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Newly discovered type of ice could hold key to finding alien life

"This could be the starting point for finally explaining liquid water."

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Part of the set-up for creating medium-density amorphous ice. (Christoph Salzmann via SWNS)

By Mark Waghorn via SWNS

A new type of ice has been discovered - and it could hold the key to finding alien life.

It resembles liquid water more than any other form, say scientists.

The substance contains "amorphous" disorganized molecules - unlike familiar crystalline ice.

It may exist inside frozen moons of the outer solar system.

Senior author Professor Christoph Salzmann said: "Water is the foundation of all life.

"Our existence depends on it, we launch space missions searching for it, yet from a scientific point of view it is poorly understood.

"We know of 20 crystalline forms of ice, but only two main types of amorphous ice have previously been discovered, known as high-density and low-density amorphous ices.

"There is a huge density gap between them and the accepted wisdom has been that no ice exists within that density gap."

In experiments, the University College London team used a process called ball milling - vigorously shaking ordinary ice together with steel balls in a jar cooled to -200 degrees Centigrade.

Rather than ending up with small bits of ordinary ice, the process yielded a novel amorphous form of ice.

Part of the set-up for creating medium-density amorphous ice. (Christoph Salzmann via SWNS)

Co-author Professor Andrea Sella said: “We have shown it is possible to create what looks like a stop-motion kind of water. This is an unexpected and quite amazing finding.”

Unlike others, it had the same density as liquid water. They named it MDA (medium-density amorphous) ice.

Salzmann said: "Our study shows the density of MDA is precisely within this density gap.

"This finding may have far-reaching consequences for our understanding of liquid water and its many anomalies."

Tidal forces from gas giants such as Jupiter and Saturn may exert similar shear forces on ordinary ice as those created by ball milling.

When MDA was warmed up and recrystallized, it released an extraordinary amount of heat.

It could trigger tectonic motions and "icequakes" in the kilometers-thick covering on Ganymede.

Jupiter's satellite is bigger than Mercury and only slightly smaller than Mars. It may host more water than all of Earth's oceans - about 100 miles below its crust.

It is believed hardy single-celled microbial life - known as extremophiles - could exist there.

The density gap has led scientists to suggest water becomes two liquids at very cold temperatures.

Theoretically, at a certain temperature, both could co-exist with one floating above the other - similar to mixing oil and water.

It has been only been demonstrated in computer simulations.

The study in the journal Science raises questions about the validity of this idea.

Salzmann said: "Existing models of water should be re-tested. They need to be able to explain the existence of medium-density amorphous ice.

"This could be the starting point for finally explaining liquid water."

Amorphous ice, although rare on Earth, is the main type found in space.

It has insufficient thermal energy to form crystals in the colder environment.

The newly discovered ice may be the true glassy state of liquid water - a precise replica - in the same way window glass is the solid form of liquid silicon dioxide.

On the other hand, MDA may not be glassy at all - but a heavily sheared crystalline.

Lead author Dr. Alexander Rosu-Finsen said: "We shook the ice like crazy for a long time and destroyed the crystal structure.

"Rather than ending up with smaller pieces of ice, we realized we had come up with an entirely new kind of thing, with some remarkable properties."

Water has many anomalies that have long baffled scientists.

For instance, optimum density occurs at 4 degrees Centigrade reducing as it freezes - which is why it floats.

Also, the more you squeeze liquid water, the easier it gets to compress, deviating from principles true for most other substances.

Amorphous ice was first discovered in its low-density form in the 1930s.

Scientists condensed water vapour on a metal surface cooled to -110 degrees Centigrade.

Its high-density state was discovered half a century later when ordinary ice was compressed at nearly -200 degrees Centigrade.

While common in space, on Earth, amorphous ice is thought only to occur in the cold upper reaches of the atmosphere.

Ball milling is a technique used in several industries to grind or blend materials, but had not before been applied to ice.

In the study, liquid nitrogen was used to cool a grinding jar to -200 degrees Centigrade.

Scanning techniques identified the structure and properties of MDA.

The researchers found if they compressed it and then warmed it up, it released a surprisingly large amount of energy as it recrystallized.

It shows water can be a high-energy geophysical material that may drive tectonic motions in the ice moons of the solar system.

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