We Still Don’t Know Why the Reign of the Dinosaurs Ended

The asteroid strike on the Yucatán Peninsula 66 million years ago is only part of the story

Dino Asteroid Strike
Although the asteroid strike that created Chicxulub crater in modern-day Mexico dramatically affected life on Earth, the fiery crash isn’t the whole story of the fate of the dinosaurs.

The reason our planet lost the terrible lizards of eras long past may seem self-evident. About 66 million years ago, an asteroid came screaming out of the sky and smacked into what is now the Yucatán Peninsula of Mexico. The devastation that followed was unprecedented, with tsunamis, an overheated atmosphere, darkened skies, a terrible cold snap, and other apocalyptic ecological events clearing away an estimated seventy five percent of known life on Earth.

Paleontologists know this catastrophe as the K/Pg extinction event because it marks the transition from the Cretaceous into the Paleogene period of Earth’s history. But even though it has been studied constantly, the details of this event still puzzle experts. The case wasn’t closed with the recognition of the impact crater in the 1990s, and exactly how the extinction played out—what differentiated the living from the dead—continues to inspire paleontologists to dig into the cataclysm of the Cretaceous.

To better understand the full story, researchers are pulling back from the moment of impact to examine the broader patterns of life at the time. Dinosaurs were not living in a stable and lush Mesozoic utopia, nor were they the only organisms around at the time—far from it. The world was changing around them as it always had. As the Cretaceous drew to a close, sea levels were dropping, the climate was trending toward a cooler world, and a part of prehistoric India called the Deccan Traps was bubbling with intense volcanic activity. Sorting through how these changes affected life on Earth is no simple task, particularly after the cataclysmic meteorite mixed things up in the rock record, but paleontologists are sifting through the wreckage to better understand what happened.

“In order to get an idea of what happened in the wake of the asteroid impact, we need solid baseline data on what rates of background extinction were like before the K/Pg took place,” Natural History Museum paleontologist Paul Barrett says. A moment of catastrophe can only make sense within the broader context of life before and after. “This would make the difference between the cataclysmic events at Chicxulub being either the primary cause of the extinction or merely the coup de grace that finished off an ecosystem whose resilience had been gradually worn away.”

Asteroid Impact
An artist’s rendering of an asteroid impacting the Earth. (NASA / Don Davis)

While the K/Pg extinction was a global crisis, how it played out at various locales around the planet is largely unknown. The amount of information at any given location depends on how well the relevant rock layers are preserved and how accessible they are to scientists. Some of the best exposures happen to be located in western North America, where there’s a continuous sequence of sedimentary layers recording the end of the Cretaceous straight through to the beginning of the Paleogene. These rocks offer before and after shots of the extinction, and it’s these exposures that has allowed Royal Saskatchewan Museum paleontologist Emily Bamforth to investigate what was happening in the 300,000 years leading up to the explosive close of the Cretaceous.

Looking at the geologic record of southwest Saskatchewan, Bamforth says, local conditions such as the frequency of forest fires and the characteristics of a particular habitat were as important as what was happening on a global scale when determining patterns of ancient biodiversity. “I think this is an important message to keep in mind when thinking of causes of the extinction,” Bamforth says. “Each different ecosystem could have had its own smaller scale biodiversity drivers that were in operation before the extinction, which underlay the big, global factors.” What was good for turtles, amphibians, plants, dinosaurs and other organisms in one place might not have been beneficial in another, underscoring that we can’t comprehend global shifts without the foundation of local diversity. “Ecosystems are complicated things, and I think that is worth keeping in mind when considering the cause and duration of the mass extinction,” Bamforth says.

As far as Saskatchewan goes, the ecological community at the time leading up to the extinction was like a big game of Jenga. “The tower remains standing, but factors like climate change are slowly pulling blocks out from it, weakening the system and making it vulnerable,” Bamforth says. The constantly shifting ecological stability made major upsets—like an asteroid striking at the wrong place, at the wrong time—especially disastrous.

This picture of shifting ecosystems inverts the focus of the K/Pg disaster. While the reason non-avian dinosaurs and other organisms died off always grabs our attention, it’s been harder for scientists to determine why the survivors were able to pass through to the next chapter of life’s history.

Species that survived the impact were typically small, semi-aquatic or made burrows, and able to subsist on a variety of foods, but there are some key contradictions. There were some small non-avian dinosaurs that had these advantages and still went extinct, and many reptiles, birds and mammals died out despite belonging to broader groups that persisted. The badger-sized mammal Didelphodon didn’t make it, for example, nor did the ancient bird Avisaurus, among others.

“This is something I struggle to explain,” Barrett says. Generally speaking, smaller dinosaurs and other animals should have had better chances at survival than their larger relatives, but this was not always the case.

T. Rex
Tyrannosaurus rex lived in the western United States from about 66 to 68 million years ago, right up until the K/Pg extinction event. (Smithsonian National Museum of Natural History)

Pat Holroyd of the University of California Museum of Paleontology likens these investigations to what happens in the wake of airline accidents. “They go in and they gather all the data and they try to figure out, ‘Well, ok, why did the people in the tail section survive, and the people in the other parts of the plane didn’t make it?’” Holroyd says. And while such disasters may be singular events with unique causes, it’s still possible to look at multiple incidents collectively to identify patterns and inform what we may think of as a singular event.

As far as the K/Pg extinction goes, the patterns are still emerging. Holroyd estimates that much of the relevant research about which species survived the impact has only been published or uploaded to the Paleobiology Database in the last decade. This new information allowed Holroyd and colleagues to study patterns of turnover—how long species persisted on land and in associated freshwater habitats—long before and after the asteroid impact. The team’s findings were presented earlier this fall at the annual Society of Vertebrate Paleontology meeting in Albuquerque, New Mexico.

Some of the patterns were familiar. Fish, turtles, amphibians and crocodylians all generally fared better than strictly terrestrial organisms. “People have been observing this pattern since at least the 50s, and probably before,” Holroyd says. But the resilience of waterbound species had never been quantified in detail before, and the new analysis is revealing that the solution to the extinction pattern puzzle may have been right in front of us all along.

The surprise, Holroyd found, was that the difference between the survivors and the extinct of the K/Pg event mimicked a pattern that has held true for tens of millions of years before and after the asteroid impact. Species living on land, particularly large species, tend not to persist as long as those living in freshwater environments. Terrestrial species often go extinct at a greater rate than those in aquatic environments even without a massive catastrophe to take them out of the picture. Species that lived in and around freshwater habitats appear to have persisted longer even when there wasn’t a crisis, and when the extinction at the end of the Cretaceous struck in full force, these organisms had an advantage over their purely terrestrial neighbors.

But even in their relatively safe aquatic environments, everything wasn’t peachy for water-faring animals. Holroyd notes that Cretaceous turtles, for example, lost fifty percent of their diversity globally, although only about twenty percent in the more localized area of western North America, further underscoring the importance of understanding local versus global patterns. Even lineages that can be considered “survivors” still suffered losses and may not have bounced back to their former glory. Marsupial mammals, for example, survived the mass extinction as a group but had their diversity and abundance drastically cut back.

Chicxulub Crater
A shaded relief image of Mexico’s Yucatan Peninsula showing the indication of the Chicxulub impact crater. (NASA / JPL)

How local ecosystems were affected by these changes is the next step toward understanding how the extinction event affected the world. Holroyd points to the familiar “three-horned face” Triceratops as an example. This dinosaur was ubiquitous across much of western North America at the end of the Cretaceous and was clearly a major component of its ecosystem. These animals were the bison of their time, and, given how large herbivores alter their habitats through grazing and migration, the extinction of Triceratops undoubtedly had major implications for ecosystems recovering in the wake of the Cretaceous catastrophe. Plants that may have relied on Triceratops to disperse seeds would have suffered, for example, whereas other plants that were trampled down by the dinosaurs might have grown more freely. How these ecological pieces fit, and what they mean for life’s recovery after the extinction, have yet to fully come into focus.

“The western interior of North America gives us our only detailed window on what happened to life on land during the K/Pg extinction, but it’s totally unclear if this was typical,” Barrett says. “We don’t know much about how the intensity of the extinction varied around the world,” especially in locations that were geographically distant from the asteroid strike. “It seems unlikely that a one-size-fits-all model would be responsible” for cutting down organisms as different from each other as Edmontosaurus on land and coil-shelled ammonites in the seas, among so many other species lost to the Cretaceous. Research in Europe, South America, Asia and Australia is just beginning to form the basis of a much sought-after global picture of the most famous extinction event in history.

“It’s like one gigantic jigsaw puzzle that we’ve started to turn up more of the pieces to,” Bamforth says. The resulting picture of this critical moment in Earth’s history will only be revealed in time.


Previously Unknown Asteroid Just Whizzed Past Earth at Close Range

NASA has been tasked with finding giant asteroids that pose a potential threat to Earth, but the smaller, less destructive ones aren’t always on their radar.

Such was the case with 2016 QA2, which came within 50,000 miles of our planet on Sunday. In astronomical terms, that’s quite close. The moon is an average of about 239,000 miles away from our planet.

According to Seeker, the asteroid was discovered about a day before it passed.

It is, at minimum, about 80 feet wide, a bit larger than the one that caused damage and injuries in Russia roughly 3-and-a-half years ago.

Had it entered Earth’s atmosphere, the fallout would not have been dinosaur-extinction level, but may have caused some troubles in the immediate area.

Notably, NASA is in the process of engaging equipment that will allow for the detection of such small and close space objects.

NASA to land on asteroid that could have once seeded life, but may now destroy Earth.

NASA is about to launch a $1 billion 7-year mission to probe asteroid Bennu, which may carry the building blocks of organic life, but also has a chance of hitting Earth late in the next century.

“It may be destined to cause immense suffering and death,” Dante Lauretta, professor of planetary science at Arizona University and the lead researcher on the OSIRIS-REx mission, told the Sunday Times.

Discovered in 1999, Bennu measures about 500 meters across, weighs over 60 million tons, and travels at over 100,000 kilometers per hour.

View image on TwitterView image on Twitter

Its trajectory is unpredictable due to what is known as the Yarkovsky effect, in which the asteroid absorbs the energy of sunlight and then gives it off as heat, which serves as a thruster that constantly makes slight shifts to its path.

Lauretta says that, if Bennu were to hit Earth, its impact would be equivalent to setting off 3 billion tons of high explosives, similar in potential effect to the asteroid that may have wiped out most life on the planet 66 million years ago – though that asteroid is thought to have been about 10 kilometers (6.2 miles) across.

“We estimate the chance of impact at about one in 2,700 between 2175 and 2196,” said Lauretta.

While OSIRIS-REx will help refine our estimate of the asteroid’s trajectory, largely by helping researchers to get a better grasp on its Yarkovsky effect, this is not the prime reason for sending it to Bennu, which is named after an Egyptian deity.

Aged over 4 billion years, Bennu is a contemporary of asteroids that, according to a hypothesis known as Panspermia, could have brought new elements and water to Earth in its early stages, giving it a ready-made foundation from which life may have emerged.

“Bennu is a carbonaceous asteroid, an ancient relic from the early solar system that is filled with organic molecules,” said Lauretta. “Asteroids like Bennu may have seeded the early Earth with this material, contributing to the primordial soup from which life emerged.”

To learn Bennu’s secrets, the 1.7-ton OSIRIS-REx, which is due to be launched on September 8, is equipped with one of the most sophisticated scanning suites in space exploration history.

OSIRIS-REx Approaches Bennu © NASA

When the spacecraft approaches the asteroid in 2018, it will first carefully examine it with visible and infrared spectrometers to determine which parts of the asteroid are likely to contain the most biologically interesting samples.

It will land only after identifying the perfect spot for collecting a sample of between 60 grams and one kilogram. The capsule containing the material will then be thrust towards Earth, where it will hopefully land somewhere in Utah in 2023.

“We need to know everything about Bennu – its size, mass and composition,” said Lauretta. “This could be vital data for future generations.”

How big does an asteroid need to be to wipe out Manhattan?

There’s a perfectly good reason why scientists around the world want to step up efforts to prevent the prospect of an asteroid hitting Earth: in a nutshell, it would only take a small near-Earth object (NEO) to generate massive destruction on the surface, whereas larger NEOs… well, they’re dangerous on a whole other scale.

And that’s where this awesome Business Insider video comes in. When you’re talking asteroids, it can be hard to visualise how NEOs of different sizes would unleash such different levels of havoc on our vulnerable little planet.

But this animation makes it easy to understand, with three simple examples showing how different kinds of space rocks would lead to three very different (but all bad) scenarios if they made landfall at the Big Apple.

In scenario 1, we’ve got a 12-metre (40-foot) asteroid, approximately the length of a bus, travelling at 19 kilometres (12 miles) per second, and with a density of 8,000kg/m3 (about the same as iron). When it hits the southern tip of New York City, the impact crater takes out the bottom half of the city, with buildings being destroyed over a diameter of nearly 6 kilometres (3.6 miles).

Pretty scary, but nothing compared to what a much larger asteroid could manage. In scenario 2, with a 274-metre (900-foot) rock – about the length of three football fields – travelling at the same speed, the impact crater now extends to much of Brooklyn and Jersey City.

But that’s not all. Buildings would be destroyed in a much wider arc, and intense heat would see your clothing ignite well outside of the city. If you were lucky enough to keep your shirt, those within a blast diameter of approximately 140 kilometres (87 miles) would still experience first-degree burns. And that’s even with a lower density asteroid of 3,000kg/m3 (the same density as rock).

But even that nightmarish example pales in comparison with the uber-badness of what a really big space rock would do to New York and its surrounds (and their surrounds, and so on).

In our final doomsday scenario, we’re about to be hit by an asteroid measuring almost 2 kilometres in length (1.2 miles), which is about five Empire State Buildings stacked on top of one another. Travelling at the same speed and with the density of rock, this bad boy would clean up, well… pretty much a fair chunk of the East Coast and let’s just say Canada wouldn’t be too happy either.

Asteroid ripped apart to form star’s glowing ring system

Asteroid ripped apart to form star's glowing ring system
An asteroid torn apart by the strong gravity of a white dwarf has formed a ring of dust particles and debris orbiting the Earth-sized burnt out stellar core. Gas produced by collisions within the disc is detected in observations obtained over twelve years with ESO’s Very Large Telescope, and reveal a narrow glowing arc. 

The sight of an asteroid being ripped apart by a dead star and forming a glowing debris ring has been captured in an image for the first time.

Comprised of dust particles and debris, the rings are formed by the star’s gravity tearing apart asteroids that came too close.

Gas produced by collisions among the debris within the ring is illuminated by ultraviolet rays from the star, causing it to emit a dark red glow which the researchers observed and turned into the image of the ring.

Led by Christopher Manser of the University of Warwick’s Astrophysics Group, the researchers investigated the remnants of planetary systems around white dwarf stars; in this instance, SDSS1228+1040.

Whilst similar to the formation of Saturn’s rings, the scale of the white dwarf and its debris is many times greater in size. Christopher Manser explains:

“The diameter of the gap inside of the debris ring is 700,000 kilometres, approximately half the size of the Sun and the same space could fit both Saturn and its rings, which are only around 270,000 km across. At the same time, the white dwarf is seven times smaller than Saturn but weighs 2500 times more”.

While debris rings have been found at a handful of other white dwarfs, the imaging of SDSS1228+1040 gives an unprecedented insight into the structure of these systems.

“We knew about these debris disks around white dwarfs for over twenty years, but have only now been able to obtain the first image of one of these disks”, says Mr Manser.

Asteroid ripped apart to form star's glowing ring system
This is the debris disc around SDSS1228+1040 (left) in scale to Saturn and his rings (right). While the white dwarf in SDSS1228+1040 is about seven times smaller than Saturn, it weighs 2500 times more. 

To acquire the image the researchers used Doppler tomography, which is very similar to Computed Tomography (CT) routinely used in hospitals. Both methods take scans from many different angles which are then combined in a computer into an image.

While in CT, the machine moves around the patient, the disk the researchers observed is rotating very slowly by itself meaning they had to take data over twelve years. Discussing what the researchers saw in the image Mr Manser says:

“The image we get from the processed data shows us that these systems are truly disc-like, and reveal many structures that we cannot detect in a single snapshot. The image shows a spiral-like structure which we think is related to collisions between dust grains in the debris disc.”

Systems such as SDSS1228+1040, the researchers argue, are a glimpse at the future of our own solar system once the Sun runs out of fuel. By observing these systems, we can answer questions such as: Are other planetary systems like our own? What will be the fate of our own solar system?

Asteroid ripped apart to form star's glowing ring system
This image of the debris disk around SDSS1228+1040 made from observations taken over twelve years. The application of Doppler Tomography results in an image of the velocities within the disk, which has an ‘inside-out’ structure, gas closer to the white dwarf appears further. The two dashed circles illustrated 0.64 and 0.2 times the radius of the Sun. 

Addressing these issues Professor Boris Gänsicke of the University of Warwick’s Astrophysics Group says:

“When we discovered this debris disk orbiting the white dwarf SDSS1228+1040 back in 2006, we thought we saw some signs of an asymmetric shape. However, we could not have imagined the exquisite details that are now visible in this image constructed from twelve years of data – it was definitely worth the wait.”

“Over the past decade, we have learned that remnants of around are ubiquitous, and over thirty debris disks have been found by now. While most of them are in a stable state, just like Saturn’s rings, a handful are seen to change, and it is those systems that can tell us something about how these rings are formed.”

The research, Doppler-imaging of the planetary disc at the white dwarf SDSS J122859.93+104032.9, is published by the Monthly Notices of the Royal Astronomical Society.

Fresh evidence for how water reached Earth found in asteroid debris

Water delivery via asteroids or comets is likely taking place in many other planetary systems, just as it happened on Earth, new research strongly suggests.

Published by the Royal Astronomical Society and led by the University of Warwick, the research finds evidence for numerous planetary bodies, including asteroids and comets, containing large amounts of water.

Fresh evidence for how water reached Earth found in asteroid debris

The research findings add further support to the possibility water can be delivered to Earth-like planets via such bodies to create a suitable environment for the formation of life.

Commenting on the findings lead researcher Dr Roberto Raddi, of the University of Warwick’s Astronomy and Astrophysics Group, said:”Our research has found that, rather than being unique, water-rich asteroids similar to those found in our Solar System appear to be frequent. Accordingly, many of planets may have contained a volume of water, comparable to that contained in the Earth.

“It is believed that the Earth was initially dry, but our research strongly supports the view that the oceans we have today were created as a result of impacts by water-rich comets or asteroids”.

In observations obtained at the William Herschel Telescope in the Canary Islands, the University of Warwick astronomers detected a large quantity of hydrogen and oxygen in the atmosphere of a white dwarf (known as SDSS J1242+5226). The quantities found provide the evidence that a water-rich exo- was disrupted and eventually delivered the water it contained onto the star.

The asteroid, the researchers discovered, was comparable in size to Ceres – at 900km across, the largest asteroid in the Solar System. “The amount of water found SDSS J1242+5226 is equivalent to 30-35% of the oceans on Earth”, explained Dr Raddi.

The impact of water-rich asteroids or comets onto a planet or white dwarf results in the mixing of hydrogen and oxygen into the atmosphere. Both elements were detected in large amounts in SDSS J1242+5226.

Research co-author Professor Boris Gänsicke, also of University of Warwick, explained:

“Oxygen, which is a relatively heavy element, will sink deep down over time, and hence a while after the disruption event is over, it will no longer be visible.

“In contrast, hydrogen is the lightest element; it will always remain floating near the surface of the white dwarf where it can easily be detected. There are many that hold large amounts of hydrogen in their atmospheres, and this new study suggests that this is evidence that water-rich asteroids or comets are common around other stars than the Sun”.

Read more at: http://phys.org/news/2015-05-fresh-evidence-earth-asteroid-debris.html#jCp

On January 26, Earth will have closest asteroid flyby until 2027

It’s not the space rock NASA is looking to target for its Asteroid Redirect Mission, but if an asteroid dubbed 2004 BL86 was just a few years later it might have been. On January 26, the half-kilometer asteroid will pass within 1.2 million kilometers of Earth — the closest any major stellar object will come for 12 more years. It’s a unique opportunity since this is an asteroid of meaningful size passing usefully close to the Earth, but it poses absolutely no threat to the Earth. Astronomers can watch and collect information at their leisure, as the space rock passes just four times further from the Earth’s surface than our own Moon. It’s such a close pass that if the night sky is clear you ought to be able to see it with a small telescope or strong binoculars.

1.2 million kilometers might seem like a long way for an object to pass, and it’s certainly a sizable miss for those of you worried about an asteroid-borne apocalypse, but in the context of super-powered optical telescopes, a million kilometers is a just stone’s throw. With such powerful spyglasses astronomers should be able to resolve all manner of interesting details about its structure and composition, perhaps even collecting some of the information projected to come from a (decreasingly likely) asteroid capture. At the very least, it should give astronomers the opportunity to gaze at a stellar time capsule bringing us information from a distant area of the galaxy — or at least, of our own solar system.

NASA will look at the asteroid first with microwaves, via its Deep Space Network of satellites, and attempt to collect some radar data. This should provide not just insights about the surface, but also the internal structure of the rock, about which astronomers currently know almost nothing. Asteroids are small and dark, meaning that astronomers rarely get the chance for a detailed look. Even their shapes make them difficult to study, as the jagged, erosion-free surfaces often cast long, jet-black shadows that render the majority functionally invisible.

An asteroid roughly ten times the size of 2004 BL86 passed about the same distance from Earth in 1967, but we only know about that close pass by tracking its path backward; tragically, this wonderful opportunity was totally missed at the time, and the mega-asteroid was only discovered in 1999. The danger posed by this asteroid, 1999 RD32, was only appreciated more than 30 years after it had already passed, and it stands as one of the best examples of the necessity of defensive star-gazing. The asteroid that killed off the dinosaurs and reshaped out planet some 65 million years ago was probably only about twice as large as 1999 RD32, so don’t dismiss the danger.

#Asteroid 2004 BL86 will safely pass Earth on Jan 26 by 745,000 mi/1.2 million kmhttp://t.co/z1ZoGXW0T2 pic.twitter.com/QwvKesPh0n

— Asteroid Watch (@AsteroidWatch) January 14, 2015

Asteroids have a lot of potential for future space science; they carry the majority of all evidence we have from other systems that doesn’t come in the form of light, and according to one NASA researcher they could represent cosmic “refueling stations” for long term missions. They are more accessible than planets and moons, more plentiful than comets, and they are often broken-off bits of larger bodies we can track back for insight.

Close passes like this should be able to offset any potential failures in asteroid redirection, granting some insight into the nature of space rocks even if we can’t use ion thrusters to push one into a stable lunar orbit. Though they are often thought of as little more than dead rocks, large bits of space debris with little function other than causing randomized extinction events, asteroids hold marvelous potential to reform the scientific understanding of space.

Massive asteroid may have kickstarted the movement of continents

Earth was still a violent place shortly after life began, with regular impactors arriving from space. For the first time, scientists have modelled the effects of one such violent event – the strike of a giant asteroid. The effects were so catastrophic that, along with the large earthquakes and tsunamis it created, this asteroid may have also set continents into motion.

That is probably an underestimate.

The asteroid to blame for this event would have been at least 37km in diameter, which is roughly four times the size of the asteroid that is alleged to have caused the death of dinosaurs. It would have hit the surface of the Earth at the speed of about 72,000kmph and created a 500km-wide crater.

At the time of the event, about 3.26 billion years ago, such an impact would have caused 10.8 magnitude earthquakes – roughly 100 times the size of the 2011 Japanese earthquake, which is among the biggest in recent history. The impact would have thrown vapourised rock into the atmosphere, which would have encircled the globe before condensing and falling back to the surface. During the debris re-entry, the temperature of the atmosphere would have increased and the heat wave would have caused the upper oceans to boil.

Donald Lowe and Norman Sleep at Stanford University, who published their research in the journalGeochemistry, Geophysics, Geosystems, were able to say all this based on tiny, spherical rocks found in the Barberton greenstone belt in South Africa. These rocks are the only remnants of the cataclysmic event.

According to Simon Redfern at the University of Cambridge, there are two reasons why Lowe and Sleep were able to find these rocks. First, the Barberton greenstone belt is located on a craton, which is the oldest and most stable part of the crust. Second, at the time of the event, this area was at the bottom of the ocean with ongoing volcanic activity. The tiny rocks, after having been thrown into the atmosphere, cooling, and falling to the bottom of the ocean, then ended up trapped in the fractures created by volcanic activity.

This impact may have been among the last few major impacts from the Late Heavy Bombardment period between 3 and 4 billion years ago. The evidence of most of these impacts has been lost because of erosion and the movement of the Earth’s crust, which recycles the surface over geological time.

However, despite providing such rich details about the impact, Lowe and Sleep are not able to pinpoint the location of the impact. It would be within thousands of kilometres of the Barberton greenstone system, but that is about all they can say. The exact location may not be that important, Lowe argued: “With this study, we are trying to understand the forces that shaped our planet early in its evolution and the environments in which life evolved.”

One of the most intriguing suggestions the authors make is that this three-billion-year-old impact may have initiated the the movement of tectonic plates, which created the continents that we observe on the planet.

The continents ride on plates that make up Earth’s thin crust; the crust sits on top of the mantle, which is above a core of liquid iron and nickel. The heat trapped in the mantle creates convection, whichpushes against the overlying plates.

All the rocky planets in our solar system – Mercury, Venus, Earth and Mars – have the same internal structure. But only Earth’s crust shows signs of plate motion.

A possible reason why Earth has moving plates may be to do with the heat trapped in the mantle. Other planets may not have as much heat trapped when they formed, which means the convection may not be strong enough to move the plates.

However, according to Redfern: “Even with a hot mantle you would need something to destabilise the crust.” And it is possible that an asteroid impact of this magnitude could have achieved that.

The Conversation 

Dinosaur impact ‘sent life to Mars’

Artist's impression of Chicxulub impact
The Chicxulub impact sparked a mass extinction – but did it send life hurtling into space?

The asteroid that wiped out the dinosaurs may have catapulted life to Mars and the moons of Jupiter, US researchers say.

They calculated how many Earth rocks big enough to shelter life were ejected by asteroids in the last 3.5bn years.

The Chicxulub impact was strong enough to fire chunks of debris all the way to Europa, they write in Astrobiology.

Thousands of potentially life-bearing rocks also made it to Mars, which may once have been habitable, they add.

“We find that rock capable of carrying life has likely transferred from both Earth and Mars to all of the terrestrial planets in the solar system and Jupiter,” says lead author Rachel Worth, of Penn State University.

A Hitchhikers GuideEarth rocks big enough* to support life made it to:

  • Venus 26,000,000 rocks
  • Mercury 730,000
  • Mars 360,000
  • Jupiter 83,000
  • Saturn 14,000
  • Io 10
  • Europa 6
  • Titan 4
  • Callisto 1

*3m diameter or larger.

Source: Worth et al, Astrobiology

“Any missions to search for life on Titan or the moons of Jupiter will have to consider whether biological material is of independent origin, or another branch in Earth’s family tree.”

Panspermia – the idea that organisms can “hitchhike” around the solar system on comets and debris from meteor strikes – has long fascinated astronomers.

But thanks to advances in computing, they are now able to simulate these journeys – and follow potential stowaways as they hitch around the Solar System.

In this new study, researchers first estimated the number of rocks bigger than 3m ejected from Earth by major impacts.

Could life be swimming in the oceans of Europa?

Three metres is the minimum they think necessary to shield microbes from the Sun’s radiation over a journey lasting up to 10 million years.

They then mapped the likely fate of these voyagers. Many simply hung around in Earth orbit, or were slowly drawn back down.

Others were pulled into the Sun, or sling-shotted out of the Solar System entirely.

Yet a small but significant number made it all the way to alien worlds which might welcome life. “Enough that it matters,” Ms Worth told BBC News.

About six rocks even made it as far as Europa, a satellite of Jupiter with a liquid ocean covered in an icy crust.

“Even using conservative, realistic estimates… it’s still possible that organisms could be swimming around out there in the oceans of Europa,” she said.

Travel to Mars was much more common. About 360,000 large rocks took a ride to the Red Planet, courtesy of historical asteroid impacts.

“Start Quote

I’d be surprised if life hasn’t gotten to Mars. It seems reasonable that at some point some Earth organisms made it”

Rachel Worth Penn State University

Big bang theory

Perhaps the most famous of these impacts was at Chicxulub in Mexico about 66 million years ago – when an object the size of a small city collided with Earth.

The impact has been blamed for the mass extinction of the dinosaurs, triggering volcanic eruptions and wildfires which choked the planet with smoke and dust.

It also launched about 70 billion kg of rock into space – 20,000kg of which could have reached Europa. And the chances that a rock big enough to harbour life arrived are “better than 50/50”, researchers estimate.

But could living organisms actually survive these epic trips?

“I’d be surprised if life hasn’t gotten to Mars,” Ms Worth told BBC News.

“It’s beyond the scope of our study. But it seems reasonable that at some point some Earth organisms have made it over there.”

Early Mars - artist's impression
Early Mars is thought to have been a muddy, watery world

It has been shown that tiny creatures can withstand the harsh environment of space. And bacterial spores can be revived after hundreds of millions of years in a dormant state.

Continue reading the main story

“Start Quote

I sometimes joke we might find ammonite shells on the Moon from the Chicxulub impact”

Prof Jay Melosh Purdue University

But even if a hardy microbe did stow away for all those millennia, it might simply burn up on arrival, or land in inhospitable terrain.

The most habitable places in range of Earth are Europa, Mars and Titan – but while all three have likely held water, it may not have been on offer to visitors.

Europa’s oceans are capped by a crust of ice that may be impenetrably thick.

“But it appears regions of the ice sheet sometimes break into large chunks separated by liquid water, which later refreezes,” Ms Worth said.

“Any meteorites lying on top of the ice sheet in a region when this occurs would stand a chance of falling through.

“Additionally, the moons are thought to have been significantly warmer in the not-too-distant past.”

Moon fossils

On Mars, there is little evidence of flowing water during the last 3.5bn years – the likeliest window for Earth life to arrive.

Bacillus subtilis endospores
The first space travellers? Bacterial endospores can survive for millions of years

But what if the reverse trip took place?

The early Martian atmosphere appears to have been warm and wet – prime conditions for the development of life.

And if Martian microbes ever did exist, transfer to Earth is “highly probable” due to the heavy traffic of meteorites between our planets, Ms Worth told BBC News.

“Billions have fallen on Earth from Mars since the dawn of our planetary system. It is even possible that life on Earth originated on Mars.”

While her team are not the first to calculate that panspermia is possible, their 10-million-year simulation is the most extended yet, said astrobiologist Prof Jay Melosh, of Purdue University.

“The study strongly reinforces the conclusion that, once large impacts eject material from the surface of a planet such as the Earth or Mars, the ejected debris easily finds its way from one planet to another,” he told BBC News.

“The Chicxulub impact itself might not have been a good candidate because it occurred in the ocean (50 to 500m deep water) and, while it might have ejected a few sea-surface creatures, like ammonites, into space, it would not likely have ejected solid rocks.

“I sometimes joke that we might find ammonite shells on the Moon from that event.

“But other large impacts on the Earth may indeed have ejected rocks into interplanetary space.”

Another independent expert on panspermia, Mauricio Reyes-Ruiz of the National Autonomous University of Mexico, said the new findings were “very significant”.

“The fact such different pathways exist for the interchange of material between Earth and bodies in the Solar System suggests that if life is ever found, it may very well turn out to be our very, very distant relatives,” he said.

Hubble Spots Odd Asteroid With Six Tails.

Silly asteroid, tails are for comets! Around five months ago, an asteroid called P/2013 P5 was seen to be kicking off dust, making it look like it had a tail like a comet. Use of more detailed imaging would show that the asteroid actually has an unprecedented six tails.

In August, researchers had noticed P/2013 P5, an asteroid with a nucleus 1400 feet (427 meters) long, looked somewhat blurred through the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS). Traditionally, asteroids appear as a sharp point of light, and this anomaly piqued the curiosity of the researchers. They figured that it might have begun rotating extremely quickly, causing it to kick off some of its surface dust and look like a comet.

On September 10, the team used the Hubble Space Telescope to get more detailed images of the oddball asteroid. The results completely dumbfounded the researchers: the asteroid had six tails that jut out in all directions, like spokes on a bicycle wheel! Even more amazing was the fact that when the team looked at it again less than two weeks later, the tails looked completely different.

After extensive analysis, it was determined that the tails are most likely the byproducts from six different dust-ejection events that were pulled out like tails by solar radiation pressure. That pressure is also believed to be what caused the asteroid to begin spinning so quickly in the first place, in a phenomenon known as radiation torque. If an asteroid is spinning too fast, its small amount of gravity is not enough to hold itself together and the dust goes flying off. Because the dust pattern does not suggest that a lot of material was ejected from the asteroid at once, the researchers are currently discounting the idea that these tails are the products of a collision. The results were published in Astrophysical Journal Letters.

So far, only a small percentage of its mass has been sloughed off into the tails, but this could be the beginning of the end for the asteroid. Future analysis will show if the dust is being ejected around the asteroid’s equator, which will be the best evidence that the asteroid is in the process of a rotational breakup.

While this is the first six-tailed asteroid that has ever been documented, researchers are confident that if there is one, there are probably many more waiting to be discovered.

– See more at: http://www.iflscience.com/space/hubble-spots-odd-asteroid-six-tails#sthash.QARL11oh.dpuf

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