On April 25th, 2018 we learned about

Mini model meteorites demonstrate how well hot rocks can deliver water to dry planets

While we live on an impressively wet planet today, the Earth probably didn’t start out with our lush collections of rivers, lakes and oceans. With no obvious way for the planet’s iron and other minerals to have spontaneously transmuted into H2O billions of years ago, scientists have long suspected that our water was instead delivered from space via icy objects like comets. Further research found that our water looked more like the water found on icy asteroids like Ceres, which was clearly abundant in the asteroid belt, but it still posed a problem. Asteroids tend to burn and explode a lot when they get too close to the Earth, so how would any of their water survived long enough to help soak our planet?

Proxy-asteroid projectiles

With no asteroids or spare planets at their disposal, researchers from Brown University turned to the Vertical Gun Range at the NASA Ames Research Center to simulate icy impactors. Marble-sized projectiles were fabricated to match the composition of carbonaceous chondrites, or meteorites suspected of being formed in ancient, icy asteroids. The miniature proxy-meteors were then fired at a chunk of dry pumice powder, which served as their stand-in for the once-parched surface of the Earth.

The small impactors hit their targets at more than 11,000 miles-per-hour, releasing heat and an impressive amount of debris in all directions. As with real asteroid impacts, enough heat was generated in these collisions to outright destroy some material, including some of the water ice. However, some of the mineral content also melted, which weirdly enough was key to some of the water’s survival. Because the rock melted and re-cooled so quickly, it could capture some of the water inside the resulting glass, keeping it “safe” from vaporizing. Additional water was similarly captured by flying breccias— random debris thrown and heated by the impact that were hot enough to become “welded” together.

Making sense of previous predictions

This experiment not only helps explain some of the water on Earth, but also some of the confusing H2O around the solar system. Since previous estimates found that asteroid impacts should vaporize water, researchers had a hard time explaining the presence of water in impact craters on places like the Moon and Mercury. The physical test proved that those estimates hadn’t captured the full complexity of such an impact, and that delivering water via screamingly-fast hunks of icy rock is apparently more practical than you might think.


My five-year-old asked: What does the Vertical Gun Range look like?

“Gun” may be a misleading term here, because the equipment in question doesn’t really look much like pistol, rifle or cannon, at least outside science fiction. A large barrel launches a projectile into an enclosed, reinforced chamber. That chamber is outfitted with a number of sensors and cameras so that researchers can learn more details about the behavior of whatever collision is being studied. NASA has more on the AVGR in this handy PDF.

Source: Projectile cannon experiments show how asteroids can deliver water by Brown University, Phys.org

On April 19th, 2018 we learned about

A meteorite delivered diamonds carrying traces of our solar system’s less successful protoplanets

Building a planet out of dust isn’t easy. Sure, the recipe basically requires innate forces like gravity to do a lot of the work, but not every clump of debris successfully forms into a durable planet. Those first steps are called protoplanets, and while we’ve seen them around other stars, we’ve only recently found evidence of the protoplanets that helped build the planets in our own solar system.

Learning from dirty diamonds

The evidence found in diamonds carried to Earth in a meteorite that struck the Earth in 2008. Those diamonds carried small bits of other metals and minerals that were present when the diamond was formed. The composition and structure of this extra material, known as inclusions, can tell us a lot about the conditions that created the diamond.

In this case, the structure of the diamond indicates that it was formed as an achondrite— a rock formed in an object large and hot enough to create a metallic core inside a layer of rock. That could include very large asteroids, but other features of these diamonds make it more likely to have been formed in a larger protoplanet instead. The inclusions also show that these diamonds were formed under at least 20 gigapascals of pressure, well beyond diamond’s normal elastic breaking point. With that reference point, geophysicists can estimate that the protoplanet that created these diamonds was somewhere between the size of Mercury and Mars.

This may seem like a crazy amount of information to infer from a single space rock, but we’ve been reading history from diamonds here on Earth for years. Actually, we’ve been getting history out of the Earth, as diamonds are known to carry information about the formation and movement of materials deep under the Earth’s crust, carrying them to the surface like shiny time-capsules, including deposits of water over a 100 miles below the Earth’s surface.

Potential planets from the past

None of this suggests that we have a new planet forming next door. Simulations of our solar system’s formation predicted that multiple protoplanets formed within 10 million years of our Sun’s formation. While at least eight of those objects managed to survive long enough to become the planets we know today, the diamonds found in the 2008 meteorite are probably just pieces of some of the other protoplanets that were destroyed in collisions in a more crowded solar system.

 

Source: Diamonds in Meteorite May Hail from Our Ancient Solar System by Doris Elin Slazar, Space.com

On April 8th, 2018 we learned about

Investigating the likelyhood of microbial life existing in Venus’ upper atmosphere

You don’t want to live on Venus, but there are a lot of places you don’t want to live on Earth as well. Hydrothermal vents, acidic lakes and the cold reaches of the upper atmosphere are all pretty inhospitable plants and animals alike, but that doesn’t mean that they’re not home to life. As we look closer at the nastiest, hottest, most acidic bits of real estate on the planet, the more bacteria we find adapted to these extreme conditions. This has scientists excited, because if life is in the market for these spots on Earth, there’s a small but real chance that it might love what’s available on Venus.

Too hostile to be a home?

Don’t feel bad if you’re not familiar with the brutal conditions on Venus. It’s such a rough part of the solar system that the probes we’ve sent to the second planet generally don’t last very long; the Soviet Venera 13 set records by surviving for a whole 127 minutes. Aside from a few photographs, we have been able to determine that the surface of Venus gets up to 863º Fahrenheit, and the air pressure is between 17 to 20 times as strong as on Earth. With the wind and acidic chemistry in the air, even the heartiest Earth-born bacteria couldn’t survive on Venus’ surface. On the other hand, the upper atmosphere may be just gentle enough to allow microbes a small chance at survival.

The upper layers of clouds on Venus are reflective and acidic, made mostly of carbon dioxide, water and sulfuric acid. It doesn’t sound pleasant, but the temperatures are low enough that life as we know it could exist there. What’s more, the sulfuric acid may even be a byproduct of microbial metabolisms– species on Earth are already known to do that (often with unfortunate consequences for their surroundings.) What’s more, observations from space have noted unexplained dark patches in these Venusian clouds, most of which are within the size range of bacteria on our own planet. This isn’t proof of alien life, but since we’ve never tested specifically for organic chemistry in Venus’ upper atmosphere, we can’t rule out the possibility of microbes without getting more information.

While spacecraft are circling Venus in space, none of them are in a position to sample these dark spots in the planet’s clouds. One proposed design is the Venus Atmospheric Maneuverable Platform (VAMP), which would fly through caustic clouds for as long as a year. With the right set of sensors, like mass spectrometers and microscopes to examine airborne samples, researchers would be in a better position to identify potentially organic materials in the atmosphere.

Originating from the past, or other planets

As hard as it is to picture life on such a harsh planet, there are actually a few possibilities for how bacteria could end up there. The first option is that the bacteria migrated from the ground, since Venus was probably a nice place 2.9 billion years ago. At that time, there’s a fair chance that the planet was a tepid 51° Fahrenheit on the surface, giving microbes a chance to evolve before the upper atmosphere was the only place left to go. Alternatively, the clouds could have been seeded by a place like Earth, as high-speed dust moving through the solar system has been calculated to be able to knock microbes in our atmosphere clear into space. So if life didn’t arise on Venus on its own, there’s still a chance that other Earthlings simply beat us to the punch of traveling to another planet.

Source: Is there life adrift in the clouds of Venus? by University of Wisconsin-Madison, Science Daily

On April 3rd, 2018 we learned about

Strangely slow galaxy attributed to missing dark matter

Some missing dark matter may help confirm that this invisible substance exists. Dark matter is as-of-yet theoretical form of matter that doesn’t interact with light as we know it, making it invisible or dark to our various probes and sensors studying the universe. It does seem to interact with gravity like other matter does though, and so most of our ideas about it come from watching how normal objects move and react to the pull of something that’s otherwise undetectable. Of course, since as much as 80 percent of the mass of the universe is actually dark, studying what is does and doesn’t do isn’t easy.

Luckily, dark matter doesn’t seem to be equally distributed. Galaxy NGC 1052–DF2, a cluster of stars 65 million light-years away from Earth, may lack dark matter entirely. NGC 1052–DF2 looks pretty normal at any given moment, but the over time the motion of some bundles of stars, called globular clusters, has turned out to be too slow. For the amount of mass we can see, the galaxy should have around 60 billion times our own Sun’s mass in dark matter. The total mass of normal and dark matter would then require the globular clusters to move much faster than they’ve been observed. The orbital speeds that have been seen only make sense if there’s no dark matter there at all.

How could the dark matter be missing?

This is weird, to say the least. Galaxies are thought to form around the gravitational well created by clumps of dark matter, so this finding raises questions about how NGC 1052–DF2 ever came together in the first place. One possibility is that the dark matter has been stolen by some of its neighbors. Some galaxies have been found with extra dark matter, and so there’s a chance that NGC 1052–DF2 lost its invisible mass to the stronger gravitational pull of another galaxy.

The last option is that there was never dark matter in NGC 1052–DF2, or anywhere else for that matter. Some researchers suggest that the best way to make sense of the movement of large galaxies is with modified Newtonian dynamics, or MOND. In this model, the physics we’re used to just aren’t correct on the scale of a galaxy, and thus need adjusting so that they make sense with what we’ve observed. However, the weird speeds of NGC 1052–DF2 are strengthening doubts about MOND, since even modified dynamics should be consistent in every galaxy. It’s then easier to imagine one weird galaxy missing its dark matter than figuring out some other caveat to explain why the math behind MOND would need further adjustments in just this case.

Source: Dark matter is MIA in this strange galaxy by Emily Conover, Science News

On March 29th, 2018 we learned about

Kepler telescope finds that short-lived supernovae are likely the result of a dispersed layer of glowing debris

Exploding stars should be easy to spot. Aside from the release of as much energy as our Sun will produce in its entire lifetime, these massive explosions light up their surroundings for weeks as all the nearby debris cools down over time. If you somehow did miss spotting a particular supernova, you might not have to wait long for the next one, as one star is probably exploding every second somewhere in the universe. Despite all this, astronomers were still having trouble with a particular kind of explosion, which broke some of these rules and would instead flicker brightly for just a couple of days then go dark. Unless we knew exactly where to expect such an event, they were often over before any telescope could find them.

Finally seeing a star’s final flicker

The mystery of Fast-Evolving Luminous Transient (FELT) supernovae has been nagging astronomers for over a decade. Many hypotheses were suggested, ranging from gamma-ray bursts to magnetar-boosted supernovae, but every idea was hard to test against such fleeting opportunities to actually observe the event in the first place. Even in cases were a telescope did capture the first flash of light from a FELT, subsequent observations usually wouldn’t be taken until 24 hours later, missing a lot of important details about how these flashes take place.

Enter the Kepler space telescope. This spacecraft was originally designed to hunt for exoplanets by detecting small, short changes in light levels around distant stars, making it a great way to gather data on a FELT-friendly timescale. Instead of detecting small dips in a star’s light as exoplanets pass in front of them, Kepler was able to observe the bursts and quick decay of light from FELT supernovae, getting a snapshot of data every 30 minutes. This allowed astronomers to discard many of their hypotheses about FELT explosions, leading them to a new model that’s apparently a bit more than a single explosion.

A glow from a globe of dust

Based on the details gathered by Kepler, researchers now believe FELT explosions get started before a star is really ready to blow up. As the start begins its final collapse, it may eject a layer of dense dust that ends up orbiting the star as a sort of shell. Once the star does finally pop, close to a year later in this case, its blast wave of kinetic energy hits the dust in the shell, causing it to quickly light up all at once. In these observations, the brightness peaked in a period of just over two days, making it fast even by FELT standards. Less energy will be emitted in that last burst, allowing the visible light to drop off much more quickly than in a “standard” star explosion.

There’s obviously more to learn about FELT supernovae, such as how the outer shell of material interacts with the core that will eventually burst altogether. Fortunately, the fact that the Kepler telescope was able to find this brief event while just looking at one small patch of sky suggests that these types of explosions aren’t horribly rare either. It will hopefully be relatively easy to collect more data and confirm more details about how these stars flicker before going dark forever.

 

Source: Kepler Solves Mystery of Fast and Furious Explosions by Armin Rest , Hubblesite

On March 18th, 2018 we learned about

Calculating what kind of push could prevent a large asteroid from colliding with the Earth

Kids supposedly want to know why the sky is blue, but that question doesn’t grip their imaginations like potentially being killed by an asteroid hitting the Earth. It’s not illogical, since knowing that giant dinosaurs were driven extinct by an asteroid strike 65 million years ago makes it clear that such an event is a severe and nearly hopeless scenario. Factor in how hard it is to explain the statistical unlikelihood that a world-ending asteroid would hit the Earth, and it’s easy to see how a kid might think that adults are weird for not worrying about suffering the same fate as the dinosaurs. Thankfully, some adults are thinking about rocks falling from space, and working out possible responses to larger asteroids that might be headed our way.

Bumping asteroids without breaking them

101955 Bennu is an 87-million-ton asteroid that passes by the Earth every six years. It’s close enough that we can track it with some certainty, and have realized that it does stand a chance of hitting our planet on September 25, 2135. At this point there’s only a 1 in 2,700 chance that it will actually collide with Earth, which is four-times lower than your odds of dying in a car crash in the next year, but it’s a good target to explore potential safety measures that could shield us from being hit.

With an object as large as Bennu, there’s already consensus that we need to nudge it, not blow it to pieces. Aside from the difficulty of really obliterating that much mass, exploding a large asteroid would probably just mean the Earth got hit by lots of smaller rocks instead of one big one. That’s arguably better nothing, but an early adjustment to the asteroid’s orbit would be preferable, and given enough time, a tad more practical.

Adjusting orbits with HAMMERs and explosions

To alter Bennu’s orbit, one proposal is to basically launch a large, Delta IV rocket at it, tipped with a 8.8-ton spacecraft called HAMMER (Hypervelocity Asteroid Mitigation Mission for Emergency Response vehicle). As you might guess, HAMMER would fly into an asteroid like Bennu to try to slow it down and alter its orbital path a small amount. If done early enough, even a small push can lead to big shifts in the asteroid’s trajectory years later. It’s a sensible plan until you work through all the math, at which point it becomes clear that 8.8 tons isn’t going push a big asteroid far enough on its own, even if they collide years in advance. One estimate found that 34 to 53 HAMMER spacecraft would be needed to move Bennu to a safer orbit if given a 10 year lead time. If the project started 25 years before 2135, the orbit could be sufficiently adjusted with only 7 to 11 spacecraft, although that still requires an enormous amount of resources with little room for error. Developing HAMMER spacecraft isn’t a totally lost cause though, as one such craft could probably divert a 295-foot asteroid if given a 10-year head start.

If HAMMER doesn’t look practical right now, an alternative idea is to deflect asteroids like Bennu with a nuclear explosion. Again, the goal wouldn’t be to destroy the rock, but to divert it before it gets to Earth. With that in mind, a warhead would be detonated near the incoming rock, hitting one side of the asteroid with radiation. That radiation could vaporize the surface of the asteroid, essentially turning that entire face into a giant, if gentle, thruster. As vaporized rock pushes off the asteroid, it would push Bennu in the opposite direction, hopefully nudging it over just enough to miss the Earth years later.

Planning for all the possibilities

Hopefully this will all be academic by 2135. As that date approaches, astronomers will track Bennu’s orbit and be able to refine their predictions about its eventual path. Even if it never intersects the Earth, figuring out responses is still worth while though. Bennu is one of 10,000 objects that NASA tracks at this point, but they can’t see everything. It’s possible that a ten-year head start to build a response will be all our planet gets, in which case these early planning exercises will save us all a bit of very precious time.

Source: Scientists design conceptual asteroid deflector and evaluate it against massive potential threat by Lawrence Livermore National Laboratory, Phys.org

On February 28th, 2018 we learned about

Scientists detect evidence of the first stars ever formed in the universe

As much as the name “Big Bang” seems like it should be noisy and active, early years of the universe were pretty dark, quiet and essentially inert. With no light, vibration or other activity, the only “stuff” out there was a lot of neutral hydrogen gas. Of course, gravity also existed, and over the course of 50  to 100 million years, it clumps of hydrogen started crushing together, eventually leading to the formation of stars, galaxies and critically, electromagnetic radiation in the radio-frequency range. This ancient radiation has now been directly detected, and promises to reveal a lot of new information on how the first stars were formed.

Finding the right frequencies

The radio waves in question were emitted only 180 million years after the universe began, which is relatively quick when looking at an overall timescale of 13.7 billion years. Searches of frequencies originating from earlier time periods found only silence, but once researchers expanded their search a signal was finally detected, although listening in wasn’t easy. The faint murmurs of the first stars were nearly too soft to detect against the background noise of the universe, eliciting comparisons to listening for hummingbirds during a hurricane.

To listen to the signals of the first stars, scientists built a special receiver, called a radio spectrometer.  While it looked a bit more like a table than an antenna, with two metal plates on a set of legs in a larger field of wire mesh, its location in the Australian desert was a critical feature.  By being place at the Murchison Radio-astronomy Observatory, the radio spectrometer would be somewhat insulated from other radio signals thanks legal restrictions on transmissions in the surrounding 161 miles. This gave researchers their best chance at isolating the correct radio signals to find the traces of stars from long ago.

Stars seen as blocked signals

With everything in place, the signals in question are actually pockets of silence. As the primordial hydrogen started clumping up to form stars, it would end up absorbing and blocking some of the background radiation already present in the universe. Learning about the details of those gaps in the signal can then inform use more about the conditions in space when stars started forming. For starters, researchers have already found that the hydrogen gas was apparently colder than previously estimated. This surprising data has already led to interesting models about why temperatures were so low, including the idea that some energy was being lost to interactions with dark matter. To confirm that idea, we’ll need more observations from other instruments to confirm just what was going on “immediately” after the Big Bang.

Source: Unlocking the secrets of the universe by Arizona State University, Phys.org

On February 14th, 2018 we learned about

TRAPPIST-1 planets orbits suggest they’re soaked in substantial amounts of water

In 2016, astronomers located a batch of presumably rocky exoplanets orbiting TRAPPIST-1, a red dwarf star 40 light years from Earth. While red dwarf stars are generally cooler than our own Sun, some of these planets have tight enough orbits to put them in habitable temperature ranges for life, assuming that life was happy living under a dim red sky. Continuing observations of the TRAPPIST-1 system has revealed more details about these worlds, including the likelihood of vast amounts of liquid water on their rocky surfaces.

Calculating exoplanet composition

At 40 light years away, astronomers aren’t observing signs of water or ice directly. Instead, they’re taking measurements of planets TRAPPIST-1b through TRAPPIST-1h and comparing how they interact with each other’s orbits. Like all matter, each planet creates its own gravitational field that pulls on its neighbors. While they’re not overpowering the pull of their star, researchers have been able to detect small wobbles in the tight orbits of each planet when they move near each other, allowing them to come up with estimates for how massive each planet might be. That information is then compared to estimates for the planets’ volumes, a figure based on how much light each planet blocks when passing in front of the TRAPPIST-1 star. To verify these estimates, researchers then plugged them into simulations of the system, making adjustments until their virtual orbits matched observed data.

Once each planet’s mass and volume were known, researchers calculated their density. The resulting picture of each planet’s composition isn’t inert pieces of rock, but worlds with large amounts of “volatile,” or more dynamic, materials on their surface. Based on the planets’ close proximity to their star, there’s a good chance that this volatile material is some form of water thanks to that molecule’s abundance in the materials that eventually go on to form planets. What’s more, there’s a good possibly that this water exists as a liquid under a thick, steamy atmosphere. Before you picture a second Earth under a reddish sky, planets like TRAPPIST-1b and TRAPPIST-1c may actually make our own planet look dry, as they’ve been estimated to be made of up to five percent water, versus Earth’s 0.02 percent.

Home to water, but without being wet

Not every TRAPPIST-1 planet is expected to be wet, spherical sauna though. TRAPPIST-1d is the smallest of the group, and may have a layer of ice on its surface. TRAPPIST-1e is a little denser than Earth, probably thanks to a more substantial iron core. It likely lacks a considerable atmosphere, with rockier composition overall. Further out, TRAPPIST-1f, g and h are probably too far from their star to maintain a large amount of liquid water, much less vapor. Any water they have would be frozen, and there’s no sign of a substantial atmosphere at this point.

Is there water around every red dwarf?

While there’s more to be learned about the TRAPPIST-1 system, researchers would also like to start using these simulations and analytical techniques on other red dwarf solar systems. It seems that not every star needs to be yellow-hot to be home to some very attractive-looking planets, but it would be great to know just how common these sorts of water-soaked spheres really are.

Source: TRAPPIST-1 planets probably rich in water by ESO, Science Daily

On January 16th, 2018 we learned about

Future spacecraft will likely navigate by the light of distant pulsars

The universe is expanding, and accelerating, every day. More locally, the planets in our solar system are whipping around the Sun at up to 107,082 miles-per-hour. All this can make it hard for a spacecraft to pick a reference point, which is part of why our current probes have to call home for directions so often. While we obviously want to communicate with our spacecraft as they explore the galaxy, finding a way for them to plot their own course a bit more would save time and energy. Fortunately, experiments with distant pulsars have been suggesting that they can be used as reliable sign-posts as we push further and further into space.

A pulsar is a special type of neutron star. They’re incredibly dense collections of debris made of the remnants of an exploded star with the added twist of also being highly magnetized. This magnetic polarization means that a pulsar emits x-ray energy from its north or south pole, rather than in all directions at once. Since the closest pulsar is around 280 light years away, we only see the emitted energy from a pulsar when it’s pointed in our direction, which happens on a regular schedule thanks to the pulsar’s rotation. In some cases those rotations are so fast that we get what appears to be a pulse of energy on a millisecond timescale, turning the pulsar into a handy blinking landmark that our spacecraft can use as a relatively stable reference point.

Piloting by pulsar

Right now, no probe is navigating by pulsar, but several instruments have been collecting data on them. The United States Navy has concluded a test with a satellite navigating by pulsar, and instruments on the International Space Station like the Neutron Star Interior Composition Explorer (NICER) have been collecting data both on the size of pulsars and how quickly they appear to “blink” from the perspective of our solar system. With these data, researches have come up with formulas that allow for a location in space to be identified within three miles.

As we refine our pulsar tracking abilities, researchers hope to reduce that margin of error to a half-mile. Once we can reliably triangulate an object’s location in relation to the energy from distant pulsars, spacecraft should be able to handle more navigation commands without calling back to Earth for updates. Pulsar-based navigation could also be used as a secondary navigation system for more sensitive missions, such as when humans attempt our first trip to Mars. The fact that tracking pulsars only requires a modestly-sized sensor makes this method of navigation quite practical, even if it requires enormous amounts of energy being blasted from from collapsed stars light years away to work.

Source: NASA test proves pulsars can function as a celestial GPS by Alexandra Witze, Nature

On January 10th, 2018 we learned about

Two meteorites found carrying liquid water and other ingredients needed for life

Delivery services are so convenient. You can get monthly boxes of toys and coffee, or even kits with ingredients for a dinner sent straight to your house. If you’re tolerant of unpredictable delivery schedule, you might even find organic compounds and liquid water, ready to be assembled into life as we know it. It’s not exactly farm-to-home, but scientists studying two particular arrivals are realizing that Ceres-to-Earth may be the next best thing.

The big catch with these deliveries is that they arrive via meteorites, and thus aren’t on the most predictable schedule. While asteroids of various sizes intersect with the Earth all the time, these particular space rocks survived a trip to the planet’s surface in 1998. One was found in Texas near a basketball court, while the other came months later in Morocco. The timing, similarity of composition and structural details suggest that these particular rocks came from two different points of origin, but may have been diverted to Earth thanks to a single collision in space. Scientists’ best guess is that the rocks were pieces of the dwarf planet Ceres and the asteroid Hebe, or at least pieces of those bodies’ descendants.

Petite portions

While the rocks themselves may have had a rough ride, the organic compounds and water molecules were safely stowed inside salt crystals the whole time. The water molecules in particular may even be 4.5 billion years old, dating back to the first days of our solar system. While the water, nitrogen carbon and other ingredients of hydrocarbons and amino acids were well-preserved, they arrived in quantities too small for even an appetizer. The crystals themselves were no bigger than 2 millimeters, and identifying these crucial compounds required the use of powerful tools like a scanning transmission x-ray microscopes (STXM).

Nonetheless, these tiny samples have bigger implications. They don’t suggest directly suggest that life exists on a place like Ceres, but they add to the growing evidence that life-friendly environments may be, or at least have been, more common than once thought. What’s more, those sources of organic compounds may be making regular deliveries around the solar system, seeding planets and other asteroids with all the ingredients needed to whip up some protein-producing goodness.

Source: Ingredients for life revealed in meteorites that fell to Earth by Lawrence Berkeley National Laboratory, Phys.org