Heavy Stellar Traffic Sends Dangerous Comets Our Way

New image of comet ISON
Comet C/2012 S1 (ISON) as imaged by TRAPPIST–South national telescope at ESO’s La Silla Observatory in 2013 (TRAPPIST/E. Jehin/ESO)

Sixty-six million years ago Earth underwent a cataclysmic change. Back then, our planet was dominated by dinosaurs, but a mass extinction event hastened the demise of these huge reptiles and paved the way for the mammalian takeover. Though there is some debate as to whether the extinction of the dinosaurs was triggered by an isolated disaster or a series of disasters, one event is clear — Earth was hit by a massive comet or asteroid and its impact had global ramifications.

The leading theory is that a massive comet slammed into our planet, creating the vast Chicxulub Crater buried under the Yucatán Peninsula in Mexico, enshrouding the atmosphere in fine debris, blotting out the sun for years.

Although there is strong evidence of comet impacts on Earth, these deep space vagabonds are notoriously hard to track, let alone predict when or how often they may appear. All we know is that they are out there, there are more than we thought, they are known to hit planets in the solar system and they can wreak damage of apocalyptic proportions.

Now, using fresh observations from the European Space Agency’s Gaia mission, astronomer Coryn Bailer-Jones, who works at the Max Planck Institute for Astronomy in Munich, Germany, has added an interesting component to our understanding of cometary behavior.

Stellar Traffic

Long-period comets are the most mysterious — and troubling — class of comet. They will often appear from nowhere, after falling from their distant gravitational perches, zoom through the inner solar system and disappear once more — often to be never seen again. Or they hit something on their way through. These icy bodies are the pristine left-overs of our solar system’s formation five billion years ago, hurled far beyond the orbits of the planets and into a region called the Oort Cloud.

In the Oort Cloud these ancient masses have remained in relative calm far from the gravitational instabilities close to the sun. But over the eons, countless close approaches by other stars in our galactic neighborhood have occurred, causing very slight gravitational nudges to the Oort Cloud. Astronomers believe that such stellar encounters are responsible for knocking comets from this region, sending them on a roller-coaster ride to the inner solar system.

The Gaia mission is a space telescope tasked with precisely mapping the distribution and motion of stars in our galaxy, so Bailer-Jones has investigated the rate of stellar encounters with our solar system. Using information in Gaia’s first data release (DR1), Bailer-Jones has published the first systematic estimate of stellar encounters — in other words, he’s estimated the flow of stellar traffic in the solar system’s neighborhood. And the traffic was found to be surprisingly heavy.

In his study, to be published in the journal Astronomy & Astrophysics, Bailer-Jones estimates that, on average, between 490 and 600 stars will come within 16.3 light-years (5 parsecs) of our sun and 19-24 of them will come within 3.26 light-years (1 parsec) every million years.

According to a press release, all of these stars will have some gravitational effect on the solar system’s Oort Cloud, though the closest encounters will have a greater influence.

This first Gaia data release is valid for five million years into the past and into the future, but astronomers hope the next data release (DR2) will be able to estimate stellar traffic up to 25 million years into the past and future. To begin studying the stellar traffic that may have been responsible for destabilizing the dinosaur-killing comet that hit Earth 66 million years ago will require a better understanding of the mass distribution of our galaxy (and how it influences the motion of stars) — a long-term goal of the Gaia project.

An Early Warning?

Spinning this idea into the future, could this project be used to act as an early warning system? Or could it be used to predict when and where a long-period comet may appear in the sky?

In short: “No,” Bailer-Jones told Astroengine via email. “Some close stellar encounters will for sure shake up the Oort cloud and fling comets into the inner solar system, but which comets on which orbits get flung in we cannot observe.”

He argues that the probability of comets being gravitationally nudged can be modeled statistically, but this would require a lot of assumptions to be made about the Oort Cloud, a region of space that we know very little about.

Also, the Oort Cloud is located well beyond the sun’s heliosphere and is thought to be between 50,000 and 200,000 AU (astronomical units, where 1 AU is the average distance between the sun and the Earth) away, so it would take a long time for comets to travel from this region, creating a long lag-time between stellar close approach and the comet making an appearance.

“Typically it takes a few million years for a comet to reach the inner solar system,” he added, also pointing out that other factors can complicate calculations, such as Jupiter’s enormous gravity that can deflect the passage of comets, or even fling them back out of the solar system again.

This is a fascinating study that goes to show that gravitational perturbations in the Oort Cloud are far from being rare events. A surprisingly strong flow of stellar traffic will constantly rattle otherwise inert comets, but how many are dislodged and sent on the long journey to the solar system’s core remains a matter for statistics and probability.

NASA Uses Gravitational Wave Detector Prototype to Detect ‘Space Mosquito’ Splats

Artist impression of ESA LISA Pathfinder in interplanetary space (ESA)

Imagine speeding down the highway and plowing into an unfortunate swarm of mosquitoes. Now imagine that you had the ability to precisely measure the mass of each mosquito, the speed at which it was traveling and the direction it was going before it exploded over your windscreen.

Granted, the technology to accomplish that probably isn’t feasible in such an uncontrolled environment. Factors such as vibration from the car’s motor and tires on the road, plus wind and air turbulence will completely drown out any “splat” from a minuscule insect’s body, rendering any signal difficult to decipher from noise.

But move your hypothetical “car and mosquitoes” into space — as silly as that may sound — and things become a lot less noisy. And now NASA is measuring its own special kind of “mosquito splat” signal by using a rather unlikely space experiment.

The European LISA Pathfinder spacecraft is a proof of concept mission that’s currently in space, orbiting a region of gravitational stability between the Earth and the sun — called the L1 point located a million miles away. The spacecraft was launched there in late 2015 to carry out precision tests of instruments that will eventually be used in the space-based gravitational wave detector eLISA. Inside the payload is a miniaturized laser interferometer system that measures the distance between two test masses.

When launched in 2034, eLISA (which stands for Evolved Laser Interferometer Space Antenna) will see three spacecraft, orbiting the sun at the L1 point, firing ultra-precise lasers at one another as part of a space-based gravitational wave detector. Now we actually know gravitational waves exist — after the US-based Laser Interferometer Gravitational-wave Observatory (or LIGO) detected the space-time ripples created after the collisions of black holes — excitement is building that we might, one day, be able to measure other phenomena, such as the ultra-low frequency gravitational waves that were created during the Big Bang.

But the only way we can do this is to send stunningly precise interferometers into space, away from our vibration-filled atmosphere to stand a chance of detecting some of the faintest space-time rumbles in our cosmos that would otherwise be drowned out by a passing delivery truck or windy day. And LISA Pathfinder is currently out there, testing a tiny laser interferometer in a near-perfect gravitational free-fall, making the slightest of slight adjustments with its “ultra-precise micro-propulsion system.”

Although LISA Pathfinder is a test (albeit a history-making test of incredible engineering ingenuity), NASA thinks that it could actually be used as an observatory in its own right; not for hunting gravitational waves, but for detecting comet dust.

Like our mosquito-windscreen analogy, spacecraft get hit by tiny particles all the time, and LISA Pathfinder is no exception. These micrometeoroides come from eons of evaporating comets and colliding asteroids. Although measuring less than the size of a grain of sand, these tiny particles zip around interplanetary space at astonishing speeds — well over 22,000 miles per hour (that’s 22 times faster than a hyper-velocity rifle round) — and can damage spacecraft over time, slowly eroding unprotected hardware.

Therefore, it would be nice if we could create a map of regions in the solar system that contain lots of these particles so we can be better prepared to face the risk. Although models of solar system evolution help and we can estimate the distribution of these particles, they’ve only ever been measured near Earth, so it would be advantageous to find the “ground truth” and measure them directly from another, unexplored region of the solar system.

This is where LISA Pathfinder comes in.

As the spacecraft gets hit by these minuscule particles, although they are tiny, their high speed ensures they pack a measurable punch. As scientists want the test weights inside the spacecraft to be completely shielded from any external force — whether that’s radiation pressure from the sun or marauding micro-space rocks — the spacecraft has been engineered to be an ultra-precise container that carefully adjusts its orientation an exact amount to directly counter these external forces (hence the “ultra-precise micro-propulsion system”).

lisa-pathfinder
When LISA Pathfinder is struck by space dust, it compensates with its ultra-precise micro-thrusters (ESA/NASA)

This bit is pretty awesome: Whenever these tiny space particles hit the spacecraft, it compensates for the impact and that compensation is registered as a “blip” in the telemetry being beamed back to Earth. After careful analysis of the various data streams, researchers are learning a surprising amount of information about these micrometeoroides — such as their mass, speed, direction of travel and even their possible origin! — all for the ultimate goal of getting to know the tiny pieces of junk that whiz around space.

“Every time microscopic dust strikes LISA Pathfinder, its thrusters null out the small amount of momentum transferred to the spacecraft,” said Diego Janches, of NASA’s Goddard Space Flight Center in Greenbelt, Md. “We can turn that around and use the thruster firings to learn more about the impacting particles. One team’s noise becomes another team’s data.”

So, it turns out that you can precisely measure a mosquito impact on your car’s windshield — so long as that “mosquito” is a particle of space dust and your “car” is a spacecraft a million miles from Earth.

NASA put together a great video, watch it:

Aside: So it turned out that I inadvertently tested the “car-mosquito” hypothesis when driving home from Las Vegas — though some of these were a lot bigger than mosquitoes…

The Ultimate Paternity Test: Are We Martian?

"Dad?" A scene from War of the Worlds.

This rather outlandish, sci-fi notion comes straight from the fertile minds of researchers from MIT, the Massachusetts General Hospital and Harvard University who are proposing a biology experiment that could be sent on a future Mars surface mission. If their hypothesis is proven, we wouldn’t only have an answer for the age old question: Are we alone? but we’d also have an answer for the not-so-age-old question: Did life from Mars spawn life on Earth?

The idea goes like this: countless tons of material from Mars has landed on Earth. We know this to be true; meteorites have been discovered on Earth that originate from the Red Planet. These rocks were blasted from the Martian surface after eons of asteroid impacts, and the rocks then drifted to Earth.

If there was once life on Mars — a concept that isn’t that far-fetched, considering Mars used to boast liquid water in abundance on its surface — then perhaps some tiny organisms (not dislike the hardy cyanobacteria that is thought to have been one of the earliest forms of life to evolve on our planet) hitched a ride on these rocks. If some of these organisms survived the harsh conditions during transit from Mars to Earth and made it though the searing heat as the meteorite fell through our atmosphere, then perhaps (perhaps!) that is what sparked life on Earth.

You may have heard a few variations of this mechanism, it is of course the “panspermia” hypothesis. Panspermia assumes that life isn’t exclusive to just one rocky body like Earth, perhaps life has the ability to hop from one planet to the next, helped on its way by asteroid impacts. Not only that, but perhaps (perhaps!) tiny microorganisms could drift, encased in interstellar dust, akin to pollen drifting in the wind, seeding distant star systems.

Naturally, when considering the distance between the planets (let alone the light-years between the stars!), one might be a little skeptical of panspermia. But it certainly would help us understand how life first appeared on Earth. After all, it’s not as if the solar system has a natural quarantine system in place — if Mars had (or has) bacteria on its surface, perhaps they have been spread to Earth, like an interplanetary flu bug. Also, as experiments are showing us, microorganisms have an uncanny ability to survive in space for extended periods of time.

So, according to my esteemed Discovery News colleague Ray Villard, the MIT team led by Christopher Carr and Maria Zuber and Gary Ruvkun, a molecular biologist at the Massachusetts General Hospital and Harvard University, are proposing to build an instrument to send to Mars. But this instrument won’t be looking for signs of life, it will be testing the hypothetical Martian DNA and RNA. Should this interplanetary paternity test prove positive, proving a relationship between Earth Brand™ Life and Mars Brand™ Life, then this could be proof of some extraterrestrial cross-pollination.

Although this is complete conjecture at this time, as there is no proof that life has ever existed on Mars (despite what research in dodgy research journals tell us), it is certainly an interesting idea that would not only test the hypothesis of panspermia, but also give us a clue about the potential human colonization of Mars.

To quote Ray:

This could give us pause about sending humans to a germ-laden alien world. It would be an ironic twist on the H.G. Wells classic 1898 novel “The War of the Worlds,” where invading Martians succumb to the common cold from Earth microbes.

See, Wells’ Martian warriors should have done genome testing first.

The Day Aliens Invaded… [UPDATE]

UPDATE (Mon. 9:50 a.m. PT): Shocker. NASA refutes Hoover’s claims. Apparently his paper failed peer review for publication in the International Journal of Astrobiology… in 2007! More here: “NASA Refutes Alien Discovery Claim — Discovery News

Original post: On Saturday, a NASA astrobiologist announced his “irrefutable proof” that aliens — the size of bacteria — exist. Using a sophisticated electron microscope, Richard Hoover looked deep into meteorite samples to see complex fossilized microscopic structures that looked suspiciously like bacteria found here on Earth.

Some of the suspect alien microorganisms even resemble cyanobacteria, a basic microorganism that helped make early-Earth hospitable to life by producing oxygen. Cyanobacteria can live in space for extended periods of time; tests on the International Space Station have shown the single-celled specks are hardy little buggers, surviving in a kind of “suspended animation,” sleeping for months (even years) in vacuous, frozen, high-radiation conditions. When brought back to Earth, the critters come back to life.

Needless to say, when Hoover announced this discovery of “alien” microbes, I wasn’t the only one who was thinking panspermia, the hypothetical mechanism where life — in the form of a microbe like cyanobacteria — hops from one planet to the next encased inside meteoroids.

Is this really proof of aliens? Is it evidence for panspermia? Does this mean life on Earth may have been seeded by alien microbes stowing away inside chunks of space rock? Does mankind need to invent an anti(alien)bacterial handwash?! (I’ve watched The Andromeda Strain.)

As mentioned in my Discovery News article on the subject, I’m skeptical about Hoover’s claims. This isn’t because I think Hoover’s work is rubbish (I have yet to finish digesting his lengthy paper), it’s just the way he decided to publish his work. The online Journal of Cosmology isn’t exactly the best place to submit your paper if you want your research to be taken seriously. And why the hell he gave FOX News the “exclusive,” I have no idea.

Sure, Hoover has discovered some odd-looking, alien-looking, bacteria-sized shapes in meteorite samples (he’s even done some interesting chemical analysis on the micro-“fossils”), but he’s going to have to do a far better job at convincing the scientific community that they are extraterrestrials.

Personally, I think these dinky “fossils” are a little too well preserved. Perhaps a far simpler explanation can be found? *cough* Contamination. *cough*

I’d love to know what NASA’s official line is, they seem to be staying remarkably quiet considering one of their employees has just announced the discovery of ET…

Read more: “Has Evidence for Alien Life Been Found?

Did the Cosmos Deliver a Googly? ‘Meteorite’ Lands on Cricket Pitch

While enjoying a cricket county match, two spectators were apparently treated to one of the rarest of cosmic events: a meteorite falling from the sky, landing right in front of them. The “dark” rock, measuring 5 inches wide, broke in two on impact. Amazingly, a piece hit one of the witnesses.

“One piece bounced up and hit me in the chest and the other ended up against the boundary board,” said Jan Marszel. “It came across at quite a speed – if it had hit me full on it could have been very interesting.”

It’s not clear from the Telegraph‘s minimally skeptical article when this happened (I’m assuming it was during the recent Middlesex vs. Sussex game in Uxbridge, northwest London, using the tidbits of information from the text) and the only expert opinion cited is that of Dr. Matthew Genge, a meteorite expert at Imperial College, who hasn’t handled the evidence yet.

“If this turns out to be a meteorite it’s very exciting and would be the first fall in the UK since 1992,” Genge points out.

(That last statement isn’t very accurate. I’m certain that there have been many meteorites falling onto the UK since 1992. If proven true, this would be the first witnessed fall in the UK since 1992.)

UPDATE (July 27, 10:22 am PT): With thanks to Philip Stobbart, who also commented on the Uxbridge object, some clarification of Genge’s quote has been provided, I stand corrected:

Ian O’Neill does a good job of debunking this, with one minor error. A ‘fall’ to a meteor expert is one of two categories of meteorites, falls and finds, referring to when they were seen – falling, or found later – not to meteorites actually physically falling. The papers made the same error, although they accepted the idea of this being the first fallen meteorite since 1992…

Original post continues:

Thank goodness the eyewitness account didn’t include a description about smoke bellowing from an incendiary-like pebble (i.e. the recent Israel spoof/weapon), but there are some huge question marks hanging over the validity of the Uxbridge object.

The first red flag is that one of the witnesses said: “…out of a blue sky, we saw this small dark object hurtling towards us.” I might be wrong, but spotting a 5-inch wide object flying through the air, at speed, ain’t easy. I would have thought the only time they were alerted of the ‘meteorite’ would have been when it hit the ground. Or when it hit Marszel in the thorax.

Secondly, was the ‘meteorite’ really 5 inches wide? After a quick search, I found a photograph of the offending object:

5 inches? Are you sure? I know us guys are known for overcompensating, but this is ridiculous. Granted, it’s probably just shoddy reporting, but that piece of rock is barely an inch wide.

Also, when a meteoroid blasts through the Earth’s atmosphere, a huge amount of heat is generated around it, creating a ‘fusion crust.’ This crust should be very obvious surrounding recently fallen meteorites. Looking at this picture, no fusion crust is visible. It could be that we are looking at the interior of the broken ‘meteorite,’ and the black fusion crust is on the other side, but there’s no indication in the photo that this is a bona fide space rock.

If I were to place a bet, I’d say that this is not a meteorite. However, it will be interesting to see what the experts think once they are able to study the sample.

Special thanks to Twitter buddy Madge Leebman for the tip!

Space Agency Confirms Indonesia ‘Meteorite’

So, according to The Jakarta Post, last week’s ‘meteorite’ (these skeptical ‘quotes’ are getting ridiculous) that smashed down in East Jakarta, through the roof of a house, was in fact a meteorite. But this time, a scientist from the National Aeronautics and Space Agency (Lapan) has confirmed the original report to be true.

“The heat exposure showed that the object came with high speed and heat,” said Thomas Djamaluddin, an astronomy researcher.

According to another publication, the meteorite “was as big as a coconut.”

However, no meteorite remnants have been recovered from the scene. While it’s possible that the meteorite vaporized on impact, I strongly doubt there would be much of a house left after such an energetic blast.

Djamaluddin does point out that perhaps the meteorite had a “fragile structure,” a potential reason why there’s no fragments left. But that begs the question: If the meteorite was that fragile, could it really slam through the roof, destroy the second floor, explode, excavate a crater in the first floor and cause damage to two neighboring properties?

I’m not totally discounting the idea that this might have been a meteorite impact, but the evidence remains as sketchy as last week. So I’m sticking with my original thought that this “blast” was more likely terrestrial and not extraterrestrial in origin. But on the outside chance this was a meteorite, the neighborhood had a very lucky escape in that the space rock was big enough to cause significant property damage, yet small enough to stay contained.

Sources: The Jakarta Post, Antara News

Indonesia ‘Meteorite’ Wiped Out a House… Or Not.

A week after Israel played host to the amazing burning ‘meteorite’, another report is coming in about a ‘meteorite’ strike in East Jakarta, Indonesia. (Note the use of the famous ‘skeptical quotes’.)

On Thursday, a falling object crashed through the roof of a house causing moderate damage. There was also light damage to two adjoining properties. Fortunately, there are no reported injuries.

According to a report in the Jakarta Globe, there was a “blast” that resulted from the impact and there was a deep crater in the floor of the house. After creating the impact crater in the floor, the ‘falling object’ bounced.

I suspect the object impacted at high velocity, hit the floor, bounced back and hit the ceiling, then fell back down,” said a researcher from the Indonesian National Aeronautics and Space Agency (Lapan). “It’s extremely difficult to recover the fragments, what with the rubble and broken glass, and it being so dark in here.”

The article also states that there was evidence for a residual heat footprint and melted items around the crater. Apparently, these facts all point to evidence that a meteorite, or some man-made space junk, was involved.

Although the details are sketchy, there are a few points that concern me about this meteorite report:

First, if this ‘meteorite’ was large enough to create a “deep” crater (there’s no information about the crater’s approximate size), that would suggest it was a hyper-velocity impact. Not only is this kind of impact very rare, I doubt there would be anything left of the building.

Unless “moderate damage” means “there is no house left,” I strongly doubt the crater was caused by a meteorite.

Secondly, according to the Lapan scientist, the space rock “bounced.” While this is possible — take the Virginia meteorite that crashed through the roof of a doctors office, bouncing off the floor of an examination room, for example — if its impact was energetic enough to excavate a sizable crater (and produce a “blast”), then I doubt much of the meteorite would be left to “bounce.” It would have disintegrated, got lodged deep in the bottom of the crater, or not produced a crater at all.

Thirdly, the article states: “the residual heat footprint and melted items pointed to a meteorite.” As I’ve said before, meteorites are usually cold when they make landfall (assuming they are small enough to be slowed by our atmosphere), so this residual heat did not come from the meteorite. If the meteorite was large enough to slam into the house at hyper-velocity speeds, or hit a gas canister, then perhaps there might be some “residual heat.” But in this case, I strongly doubt there would be any house left.

Fourthly, according to Evan Irawan Akbar, from the Bosscha Observatory in Lembang, this event has occurred shortly after the Lyrid meteor shower which ended on Monday. So he rules out any connection. Which is fortunate, as this meteor shower is caused by the Earth passing through a harmless dust tail created by the periodic Comet C/1861 G1 Thatcher.

But then he drops this clanger: “It could, however, be part of the Eta Aquariid meteor shower, which peaks on May 7 and 8.”

The Eta Aquariid meteor shower is caused by dust trail from Halley’s Comet… last time I checked, dust grains from comets have never been linked with house-killing chunks of rock. Comets are made from ice and dust, stuff that easily burns up when hitting our atmosphere. These are meteor showers, not meteorite showers.

The extent of the damaged caused is also a little strange. From the article: “It blasted a hole in the second floor of the house, sending furniture falling to the first floor, and tore big holes in the walls.” Doesn’t that sound like an explosion?

Apparently the police have ruled out speculation that this was a gas canister explosion and although there is “no conclusive proof the damage was caused by a meteorite, it was the most likely explanation.”

Alas, meteorite impacts aren’t likely explanations, terrestrial explanations are the most “likely.” The fact that an Indonesian counter-terrorism squad has been dispatched to the area to look for traces of explosives suggest the authorities aren’t placing all their bets on this being a meteorite impact either.

Thanks to @antonwilliam for the tip!

Source: Jakarta Globe

Israel ‘Meteorite’ Isn’t a Meteorite [UPDATE]

That's no space rock: The Israeli 'meteorite' that never was (Ilan Lilush, Tel Aviv Police).
That's no space rock: The Israeli 'meteorite' that never was (Ilan Lilush, Tel Aviv Police).

UPDATE (April 25): The unidentified combustible object has been identified as being “man made” rather than anything cosmic in origin.

“It is definitely not a meteor and not a different natural substance – somebody created it, and it did not appear from outer space,” said Ittai Gavrieli of the Geological Survey of Israel when reporting after analysis of the ‘meteorite.’

Also, it looks like my original assertion that this resembled an incendiary device wasn’t far off. This object contained high quantities of phosphorus, a chemical commonly used in incendiary weapons.

“The object had high concentrations of phosphorus, which is naturally ignited when it comes in contact with air and with inflammatory material,” Gavrieli added.

However, I still stand by my theory that the Moonpeople are behind it.

(Once again, thanks Avi for keeping me in the loop of these meteorite misadventures!)

[Original post below]

ORIGINAL POST: It has all the hallmarks of being a meteorite: It’s on fire! There’s smoke! Hell, even the BBC is reporting about it!

That’s right, isn’t it? When a chunk of rock flies through the Earth’s atmosphere it burns bright, sometimes exploding during re-entry, scattering the ground like a hellish incendiary device? Scary stuff if you’re standing underneath the cosmic fireball.

It seems that some surfers on the beach near the town of Bat Yam, near Tel Aviv, Israel had a lucky escape when an unidentified-smoldering object punched a hole through a surfboard and then sat, for some time, burning amongst the seashells. Lots of excitement ensued, and the whole event was captured on videophone. The Israeli police are investigating, saying the unidentified object “fell from the sky.”

However, looking at the video above, that’s no meteorite.

Sure, when a chunk of space rock enters the Earth’s atmosphere it produces light and flame due to atmospheric ram pressure heating the outer layers, producing a trail of ionized gas. But it’s also worth remembering that space rock is very cold (as it’s been deep frozen in space), so the brief heating during re-entry will not heat the cold rock up substantially when it makes landfall, definitely not enough to make it combust when it lands. Re-entry happens for a very short time, although the shell of the meteorite might heat up a little, the insides of the meteorite remain very cold. Even if the rock was heated up during those few fiery seconds of re-entry, it will decelerate very quickly, falling to the ground at terminal velocity. This would have the effect of cooling it down some more.

In fact, it’s been reported that frost has formed on meteorites as soon as they land. That’s radically different to what we’re seeing here.

Even if this could possibly be a meteorite, what’s burning? Last time I checked, space rock didn’t burn like a firework and produce smoke like a signal flare. And meteorites certainly don’t contain any nitroglycerin. That is unless the Moonpeople are throwing bombs at us again, but I’ll save that theory for another day.

Thanks Avi Joseph for pointing me to this video!

Now THAT is what I call a fireball!

Three frames from the South African CCTV footage.
Three frames from the South African CCTV footage.

Having seen some footage of the South African fireball last weekend, I thought it was quite impressive. However, a new video looking along a Johannesburg motorway has appeared online, and it’s superb.

I can’t find much information about this event, but it happened on November 21st and no fragments have been found so far.

Just in case you were in any doubt as to how much energy is released when a chunk of rock hits our atmosphere, this should give you a good impression:

I could almost feel the heat and hear the *KABLAAAM*.

Opportunity Investigates Possible Martian Meteorite

opportunity_meteorite2

On its epic journey to Endeavour Crater, Mars Expedition Rover (MER) Opportunity passed a suspect looking boulder on July 18th. Dubbed “Block Island” by MER controllers, this dark rock looks very different from its surroundings, so Opportunity has been ordered to go off its planned route by 250 meters and have closer look.

Measuring approximately 0.6 meters across, the jagged specimen could be a meteorite, giving the rover a chance to carry out an in-situ analysis of its composition, determining whether or not this is indeed of extra-martian origin.

The odd-shaped and dark rock sits atop the regolith, and Opportunity will use its APXS instrument to determine its composition (NASA)
The odd-shaped and dark rock sits atop the regolith, and Opportunity will use its APXS instrument to determine its composition (NASA)

The next step is for the rover to extend its robotic arm, pressing the Alpha Particle X-Ray Spectrometer (APXS) up against the rock’s surface. The spectrometer will basically give the sample a blast of radiation, consisting of alpha particles and X-rays. The analysis of scattered alpha particles (after they have bounced off the material) will reveal the mass of the elements they collide with and the emission of X-rays will also reveal a lot about the material.

So could this be a meteorite? We’ll have to wait until the little robot has carried out its experiment… she may be getting old, but Opportunity is still carrying out some awesome science.

Source: NASA