astrobiology – Australian Science

Lake Vostok and the search for extraterrestrial life

Sharon — Mon, 25 Mar 2013 00:17:53 +0000

When Russian geographer and Antarctic explorer Andrey Kapitsa travelled to Vostok Station in 1959 he was looking for evidence of a subglacial lake that was first proposed by Russian scientist Peter Kropotkin at the end of the 19th century. Whilst Kropotkin was not able to specify the location of subglacial lakes, he theorised that masses of fresh water could be trapped far below the Antarctic ice sheets. He believed that the massive pressure of thousands of meters of solid ice would mean that temperatures at the bottom of the ice sheet would be high enough to create isolated water lakes.

Lake Vostok (Image courtesy of the National Science Foundation)

During expeditions to the region around Vostok Station in 1959 and 1964 Kapitsa took numerous seismic readings of the thickness of the Antarctic ice sheet. When Kapitsa analysed his measurements he was able to confirm that he had found a subglacial lake – just as Kropotkin predicted.

It wasn’t until the 1970s that further tests were conducted on Lake Vostok. British scientists performed numerous tests including airborne ice-penetrating radar surveys over the site. Results confirmed the presence of a liquid, freshwater lake far below the icy surface. In the 1980s and 1990s subsequent studies confirmed the details of the lake and revealed that it was the largest of 140 known Antarctic subglacial lakes (about 400 subglacial lakes exist worldwide). Measurements showed that the lake was more than 250km long, 50 km wide, about 400m deep, and was submerged more than 4km under the surface. In 2005 it was discovered that Lake Vostok had a number of islands, and that it’s likely that Lake Vostok is connected to other Antarctic subglacial lakes by a series of subglacial rivers. Unfortunately, scientists are still unsure how water might travel between the lakes, however it appears that the water in Lake Vostok may have been trapped under the ice for 15 – 25 million years. Lake Vostok is interesting to astronomers and astrobiologists, who theorise that if life exists somewhere in the cold murky depths of the lake, then perhaps it could also survive in the cold icy moons of our outer solar system.

Since 1989 there have been various efforts to drill down into the lake to obtain samples to test for microbes. However, drilling Lake Vostok has proven to be a very difficult exercise due to the remote location, freezing temperatures (the coldest recorded temperatures on Earth were recorded at Lake Vostok at -89 degrees Celsius), and long dark winters that reduce drilling times. Samples were taken from an ice core that reached within 100m of the lake in 1998, 2011 and 2012 but these results were inconclusive.

Black Smoker Hydrothermal Vent (Image Courtesy University of Victoria)

Recently researchers announced that they had penetrated the ‘surface’ of Lake Vostok and had analysed samples taken from the drill head in the borehole. Results indicated a type of bacteria that was ‘unknown’ – a result that initially excited scientists. However, the next day, it was announced that the bacteria in the sample was found to use kerosene as an energy source. This was problematic for the team, as they use significant amounts of kerosene and freon at the site to stabilise the borehole (54 tonnes over the last few years). This result pointed to a likely contamination of the sample. Researchers advised they would be conducting further tests in order to collect ‘clean’ samples.

So – why are we so interested in Lake Vostok?

Until the mid 1980s we had a very narrow idea of where life could survive on our planet. We essentially applied the ‘Goldilocks’ theory; in order to foster ‘life’ the environment had to be not too hot, not too cold, must have water, sunlight etc… In the 1980s and 1990s, scientists discovered that microbial life has an amazing ability to survive in what we would consider extreme environments, niches that are blisteringly hot, dry, acidic, or even extremely cold. The discovery of these microbes, known as extremophiles has shown us that the boundaries of where life can exist, and even thrive are far wider than previously imagined. The image above shows a ‘black smoker’ hydrothermal vent – deep in the ocean spewing out water anywhere from 60 – 400 degrees Celsius. Typically these objects are surrounded by life forms, including Thermophiles, microbes that thrive in extremely hot temperatures. Until these deep sea hydrothermal vents were discovered in the early 1980’s we had no idea that life could survive, let alone thrive in such an inhospitable environment without sunlight and under such enormous pressure. The Grand Prismatic Spring in Yellowstone National Park in the U.S. is also home to various types of thermophiles, which thrive in the Grand Prismatic hot spring, despite it’s average 70 degree Celsius temperature.

Grand Prismatic Spring – Yellowstone National Park (Image courtesy of Wikimedia)

By looking at sites such as Lake Vostok we hope that we will discover something that will confirm our understanding of the boundaries for life or perhaps give us new information! We hope to find a new type of bacteria, similar perhaps to the psychrophile, or cryophile, extremophiles that can grow and reproduce in temperatures as low as -15 degrees Celsius. These organisms are currently found on Earth in small pockets of briny water surrounded by sea ice, alpine and arctic soils, deep ocean waters, glaciers and snowfields.

Although the Russians have been working on Lake Vostok for some time, they aren’t the only ones taking a good look at sub glacial lakes. Researchers from Britain and the U.S. are also working on Antarctic sites. The Americans have drilled more than 800m to reach Lake Whillans, whilst British researchers have stalled testing on Lake Ellsworth while they test new hot-water drilling methods.

If we find microbes surviving in the waters of Lake Vostok, or another subglacial lake that has been subject to enormous pressure, freezing conditions, lack of sunlight – that suggests that life could exist on one of the icy moons of the solar system. With the knowledge gained from sites like Lake Vostok we can plan missions to the icy moons in search of life. Research has shown that subsurface oceans may exist on a number of solar system moons including Enceladus (Saturn), Titan (Saturn), Europa (Jupiter), and Triton (Neptune). Each of these moons may have an environment capable of harbouring life.

It just may not be life as we know it.

Enceladus and it’s ‘tiger stripes’ – an area near the south pole of the moon that may cover a sub surface ocean (Image courtesy of NASA)

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Asteroids, extinctions, and biodiversity: Wiping the slate clean for new life to flourish

Markus — Fri, 08 Mar 2013 00:24:56 +0000

The recent meteor strike in Russia has been a rather sobering reminder that Earth has been regularly battered during its history, by space rocks. Actually, the amount of meteoritic material constantly landing on Earth is startling – on average, over 100 tons every day which we don’t even notice. Now, most of that is in the form of tiny rock fragments and dust; with most being small enough to be vapourised as they burn up in Earth’s atmosphere, relatively few meteorites ever end up on the ground. The part which may make us uneasy, however, is the fact that occasionally something larger crosses Earth’s path. Something much larger.

We already know with some degree of certainty that a gigantic asteroid impact may have played a role in wiping the dinosaurs off the face of our world, and we also know it’s not the only such large impact in Earth’s history. Now there’s evidence of another huge impact – and this one was in Australia!

With a diameter spanning around 200 km in South Australia’s East Warbuton basin, an ancient impact site has been uncovered. Created by an asteroid which was probably between 10-20 km in diamater, affecting an area of terrain of around 30,000 km, this impact zone is the third largest currently known. When this particular asteroid struck Earth some 360 million years ago, its effects would have been profound and global.

Andrew Glikson, a visiting fellow at the Australian National University, first started investigating the area after hearing about structural abnormalities in the rocks there. He spent time in a crystallography lab, studying the orientation of crystals in rocks collected from the site, and found that the most likely cause for what he was seeing was the result of the rocks being subjected to a huge shock. Given the extent and area of the shocked rocks, the most likely explanation is a giant extraterrestrial impact.

The most well known giant impact, known as the Chicxulub Impact Event, occurred about 66 million years ago causing the Cretaceous-Tertiary extinction event, and quite probably being the final nail in the coffin of the dinosaurs. This newly discovered Australian impact site, however, is much older. In fact, when this asteroid struck Earth, it was around 100 million years before any dinosaurs had even evolved. In fact, it would have likely been during the Carboniferous Period in Earth’s geologic history. Interestingly enough, there was a minor extinction event during the Carboniferous. A minor extinction caused by a change in Earth’s climate.

Glikson went on to explain that this impact was likely one of part of a cluster which caused a number of impacts around that time. This cluster of impacts was very likely behind an extinction event. Simply, a huge impact like the one discovered in the middle of Australia would cause devastation. The effects locally would be severe, splattering molten rock into the air which would then rain back down to the ground hundreds of kilometres away, and a blast wave of superheated air would cause widespread forest fires near the impact zone – particularly in the oxygen rich atmosphere of Earth’s Carboniferous forests.

The global repercussions of such an impact, however, would be much worse. A huge amount of dust would be thrown up into Earth’s atmosphere, choking out the sunlight. This would cause Earth’s surface to cool, and the reduced light would make plants die off. A big enough impact – or a series of them – would throw enough dust into the skies that this could happen on a global scale. With the food chain cut off at the plants which are its source, a mass extinction would follow as animals would have trouble finding food to survive on.

These events are mercifully rare. A giant impact may happen on Earth once every ten million years or so. Interestingly enough though, researchers in a different study have found evidence that extinction events on planet Earth may actually be beneficial to biodiversity.

Kale Sniderman, part of a group of researchers working at the University of Melbourne and the University of Tasmania, focussed on an event much more recent than the East Warburton impact. Instead, he and the others looked at the last ice age, around one million years ago and together they constructed a hypothesis that extinction events may be even more important for biodiversity than rapid evolution. While their work concerns species which went extinct during ice ages as opposed to impact events, a suitably large meteor strike may be a factor in what causes an ice age to begin.

The traditional view of most biologists is that some areas have greater biodiversity due to evolution in those places progressing more rapidly. Evolution has always been the only thing emphasised in biodiversity studies, but Sniderman and his colleagues have taken the first step in overturning this picture.

Their work looked at regions in South Africa and Australia – notable as two of the most diverse areas on planet Earth. South Western Australia is known among botanists for having a huge variety of plants, particularly tough leaved shrubs and trees. The very tip of the South African cape is even more diverse, populated by very similar types of plant. For a long time, biologists have theorised that the diversty in these rather similar areas was down to the dry, arid summer conditions and the nutrient poor soils in these areas. The exact connection, however, has never been entirely apparent.

As it happens, the status may not be quite so quo here. Studying fossils from an ancient lake in South Eastern Australia, it was found that plant life in Australia tended to die off as the continent has gradually become drier – a process taking millions of years. In particular, during the last ice age, a huge amount of rainforest plants died off. This allowed other hardier plants to fill the space they’d left and plant diversity expanded as they did so – creating what was described by University of Tasmania’s Greg Jordan as “a remarkable number of tough-leaved, shrubby plants.” Thinking about this process logically, it seems to make perfect sense. In any place on Earth where there’s a vacant ecological niche, life will typically evolve to try and fill that niche. Where an extinction occurs, a huge niche will suddenly become empty. This would prompt a veritable explosion of new life forms to fill in the gap.

This study not only gives new insight into how extinction events can affect diversity of life forms, but also has implications for current and future climate change, and how species may be able to cope with it. As I mentioned previously when talking about the Great Barrier Reef, Australian wildlife is already suffering from climate change. However, at least for plant life on land, there’s a good chance that the species most easily affected by rapid environmental changes may have already died off during the last ice age.

To loop this discussion back to the beginning, if an extinction due to an ice age could help to boost biodiversity, logically an extinction due to an asteroid impact event could do the same. To my knowledge, there are no studies in this context concerning what happened to biodiversity after the Chicxulub impact event (though I’ll admit that I may be wrong on this), but it would be very interesting to see what such studies might find. Similarly, it would be interesting to know if any such flourishes of biodiversity occurred after the newly discovered East Warbuton impact too. It could be that only certain types of extinction event can boost diversity of life on a planet. That said, if the same thing can occur after an asteroid impact then it may have implications reaching beyond Earth.

If a giant impact event could serve to actually boost life on a planetary scale, then it may imply that once life has taken hold on a planet, it’s more robust than we’ve been giving it credit for. The implications for astrobiologists and the search for life elsewhere in the galaxy are quite clear.

To end on an aside, a large enough asteroid strike even on Earth today would cause widespread fires kilometres away from the impact site. Back in the Carboniferous Period, around the time when the East Warbuton impact occurred, the situation would have been much more dramatic; the oxygen content of Earth’s atmosphere was up to 15% higher then, than it is today. In such a combustible atmosphere, where fires could have been started by a simple lightning strike, a large asteroid impact could cause a widespread inferno. However, South Africa (one of the places considered in the biodiversity study) is home to a number of species which have evolved specifically to survive fires. In particular, the highly diverse Fynbos region is known for a number of plants for which fire is actually an integral part of their lifecycle. Some seeds belonging to protea species simply don’t germinate unless they’re exposed to the intense heat of a wildfire. Provided they could gather sufficient amounts of sunlight under the darkened skies, plants like these may be able to rapidly repopulate an area after an impact event.

Life on Earth, evidently, has resilience which can still surprise us.

Image credits:
Top – Artists impression of a large scale impact event – Don Davis/NASA
Upper Middle – Australia seen from orbit – NASA
Lower Middle – League Scrub sub tropical rainforest, near Bowraville NSW, Australia – Peter Woodard/Wikimedia Commons
Bottom – Garden – https://croatia-real.estate

Cite this article:
Hammonds M (2013-03-08 00:24:56). Asteroids, extinctions, and biodiversity: Wiping the slate clean for new life to flourish. Australian Science. Retrieved: Aug 25, 2026, from https://australianscience.com.au/environmental-science/asteroids-extinctions-and-biodiversity-wiping-the-slate-clean-for-new-life-to-flourish/

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Interstellar travel: how to spot a ‘starman’ going by

Kevin Orrman-Rossiter — Mon, 18 Feb 2013 00:03:41 +0000

Massive objects moving at near light speeds do not occur naturally in the universe as we know it. If we detect such objects it is a reasonable to assume they are artificial artifacts from advanced intelligent life. This according to Garcia-Escartin and Chamorro-Posada, authors of a recent paper, is a low-cost, sure-fire way of searching for intelligent life outside earth.

The habitable zone of Gliese 581 compared with our Solar System’s habitable zone. Image credit NASA.

Searching for life beyond earth is a grand and varied enterprise.

For a start we can look for exoplanets that fall inside the habitable zone of a star. A planet found in this zone may fulfill the requirements for life: liquid water, energy, elements and other nutrients, and appropriate physical conditions. Though we have located many exoplanets in recent times they are far from earth – many light years distant. For example one star system, Gliese 581, is 20.3 light years away (192,048,720,000,000 kilometres). With three planets in its habitable zone, we know nothing about conditions on them. The techniques used to find them can tell us nothing about their ecology – if any. Being in a habitable zone does not guarantee life. It is only in recent years that we have realised how inhospitable Venus and Mars are to life – despite being in our habitable zone.

By looking for alien signals or transmissions, as in the SETI programme, we extend our search from ‘possible life’ to intelligent life. For advanced civilisations we look for artificial illumination or interstellar probes.

Let’s face it though, to know we are not alone will require quite good proof for most of us (apart from the misguided minority of UFO believers), and especially for the skeptical scientists.

Bussard ram-jet interstellar drive. Image credit NASA.

The intriguing proposition of Garcia-Escartin and Chamorro-Posada is based on three ideas. The first is that anything travelling faster than 3.3% of light speed (5,935,890 kilometres per hour) is artificial. All known natural objects travel slower than this speed, as do our current space probes. This speed was chosen as it is the estimated speed of the nuclear propulsion ship proposed by Freeman Dyson in the Orion project. Although the propulsion technology is feasible today the technological and economic hurdle of creating such a craft is way beyond our current means. Although it is certainly not inconceivable to achieve such interstellar travel in the next 100 years.

Scales of speed with respect to the speed of light in vacuum (logarithmic scale). The fastest man-made objects are in the range of velocities from 1/100,000 c to 1/1,000 c. Examples are the fastest manned ship, Apollo 10 on entry, the Galileo probe during its descent into Jupiter and the solar probe Helios 2. For comparison, we have included the average speed of Earth during its orbit around the Sun and the motion of the Solar System with respect to the cosmic microwave background frame. The fastest natural objects, like hypervelocity star HE 0437-5439 and neutron star RX J0822-4300, move in the scale of 1/1,000 c-1/100 c. We define a region of extraordinary propulsion (REP) for speeds which would point to an artificial object. The REP starts at the estimated speed for the nuclear propulsion Orion ship, which could be built with present human technology. Source original paper, Cornell University.

You are possibly thinking about now: “Doesn’t the mass of an object increases massively as its speed approaches light speed?” You would be correct, this consequence of Einstein’s theory of special relativity is demonstrated quite satisfactorily in particle accelerators around the world. To cover this the authors next identify a consequence of relativity theory: relativistic effects amplify the light reflected from a body travelling at near light speed – in some key situations. Allowing for the detection of ‘small’ objects.

This brings in the authors third criteria. Interstellar travel will be from one star system to another. The reflected-light magnifying effect would be greatest for the cases where earth is almost in line with the departure stellar system and the destination stellar system.

Earth’s position with respect to the ship’s trajectory. (a) Earth receives the light from the destination star reflected from an approaching ship. (b) Earth receives the light from the origin star reflected from an outbound ship. (c) Earth receives the light from a third star, which is reflected from the ship at an angle. Source original paper, Cornell University.

The authors propose to limit the first search to star systems that are reasonably close to each other (no further than 10 light years apart) to maximise the probability of stellar travel opportunities. Considering that Gliese 581, for example, is greater than 20 light years distance from us, I suggest that this criteria is too limiting.

The paper is an interesting, if not compelling, proposition. The authors do calculate what size an artifact would need to be, travelling at their minimum speed (3.3% light speed), to be detected at the distance of one of our closer stellar neighbours. Could such an artifact be detected by the Hubble or James Webb space telescopes, for example? What is the probability of success of such an experiment, compared to say the SETI experiments?

One idea I did find interesting is by focussing on detecting light reflected from ships, we do not need to assume any intention by the interstellar travellers to communicate with us. The ‘signal’ is independent of alien psychology. It is also independent of propulsion technology – we aren’t looking for any ‘signature’ of any particular technology, known or unknown.

It is an interesting paper. I’m not sure they have presented a compelling enough case to convince a funding body – yet.

Cite this article:
Orrman-Rossiter K (2013-02-18 00:03:41). Interstellar travel: how to spot a 'starman' going by. Australian Science. Retrieved: Aug 25, 2026, from https://australianscience.com.au/space/interstellar-travel-how-to-spot-a-starman-going-by/

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Searching for Life on Titan

Lauren — Wed, 13 Feb 2013 07:53:51 +0000

Titan against Saturn. Credit: NASA

Discovered in 1655 by Dutch astronomer Christiaan Huygens, Titan is one of Saturn’s 62 moons, named for a race of giants in Greek myth who were Saturn’s brothers and sisters. Over 5000 km in diameter, it’s roughly twice the size of our own Moon and is one of the largest moons in our solar system, second only to Jupiter’s Ganymede. It’s even bigger than the planet Mercury, and is covered with an orange haze that shields the secrets of its surface. That alone makes it interesting, but a glimpse into the workings of the planet makes it more intriguing still—astronomers even believe Titan could harbour life.

In the 1980s, the Voyager 1 and 2 spacecraft flew past Titan; in the 2005 Huygens probe parachuted through its atmosphere and landed on the surface; and the Cassini spacecraft still studies Titan from its orbit around Saturn. Their images and measurements have revealed a vibrant alien world beneath the haze—complete with rivers, lakes, and ice volcanoes.

Credit: NASA

Titan is an incredibly frigid place, with an average temperature of -178 degrees Celsius (-289 Fahrenheit)—too brutally cold for life as we know it, but still of incredible interest to astrobiologists. It’s the only moon known to have an atmosphere—a thick and cloudy one, composed primarily of nitrogen—and it also exhibits weather and changing seasons. The orange haze that shrouds its surface is made up of trace gases such as benzene and hydrogen cyanide, and at the pole closest to the sun, sunlight heats the toxic orange haze and makes it circulate towards the other pole, so the gases concentrating there. Since a year on Titan lasts almost 30 Earth years, each season is 7 years long.

Titan’s seasonal changes. Credit: NASA

However, unlike Earth, its weather system is methane-based—and aside from Earth, Titan is the only object in the solar system to have permanent bodies of liquid on its surface, including an enormous river system that flows 400km across the moon’s surface to meet a large sea.

River network on Titan. Credit: Cassini

The darkness of the river in the image indicates a smooth surface, which in turn indicates that the river is not a dry bed, but filled with liquid—but this liquid is likely methane or ethane, which are more closely related to gasoline than water. Even though the mechanics seem to be similar, Titan’s weather would be alien to us because the skies fall with methane rain and lakes and oceans pool with liquid methane—but still, this presents possibilities of methane-based life.

Credit: Cassini.

It is also suspected that Titan harbours cyrovolcanoes, which spew water ice and hydrocarbons into the atmosphere instead of lava. Speculations began after NASA’s Cassini spacecraft captured images of a landform on Titan’s surface called Sotra Facula. The images showed three conical features with material flowing from them, their peaks up to 1,500 metres tall, as well as several pits equally as deep. Researchers gravitated towards the idea that these landforms were cyrovolcanoes, as it would help explain a long-standing mystery of Titan’s thick, methane- and nitrogen-filled atmosphere. Calculations show sunlight would have broken the methane down long ago if something hadn’t been replenishing it, and a cyrovolcano is a good candidate—it could erupt methane, dragging it from the planet’s interior into the atmosphere.

Sotra Facula. Credit: APOD.

However, these intriguing surface features could have also been created by weather and meteorite strikes than by volcanic activity, and it is difficult to tell without further data. Researchers believe cyrovolcanoes might be fairly common on the frigid moons of the outer planets—one has been confirmed on another of Saturn’s moons, Enceladus—which is incredibly interesting, because volcanic activity would prove that Titan is an active world, and could increase the likelihood that this huge, distant moon may harbour life. While searing lava destroys life on Earth, ice volcanoes on Titan would provide a way to mix complex chemicals from the surface and the interior. It could bring life forms up to the surface so our instruments have a better chance of detecting them—because fascinatingly, Titan seems to have subsurface oceans.

Further data from Cassini indicates that Titan has a layer of liquid water under its icy outer shell. The evidence is tidal—as Titan orbits Saturn, the planet’s powerful gravitational pull stretches and deforms the moon, like pulling and stretching an elastic band. If Titan were solely composed of rock, this stretching would only cause bulges (tides) of about 1 metre, but instead the moon experiences tides of about 10 metres—suggesting that its interior is not entirely solid. This ocean may not be enormous or deep; just a liquid layer between the solid mantle and the external icy shell would be enough to compress and bulge as Cassini has observed. Since Titan’s ice surface is composed mostly water ice, researchers believe its ocean could be liquid water.

However, just the presence of an ocean alone does not indicate life—researchers think that life is more likely to occur when the water comes into contact with rock, and we can’t currently tell if this exists beneath the surface.

Possible scenario for internal structure of Titan. Credit: NASA

Another intriguing phenomenon is the hydrogen gas flows through its atmosphere, and yet there is a lack of the chemical on the planet’s surface—so how did it disappear? One theory suggests that hydrogen-breathing, methane-based life forms consume the gas, similar to how we consume oxygen on Earth.

Liquid water, a possibly active interior, complex chemistry, a thick atmosphere, seasons, weather… All of these factors reflect the environment of life as we know it, so researchers have long thought that Titan is an excellent candidate to harbour life. None of these factors alone are solid evidence for life—they are just conditions necessary for it—but Titan is a fascinating place deserving of further study. Since its nitrogen-rich atmosphere is similar to Earth, just significantly colder, it also demonstrates how atmospheres of cold moons and planets behave, and thus allows us to speculate about how the atmospheres of exoplanets far from their stars might behave.

But our questions about Titan will remain unanswered until we obtain sufficient evidence to draw conclusions—but to do this, we need data. Two possible missions have recently been proposed. The first is the Titan Mare Explorer (TiME), which would have sent a floating buoy to land in Titan’s methane sea and measure the chemistry and organic composition, study the sea’s interaction with the atmosphere, and basically perform the first nautical exploration of this extraterrestrial ocean. It also would have observed Titan’s methane cycle to help us compare it to the water cycle on Earth. TiME was proposed to launch in 2016, but unfortunately it lost its funding to a Mars mission.

Artist’s concept for the TiME lander. Credit: NASA/ESA

Another possibility, however, is the Titan Saturn System Mission (TSSM), which is a proposed exploration of Saturn, Titan, and Enceladus—focusing on the complex phenomena the Cassini spacecraft has already noted. It is proposed to launch in 2020 and reach Titan by 2029, and during its 4-year-tenure, it would spend time circumnavigating Titan and studying its astrobiological potential. The mission consists of an orbiter and two Titan exploration probles—one that’s basically a hot air balloon, and another that land on the methane seas. One of the proposals for this second lander is the lake-lander of the discarded TiME mission, which will hopefully be included. TSSM, if it goes ahead, would be the first mission to extensively survey the organic chemistry and climate of the land, sea, and air of another world.

If life is detected on Titan, it would undoubtedly be moving and crucial to us as a species—not only because it’s the first extraterrestrial life we have detected, but also because it would behave differently to the water-based, oxygen-breathing life we’ve developed here. Even if life has not yet developed on Titan, the chemistry for life to form is present, so just give the moon four billion years…and who knows?

Cite this article:
Fuge L (2013-02-13 07:53:51). Searching for Life on Titan. Australian Science. Retrieved: Aug 25, 2026, from https://australianscience.com.au/space/searching-for-life-on-titan/

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The Oldest Fossils in the World

Markus — Tue, 08 Jan 2013 00:05:16 +0000

Life has existed on planet Earth for a long time. Precisely how long, however, is a question which many are still searching for an answer to. The most recently discovered piece in that puzzle may put us another step closer to finally answering that. Discovered in Pilbara, Western Australia, are what are quite probably the oldest fossils discovered on Earth so far!

At approximately 3.49 billion years old, these fossils come from a time long before complex organisms like us existed. Before evolution forged living things into the structures we recognise around us today, and before distinctions like “plant” and “animal” had even been drawn, our world was populated by bacteria and other single celled life. In fact, on a cosmological timescale, this wasn’t long after our planet had formed.

Being left by bacteria, these fossils appear as little more than patterns left behind in sandstone, but after careful analysis they’ve been found to very definitely be fossils and not simply mineral formations. Discovered in some of the best preserved sedimentary rocks on Earth, at Strelley Pool in Pilbara, these fossils offer a fascinating glimpse at some of the oldest known life on Earth. Excitingly, as well as the discovery of this life, these is some evidence that it may have had some organisation to it as well.

Found preserved in quartz sand grains, the fossils show several cell-like structures all of a similar size, much like bacterial colonies still found on Earth today. The age of these fossils can also be estimated with some precision, due to the rocks in which they were found. These particular rocks were formed between two volcanic successions, which means that their age can be determined down to a few tens of millions of years!

Interestingly enough, any life this old would have been living without any oxygen – oxygen wasn’t abundant in Earth’s atmosphere until around 2.4 billion years ago. It’s quite likely then, that these bacteria had a metabolism based around sulfur, just like bacteria found in marshes and other oxygen-poor environments in the world today.

The most exciting implications behind this find are those for life on other planets. If life could form so soon on planet Earth, it means that life might well have existed on other planets in the solar system too. Venus before it developed its hellish greenhouse effect and Mars before it lost all of its water, may have been home to similar primitive life. While few are hopeful of finding life on our neighbouring planets today, it still gives hope of discovering fossils as we continue to explore them. For astrobiologists hoping to find life on planets outside our solar system, it means that where life develops, it may occur quite soon after planets form.

Image credits: Top – D. Wacey/UWA, Bottom – Abigail Ailwood

Cite this article:
Hammonds M (2013-01-08 00:05:16). The Oldest Fossils in the World. Australian Science. Retrieved: Aug 25, 2026, from https://australianscience.com.au/research-2/the-oldest-fossils-in-the-world/

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Weekly Science Picks

Kelly Burnes — Sun, 11 Nov 2012 08:49:21 +0000

It seems the rate of everything has increased exponentially. A very bold, vague, yet intriguing statement, you might say.

During the course of the past 2 weeks, Hurricane Sandy devastated the East Coast of America, followed closely by a nor’easter. So my science picks for this week center on the themes of natural disasters, planning, global warming and Space, and the rate of which we have to increase our thinking and innovation in order to get ahead of these issues, before they become serious problems.

So let’s get started.

I was out of town when Hurricane Sandy struck. My neighborhood in Brooklyn was pretty much untouched. While I heard reports from friends not having power, and subways and airports being closed, it wasn’t until watching the hurricane relief telethon that I realized the magnitude of destruction. And I chose the following article by our very own Charles Ebikeme because it is important to remember that Haiti has yet to recover from several rounds of natural disasters. The U.S. will rebuild. Considering a large portion of the Haitian population still remains housed in tents from the earthquake, will they be able to rebuild? Before the next natural disaster strikes?

Sandy’s aftermath by Charles Ebikeme

While most of the focus of western media centred on the damage Sandy caused in America, especially this close to a Presidential election; there were few news outlets that reported what had passed in the Caribbean — outside the death tolls and damaged infrastructure. Indeed, as it is becoming more and more apparent, it is always the blogosphere that provides an adequate source of information. Hurricane Sandy’s progression was followed by bloggers on the ground, giving another side of the story we don’t often get to see.

But it is in Haiti, a country that has yet to recover from tropical storm Isaac that hit in August of this year, as well as the earthquake of 2010, that felt the worst of Sandy’s wrath. 1.8 million people in Haiti are affected by the storm, according to the United Nations relief agency.

This next story appears in the current issue of Scientific American and drives home the point why immediate action on climate change, energy and planning (community planning) is necessary to attempt to prevent incidences such as Sandy, or at least lessen the amount of destruction as much as possible. Obama won re-election this week. And while there is no shortage of issues to tackle, the President needs to implement an energy policy for this country. And it’s called global warming, so I hope the world can come together within the next four years and knock out a sound plan.

Global Warming: Faster Than Expected? by John Carey

The potential for faster feedbacks has turned some scientists into vocal Cassandras. Those experts are saying that even if nations do suddenly get serious about reducing greenhouse gas emissions enough to stay under the 450-ppm limit, which seems increasingly unlikely, that could be too little, too late. Unless the world slashes CO₂ levels back to 350 ppm, “we will have started a process that is out of humanity’s control,

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Does my science look big in this? The astrobiology edition

Kevin Orrman-Rossiter — Fri, 09 Nov 2012 00:07:51 +0000

During the 20th century a powerful new idea gradually entered our consciousness and culture: cosmic evolution. We are all par of a huge narrative: a cosmos billions of years old and billions of light years in extent. It is this idea that caught my attention this month via the proceedings of the Sao Paulo Advanced School of Astrobiology SPASA 2011, published in the October International Journal of Astrobiology.

Although the question of extraterrestrial life is very old, the concept of full-blown cosmic evolution – the connected evolution of planets, stars galaxies and life on Earth and beyond – is much younger. In a rather breathtaking paper, Steven Dick formerly of the Aerospace History at the National Air & Space Museum places his arguments for cosmic evolution. Dick traces the idea from its roots in the 19th century theories of Pierre-Simon Laplace and Robert Chambers through its philosophical, astronomical, and biological upbringing to the present day. He examines evolution, the worldview that it had become in the 1950s and 1960s and how it had permeated culture in numerous ways and different cultures in diverse ways. Dick cautions us though noting “we need to remember that ‘culture’ is not monolithic and that ‘impact’ is a notoriously vague term.”

Cosmic evolution. Image credit: Harvard University.

In addition to the impact of our new understanding on culture, cosmic evolution also provides a window on long-term human destiny, asserts Dick. He presents this idea via three scenarios, the: the physical , biological, and postbiological universe. Life is unique to earth in the physical universe scenario, and the options flow from this situation – think of Isaac Asimov’s Foundation series. We will certainly interact with extraterrestrials in the biological universe – here cosmic evolution commonly ends in life, mind and intelligence. Cultural evolution in a biological universe may replace biologicals with artificial intelligence creating what Dick calls a postbiological universe. We do not know yet, which of these is our reality, that is one of the challenges of astrobiology, maintains Dick.

In a second ‘big-picture’ paper Marcelo Gleiser presents his four ages of astrobiology. For Gleiser the influx of astrophysical data, particularly on the prevalence of exoplanets “indicates that there are plenty of potentially life-bearing platforms within our galaxy.” He then presents the ‘history’ of life in the universe in terms of the steps needed for matter to have sequentially self-organised into more and more complex structures. His sequence is best viewed as a prelude to the physical or biological universe scenarios of Dick. Gleiser’s fourth age, the Cognitive Age (the age of thinking biomolecules), really addresses whether we are unique or not i.e. which of Dick’s two scenarios, the physical or biological are reality. Gleiser’s first three ages: physical, the creation of stars and planets from atomic nuclei; chemical, in which elements organise into biomolecules; and thirdly biological, in which living creatures of growing complexity form from biomolecules. the papers by Dick and Gleiser are both papers heady and exhilarating conceptual reads.

Jorge Horvath and Douglas Galante accept the premiss that life exists, and then argue we need to take high-energy astrophysical events seriously. Scientists and the public account for meteor impacts in both academic studies, science-fiction writing and film – not so for events such as supernovae, gamma-ray bursts and flares. They show that these events are more frequent than asteroid strikes and that the effects are non-negligible (academic speak for potentially fatal to planet based species). They conclude that just because we have not yet been wiped out by such events can be seen as either a measure of earthlife’s resilience or a threat we are statistically yet to encounter.

My attention was captured by two other papers from the proceedings. Martin Brasier and David Wacey address the problem of studying life in deep space – comparing it to study of life remote in time. This view is pertinent, as it is non-trivial for scientists to determine what is a viable signal of extinct life. The authors develop a set of protocols and then apply these to earth samples, of varying ages. They do this to show how we could interpret similar samples, where much of the desirable information (the context) has been filtered out during the process of transmission (either physical or data) across vast distances of space, or time or both (as is likely on Mars). Even 10 years ago these questions were moot, but we have learned much over the recent past about metabolic pathways and living microbial systems. Brasier and Wacey conclude that there is still work required on pseudo-fossils, structures that arise naturally within complex physico-chemical systems, so that we can confidently agree on signs of life that are remote in space and time.

The Dry Valleys in Antarctica. Photo credit: NASA

My final pick is an experimental paper that looks at the ExoMars mission. The European Space Agency and (initially NASA ) ExoMars mission is scheduled for launch in 2018 – specifically to detect life signatures on the surface and subsurface of Mars. This probe will carry, for the first time, a Raman spectrometer, a technique with proven ability to determine the spectral signals of key biochemicals. The authors support these assertions by assessing samples acquired from Arctic and Antarctic cold deserts and a meteorite crater. These terrestrial environments are similar to those found on Mars. The experimental results presented in this paper demonstrate that it will be possible using this technique to assess and detect spectral signals of extra-terrestrial (Mars in this case) extremophilic life signatures.

Cite this article:
Orrman-Rossiter K (2012-11-09 00:07:51). Does my science look big in this? The astrobiology edition. Australian Science. Retrieved: Aug 25, 2026, from https://australianscience.com.au/biology/does-my-science-look-big-in-this-the-astrobiology-edition/

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Weekly Science Picks

Markus — Sun, 23 Sep 2012 00:48:37 +0000

It’s been an interesting week for science news, and I’ve been lucky enough to be asked to give this week’s science picks! This made me spend a little while sipping contemplatively on a cup of vanilla iced coffee and wondering where to even start…

The articles I’ve selected are, of course, slanted towards my own (rather geeky) interests, but all the same I hope you find them all as fascinating as I did!

First up, the news that Star Trek style warp drives may actually be possible, at least in theory, made me exclaim “Oh wow!” out loud. Fortunately, people who spend any time with me are generally used to me talking to myself while staring at a computer screen…

Warp Drive May be More Feasible than Thought

“Everything within space is restricted by the speed of light. But the really cool thing is space-time, the fabric of space, is not limited by the speed of light.”
– Richard Obousy, president of Icarus Interstellar

Artists impression of Mimivirus, the first giant virus to be discovered. Image Credit: InvaderXan/Wikimedia Commons

From the vastness of space to life under the microscope, biologists have been debating for years whether or not viruses qualify as a form of life. The latest evidence is that they may indeed be a life form in their own right, and an old one at that!

Giant Viruses are Ancient Living Organisms

They found that many of the most ancient protein folds in living organisms were present in the giant viruses, which “offers more evidence that viruses are embedded in the fabric of life,” Caetano-Anollés said.

Heritage Daily had a fascinating article about the archaeology of the future, and what precisely our distant descendents may one day think of us and the way we lived…

The Archaeology of the Future

The point is that most of what survives will not be determined by conscious decisions on our part. This may not be for want of trying, as shown by the current popularity of time capsules. The most impressive of these must be the KEO satellite, due to be launched in 2014 and to return to Earth 50,000 years later.

And speaking of what we know of the past, it’s been shown again and again that our primitive relatives, the neanderthals, were likely not the brainless savages they’re often depicted to be. Evidence suggests that neanderthals liked to collect bird feathers as ornaments.

Neanderthals Used Feathers as ‘Personal Ornaments’

“I think this is the tip of the iceberg,” said Prof Finlayson: “It is showing that Neanderthals simply expressed themselves in media other than cave walls. The last bastion of defence in favour of our superiority was cognition.” Neanderthals, he said, may have been “different”, but “their processes of thinking were obviously very similar”.

Curiosity self-portrait. Image Credit: NASA/JPL-Caltech/Malin Space Science Systems

As the Curiosity rover settles into its new home in Gale Crater on our neighbouring planet, one small worry is growing in the backs of the minds of certain NASA scientists. Could a blunder on the part of some engineers lead to Curiosity contaminating the surface of Mars with Earth life?

Drill Bits on Rover Could Contaminate Mars

John D. Rummel, a professor of biology at East Carolina University, said, partly in jest: “It will be a sad day for NASA if they do detect ice or water. That’s because the Curiosity project will most likely be told, ‘Gee, that’s nice. Now turn around.’ “

And finally, planet hunters are scouring the sky for exoplanets. Astrobiologists are hoping to soon be able to look into the atmospheres of those planets in search of life signs, in the form of certain molecules created by living organisms. But could they be fooled by those molecules coming from somewhere else?

Meteors Might Add Methane to Exoplanet Atmospheres

One key gas astrobiologists looking for extraterrestrial life would concentrate on would be oxygen […] Another possibility would be methane, a colorless, odorless, flammable organic gas that microbes on Earth produce. Seeing both together in an exoplanet’s atmosphere might be an especially significant sign of life, since they would both ordinarily remove each other from the atmosphere without something like life to constantly replenish them.

Have a good weekend!

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Mysterious Mars

Markus — Wed, 08 Aug 2012 06:39:57 +0000

Mars is full of secrets and mysteries. The classic definition of a desert world, our planet’s arid sibling is a parched wilderness of dunes and planetwide dust storms. With a thin carbon dioxide atmosphere and only 38% the gravitational pull of Earth, there are a lot of puzzles about this cold and frosty little planet, and a lot of scientists who are longing to solve them.

El Dorado, Gusev Crater. Mars is a world of dust and dunes...

By now, anyone keeping up with the news is bound to have heard that NASA’s Curiosity rover made a flawless descent through the atmosphere of Mars and is now busy eyeing up its new home in the Gale Crater. As was discussed previously here on Australian Science, a big question still on everyone’s mind is the same one which David Bowie sang about back in 1971. Is there life on Mars? However, it seems that NASA’s plans are not to answer this question directly. John Grotzinger, project scientist for the Curiosity mission, is quoted as saying; “Curiosity is not a life detection mission. We’re not actually looking for life; we don’t have the ability to detect life if it was there.” Instead, the main objective of Curiosity is to look for signs of life.

The trouble is that looking for life directly is a difficult task. Back here on Earth, new discoveries are still being made frequently, with life being found in environments and habitats where no one was expecting. There’s a lot which we still don’t fully understand about life here on our own world. When we’re talking about another planet, it’s safe to say that all bets are off. As a result, Curiosity’s goal is to look for the various elements and chemical compounds which life might use – or might have used once upon a time when the planet may have been more hospitable. The focus has shifted from the search for life on Mars right now, to life which may once have lived there.

Arabia Terra – one of the three locations on Mars where methane plumes have been spotted.

One point which is worth remembering right now, however, is that there’s one big unsolved mystery about Mars. A gaseous mystery. Large quantities of methane have been detected in the martian atmosphere, which gives rise to a real puzzle. Methane is destroyed by sunlight, and with the thin atmosphere found on Mars, any methane should be rapidly broken apart by solar ultraviolet. The only possible conclusion is that the methane seen on Mars is being replenished somehow. There are only really two possibilities for how this might happen.

One scenario sees the martian methane caused by a geological process called serpentinisation. This is where a type of mineral known as olivine (more familiar to us as the gemstone peridot) chemically reacts with water and carbon dioxide. The reaction creates methane and a green mineral called serpentine (commonly found in certain parts of Western Australia and Tasmania), and releases methane gas. If this is the process which is occurring, it would mean that not only is there a suitable amount of water somewhere under the surface of Mars, but there must also be geological activity for that water to continue being brought into contact with further olivine to react with. This would suggest that there are things which we don’t know about current geological processes on Mars.

The other possibility, more radically, is that this methane is being produced by life. Here on Earth, bacteria known as methanogens are responsible for most of the methane present in Earth’s atmosphere. In fact, on Earth, methane is so regularly produced by living organisms that it can used as an indicator of biological activity.

When three distinct plumes of methane were discovered on Mars in 2009, it was noted that there was an equal probability of either of those two scenarios being the source of the methane – and that both would be huge revelations in our understanding of our neighbouring world. So maybe the Curiosity rover isn’t set up to hunt for life, and maybe it won’t be directly looking for it. But I, for one, do hope it finds some clues about the origin of the mysterious martian methane. Just as any scientist should, I love a good mystery!

The three methane plumes seen on Mars at South-East Syrtis Major, Nili Fossae and Arabia Terra.

Image credits:
Top – NASA JPL/Cornell
Middle – ESA/DLR/FU Berlin (G. Neukum)
Bottom – NASA

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Did life’s building blocks crash land?

Markus — Wed, 25 Jul 2012 03:52:18 +0000

In 1969, on September 28, the skies near Murchison, Victoria (not to be confused with Murchison, Western Australia) were illuminated by a dramatic sight. A spectacular fireball blazed its way through Earth’s atmosphere, its outer layers heated to extreme temperatures by its speed. Residents of the town reported seeing the fireball split into three pieces before it faded from view, leaving a trail of smoke in its wake. Seconds later, a tremor was heard as meteorite fragments crashed into the ground, signalling the arrival of what would become one of the most well studied meteorites ever.

A meteorite streaks across the Australian night sky, in front of the Milky Way. But just what might it be carrying with it? Image credit: Alex Cherney/terrastro.com

If you like to watch the sky at night, chances are good that you’ve seen a meteor or two streaking across the night sky, and while many of them burn up in the atmosphere, it’s quite possible that one which you’ve seen might have eventually reached the ground. Meteorites strike Earth a lot more frequently than most people realise. By most estimates, a few hundred tons of meteorite material make it to our planet’s surface every day. Large meteorites like the Murchison meteorite, however, are a lot less common.

A fragment of the famous Murchison meteorite. Image credit: Art Bromage, Wikimedia Commons

While the Murchison meteorite shattered into fragments before it landed (known as an “airburst”), over 100 kg of meteorite have been collected from around Murchison, and scientists have been analysing those fragments ever since. This particular meteorite is a specific type known as a carbonaceous chondrite. These meteorites are fascinating to scientists, because carbonaceous chondrites are chemically very primitive – they’re thought to be very close in composition to the solar nebula from which the Sun and planets condensed 4.5 billion years ago. In other words, the meteorite which crash landed in Murchison 43 years ago was probably older than our entire planet!

Several things about the Murchison meteorite are very interesting. For one, it shows evidence that it was altered by water. This would have happened a long time ago, wherever this meteorite originally formed, and certainly a long time before it landed on Earth. Secondly, it’s peppered with Calcium-Aluminium-Inclusions (CAIs). These humble crystals are older than the Sun itself. When they formed, the Sun itself was little more than a huge cloud of warm hydrogen gas. Most interestingly to some scientists, however, is the fact that the Murchison meteorite is full of amino acids.

Uracil, one of the four "nucleobases" used by DNA to encode genetic information, was discovered inside the Murchison meteorite.

Amino acids are one of the basic building blocks of all living things. The proteins which make up almost everything in your body are made from these small molecules. To date, over 100 amino acids have been found inside the meteorite, including many of those used by life on Earth. Several things about the chemical and isotopic compositions of these molecules suggest that they didn’t come from Earth, but were in this meteorite when it landed. As an example, amino acids have two forms, referred to as left-handed and right-handed. Earth life only uses the left-handed forms, while the acids discovered in this meteorite are a mixture of the two (known to chemists as a racemic mixture). Other Earthly molecules which frequently show up as contaminants were absent from the samples analysed, suggesting that these molecules, the bare essentials of life, are extraterrestrial in origin.

These amino acids aren’t the only familiar molecules in the Murchison meteorite either. Amongst over 14000 different molecules found inside the meteorite, the chemists who were analysing the meteorite discovered ring-shaped molecules called purines and pyrimidines. These ring molecules are from the same family as the four nucleobases which make up DNA.One of the molecules found was one called uracil, which is actually used by DNA. This same molecule is in every strand of DNA in your body.

While some still argue over the validity of these studies, if they’re correct then the overall conclusion is a breathtaking one. This space rock is older than the Sun, and it already contained all of the basic ingredients for life to form back when Earth was nothing more than a patch of interstellar dust. We might never know exactly how life started on Earth. Though maybe in the distant past, life’s raw materials crash landed here on Earth in meteorites, just like one meteorite did in Murchison that night 43 years ago.

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