According to papers published this week in Geophysical Research Letters, NASA has discovered traces of ancient icecaps with a massive reservoir of frozen water on Mars, making it the most conclusive proof that life existed there, till date.
The Mars Reconnaissance Orbiter (MRO) that has been studying the Red Planet since 2006, spotted signs of a huge volume of water ice around its north pole earlier this month, leading scientists to believe this could be the remnants of Mars’ long-lost icecaps.
Preliminary studies have suggested that the water if thawed could submerge the entirety of the planet in a depth of at least 1.5m.
Similar discoveries have been made in the past, but what sets this one apart?
For one, the earlier caches of ice found on Mars were on the surface and minuscule compared to the newly discovered reservoir of water, which is situated deep beneath the northern ice cap, nearly 2 km below the surface.
More importantly, it is believed to be the hird largest body of water on the Red Planet; the amount of condensed water could cover the entire surface of Mars in five feet of water.
The ice caps covering the giant cache of water are located within Mars’ northern cavi unit, under the planet’s current ice caps which are a mix of water and carbon dioxide ice, according to the new paper authored by Stefano Nerozzi, a PhD student at the University of Texas at Austin.
The findings were corroborated by an independent study using gravity data instead of radar, led by researchers at Johns Hopkins University and co-autored by Nerozzi. All the papers were simultaneously published on May 22.
Role of radar
Detected by the Shallow Radar (SHARAD), a surface-penetrating scanning instruments aboard the NASA spacecraft, Nerozzi’s team was able to discern the internal structures and composition of the cavi unit.
“Surprisingly, the total volume of water locked up in these buried polar deposits is roughly the same as all the water ice known to exist in glaciers and buried ice layers at lower latitudes on Mars, and they are approximately the same age,” said co-author Jack Holt in the University of Texas press release.
A reseracher at the university of Arizona, Holt had previously used SHARAD to uncover gigantic subterranean glaciers in the Martian mid-latitudes.
Sandwiched by layers of sand
The sheer volume aside, the way the ice is packed away inside the planet has turned out to be of great scientific value.
The American Geophysical Union, which published the new research based on NASA data, explains that the ice in separated by sand into layers.
SHARAD data showed that water ice accounts for 60-90% percent of the formation by volume, and the frequency and volume of the ice slabs increased with proximity to the north pole.
In one region, for example, the researchers detected a layer of ice ranging in depth from 50 to 100m below two sheets of sand nearly 40 km wide.
“Understanding how much water was available globally versus what’s trapped in the poles is important if you’re going to have liquid water on Mars,” Nerozzi said. “You can have all the right conditions for life, but if most of the water is locked up at the poles, then it becomes difficult to have sufficient amounts of liquid water near the equator.”
Prior to the new study, scientists were under the impression that the Martian icecaps were lost and that the cavi unit was primarily composed of sand dunes and contained less than 50 percent water ice by volume.
These estimates were based on observations of visible outcrops, which revealed significant amounts of dark sands intermixed with small amounts of frozen water.
Why it matters
From the current vantage point, it has been surmised that the icecaps formed over the course of hundreds of millions of years. The recent discovery is crucial because it attests to past climate cycles in the north polar region.
The buried structures of alternating sand and ice are clearly the remnants of former ice caps which shrunk and were buried during warm periods, according to the paper.
Like Earth, Mars too experienced multiple ice ages. During the warm periods, sand enabled by wind covered the shrunken ice caps to prevent the ice from evaporating into the atmosphere. These intra-dune sand deposits were later buried repeatedly with various levels of ice.
The layers of ice are, therefore, like the rings on a tree, showing the growth and retreat of ancient polar caps over the years.
The geometry and composition of these layers could tell scientists whether climate conditions were previously favorable for life, researchers said.
Studying the geometry, composition, history and formation of these layers could tell scientists whether climate conditions were previously favourable to life. It will help to ascertain the evolution of the planet’s environment, that will further inform the search for ancient life on Mars — one of the objectives for NASA’s 2020 rover.
The existence of water on Mars will further support the quest for viability of human life on the planet, as the race to colonise space continues in earnest, with Elon Musk intent on setting up a colony on Mars soon. Even though harvesting this water can prove to be quite a task, the discovery bodes well for future colonists in search of the liquid elixir.
At The Humans to Mars Summit in Washington DC last week, on May 16, NASA Planetary Protection Officer Lisa Pratt also briefly brought up the possibility of Mars microbes in a panel discussion, saying that future explorers should be concerned about possible biological agents in the Martian dust.
Prarthana Mitra is a Staff Writer at Qrius.
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