UFO'S of UAP'S, ASTRONOMIE, RUIMTEVAART, ARCHEOLOGIE, OUDHEIDKUNDE, SF-SNUFJES EN ANDERE ESOTERISCHE WETENSCHAPPEN

Finding Extraterrestrial Life May Rely on Identifying Traces Rather Than Aliens — **The surface of Mars.**
**Credit: NASA/JPL**

When the famous 15th-century inventor and scientist Leonardo da Vinci examined petrified shells with borings in them long ago, he had a remarkable insight. The strange fossilized formations, he determined, were likely left behind by ancient organisms.

Half a millennium later, this perspective is potentially useful in our search for alien life, argues a new paper that appears in Earth-Science Reviews, whose findings were recently presented at the European Astrobiology Network Association congress in the Netherlands.

Astronomers have been weighing options for how to identify the existence of life on other planets and moons in our solar system. There are a range of possibilities. Mars could be host to ancient or current life, depending on how much water flows on the surface and how salty it is. There are also many icy moons (some with water geysers) in the outer regions of our solar system — among them Saturn's Titan and Enceladus, and Jupiter's Europa and Ganymede.

"Leonardo understood the biological nature of borings based on their shape, not their biochemistry," said Andrea Baucon, the lead researcher. Baucon is an ichnologist, a type of scientist that studies life's traces through burrows, borings and trails. He previously studied da Vinci's work and is a researcher at the University of Modena and UNESCO Geopark Naturtejo.

"This observation appears to be trivial," he went on, "but it potentially allows [us] to detect extra-terrestrial life that differs from known life."

A major limitation of this kind of study, however, is that animal traces and alterations by geology can sometimes appear very similar. For example, researchers have identified what they say are more than four-billion-year-old fossils in formations in northern Quebec, Canada. This finding was announced earlier this year; in 2016, a separate team claimed to find 3.7-billion-year-old microbial mats in Greenland.

But given that the Earth is about 4.5 billion years old, critics of these discoveries argue, the changes in Earth's geology over billions of years can sometimes mimic the appearances of lifeforms. Microbiologists therefore need to prove that the older lifeforms did indeed exist by comparing the older fossils to much younger and better-verified examples of life. Researchers must also attempt to verify markings by life against the chemistry in the rocks, although again this can be altered by rock deformation over time.

Baucon is a member of ROSAE, an Italian acronym that in English stands for Organism-Sediment Relationships in Extreme Environments. It's a scientific project that looks at how organisms and sediments interact in so-called "extreme environments," such as the deep sea.

In this latest study, Baucon and his colleagues attempt to explain the best way to find extra-terrestrial traces. One method could be looking for "meandering" trails and burrows, which is an efficient way for microorganisms to look for food. Rather than making straight lines in an environment or repeatedly crossing a surface, the meandering allows a creature to search for food without exerting too much energy.

"Rangers look for tracks on the snow to determine the presence of elusive animals such as the lynx," said Baucon, pointing out that the traces work for creatures ranging from microscopic organisms to large dinosaurs. "Why not to do the same with alien tracks, borings, and burrows?"

"Traces of interactions with the substrate" — the natural environment for a creature — "are a common evidence for life on Earth, and their fossils can survive the humongous pressures and temperatures generated by colliding continents," he added.

Originally published on Seeker.

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Comet Hale-Bopp as imaged in 1997, showing dual tails of ions and dusty particles. Comets and icy satellites may form an ultradense phase of ice, ice vii, during collisions.

Credit: E. Kolmhofer/H. Raab.Johannes-Kepler-Observatory/Vesta~commonswiki/Wikimedia Commons

In a new experiment, researchers have created a superdense version of ice found deep within icy moons and colliding comets, and watched it form in nanoseconds.

The scientists created the ice by exposing ordinary water to a sudden, intense, laser-generated shock wave, and they observed the formation of the superdense phase of ice, called ice VII, using rapid X-ray pulses to document its nearly instantaneous phase change. The transformation took place at the SLAC National Accelerator Laboratory's Linac Coherent Light Source — the world's most powerful X-ray laser.

"We're really excited about this work because it's the first diffraction evidence, or structural evidence, of seeing liquid water transform in real time, in situ, into a high-pressure crystalline phase," Arianna Gleason, lead author of the new work, told Space.com. "The implications for this work in the planetary science context and geoscience context, for icy satellites or icy large planetary bodies — say, the ice giants even in our own solar system — is really exciting." Gleason is a researcher at Los Alamos National Laboratory and a visiting scientist at Stanford University in California, where the SLAC National Accelerator Laboratory is located. [Rosetta Sees Signs of Water Ice on Comet Surface (Photos)]

Water molecules in their many forms are found all over the solar system; they gush from subsurface oceans on Saturn's moon Enceladus and Jupiter's moon Europa, form the bodies of icy comet visitors from the distant Kuiper Belt and appear in trace amounts in many planets' atmospheres.

On Earth, humans are familiar with the way water vapor can turn into liquid water, and liquid water to ice, as temperature decreases or pressure increases (and it can go from ice to water to vapor with the reverse). In certain conditions, ice can even turn straight into water vapor — a process called sublimation. But those are far from the only forms water can take; by going to otherworldly extremes of temperature and pressure, water molecules can slip into different crystalline forms.

Ordinary ice forms hexagonal crystals, but the form of ice the researchers investigated, ice VII, has a cubic structure. This form of ice is difficult to create and sustain in the lab, and until now, it's been impossible to measure its formation. However, researchers theorize that it forms briefly when comets or icy moons collide, affecting the way craters are shaped.

A circular layer of water is sandwiched between a diamond platelet coated with gold and a quartz platelet. When the surface is blasted with an intense green laser, the shockwave transforms the water layer into ice VII. Ultra-rapid X-rays image the transformation process as it happens.

Credit: Arianna Gleason

To re-create that collision environment, Gleason's group sandwiched a tiny, pen-tip-size package of liquid water in a tiny cell measuring 2 by 2 millimeters (0.08 by 0.08 inches). They shined a powerful green laser at a piece of diamond on the edge of the cell, vaporizing its edge "almost instantaneously" into plasma. That force sent shock waves blasting in the other direction, passing through the water.

"It really is like a tiny rocket effect," Gleason said. "We discovered that we can transform the liquid into a solid just by moving the shock wave through. And during that tiny, short amount of time — it really is only a few nanoseconds, that's a billionth of a second — we probe with these ultrafast and brilliant X-ray pulses."

Although this type of shock-compression process has been done before, documenting how the water molecules rearranged is only possible with the Linac X-ray laser, Gleason said. Like a flip-book, the X-ray images provide a moving record of how the ice formed.

"Collisions and impacts between large bodies [in space] — that dynamic process is very hard to model," Gleason said. "And so having a shock compression experiment like this, where we can actually see, [in] real time, how the constituent materials transform from one to another, is really exciting and providing new constraints on the formation of these bodies." [Water Ice in Moon's Shackleton Crater Identified]

Researchers tested tiny water cells in a vacuum chamber to try and image the freezing process before the experiment began. Later, they shock-compressed and destroyed the cell — but just before it was destroyed, they gathered X-ray records of the water transforming to a high-pressure ice VII phase.
**Credit: Arianna Gleason**

Space collisions on Earth

Sarah Stewart, a researcher at the University of California, Davis, who was not involved with the new work, studies how giant impacts shape the craters found on solar system bodies. For her thesis work, she also formed phases of ice like ice VII in the laboratory. The only way that Stewart could confirm that she had created a particular ice was by measuring its density, she said. The new work lets researchers track the structure of the ice as it forms.

"What's amazing about Arianna's work is that she can reproduce in the lab a little parcel of what nature has done millions of times in the solar system, and let us understand what's possible in terms of these phase changes," Stewart told Space.com. "Nature makes shock waves, just like these lab experiments, by impact cratering, and we have these icy surfaces all over the solar system with impact craters on them."

Knowing the way ice VII forms during comet and moon collisions is crucial to scientists' understanding of how craters form. In Stewart's work, she wondered whether it formed quickly, which would lead to a crater structure similar to what's seen in reality, or slowly — which might demand another explanation for crater shape. This work affirms that ice VII can form extremely quickly.

But beyond that, both Gleason and Stewart said they look forward to researchers applying this technique to a range of materials, to learn how they change form when exposed to sudden shock. That would help scientists not only pin down what's going on in a tumultuous solar system but also learn much more about how materials in general change phase — a crucial question for physicists and chemists.

"Looking at the fundamental materials that are everywhere in the solar system to understand what happens under dynamic pressure — as a materials scientist, you eat this up," Stewart said. With this experiment, "I know what the structure is; I can show you how long it takes to get there. It's absolutely convincing. There's no hand waving. It took this amazing new facility to be able to do that."

The new work was detailed today (July 11) in the journal Physical Review Letters.

Email Sarah Lewin at slewin@space.com or follow her @SarahExplains Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.