Earth Science

Extremophiles: Life on Mars and What Causes Magenta Lakes

In terms of microbes, there’re none more remarkable than the extremophiles. These organisms may be the best contestants for finding life on Mars, and they are responsible for the most alluring pink lakes found here on Earth. Whether they inhabit environments with life-threatening temperatures or exist in acidic, salty waters, various kinds of these resourceful critters have existed for eons on our planet (and maybe on other worlds).

There are many types of extremophiles on Earth. Take, for example, halophiles. These are the salt lovers of extreme microbes. They thrive in locations that are nearly completely saturated with salt; in fact, they can live anywhere that the concentration is 5x more than that of the ocean. Halophiles are a type of archaea. The branch of life known as Archaea includes only those varieties of microbes that can exist in the most volatile environments.

Halophiles also go by the name Halobacterium; yet, genetically speaking, they are separate from bacteria. This can be slightly confusing, given their name; however, like bacteria, halophiles are single-celled and among the oldest living organisms on Earth. In fact, the word “archaea” is Greek, meaning “ancient.”

BUBBLE GUM LAKES:

Lake Hillier via Ralph Roberts

Lake Hillier is one of the most uniquely colored lakes on Earth. It is located on Middle Island in Western Australia. Its bright pink hue isn’t due to clever photographic angling; in fact, if you were to remove a sample of the liquid from the lake, it would remain the same color. The water is believed to be blushing because it is chock full of Halobacterium. The Pepto-Bismol color is caused by the carotenoids producing pigments within the cellular membrane.

Scientists believe that the coloring produced by these microbes is beneficial for multiple reasons. Not only does it help protect against the Sun’s ultraviolet radiation, it may also be useful in converting light into chemical energy, similar to the light-harvesting reactions of chlorophyll in green plants.

It is thought to be completely safe to swim in. Unfortunately, Lake Hillier is extremely remote and usually only seen by tourists as they fly past it. But if you still can’t get the dream of swimming in bubblegum lakes out of your head, you may have better luck at one of these other pink lakes.

ASTROBIOLOGY:

n images taken of Newton Crater by the Mars Reconnisence Orbiter in 2011 show what may be salt water flowing on Mars. Photo Credit: NASA

n images taken of Newton Crater by the Mars Reconnisence Orbiter in 2011 show what may be salt water flowing on Mars. Photo Credit: NASA

In 2011, NASA released images of what may be the best evidence of salt water flowing on Mars. For this reason, the longevity of halophilic strains is of considerable interest to astronomers seeking to find life in outer-space. Since microorganisms were the first creatures to exist on Earth, they seem a good place to start in the search for life outside the boundaries of our planet.

Even if these mysterious streaks on Mars turn out not to be caused by liquid salt flows, the possibility still exists that halophiles may be found on the red planet. Chemical analysis of Mars’ SNC meteorites (shergottite, nakhlite, and chassigny) indicates the presence of halite rock salt. Halophiles could potentially be found somewhere on Mars where salt formations occur.

In 2009, Jong Soo Park of Dalhousie University examined ancient rock salt from varying locations and found that the oldest known DNA on Earth belongs to a form of halophilic bacterium that existed 419 million years ago. We know that these organisms can withstand extreme conditions, and they can do so for unimaginable lengths of time; but will they prove to be fruitful in finding life on other planets? Only further observations and analysis will tell.

 

 

Additional References:

Extremophiles: Archaea and Bacteria“. Map of Life. May 26, 2014

Extremely halophilic archaea and the issue of long-term microbial survival”.

US National Library of Medicine National Institutes of Health

Archaea”. MicrobeWorld.org

Secluded Lake Hillier is a Bubble Gum Pink” Lake Scientist. January 23, 2014


This article originally appeared at From Quarks to Quasars.

Supercooled Water and Bacteria’s Bag of Tricks

Ice crystals have the potential to rupture cells, killing plants. Image source

Ice crystals have the potential to rupture cells, killing plants. Image source

It may seem intuitive to think water freezes at 0°C (32°F) and boils at 100°C (212°F), but unfortunately you’d be wrong. Supercooling is when water can be lowered well past its freezing point without it turning to a solid. Normally water is liquid at room temperature. This means that water molecules are passing freely through each other. Once water turns to solid ice the molecules can no longer move past one another. They are not completely still mind you, they still vibrate; however, the molecule is held in place and cannot escape.

Phase transition refers to changing from one form of matter into another (liquid, solid, gas). These changes are dependent on both temperature and pressure. Here on Earth, we are accustomed to the weight of 14.7 pounds of pressure per square inch (at sea level). Trillions of air molecules in our atmosphere provide this weight, and this affects the phase transitions of substances. By now you may be curious, if water can be supercooled then what else is needed to freeze it other than adequate temperature and pressure? The answer might shock you, it has to do with nucleation and that is where bacteria come into play!

 FREEZING WATER IS HARDER THAN YOU MIGHT THINK

Water generally won’t freeze without the aid of microscopic particles. A nuclei, nucleator, or seed, (all different ways of saying the same thing) is needed to jump start the transition of water into ice. If the sample is pure, meaning free of all particles except the water molecules themselves, it may exist as a liquid much lower than freezing. Theoretically, water can get to -55°C before solidifying, and astonishingly, scientists have discovered liquid water in clouds at -40°C (The Naked Scientists, Cambridge University).

The term heterogeneous ice nucleation is just a fancy way of saying that an impurity is used to start the seeding of ice crystals. As you may know, a lot of stuff is floating around in the atmosphere; pollen, dust, soot, aerosols, algae, sand, and spores are just to name a few, these can all be used as nuclei to freeze water. In general terms, the water molecules form a cage around these particles. This allows the substance to take the approximate shape of an ice crystal. That crystal is now the platform needed to form more crystals, changing the sample from a liquid to a solid as it freezes. It is exciting to realize that every snowflake caught on your tongue contains a seed.

 BACTERIA’S BAG OF TRICKS

Now we can get to those ever so evolutionarily clever microbes. Not every microscopic particle will nucleate water at the same rate. We can thank bacteria for their most amazing ability to freeze water at relatively high temperatures (-8°C to -2°C). Some of the most affective ice nucleators are found in the types of bacteria: Erwinia, Pseudomonas and Xanthomonas (Nature). But why would these bacteria be so efficient at freezing water?

It is thought that bacteria use this skill for mobility. If they’re able to freeze the water around them, for instance while in a cloud, they can then be carried back to Earth in the search for food as hale or snowflakes. These unique plant pathogenic microbes can now use their talented freezing ability for a second time. Once the microbe lands on a leaf it uses a special protein on its outer membrane to mimic the shape of ice crystals.

Pseudomonas syringae shown using SEM. Source: Gordon Vrdoljak, Electron Microscopy Laboratory, U.C. Berkeley

Pseudomonas syringae shown using SEM. Source: Gordon Vrdoljak, Electron Microscopy Laboratory, U.C. Berkeley

Once ice is introduced into a plant cell the membrane bursts. It is the same way for water that gets into cracks in the road, once frozen the concrete ruptures. Now that the bacterium has cracked the shell it can feast on the rich intercellular nutrients.

One of the most amazing things to consider is that scientists estimate 40% of the nuclei floating in the atmosphere are organic in composition. It was also found that cross sections of hale could contain a thousand viable bacteria per milliliter. Without organic material and other microscopic particles, ice would be harder to come by. The ability for water to be supercooled is a fascinating aspect of chemistry. And bacterial nucleators have real world applications in food science, medicine and possible weather modification. So the next time you fill your glass with ice think about the creatures contained within that made that ice possible!

The Anatomy of Lightning

Image credit: Flickr

Image credit: Flickr

There is something nostalgic about sitting on a porch and watching a storm come in on a carefree summer’s day. Observing the clouds growing larger and blacker each minute, with the occasional flicker of lightning in the distance, I’d sit there and wonder about the storm. What are the bolts made of? Why do thunderstorms seem to be born out of distinct cloud formations? And how in the world is it possible for electricity to spring out of a cloud? This article aims to explain each of those questions, as well as, how the components of lightning are constructed out of atmospheric conditions, what exactly a lightning bolt looks like in slow motion, and lastly it will touch on more exotic forms of lightning.

 To understand lightning we must first get a sense of how the right atmospheric conditions help to create a storm. Cumulonimbus clouds are the type that are massive in size, fluffy, vertical in shape, and close to the ground. They are often called mushroom heads and are associated with thunderstorms.

Because these clouds require a lot of energy to be created they are most frequent in the summer when the sun’s rays are at their strongest. The sun radiates its energy onto the surface of the Earth. This energy is absorbed and then radiated back in the atmosphere as heat.

As we know, hot air rises. An updraft carries water and gas molecules from lower in the atmosphere to higher and higher altitudes in the Troposphere, this process is called  convection. As the water vapor rises farther it begins to cool down, this causes the vapor to condense into a water droplet. After enough material condense a cloud is formed.

[side note: have you ever wondered why it’s cooler after a thunderstorm? It is also due to convection. Just as hot air rises, cool air is pushed by downdrafts high within the cloud. Rain helps capture the coldness from inside a cloud, as well, bringing those of us on the surface of Earth, a much welcome relief from a hot summer’s day. Good ol’ convection!]

When water is in a vapor state and wants to condenses into a liquid state it must release some energy to do so; this energy is in the form of heat. The convection process works like a cycle, the heat released causes the moisture and air molecules to continue to rise within the cloud. The upwards draft pulls even more material into the cloud, growing ever more vertical until it hits the base of the Stratosphere. The cycle of convection within the cloud is called the hot air balloon effect.

When the cloud hits the edge between the first and second layer of atmosphere, it fans out due to the differences in air pressure and temperature between these layers. This is why so many cumulonimbus clouds have an anvil shape.

Anvil cloud sketch courtesy of CloudMan

Anvil cloud sketch courtesy of CloudMan

Each cloud column is called a cell and each cell lives for about a half hour before it’s energy runs out. The life time of a cumulonimbus is so short due the high amount of energy needed to create this type of cloud, thus it can not be sustained for long periods.

The primary reason why a cloud can conduct electricity is because of ions! It is both the ionization of water molecules and atmospheric gases that contribute to a lightning strike. These charged particles are incredibly interesting when you realize that without ions there would be no neon signs, no fluorescent lights, no auroras, no lightning and even no sun.

An ion is simply a particle or molecule that has either lost or gained an electron, leaving it with a net charge (if you need to brush up on the basic structure of an atoms check this out real quick).

Keep in mind there is never a transfer of positive charge like there is negative charge; protons never bounce from one atoms to another, only electrons can beshared between atoms.The one thing you need to remember is that a loss of electrons from an atom will give it a positive charge. A gain of electrons in an atom will give it a negative charge. To get a visual of this, click to enlarge the picture to the right.

Now let’s get back to the cloud. Once liquid water droplets have risen high enough, the water changes state once again, from liquid now into solid ice as it freezes. At high enough altitudes the updraft is no match for the weight of the ice particles, they now surrenders to gravity and begin to fall.

The interior of the cloud can be quite fierce. Updrafts can reach speeds of 15-30 miles per hour. It is due to this turbulent nature of the wind that sends ice molecules colliding into each other; in doing so they shed or gain electrons, becoming either an Anion (an ion with a negative charge) or an Cation (an ion with a positive charge). Some of the electrons shed during impact do not reconnect with other atoms, theses float around by themselves, they are called free electrons. (Electricity is made out of free electrons).

SEPARATION OF CHARGE: Ions with extra negative electrons collect at the base of the cloud and the positive ions are carried along with the updraft to fill the top of the cloud. The picture to the below is quite simplistic, however, you can get a visual of how the charges separate within the cloud. In reality  it is never this cut and dry. Charges mix a bit more than this through out the cloud and it is possible to find pockets of cations in the base of the cloud along with the anions. But just to keep things simple imagine it looking like this:

 

PLASMA. The cloud is now primed to conduct electricity! This ionized cloud may now act as a plasma when agitated by an electrical current. Plasma is a distinct form of matter (as compared to solid, gas, or liquid). It is like a gas in that it has no defined shape and would distribute  evenly within a container. However, unlike a gas, this matter it is made of ions and free electrons which have the ability to conduct electricity because they are charged. Plasmas are also very susceptible to magnetism, meaning the ions will follow along any magnetic field lines that may be near.

The large amount of negative charge at the base of the cloud causes the equilibrium of neutral charge between the cloud and the ground to break down. The surface of Earth has an overall neutral charge. It is mixed evenly with equal amounts of + and – charges. However, when something like a thundercloud is hovering overtop, the charges within the Earth begin to align according to the charge of the cloud. Meaning that the Earth can become positively charged due to electrostatic induction! In simple terms, this means that the charge of one material can affect the charge of another without even touching.

The electrons gathered in the cloud causes a repulsion of the electrons on the ground. They are pushed further down into the ground. Just as electrons are repelled by the cloud, positively charged ions are attracted to the cloud. This creates a static charge build up between the cloud and the surface of Earth.

THE BOLT BEGINS! Now that we have covered how ions and charges build up within the cloud and also within the  ground, we can finally get to the really cool part, the lightning strike itself! When ever there is a static build up between two objects they yearn to meet and discharge their energy.

It is only because of the recent use of high-speed cameras and years of trying to point them in the right directions, that we know the anatomy of a lightning strike.

It begins with a small spark in the cloud. A stream of electrons flies out of from the base, it travels along a route to ground in about 50 yard segments; it then stops, pools for a couple billionths of a second and then splits and continues on path in a new direction toward the ground.

This initial bolt is called a stepped leader (SL). The picture of the house below shows this SL as it gets close the surface of Earth. This path of electrons is much fainter than what we would normally think of as a lightning bolt. Keep in mind there is still a build up of charge in the SL, it has not yet discharged any of its negative energy.

 

Notice the arrow coming out of the tree with little +’s leading to it. This is actually what is called a positive streamer (PS). This is a “stream” of positively charged ions that are attracted to the stepped leader, once again, due to electrostatic induction.

The PS exists for just a fraction of a second and is very rarely visible to the human eye. The length of a PS varies from just a few inches up to a few hundred feet above the ground.

The closest positive streamer to a particular stepped leader will become the most preferred route for electrical discharge. A SL might even bypass a taller object and connect with a PS closer to the ground. There are ways to predict the path of the stepped leader; they have to do with flux lines and, although, quite interesting it is not relevant to this discussion.

Positive streamers can reach out of anything on the surface of Earth, they can stretch out of blades of grass, tops of trees, roofs and even out of the top of your head. So if you are caught in a storm and your hair starts to get electrically charged, or you feel a tingling on your skin you better get the hell outta there, and fast, because you are now statically charged and a strike may be imminent.

The video below shows in slow motion detail how the stepped leader protrudes from the cloud and shows some great images of positive streams, as well.

 

 

 

Putnisite, Earth’s Unique New Mineral Discovered

In the newest release of the Mineralogical Magazine (v.78) a study was published that indicates the discovery of the new mineral, putnisite. It’s named after Christine and Andrew Putnis who together are established contributors to the study of mineralogy.

Dr. Peter Elliott of South Australian Museum and the University of Adelaide led the team of research scientists. Dr. Elliott continues to add to his résumé, as this was just one of twelve other minerals he has discovered in Australia within the last few years. The team was sent to study the material after a prospecting mining company initially discovered it. The new mineral was found at a surface outcrop at Lake Cowan, in Australia.

Crystals of putnisite ( in purple). © Peter Elliott

Crystals of putnisite ( in purple). © Peter Elliott

What makes this mineral so special is its composition. Compared to the 4,000 other known minerals, putnisite is unique because it is composed of an interesting array of elements: strontium, calcium, chromium, sulfur, carbon, oxygen and hydrogen. The molecular formula is pretty complex: SrCa4Cr8(CO3)8SO4(OH)16•25H2O

The mineral is a translucent vivid purple with a pink streak. It is composed of brittle pseudocubic crystalline structures with a maximum size of 0.5 mm each. Dr. Elliot states in the Mineralogical Magazine, “By x-raying a single crystal of mineral you are able to determine its crystal structure and this, in conjunction with chemical analysis, tells you everything you need to know about the mineral”. He continues, “Most minerals belong to a family or small group of related minerals, or if they aren’t related to other minerals they often are to a synthetic compound – butputnisite iscompletely unique and unrelated to anything”.

It has a Mohs hardness score of 1.5–2 (the scale is from 1-10). In comparison, a human fingernail has a hardness of 2.2. The bonds between atoms within the crystal structure determine the hardness of a mineral. This means that putnisite lays between talc (the softest mineral) and gypsum (the second softest) when it comes to its texture. Diamonds score a 10 on Mohs’ scale, as they are the hardest known minerals.

It is still not yet known if there are any practical uses for the new mineral. Other soft minerals are used in a variety of bath and baby powders, also in sandpaper. Graphite has a hardness of 1.5 and is used in pencils. As a side note, putnisite and ice share the same Mohs’ scale hardness, ice is in fact technically a mineral. Being a soft material it is susceptible to weathering and breakage.

Sources and further reading:

 

Prehistoric Relic: Otzi the Iceman

A reconstruction of the ancient man know as Otzi. Photo credit: The South Tyrol Museum of Archaeology

A reconstruction of the ancient man know as Otzi. Photo credit: The South Tyrol Museum of Archaeology

Otzi is a man shrouded in mystery and wonder. His name was given to him because of the Ötztal mountain ridge in the Alps where his body was found, immaculately preserved for 5,300 years deep within a glacier. Just to put that timeline into prospective, he lived a thousand years before the pyramids and before the invention of the wheel. Otzi the Iceman, as he is commonly referred to, is the oldest, well-preserved, naturally mummified human body ever found.

If that’s not enough to get you excited, there’s more; he also has the oldest known tattoos, he is the oldest victim of homicide ever to be unearthed, and he was also carrying an axe that proves the Stone Age was ending a thousand years earlier than originally thought!

 

PRESERVING OTZI

In 1991 when hikers in the Swiss Alps stumbled upon a human corpse, they had no idea how significant the find would be. In fact, it is pure luck that he survived the 5000 plus years of deep-freeze. Normally, when objects are trapped within a glacier they are pummeled to bits by the shifting ice sheet as it moves down hill. The force is strong enough to crush mountain ridges into pebbles, so how was Otzi spared?

The reason why the mummy still exists today is due to the trench he died in. With his body face down over a bolder, large rocks lined the small nook he was in. Eventually, massive amounts of snow fell over the body, the snow compacted and froze forming a glacier. Over thousands of years the glacier built up layers and inched its way forward. Because of the trench Otzi was in, the ice creaked along above him, completely shielding him from any outside influences for many years.

 

PHYSICAL AND BIOLOGICAL TRAITS  

(and the awesome stuff he was carrying)

The ice essentially freeze-dried his body, even his eyeballs were found undamaged. Along with his body he had items that remained almost fully intact, as well. He was wearing shoes made of grass, skin and cording. He had a bearskin hat, leggings, a coat, loincloth and belt. He was traveling with a pack that contained a first aid kit consisting of medicinal tree fungi, leather, rope, a net, dagger, and maple leaves to carry embers. He had a stone knife and a bow and arrows.

Otzi's copper axe. Photo credit: The South Tyrol Museum of Archaeology

Otzi’s copper axe. Photo credit: The South Tyrol Museum of Archaeology

The most perplexing item found with the iceman was his copper axe. Until Otzi’s discovery, it was not believed that humans had the technology to extract ore and cast metal tools at such an early age of human development. This alone was a major discovery that rewrote history books. It also may suggest that Otzi was a pivotal person in his community.

“Based on scant Copper Age finds discovered in what is today South Tyrol, everything indicates that Ötzi was a member of the first independent Alpine cultural group… Emerging during the last centuries of the fourth millennium BC.”- South Tyrol Museum of Archaeology

Through elaborate scientific studies done on the body, which includes X-rays, specialized autopsies, carbon dating and DNA sequencing, we now know much more about the man of mystery.

He was 5’2, in his 40’s. He had diastema, a gap between his two front teeth. Otzi had muscular legs, which seem to indicate he was accustomed to mountain hikes. The skin on his hands was not rough and calloused like that of a farmer’s, instead he may have been a Shepard or hunter. Grain, pollen, fat and Ibex meat were found in his stomach. This is an important clue because he lived at a time when groups of humans were just starting to settle into communities and beginning to cultivate wheat for the first time.

Otzi’s DNA can tell us a lot about humans during his time. It was found that he was suffering from arthritic Lyme disease; he was also genetically predisposed to heart disease and was lactose intolerant. Until Otzi, we had no idea that such diseases could be traced back so early through human history. Like all adults at that time, he could not digest milk. At the end of the Stone Age, humans had not yet acquired this capability. Infants could produce enzymes necessary to break (breast) milk down for digestion, but as they aged they lost the ability. Since then, a genetic mutation has occurred allowing most human the adaptation to consume dairy their entire lives.

And what about the fifty tattoos he had? “Several tattoos, mostly in the form of small lines and crosses, [were found in various places all over his body; some were] etched in soot around his joints. The markings are suspected to have been less decorative than therapeutic, since Otzi is thought to have suffered from joint pain” (Washington Post).

Otzi's naturally mummified remains. Photo credit: The South Tyrol Museum of Archaeology

Otzi’s naturally mummified remains. Photo credit: The South Tyrol Museum of Archaeology

CSI: STONE AGE

How do we know he was murdered? An arrowhead was found lodged in his shoulder. By examining the body we know he was shot from the back and fell face down onto a large rock. Blood was found on his brain, which indicates that he was either struck in the head as well, or hit his head on the bolder as he fell. What is known for sure is that after he was shot, the killer pulled the arrow’s shaft out of the Otzi’s body, as it was never recovered at the scene.

There is a lot of conjecture about his death. Some believe he was killed by roaming packs of hunters which were still frequent in his time. Others think he was murdered by someone from his community, someone who wanted to keep their identity hidden by taking the murder weapon.

“Copper began to be used in the late Neolithic period, but only in the Copper Age (3500 – 2300 BC) did it begin to be worked regularly into weapons, tools and jewelry. The knowledge of how to extract and refine copper spread came to Europe from the Near East via the Balkans and the Mediterranean region. The new resource brought about a fundamental economic and social transformation.
New trades in metallurgy emerged, leading to differentiation within the social structure”(A Time of Upheaval).

Could it have for social reasons that his life was taken? What is known for sure is that we may never who killed Otzi or why. However, he does have a massive amount of information to share with us and for that he will always be treasured.