not necessarily imply a warmer planet.
Does this imply that life on Mars was less likely than we thought? Not at all. Indeed, the layers of ice would have kept the water at a fairly constant temperature, and they would have been a ‘shield’ against dangerous radiation from the Sun.
Indeed, it could be argued that this scenario may even have been more conducive to the survival of some form of primitive life than the concept of life existing among exposed oceans and rivers.
We’ll certainly be learning more about Mars and its history as spacecraft continue to arrive to make their studies.
Recently, three have been sent on their way, and in 2022 the European Space Agency, in collaboration with Russia, will send its next mission.
I’m thrilled that Tasmanian scientist Dr Elyse Allender is working on that mission, and that she also participated in QVMAG’s livestreams during science week.
Recordings of those sessions are available on the internet for all to see.
Simply visit the QVMAG YouTube Channel and see the Science Week playlist.
INDEED, IT COULD BE ARGUED THAT THIS SCENARIO [OF GALATIAL EVIDENCE ON MARS] MAY EVEN HAVE BEEN MORE CONDUCIVE TO THE SURVIVAL OF SOME FORM OF PRIMITIVE LIFE THAN THE CONCEPT OF LIFE EXISTING AMONG EXPOSED OCEANS AND RIVERS.