astroengine.com

Mars Rover Curiosity’s Wheels Are Taking a Battering

The NASA robot continues to rove the unforgiving slopes of Mount Sharp, but dramatic signs of damage are appearing on its aluminum wheels.

In 2013, earlier than expected signs of damage to Curiosity’s wheels were causing concern. Four years on and, unsurprisingly, the damage has gotten worse. The visible signs of damage have now gone beyond superficial scratches, holes and splits — on Curiosity’s middle-left wheel (pictured above), there are two breaks in the raised zigzag tread, known as “grousers.” Although this was to be expected, it’s not great news.

The damage, which mission managers think occurred some time after the last wheel check on Jan. 27, “is the first sign that the left middle wheel is nearing a wheel-wear milestone,” said Curiosity Project Manager Jim Erickson, at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., in a statement.

After the 2013 realization that Curiosity’s aluminum wheels were accumulating wear and tear faster than hoped, tests on Earth were carried out to understand when the wheels would start to fail. To limit the damage, new driving strategies were developed, including using observations from orbiting spacecraft to help rover drivers chart smoother routes.

It was determined that once a wheel suffers three grouser breaks, the wheel would have reached 60 percent of its useful life. Evidently, the middle left wheel is almost there. According to NASA, Curiosity is still on course for fulfilling its science goals regardless of the current levels of wheel damage.

“This is an expected part of the life cycle of the wheels and at this point does not change our current science plans or diminish our chances of studying key transitions in mineralogy higher on Mount Sharp,” added Ashwin Vasavada, Curiosity’s Project Scientist also at JPL.

While this may be the case, it’s a bit of a downer if you were hoping to see Curiosity continue to explore Mars many years beyond its primary mission objectives. Previous rover missions, after all, have set the bar very high — NASA’s Mars Exploration Rover Opportunity continues to explore Meridiani Planum over 13 years since landing in January 2004! But Curiosity is a very different mission; it’s bigger, more complex and exploring a harsher terrain, all presenting very different engineering challenges.

Currently, the six-wheeled rover is studying dunes at the Murray formation and will continue to drive up Mount Sharp to its next science destination — the hematite-containing “Vera Rubin Ridge.” After that, it will explore a “clay-containing geological unit above that ridge, and a sulfate-containing unit above the clay unit,” writes NASA.

Since landing on Mars in August 2012, the rover has accomplished an incredible array of science, adding amazing depth to our understanding of the Red Planet’s habitable potential. To do this, it has driven 9.9 miles (16 kilometers) — and she’s not done yet, not by a long shot.

Mars May Have Once Been a Ringed Planet — and It Could Be Again

Mars’ moons were likely formed by a ring of debris blasted into space after the Red Planet was hit by a massive impact and, when the moon Phobos disintegrates in 70 million years, another ring may form.

mars-rings — Sunrise over Gale Crater as seen by NASA’s Mars rover Curiosity and how it might look if the Red Planet had a ring system (NASA/JPL-Caltech-MSSS, edit by Ian O’Neill)

Mars is currently known as the “Red Planet” of the solar system; its unmistakable ruddy hue is created by dust rich in iron oxide covering its landscape. But in Mars’ ancient past, it might have also been called the “Ringed Planet” of the inner solar system and, in the distant future, it may sport rings once more.

The thing is, we live in a highly dynamic solar system, where the planets may appear static over human (or even civilization) timescales, but over millions to billions of years, massive changes to planetary bodies occur frequently. And should there be a massive impact on a small rocky world — on Mars, say — these changes can be nothing short of monumental.

In new NASA-funded research published in the journal Nature Geoscience, planetary scientists have developed a new model of Mars when it was hit by a massive impact over 4 billion years ago. This catastrophic impact created a vast basin called the Borealis Basin in the planet’s northern hemisphere and the event could be part of the reason why Mars lacks a global magnetic field — it’s hypothesized that a powerful impact (or series of impacts) caused massive disruption to the Martian inner dynamo.

But the impact also blasted a huge amount of rocky debris from Mars’ crust into space, ultimately settling into a ring system, like a miniaturized rocky version of Saturn. Over time, as the debris drifted away from Mars and settled, rocky chunks would have formed under gravity and these “moonlets” would have clumped together to form larger and larger moons. So far, so good; this is how we’d expect moons to form. But there’s a catch.

Phobos as imaged by Europe’s Mars Express mission (ESA)

After forming in Mars orbit, any moon would have slowly lost orbital altitude, creeping toward the planet’s so-called Roche Limit — a region surrounding any planetary body that is a bad place for any moon to hang out. The Roche Limit is the point at which a planet’s tidal forces become too great for the structural integrity of an orbiting body. When approaching this limit, the closest edge of the moon to the planet will experience a greater tidal pull than the far side, overcoming the body’s gravity. At some point, something has to give and the moon will start to break apart.

And this is what’s going to happen to Phobos in about 70 million years. Its orbit is currently degrading and when it reaches this invisible boundary, tidal stresses will pull it apart, trailing pieces of moon around the planet, some debris falling onto the Martian surface as a series of meteorite impacts, while others remain in orbit.

The research, carried out by David Minton and Andrew Hesselbrock of Purdue University, Lafayette in Indiana, theorizes that mysterious deposits of material around Mars’ equator might have come from the breakup of ancient moons that came before Phobos and Deimos.

“You could have had kilometer-thick piles of moon sediment raining down on Mars in the early parts of the planet’s history, and there are enigmatic sedimentary deposits on Mars with no explanation as to how they got there,” said Minton. “And now it’s possible to study that material.”

According to their model, each time a moon broke apart to create a ring, the next moon would be five times smaller than its predecessor.

In short, Mars and its moon may appear to be pretty much unchanged for billions of years, but the researchers think that up to seven moon-ring cycles have occurred over the last 4.3 billion years and Mars is on the verge (on geological timescales) of acquiring rings once more. Fascinating.

Mysterious Fomalhaut b Might Not Be an Exoplanet After All

The famous exoplanet was the first to be directly imaged by Hubble in 2008 but many mysteries surround its identity — so astronomers are testing the possibility that it might actually be an exotic neutron star.

Located 25 light-years from Earth, the bright star Fomalhaut is quite the celebrity. As part of a triple star system (its distant, yet gravitationally bound siblings are orange dwarf TW Piscis Austrini and M-type red dwarf LP 876-10) Fomalhaut is filled with an impressive field of debris, sharing a likeness with the Lord Of The Rings’ “Eye of Sauron.” And, in 2008, the eerie star system shot to fame as the host of the first ever directly-imaged exoplanet.

At the time, the Hubble Space Telescope spotted a mere speck in Fomalhaut’s “eye,” but in the years that followed the exoplanet was confirmed — it was a massive exoplanet approximately the size of Jupiter orbiting the star at a distance of around 100 AU (astronomical units, where 1 AU is the average distance the Earth orbits the sun). It was designated Fomalhaut b.

This was a big deal. Not only was it the first direct observation of a world orbiting another star, Hubble was the aging space telescope that found it. Although the exoplanet was confirmed in 2013 and the International Astronomical Union (IAU) officially named the exoplanet “Dagon” after a public vote in 2015, controversy surrounding the exoplanet was never far away, however.

Astronomers continue to pick at Fomalhaut’s mysteries and, in new research to be published in the journal Monthly Notices of the Royal Astronomical Society, Fomalhaut b’s identity has been thrown into doubt yet again.

“It has been hypothesized to be a planet, however there are issues with the observed colors of the object that do not fit planetary models,” the researchers write. “An alternative hypothesis is that the object is a neutron star in the near fore- or background of Fomalhaut’s disk.” The research team is lead by Katja Poppenhaeger, of Queen’s University, Belfast, and a preprint of their paper (“A Test of the Neutron Star Hypothesis for Fomalhaut b”) can be found via arXiv.org.

Fomalhaut b was detected in visible and near-infrared wavelengths, but followup studies in other wavelengths revealed some peculiarities. For starters, the object is very bright in blue wavelengths, something that doesn’t quite fit with exoplanetary formation models. To account for this, theorists pointed to a possible planetary accretion disk like a system of rings. This may be the reason for the blue excess; the debris is reflecting more starlight than would be expected to be reflected by the planet alone. However, when other studies revealed the object is orbiting outside the star system’s orbital plane, this explanation wasn’t fully consistent with what astronomers were seeing.

Other explanations were put forward — could it be a small, warm world with lots of planetesimals surrounding it? Or is it just a clump of loosely-bound material and not a planet at all? — but none seem to quite fit the bill.

In this new research, Poppenhaeger’s team pondered the idea that Fomalhaut b might actually be a neutron star either in front or behind the Fomalhaut debris disk and, although their work hasn’t proven whether Fomalhaut b is an exoplanet or not, they’ve managed to put some limits on the neutron star hypothesis.

Neutron stars are the left-overs of massive stars that have run out of fuel and gone supernova. They are exotic objects that are extremely dense and small and, from our perspective, may produce emissions in visible and infrared wavelengths that resemble a planetary body. Cool and old neutron stars will even generate bluer light, which could explain the strange Fomalhaut b spectra.

Neutron stars also produce ultraviolet light and X-rays and, although it is hard to separate the UV light coming from the exoplanet and the UV light coming from the star, X-ray emissions should be resolvable.

Artist’s impression of a magnetar, an extreme example of a neutron star (ESO/L.Calçada)

So, using observations from NASA’s Chandra X-ray Observatory, the researchers looked at Fomalhaut b in soft X-rays and were able to put some pretty strong constraints on whether or not this object really could be a neutron star. As it turned out, Chandra didn’t detect X-rays (within its capabilities). This doesn’t necessarily mean that it isn’t a neutron star, it constrains what kind of neutron star it could be. Interestingly, it also reveals how far away this object could be.

Assuming it is a neutron star with a typical radius of 10 kilometers, and as no X-ray emissions within Chandra’s wavelength range were detected, this object would be a neutron star with a surface temperature cooler than 90,000 Kelvin — revealing that it is over 10 million years old. For this hypothesis to hold, the neutron star would actually lie behind the Fomalhaut system, around 44 light-years (13.5 parsecs) from Earth.

Further studies are obviously needed and, although the researchers point out that Fomalhaut b is still most likely an exoplanet with an extensive ring system (just with some strange and as-yet unexplained characteristics), it’s interesting to think that it could also be a neutron star that isn’t actually in the Fomalhaut system at all. In fact, it could be the closest neutron star to Earth, providing a wonderful opportunity for astronomical studies of these strange and exotic objects.

Plasma ‘Soup’ May Have Allowed Ancient Black Holes to Beef up to Supermassive Proportions

How ancient supermassive black holes grew so big so quickly is one of the biggest mysteries hanging over astronomy — but now researchers think they know how these behemoths packed on the pounds.

Supermassive black holes are the most extreme objects in the universe. They can grow to billions of solar masses and live in the centers of the majority of galaxies. Their extreme gravities are legendary and have the overwhelming power to switch galactic star formation on and off.

But as our techniques have become more advanced, allowing us to look farther back in time and deeper into the distant universe, astronomers have found these black hole behemoths lurking, some of which are hundreds of millions to billions of solar masses. This doesn’t make much sense; if these objects slowly grow by swallowing cosmic dust, gas, stars and planets, how did they have time only a few hundred million years after the Big Bang to pack on all those pounds?

Well, when the universe was young, it was a very different place. Closely-packed baby galaxies generated huge quantities of radiation and this radiation had a powerful influence over star formation processes in neighboring galaxies. It is thought that massive starburst galaxies (i.e. a galaxy that is dominated by stellar birth) could produce so much radiation that they would, literally, snuff-out star formation in neighboring galaxies.

Stars form in vast clouds of cooling molecular hydrogen and, when star birth reigns supreme in a galaxy, black holes have a hard time accreting matter to bulk up — these newly-formed stars are able to escape the black hole’s gravitational grasp. But in the ancient universe, should a galaxy that is filled with molecular hydrogen be situated too close to a massive, highly radiating galaxy, these clouds of molecular hydrogen could be broken down, creating clouds of ionized hydrogen plasma — stuff that isn’t so great for star formation. And this material can be rapidly consumed by a black hole.

According to computer simulations of these primordial galaxies of hydrogen plasma, if any black hole is present in the center of that galaxy, it will feed off this plasma “soup” at an astonishingly fast rate. These simulations are described in a study published in the journal Nature Astronomy.

“The collapse of the galaxy and the formation of a million-solar-mass black hole takes 100,000 years — a blip in cosmic time,” said astronomer Zoltan Haiman, of Columbia University, New York. “A few hundred-million years later, it has grown into a billion-solar-mass supermassive black hole. This is much faster than we expected.”

But for these molecular hydrogen clouds to be broken down, the neighboring galaxy needs to be at just the right distance to “cook” its galactic neighbor, according to simulations that were run for several days on a supercomputer.

“The nearby galaxy can’t be too close, or too far away, and like the Goldilocks principle, too hot or too cold,” said astrophysicist John Wise, of the Georgia Institute of Technology.

The researchers now hope to use NASA’s James Webb Space Telescope, which is scheduled for launch next year, to look back to this era of rapid black hole formation, with hopes of actually seeing these black hole feeding processes in action. Should observations agree with these simulations, we may finally have some understanding of how these black hole behemoths grew so big so quickly.

“Understanding how supermassive black holes form tells us how galaxies, including our own, form and evolve, and ultimately, tells us more about the universe in which we live,” added postdoctoral researcher John Regan, of Dublin City University, Ireland.

This Black Hole Keeps Its Own White Dwarf ‘Pet’

The most compact star-black hole binary has been discovered, but the star seems to be perfectly happy whirling around the massive singularity twice an hour.

Credits: X-ray: NASA/CXC/University of Alberta/A.Bahramian et al.; Illustration: NASA/CXC/M.Weiss

A star in the globular cluster of 47 Tucanae is living on the edge of oblivion.

Located near a stellar-mass black hole at only 2.5 times the Earth-moon distance, the white dwarf appears to be in a stable orbit, but it’s still paying the price for being so intimate with its gravitational master. As observed by NASA’s Chandra X-ray Observatory and NuSTAR space telescope, plus the Australia Telescope Compact Array, gas is being pulled from the white dwarf, which then spirals into the black hole’s super-heated accretion disk.

47 Tucanae is located in our galaxy, around 14,800 light-years from Earth.

Eventually, the white dwarf will become so depleted of plasma that it will turn into some kind of exotic planetary-mass body or it will simply evaporate away. But one thing does appear certain, the white dwarf will remain in orbit and isn’t likely to get swallowed by the black hole whole any time soon.

“This white dwarf is so close to the black hole that material is being pulled away from the star and dumped onto a disk of matter around the black hole before falling in,” said Arash Bahramian, of the University of Alberta (Canada) and Michigan State University. “Luckily for this star, we don’t think it will follow this path into oblivion, but instead will stay in orbit.” Bahramian is the lead author of the study to be published in the journal Monthly Notices of the Royal Astronomical Society.

It was long thought that globular clusters were bad locations to find black holes, but the 2015 discovery of the binary system — called “X9” — generating quantities of radio waves inside 47 Tucanae piqued astronomers’ interest. Follow-up studies revealed fluctuating X-ray emissions with a period of around 28 minutes — the approximate orbital period of the white dwarf around the black hole.

So, how did the white dwarf become the pet of this black hole?

The leading theory is that the black hole collided with an old red giant star. In this scenario, the black hole would have quickly ripped away the bloated star’s outer layers, leaving a tiny stellar remnant — a white dwarf — in its wake. The white dwarf then became the black hole’s gravitational captive, forever trapped in its gravitational grasp. Its orbit would have become more and more compact as the system generated gravitational waves (i.e. ripples in space-time), radiating orbital energy away, shrinking its orbital distance to the configuration that it is in today.

It is now hoped that more binary systems of this kind will be found, perhaps revealing that globular clusters are in fact very good places to find black holes enslaving other stars.

The Strangely-Named “Worm Moon” of March 12, 2017

Full moon of March 12, 2017, the so-called “Worm Moon.” Taken with Canon EOS Rebel T5i (©Ian O’Neill)

“Super Moon,” “Harvest Moon,” “Blood Moon,” “Super-Blood Moon” … we have a lot of weird names for the moon’s phases depending on the time of year and today plays host to yet another kind of moon. Ready for it? (drumroll) Introducing the “Worm Moon,” possibly my favorite moon name.

So what is it? Courtesy of The Old Farmer’s Almanac:

March’s Full Moon is traditionally called the Full Worm Moon by the Native Americans who used the Moons to track the seasons; Colonial Americans also used these names, especially those of the local Algonquin tribes who lived between New England and Lake Superior. At the time of this Moon, the ground begins to soften enough for earthworm casts to reappear, inviting the return of robins and migrating birds.

So there you have it, the Worm Moon is the first full moon of March and I was able to get a nice view of it from my backyard late last night. Enjoy!

Could Alien Spacecraft Propulsion Explain the Cosmic Mystery of Fast Radio Bursts?

It’s an “out there” hypothesis, but radiation from alien spacecraft zooming around space could account for the strange bursts of radio waves coming randomly from the deep cosmos.

Powerful bursts of radio waves have been observed at random all over the sky and astronomers are having a hard time figuring out what the heck could be causing them. Many natural phenomena have been put forward as candidates — from massive stellar explosions to neutron star collisions — but none seem to fit the bill. It’s a mystery in its purest sense.

Pulling the alien card will likely raise some eyebrows in some academic circles, but if these so-called fast radio bursts (FRBs for short) end up lacking a satisfactory explanation, according to Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA), an artificial source (e.g. advanced extraterrestrial intelligence) could become the prime suspect.

“Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven’t identified a possible natural source with any confidence,” said Loeb in a statement. “An artificial origin is worth contemplating and checking.”

FRBs are super weird. First detected in 2007, several radio observatories on Earth — including the famous Arecibo Observatory in Puerto Rico and the Parkes Observatory in Australia — have serendipitously detected only a couple of dozen events. And they are powerful; in a fraction of a second, they erupt with as much energy as our sun pumps out in 10,000 years. These are lucky detections as they only occur when the radio dishes just happen to be pointing at the right place at the right time. Astronomers predict there could be thousands of FRB events across the entire sky every single day. There seems to be no pattern, they appear to originate from distant galaxies billions of light-years away and they have no known progenitor.

So far, FRBs have been mainly identified from looking back through historic radio data, but now, the Parkes Observatory has a real-time FRB detection system that will alert astronomers of their detection, allowing rapid follow-up investigations of source regions. This system resulted in a breakthrough last year when astronomers were able to work out that one FRB originated in an old elliptical galaxy some six billion light-years away. This single event helped researchers narrow down FRB sources — as the galaxy is old and exhibits little star formation processes, some production mechanisms could be ruled out (or at least determined to be less likely).

“This is not what we expected,” said Simon Johnston, Head of Astrophysics at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) which manages Parkes, at the time. “It might mean that the FRB resulted from, say, two neutron stars colliding rather than anything to do with recent star birth.”

But say if the source is a little more, well, alien; why would extraterrestrial intelligence(s) be blasting this incredibly powerful radiation into space in the first place?

In their research to be published in Astrophysical Journal Letters, Loeb and co-investigator Manasvi Lingam of Harvard University looked at a form of beamed energy that could be used to propel interstellar probes to the stars. Vast planet-sized solar receivers could collect the required energy and the power collected could be transferred into a laser-like device that is bigger than we can currently imagine. Although the technology required to create such a device is in the realms of science-fiction, according to the researchers’ work, it’s not beyond the realms of physics.

This hypothetical mega-laser could then be used to blast a huge solarsail-like spacecraft across interstellar — perhaps even intergalactic — distances. The photon pressure exerted by this kind of propulsion technique could accelerate spacecraft of a million tons to relativistic speeds. The engineering details of such a device are only known to these advanced hypothetical aliens, however.

Like this… kinda. (Credit: Walt Disney Studios Motion Pictures)

This form of beamed energy would need to be continuously aimed at the departing spacecraft, like a dandelion seed being constantly blown through the air by a steady breeze, to help it accelerate sufficiently to its desired destination — so why would such a technology manifest itself on Earth as a mere radio flash in the sky? Well, to keep the beamed energy on target (i.e. centered on the spacecraft’s sail), it will remain fixed on the spacecraft. But the spacecraft, planet and star will all be moving relative to us, sweeping the beam across the sky, so the beam will only briefly appear in our skies and then disappear as a random FRB. Even if there’s a permanent “beamed energy station” continuously firing spacecraft into deep space, we may only ever see one flash from that location — space is a big place, we’d need to lie directly in the firing line (over millions to billions of light-years away) for us to even glimpse it.

And if these FRBs are originating all over the sky, from many different stars in many different galaxies, it could mean that this beamed propulsion technology is a natural progression for sufficiently advanced civilizations. We could be in the middle of a vast intergalactic transportation network that we can only join when we are sufficiently advanced ourselves to build our own beamed energy station — like an intergalactic bus stop. Mind-bending stuff, right?

Alternatively, FRBs could just be a natural phenomena that our current understanding of the universe cannot explain, but it’s good to investigate all avenues, scientifically.

“Science isn’t a matter of belief, it’s a matter of evidence. Deciding what’s likely ahead of time limits the possibilities. It’s worth putting ideas out there and letting the data be the judge,” concludes Loeb.

And you know what? I couldn’t agree more.

Cassini Says “Ciao!” to Pan, Saturn’s Ravioli Moon

Never before has a space probe come so close to the pint-sized moon embedded in Saturn’s rings — and when NASA’s Cassini buzzed Pan, the spacecraft revealed what a strange moon it really is.

NASA/JPL-Caltech/Space Science Institute

This is Pan, a 22 mile-wide moon that scoots through Saturn’s rings, orbiting the gas giant once every 13.8 hours. And it’s weird.

Resembling a giant ravioli or some kind of “flying saucer” from a classic alien invasion sci-fi comic, Pan is known as a “shepherd moon” occupying the so-called Encke Gap inside Saturn’s A Ring. This gap is largely free of particles and it has become Pan’s job to hoover up any stray material — the moon’s slight gravity pulls particles onto its surface and scatters others back out into the ring system. This gravitational disturbance creates waves that ripple through the ring material, propagating for hundreds of miles.

On March 7, NASA’s Cassini mission came within 15,268 miles of Pan, revealing incredible detail in the moon’s strange surface. It’s thought that its characteristic equatorial ridge (a trait it shares with another Saturn moon Atlas) is caused by the gradual accumulation of ring material throughout the moon’s formation and with these new observations, scientists will be able to better understand how Pan came to be.

As Cassini rapidly approaches the end of its mission, eventually orbiting through Saturn’s ring plane as a part of its “Grand Finale,” we can expect more of these striking views from orbit before the veteran probe is steered into Saturn’s atmosphere in September, bringing its historic mission to an end.

Doomsday, Whenever: Massive Asteroid Impacts Probably Happen at Random

We always seem to be “overdue” a devastating asteroid impact, but how can we be overdue if asteroids don’t have an impact schedule?

Humans are naturally tuned to seek out patterns in seemingly random events. It’s an evolutionary trait that has helped us become the smart Homo sapiens we are today.

This ability to spot patterns and predict cyclical events continues to dominate our everyday lives. For example, geologists chart seismic activity in hopes of seeing a tell-tail earthquake signal before the “big one” happens; farmers track seasonal cycles in an attempt to predict periods of drought; Wall Street traders use complex numerical models to warn of the next financial crisis (or, indeed, profit from the downturn). Also, astronomers try to find patterns in cosmic occurrences that could pose an existential threat.

We are, of course, talking asteroid impacts — cataclysmic events that have shaped all of the planets in our solar system. Although Earth’s atmosphere is very good at eroding away ancient impact craters, evidence for asteroid impacts in the geological history of our planet is very common. Frankly, it’s perfectly natural to be hit by large asteroids and comets; that’s how planets accrete rocky material, collect water and accumulate organic chemistry for life (on Earth, at least).

But should we get hit by a massive asteroid in the near future, it could be curtains for our civilization. So it sure would be handy if we could somehow use the geologic record of our planet, see how often we get punched, spot a cycle or some kind of pattern, predict then the next impact is likely to happen and — hopefully — plan for the next marauding space rock to make an appearance in our skies! (Whether we’ll be able to do anything about it is an entirely different matter.)

Although seeking out cycles in asteroid and comet strikes is a doomsayer’s favorite hobby, scientists have had a challenging time at pinning down any kind of pattern in historic asteroid impacts and, as a new study published in the journal Monthly Notices of the Royal Astronomical Society dramatically concludes, there may be no pattern at all.

But what could drive periodic asteroid or comet impacts in the first place? One hypothesis claims that the solar system’s “wobble” through the galactic plane may destabilize comets in the Oort Cloud periodically, causing an uptick in massive planetary impacts. Also, the much hyped solar twin, Nemesis, could gravitationally jumble asteroids during its long orbit around the sun. But neither hypothesis stands up to scrutiny and the existence of an extremely dim solar partner is becoming increasingly unlikely.

Regardless, previous studies have suggested that extinction-level impacts (of the magnitude of the one that wiped out, or at least greatly contributed to the extinction of the dinosaurs) occur roughly every 26 million years (the cause of which is open to debate), but researchers from ETH Zurich and Lund University in Sweden now refute this claim.

“We have determined … that asteroids don’t hit the Earth at periodic intervals,” Matthias Meier, of ETH Zurich’s Institute of Geochemistry and Petrology, said in a statement.

After studying precisely-dated impact craters around the world that were formed in the past 500 million years, Meier and Sanna Holm-Alwmark of Lund University dated some 22 craters with dates of impacts known to a precision of one percent.

Then, using a technique known as circular spectral analysis (CSA), they attempted to find the approximate-26 million year period in this set of craters. They found no such period.

Interestingly, Meier and Holm-Alwmark also found that some of the impact craters were of the same age, hinting at a common source. “Some of these craters could have been formed by the collision of an asteroid accompanied by a moon,” said Meier. “But in other cases, the impact sites are too far away from each other for this to be the explanation.”

One interesting example is the apparent close similarity in age of the famous 66 million-year-old, 110 mile-wide Chicxulub Crater in Mexico (that has been linked with the extinction of the dinosaurs) and the 15 mile-wide Boltysh Crater in the Ukraine. As pointed out by the researchers, although a definitive explanation for this coincidence isn’t immediately clear, the two impactors may have originated from a collision in the asteroid belt, sending fragments to Earth, hitting the planet within a very short period of one another.

And it’s these kinds of clustering impacts that the researchers have identified as being potential problems with previous statistical studies — they assumed each impact is distinct, when in fact, they happened at the same time, possibly skewing results and creating a pattern when, in fact, there wasn’t one.

“Our work has shown that just a few of these so-called impact clusters are enough to suggest a semblance of periodicity,” said Meier.

I have little doubt that these new findings will be disputed, spawning more studies pointing to other statistical techniques and a bigger impact crater data set, but it is interesting to think that, as far as extinction-level impact events go, there really may be no pattern to their occurrence.

We know that a doomsday asteroid is out there, and it will hit us, but it has a random impact date that is only known to our planet’s geological future.

This Is Why NASA’s Space Station Bose-Einstein Experiment Will Be so Cool

An instrument capable of cooling matter to a smidgen above absolute zero is being readied for launch to the International Space Station, possibly uncovering new physics and answering some of our biggest cosmological questions.

This summer, a rather interesting experiment will arrive at the International Space Station. Called the Cold Atom Laboratory (CAL), this boxy instrument will be able to chill material down to unimaginably low temperatures — so low that it will become the coldest place in the known universe.*

At a temperature of a billionth of a degree above absolute zero, CAL will investigate a state of matter that cannot exist in nature. This strange state is known as a Bose-Einstein condensate (or BEC), which possesses qualities that, quite frankly, don’t make a lot of sense.

When a gas is sufficiently cooled and the subatomic particles (bosons) drop to their lowest energy state, “normal” physics start to break down and quantum mechanics — the physics that governs the smallest scales — starts to manifest itself throughout a material (on a macroscopic scale). When this occurs, a BEC is possible. And it’s weird.

BECs act as a “superfluid,” which means it has zero viscosity. Early experiments on supercooled helium-4 exhibited this trait, causing confusion at the time when this mysterious fluid was observed flowing up, against the force of gravity, and over the sides of its containing beaker. Now we are able to cool gases to sufficiently low temperatures, this superfluid trait dominates and gases move as one, apparently coherent, mass.

So far, BEC experiments have only been carried out in a gravitational environment and can only be observed for a very short period of time as gravity continually pulls the BEC particles to the bottom of its container, thereby limiting its stability. But remove gravity from the equation and we enter a brand new observational regime with the potential for brand new insights to fundamental physics, and this is why NASA built CAL — humanity’s first microgravity BEC laboratory that could unlock some of the universe’s biggest mysteries.

CAL works by trapping the BEC in magnetic containment and lasers will be used to cancel out energy in the gas, thereby cooling it (pictured top). The gas will then be further cooled through evaporative cooling (using a radio frequency “knife”) and adiabatic expansion. When sufficiently cooled, experiments can be carried out on the BEC — the first time a BEC has been tested in space. (The technical details behind CAL’s technology can be found on the experiment’s website.)

“Studying these hyper-cold atoms could reshape our understanding of matter and the fundamental nature of gravity,” said Robert Thompson, CAL Project Scientist from NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., in a statement. “The experiments we’ll do with the Cold Atom Lab will give us insight into gravity and dark energy — some of the most pervasive forces in the universe.”

It is hoped that BECs will be observable inside CAL for five to twenty seconds and the ultra-low temperature technologies developed will allow for future experiments that could contain stable BECs for hundreds of times longer.

CAL isn’t a pure physics curiosity, even if it is pretty awesome just to observe quantum physics manifest itself across an entire mass of particles (in free-fall, no less). Producing stable BECs could have technical applications, such as in quantum computer development and improving the precision of quantum clocks. In addition, creating a stable BEC in a lab setting could, quite literally, give us new eyes on fundamental universal mysteries. Lower temperatures means more stability and more stability means boosted sensor precision. Astronomy is all about precision, so the spin-off technologies from the techniques developed in CAL could usher in a new generation of ultra-sensitive telescopes and detectors that could, ultimately, reveal the mechanisms behind dark energy and dark matter.

“Like a new lens in Galileo’s first telescope, the ultra-sensitive cold atoms in the Cold Atom Lab have the potential to unlock many mysteries beyond the frontiers of known physics,” said Kamal Oudrhiri, CAL deputy project manager also at JPL.

CAL is set for launch on a SpaceX resupply mission to the International Space Station in August and I can’t wait to see what new physics the instrument might uncover.

*Assuming there are no other intelligent lifeforms also playing with supercooled matter elsewhere in the universe, of course.