Glaciers on Mars!

In these troubled times with COVID-19 around, I am using my quarantine time to follow an online course on the Science of the Solar System with the California Institute of Technology.

As you know it already, glaciers became of interest for me since I have created this blog. I have recently taken part in a project with the British Antarctic Survey, which was, unfortunately, cancelled due to COVID-19. I thought it would be interesting to learn a bit about glaciers on Mars in further details. Yes, there are glaciers on Mars!

Consequently, I decided to expand my blog to space research and try to combine my knowledge in Earth Sciences, Physics and Geochemistry to understand what's going on other planets like Mars. Of course, I will keep talking about climate change issues concerning the Earth planet. But let's talk about glaciers on Mars for now!

Are these glaciers similar to those seen on the Earth?

On Earth, glaciers can be observed in mountain ranges on every continents and latitude, with the vast majority of them being in Antarctica, the Himalaya and Greenland as shown in Map 1. On Mars, however, Brough et al. (2018) found glaciers appear in many places around the planet but extend to the southern and northern mid-latitudes of Mars as seen on Map 2.

Map 1 - Obtained as part of the Randolph Glacier Inventory using analysis from satellite images; the glacier areas are highlighted in blue. Credit: Nasa Earth Observatory.

Map 2 - Map of Mars showing known mid-latitude glaciers and their corresponding volume. Global glacier volume is 1743.60 km³, with 1045.10 km³ across the northern hemisphere and 698.49 km³ in the southern hemisphere. Credit: Brough et al. 2018; The Space Resource

Glacier processes on Earth create flow features as they migrate within valleys as on Figure 1. Similar features can be seen on Mars (Figure 2 & 3). More generally, these flow features, known as moraines, are rocks and debris that were transported by the glacier during its migration down the hill slope. Where the glacier ends are found these features. Those can be (1) terminal moraines, features found at the terminal point of the glaciers; (2) lateral moraines formed as the glaciers is moving and pushing material off to the sides; or (3) medial moraines formed in the middle of a valley when two glaciers meet and two lateral moraines from the different glaciers are pushed together.

Figure 1 - Satellite images showing flow features on the Bearing glacier in Alaska; Red lines= terminal moraines, green lines= lateral moraines, blue lines= medial moraines, black lines= multiple sources; Credit: NASA

Figure 2 - Flow-like ridges as proofs for the presence of glaciers on Mars; Credit: NASA/JPL/University of Arizona

Why can’t we see ice directly on the surface of Mars?

Glaciers on Mars are covered in dust whereas those found on Earth are exposed to the atmosphere. The SHARAD instrument (an acronym for Shallow Radar) was used to analyze what was under the dust at these intriguing locations. The SHARAD sends radio waves from the spacecraft that bounce off the surface after having penetrated a light layer of dust and potentially ice. These beams reflect back to the spacecraft and the timing is measured together with the elevation of the designated areas. An example is illustrated in Figure 4 where reflective layers were observed on the edges of mountains, just under the dusty layers, this being evidence for the presence of ice under the dusty surface of Mars.

Figure 3 - Flow-like features from potential glaciers on Mars; Credit: Head et al. (2005)

Figure 4 - Cross-sections obtained from SHARAD; the green lines illustrate the thin layer of dust covering the surface of Mars; the red lines are for the reflective surfaces found under the dust, evidence for glacier and ice beneath the dust; Credit: Holt et al. (2008)

Other instruments were used to verify the hypothesis of water ice under the dusty surface of Mars. The Phoenix lander was landed in the high latitudes of the Northern Hemisphere at about 65° in order to dig the surface and reveal ice under the dust. Figure 5 shows evidence for scraped snow in white.

Figure 5 - Evidence for ice under the dusty surface of Mars found by the Phoenix Rover in 2008; Credit:JSP, NASA

What implications do they have?

Glaciers are strong evidences for the presence of solid water on Mars. These icy bodies are one of the best indicators of past climate changes. Consequently, drilling and analysing ice cores on Mars, as we do in Antarctica, could help in revealing how the Mars climate has evolved through its geological time. For that new technologies have to be developed in order to be able to drill these ice core on another planet than Earth! This is what we will be exploring on the next post. Thank you for reading and watch this space!