Earth is a water-rich world.
It is believed that water is crucial for supporting life.
As astronomers peered deeper into space they discovered more and more water.
In fact, everywhere we looked we found water.
In most of these cases, the water is found not in the form of a liquid but either as
a gas, on the surface of the sun and in vast clouds surrounding quasars, and as a solid,
harder than rock on the likes of Pluto forming vast mountain ranges.
New experiments reveal that water can behave in very strange ways at both ends of this
spectrum, one end with ice behaving like a liquid and the other superheated gas behaving
like a crystalline solid.
Let's dive in and find out more.
In a lab in Brighton, New York, one of the world's most powerful lasers blasted a droplet
of water.
This created a shock wave that raised the water's pressure to millions of atmospheres
and its temperature to thousands of degrees.
At the same time, it was exposed to X-rays to reveal the underlying structure of the
water.
Rather than the water turning into a superheated liquid or gas, the atoms froze solid, forming
crystalline ice.
Their findings confirmed for the first time the existence of superionic ice, a new phase
of water with some very bizarre properties.
Unlike the ice we are used to here on Earth, superionic ice is black and hot.
It has a density which is four times higher than that of normal ice.
It was originally predicted more than 30 years ago.
In this state, the water molecules break apart and the oxygen ions crystallise into an evenly
spaced lattice while the hydrogen ions float freely within the oxygen lattice.
The freely mobile hydrogen ions make superionic water almost as conductive as typical metals.
It wasn't until the 1990's that the first experimental evidence emerged for superionic
water and it would take nearly another 30 years for experimental evidence of superionic
ice to be confirmed.
All previously known water ices are made of intact water molecules, each with one oxygen
atom linked to two hydrogen atoms.
Superionic ice is very different.
It exists in an in-between state, part solid, part liquid.
Individual water molecules break apart.
The oxygen atoms form a cubic lattice, but the hydrogen atoms spill-free, flowing like
a liquid through the rigid cage of oxygens.
Under extreme pressure and heat, the oxygen atoms lock into a cubic lattice.
The hydrogen starts to jump from one position in the crystal to another, then again, and
so on.
These hydrogen atoms are ionised and move so fast that they appear to move like water.
This suggests that it would also conduct electricity but here the hydrogen ions play the usual
role of electrons.
Having these loose hydrogen atoms moving around would also boost the ice's disorder, this,
in turn, makes this ice much more stable than other kinds of ice crystals, causing the melting
point to soar upwards.
Their experiments confirmed that the superionic ice melted at 4700C which was as expected
and that it did conduct electricity due to the movement of the protons.
X-ray diffraction also confirmed the crystalline structure with a cubic lattice of oxygen.
Scientists now believe that across the solar system, more water probably exists as superionic
ice.
The interiors of Uranus and Neptune may contain superionic ice and the liquid form may be
found sloshing in the oceans on Earth, Europa, and Enceladus.
They speculate that many ice giant-sized exoplanets might also contain superionic ice suggesting
that it could be very common throughout the galaxy.
Now most of these gas giants also mix in other chemicals species like methane and ammonia.
So the extent to which superionic behaviour actually occurs in nature is still an open
question and will depend on whether these phases still exist when we mic water with
other materials.
The scientists have argued that superionic ammonia should also exist although this has
not been confirmed experimentally.
As if this discovery is not bizarre enough a different experiment has found very strange
properties of water but not at extreme temperatures.
Common ice is a crystalline material with the molecules regularly arranged in a hexagonal
lattice.
If you rapidly cool liquid water, compress ordinary ice, or expose it to ultraviolet
photons or high energy electrons and ions amorphous ice can form.
Due to this, it is thought that amorphous ice dominates in the depth of space and is
likely the most common structure of ware in the universe at large.
In general, amorphous ice can form below 130K.
At this temperature, water molecules are unable to form a crystalline structure.
In a new experiment, researchers have discovered that ultraviolet irradiated amorphous ice
exhibits liquid-like behaviour at extremely low temperatures.
This finding should help unravel the mechanisms behind the formation of prebiotic molecules.
The team sprayed a mixed gas of water, methanol, and ammonia onto a substrate which was cooled
to -263C.
At the same time, they irradiated it with ultraviolet light.
After the ice had formed they then observed the ice with a microscope as the temperatures
rose.
To their surprise, the ice bubbled like boiling water at temperatures between -210 and -120C.
Analysis of the gas showed that it was hydrogen, which the researchers believe was formed when
the methanol and ammonia was broken up by UV radiation.
This bubbling allowed the ice to behave like a liquid, with a viscosity estimated to be
similar to that of firm honey.
They then turned their attention to pure water and repeated the experiments.
Now they observed islands of amorphous water ice.
When they then raised the temperature the islands changed shape and started spreading
over the substrate.
This was once more a sign that the ice was behaving like a liquid.
These experiments suggest that real interstellar ice might behave like a liquid, enhancing
the formation of organic compounds, including prebiotic molecules.