May 9, 2013
In September 2009, after decades of speculation, evidence of water on the surface of the Moon was discovered for the first time. Chandrayaan-1, a lunar probe launched by India’s space agency, had created a detailed map of the minerals that make up the Moon’s surface and analysts determined that, in several places, the characteristics of lunar rocks indicated that they bore as much 600 million metric tonnes of water.
In the years since, we’ve seen further evidence of water both on the surface and within the interior of the Moon, locked within the pore space of rocks and perhaps even frozen in ice sheets. All this has gotten space exploration enthusiasts pretty excited, as the presence of frozen water could someday make permanent human habitation of the Moon much more feasible.
For planetary scientists, though, it’s raised a knotty question: How did water arrive on the Moon in the first place?
A new paper published today in Science suggests that, unlikely as it may seem, the Moon’s water originated from the same source as the water that comes out of the faucet when you open a tap. Just as many scientists believe the Earth’s entire supply of water was initially delivered via water-bearing meteorites that traveled from the asteroid belt billions of years ago, a new analysis of lunar volcanic rocks brought back during the Apollo missions indicates the Moon’s water has its roots in these same meteorites. But there’s a twist: Before reaching the Moon, this lunar water was first on Earth.
The research team, led by Alberto Saal of Brown University, analyzed the isotopic composition of hydrogen found in water within tiny bubbles of volcanic glass (supercooled lava) as well as melt inclusions (blobs of melted material trapped in slowly cooling magma that later solidified) in the Apollo-era rocks, as shown in the image above. Specifically, they looked at the ratio of deuterium isotopes (“heavy” hydrogen atoms that contain an added neutron) to normal hydrogen atoms.
Previously, scientists have found that in water, this ratio changes depending on where in the solar system the water molecules initially formed, as water that originated closer to the Sun has less deuterium than water formed further away. The water locked in the lunar glass and melt inclusions was found to have deuterium levels similar to that found in a class of meteorites called carbonaceous chondrites, which scientists believe to be the most unaltered remnants of the nebula from which the solar system formed. Carbonaceous chondrites that fall to Earth originate in the asteroid belt between Mars and Jupiter.
Higher deuterium levels would have suggested that water was first brought on to the Moon by comets—as many scientists have hypothesized—because comets largely come from the Kuiper belt and Oort Cloud, remote regions far beyond Neptune where deuterium is more plentiful. But if the water in these samples represents lunar water as a whole, the findings indicate that the water came from a much closer source—in fact, the same source as the water on Earth.
The simplest explanation for this similarity would be a scenario in which, when a massive collision between a young Earth and a Mars-sized proto-planet formed the Moon some 4.5 billion years ago, some of the liquid water on our planet was somehow preserved from vaporization and transferred along with the solid material that would become the Moon.
Our current understanding of massive impacts, though, doesn’t allow for this possibility: The heat we believe would be generated by such an enormous collision would theoretically vaporize all lunar water and send it off into space in a gaseous form. But there are a few other scenarios that might explain how water was transferred from our proto-Earth to the Moon in other forms.
One possibility, the researchers speculate, is that the early Moon borrowed a bit of Earth’s high-temperature atmosphere the instant it formed, so any water that had been locked in the chemical composition of Earth rocks pre-impact would have vaporized along with the rock into this shared atmosphere after impact; this vapor would have then coalesced into a solid lunar blob, binding the water into the chemical composition of lunar material. Another possibility is that the rocky chunk of Earth was kicked off to form the Moon retained the water molecules locked inside its chemical composition, and later on, these were released as a result of radioactive heating inside the Moon’s interior.
Evidence from recent lunar missions suggests that lunar rocks—not just craters at the poles—indeed contain substantial amounts of water, and this new analysis suggests that water originally came from Earth. So the findings will force scientists to rethink models of how the Moon could have formed, given that it clearly didn’t dry out completely.
April 19, 2013
Last year, to celebrate the 42nd Earth Day, we took a look at 10 of the most surprising, disheartening, and exciting things we’d learned about our home planet in the previous year—a list that included discoveries about the role pesticides play in bee colony collapses, the various environmental stresses faced by the world’s oceans and the millions of unknown species are still out in the environment, waiting to be found.
This year, in time for Earth Day on Monday, we’ve done it again, putting together another list of 10 notable discoveries made by scientists since Earth Day 2012—a list that ranges from specific topics (a species of plant, a group of catfish) to broad (the core of planet Earth), and from the alarming (the consequences of climate change) to the awe-inspiring (Earth’s place in the universe).
1. Trash is accumulating everywhere, even in Antarctica. As we’ve explored the most remote stretches of the planet, we’ve consistently left behind a trail of one supply in particular: garbage. Even in Antarctica, a February study found (PDF), abandoned field huts and piles of trash are mounting. Meanwhile, in the fall, a new research expedition went to study the Great Pacific Garbage Patch, counting nearly 70,000 pieces of garbage over the course of a month at sea.
2. Climate change could erode the ozone layer. Until recently, atmospheric scientists viewed climate change and the disintegration of the ozone layer as entirely distinct problems. Then, in July, Harvard researcher Jim Anderson (who won a Smithsonian Ingenuity Award for his work) led a team that published the troubling finding that the two might be linked. Some warm summer storms, they discovered, can pull moisture up into the stratosphere, an atmospheric layer 6 miles up. Through a chain of chemical reactions, this moisture can lead to the disintegration of ozone, which is crucial for protecting us from ultraviolet (UV) radiation. Climate change, unfortunately, is projected to cause more of these sorts of storms.
3. This flower lives on exactly two cliffs in Spain. In September, Spanish scientists told us about one of the most astounding survival stories in the plant kingdom: Borderea chouardii, an extremely rare flowering plant that is found on only two adjacent cliffs in the Pyrenees. The species is believed to be a relic of the Tertiary Period, which ended more than 2 million years ago, and relies on several different local ant species to spread pollen between its two local populations.
4. Some catfish have learned to kill pigeons. In December, a group of French scientists revealed a phenomenon they’d carefully been observing over the previous year: a group of catfish in Southwestern France had learned how to leap onto shore, briefly strand themselves, and swim back into the water to consume their prey. With more than 2,000,000 Youtube views so far, this is clearly one of the year’s most widely enjoyed scientific discoveries.
5. Fracking for natural gas can trigger moderate earthquakes. Scientists have known for a while that whenever oil and gas are extracted from the ground at a large scale, seismic activity can be induced. Over the past few years, evidence has mounted that injecting water, sand and chemicals into bedrock to cause gas and oil to flow upward—a practice commonly known as fracking—can cause earthquakes by lubricating pre-existing faults in the ground. Initially, scientists found correlations between fracking sites and the number of small earthquakes in particular areas. Then, in March, other researchers found evidence that a medium-sized 2011 earthquake in Oklahoma(which registered a 5.7 on the moment magnitude scale) was likely caused by injecting wastewater into wells to extract oil.
6. Our planet’s inner core is more complicated than we thought. Despite decades of research, new data on the iron and nickel ball 3,100 miles beneath our feet continue to upset our assumptions about just how the earth’s core operates. A paper published last May showed that iron in the outer parts of the inner core is losing heat much more quickly than previously estimated
, suggesting that it might hold more radioactive energy than we’d assumed, or that novel and unknown chemical interactions are occurring. Ideas for directly probing the core are widely regarded as pipe dreams, so our only options remains studying it from afar, largely by monitoring seismic waves.
7. The world’s most intense natural color comes from an African fruit. When a team of researchers looked closely at the blue berries of Pollia condensata, a wild plant that grows in East Africa, they found something unexpected: it uses an uncommon structural coloration method to produce the most intense natural color ever measured. Instead of pigments, the fruit’s brilliant blue results from nanoscale-size cellulose strands layered in twisting shapes, which which interact with each other to scatter light in all directions.
8. Climate change will let ships cruise across the North Pole. Climate change is sure to create countless problems for many people around the world, but one specific group is likely to see a significant benefit from it: international shipping companies. A study published last month found that rising temperatures make it probable that during summertime, reinforced ice-breaking ships will be able to sail directly across the North Pole—an area currently covered by up to 65 feet of ice—by the year 2040. This dramatic shift will shorten shipping routes from North America and Europe to Asia.
9. One bacteria species conducts electricity. In October, a group of Danish researchers revealed that the seafloor mud of Aarhus’ harbor was coursing with electricity due to an unlikely source: mutlicellular bacteria that behave like tiny electrical cables. The organisms, the team found, built structures that traveled several centimeters down into the sediment and conduct measurable levels of electricity. The researchers speculate that this seemingly strange behavior is a byproduct of the way of the bacteria harvests energy from the nutrients buried in the soil.
10. Our Earth isn’t alone. Okay, this one might not technically be a discovery about Earth, but over the past year we have learned a tremendous amount about what our Earth isn’t: the only habitable planet in the visible universe. The pace of exoplanet detection has accelerated rapidly, with a total of 866 planets in other solar systems discovered so far. As our methods have become more refined, we’ve been able to detect smaller and smaller planets, and just yesterday, scientists finally discovered a pair of distant planets in the habitable zone of their stars that are relatively close in size to Earth, making it more likely than ever that we might have spied an alien planet that actually supports life.
March 20, 2013
Update: Since the press release announcing Voyager 1′s exiting the solar system, NASA has clarified that the final indicator of this event—a change in the direction of the magnetic field surrounding the craft—has still not been observed. As was first observed in December 2012, Voyager 1 is in a new outermost region of the solar system called “the magnetic highway,” not true interstellar space. This post has been edited to reflect the clarification.
Since the dawn of the Space Age, our manned missions and unmanned probes have reached the Moon, asteroids and other planets. But only now do we have confirmation that a human-made object has reached a new milestone: The Voyager 1 space probe is at the furthermost edge of the solar system.
According to a paper recently accepted for publication by the journal Geophysical Research Letters, data transmitted by probe—which is now more than 11 billion miles away from the Sun—reveal that it has exited the heliosphere. The heliosphere (also called the heliosheath) is the region of space influenced by the solar wind and is commonly accepted as the outer border of the solar system. Thirty-five years, 6 months and 15 days after its launch, the spacecraft will soon enter the second phase of its mission—studying the interstellar medium that exists between our galaxy’s star systems.
Bill Webber of New Mexico State and F.B. McDonald of the University of Maryland (who has passed away since the paper was written) came to the conclusion after analyzing radiation data transmitted by Voyager 1 last August 25. The probe’s sensors detected that the levels of radiation from cosmic rays that had come from the Sun dropped to less than 1 percent of what they’d been previously, while radiation from galactic cosmic rays (which originate from beyond the solar system) doubled in intensity.
Although there is no exact boundary that defines the edge of the solar system, the point at which the Sun’s cosmic rays and galactic cosmic rays meet indicates the edge of the region dominated by our Sun’s solar wind, and thus the outside border of our star’s system. Webber says that the sudden change in radiation indicates Voyager 1 passed this point.
“Within just a few days, the heliospheric intensity of trapped radiation decreased, and the cosmic ray intensity went up as you would expect if it exited the heliosphere,” he said in a press release issued by the American Geophysical Union today. He also noted that it’s possible the probe hasn’t reached true interstellar space, but rather a separate, not-yet-understood region that lies in between our solar system and the interstellar medium.
Since its launch in 1977, the spacecraft has conducted a grand tour of the solar system, passing by and photographing Jupiter and Saturn and providing us with some of the first-ever close-ups of the gas giants. Voyager 2, a twin probe, visited Jupiter, Saturn, Uranus and Neptune, and is still firmly within the solar system for now, 9.4 billion miles away from the Sun.
In 2005, Voyager 1 entered the heliosheath (the region in which the solar wind begins to slow down due to encountering the interstellar medium), and last October, researchers reported that it may have left the heliosphere altogether. Soon afterward, though, scientists cautioned that it may not have exited the heliosphere’s outer boundary, because a shift in the direction of the magnetic field had not yet been detected.
Despite the announcement alongside the new paper, this may still be the case—Voyager 1 may have finally exited the heliosphere, but not yet entered interstellar space per se. According to NASA, “A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space and that change of direction has not yet been observed.” Thus, the probe is in an unexpected region in between the heliosphere and interstellar space, previously referred to as a magnetic highway.
Either way, though, it’s still in the starting stages of its journey, set to spend millennia—yes, millenia—traveling through the interstellar medium, though it will probably not be able to record or send back data after around 2025.
After an estimated 40,000 years, it will come relatively close (within a light year) to another star—and at that point, could serve as something of a time capsule. The Voyager 1 carries a Golden Record, designed to present a virtual snapshot of humankind to other life forms, contains everything from images of DNA and the Taj Mahal to recordings of whale sounds and Chuck Berry’s “Johnny B. Goode.”
As Timothy Ferris wrote in Smithsonian last May when he reflected on the 35th anniversary of the Voyager mission, “The Voyagers will wander forever among the stars, mute as ghost ships but with stories to tell…Whether they will ever be found, or by whom, is utterly unknown.”
March 7, 2013
Roughly 3.5 billion years ago, Mars began to shift from a wetter, warmer climate to the dry and cold planet we see today. This period of geologic change, known as the Hesperian age, was a turbulent time. The red planet saw widespread volcanic eruptions and catastrophic flooding as melted ice rushed into wide craters, forming lakes. These natural disasters carved a network of basins into its surface called outflow channels, eroding the terrain and reshaping the landscape of the planet. The exact end of this geologic period in Mars’ history is unknown, but scientists give a rough estimate of 3 billion years ago.
Later, many of these outflow channels became covered with lava, burying evidence of Mars’ geologic history. But now, a new map of the planet’s subsurface shows for the first time what one of these buried channels looks like in three dimensions. The findings, published today in the journal Science, reconstruct the Marte Vallis, the largest of the youngest channels on Mars. Marte Vallis is located in the Elysium Planitia region, an expanse of plains along the equator and the youngest volcanic region on the planet.
To create the 3D map, the researchers used data from Shallow Radar, a device that probes for liquid or frozen water underneath Mars’ crust. Known as SHARAD, the technology is on board NASA’s Mars Reconnaissance Orbiter spacecraft, which is currently circling the planet to study its climate. SHARAD’s orbital sounding radar works in much the same way as medical imaging scans. It sends signals to the surface, some of which automatically bounce back to the spacecraft. The signals that don’t readily bounce back can penetrate Mars’ crust and register buried structures before returning to the device. The data appears in two-dimensional cross sections, which are then pieced together to build the 3D representation. In this manner, a deeply grooved set of channels was revealed.
The system of channels, which is somewhere between 10 million to half a billion years old, spans 60 miles in width and stretches for more than 600 miles in length. From what can be seen of Marte Vallis from the surface, the channels are similar in structure to more ancient channel systems traced to the Hesperian, but the lava that had obscured many of their features made it difficult for researchers to make accurate estimates about its depth.
The new data reveals that the scale of erosion for Marte Vallis had indeed been underestimated: the 25-mile-wide main channel is at least twice as deep than earlier approximations indicated. The map shows multiple perched channels which feed into the deeper and wider main channel. These channels once lay along a series of four islands, which floods eroded into teardrop-shaped hills.
The researchers found that the geometry of the features are similar to those of the planet’s oldest channels, which are less obscured by lava, making them easier to study. This also suggests that the Marte Vallis could have been carved entirely by water, says lead study author Gareth Morgan, a geologist at the National Air and Space Museum’s Center for Earth and Planetary Studies. In fact, most Mars scientists accept that outflow channels on Mars were carved by water. Lava also carves out tunnels through thermal erosion heating up the terrain, but Morgan says that this process is implausible for the scale of erosion at the Marte Valle channels. The speed of rushing water is also more efficient at erosion that the flow of lava, which can get stuck on rock, Morgan says. In addition, lava creates tunnels that aren’t as wide—typically only several miles across—so collapsed tunnels couldn’t account for the broad size of the channels.
Using the map, researchers were also able to pinpoint the source of the
floodwater: a now buried portion of the Cerberus Fossae fracture, a series of fissures in the planet’s surface. The researchers posit that water from a reservoir deep below Mars’ surface was released by nearby tectonic or volcanic activity, and it worked quickly to form the channels. These channels would have been a short-lived affair,” Morgan says. “The fracture would have connected this groundwater to the surface. After a short duration of weeks or months, the source would have been exhausted.”
But why was water in that reservoir during a time when the rest of Mars is believed to have been dry? Water, the authors believe, could have collected in aquifers below the surface during the Hesperian. This water hypothetically could have remained stable in liquid form long after the Hesperian ended. Morgan feels that the 3D map could provide more
evidence to support this hypothesis, showing that Mars was wet place in the more recent—as opposed to far ancient—past.
More than 20 similar outflow channels are spread out on the surface of the planet, extending hundreds of miles in length. The most prominent are located in the Chryse Planitia, a circular volcanic plain in the northern hemisphere of Mars. The largest, the Kasei Valles, runs for 1,500 miles along the plain.
Cataclysmic floods like the ones that shaped Mars’ channels aren’t unique to the red planet. Approximately 14,000 years ago, the largest known flood on Earth sprang from Lake Missoula, a prehistoric body of water that existed at the end of the last Ice Age in present-day Montana. The waters eroded part of the landscape of Washington state, forming the Channeled Scablands, a terrain that resembles Martian outflow channels. Marte Vallis’ main channel is estimated to be between 226 and 371 feet deep, a depth that’s comparable to the Channeled Scablands.
So if Mars’ expansive outflow channels were formed by gushing water, the question remains: Where did it all ago?
Some of it vaporized, drifted to the planet’s poles, and precipitated as ice on polar caps, Morgan says. Similar to the ones we have on Earth, the polar ends on the Red Planet are covered in miles-thick layers of ice. The water also could have pooled into shallow areas below the surface, where it also froze—in 2008, NASA’s Phoenix mission confirmed that ice exists in the porous soil that makes up much of the planet’s surface.
Another possibility, Morgan says, is that the ancient water again escaped deep underground, forming a large reservoir that awaits its chance to flood again.
February 22, 2013
On Wednesday, NASA released an image of a series of enormous sunspots snapped by at the Solar Dynamics Observatory, an orbiting telescope. The sunspots—the dark spots in the center of the image—are estimated to be larger in diameter than six Earths placed next to each other.
These sunspots pose no inherent danger—they’re merely temporary areas of intense magnetic activity that inhibit the sun’s normal convection currents—but, on occasion, the unstable area around a sunspot can trigger an unusually large solar flare (below), flinging streams of radiation outward from the sun. And a big enough solar flare can lead to an alteration in solar wind significant enough to set off a geomagnetic storm here on Earth, with the potential to short the circuitry on satellites and disrupt our telecommunications infrastructure worldwide.
It so happens that at least once during recorded history, a solar event of this magnitude did occur: the solar storm of 1859. On September 1 and 2 of that year, the largest geomagnetic storm in recorded history occurred, causing aurorae (the northern and southern lights) to be visible around the world. The Baltimore American and Commercial Advertiser wrote:
Those who happened to be out late on Thursday night had an opportunity of witnessing another magnificent display of the auroral lights…The light appeared to cover the whole firmament, apparently like a luminous cloud, through which the stars of the larger magnitude indistinctly shone. The light was greater than that of the moon at its full, but had an indescribable softness and delicacy that seemed to envelop everything upon which it rested.
Of course, the massive solar storm also caused damage, triggering telegraph malfunctions (even giving operators electrical shocks) and causing some telegraph pylons to suddenly spark and catch fire.
A much smaller solar storm occurred in 1989, knocking out power throughout much of Quebec for over 9 hours, disrupting communications with several satellites in orbit and interfering with the broadcast of short-wave radio in Russia. Aurorae were reportedly visible as far south as Florida and Georgia; given the ongoing Cold War and the fact that many had never seen this phenomenon before, some feared that a nuclear strike was in progress.
How did solar activity 93 million miles away lead to such destruction? These types of storms are the result of a sudden coronal mass ejection (CME)—a massive burst of solar plasma (electrons, protons, and ions) that is hurtled out into space—which often occurs alongside particularly large solar flares.
The solar wind is a continuous stream of charged particles thrown out from the sun towards earth, but a particularly large CME can lead to a big enough surge in the speed and energy of the particles to disrupt the magnetic field surrounding Earth. This, in turn, causes aurorae and the disruptions to our telecommunications equipment, which rely upon electromagnetic forces.
If a CME as large as the one that triggered the 1859 storm were to occur today, the consequences could be devastating. Given the increase in our reliance on electricity and telecommunications (even since 1989), the effects would certainly be far more significant than malfunctioning telegraph pylons.
It’s hard to appreciate just how many aspects of modern life rely on technologies that could be affected. As Daniel Baker of the University of Colorado’s Laboratory for Atmospheric and Space Physics told National Geographic in 2011, ”Every time you purchase a gallon of gas with your credit card, that’s a satellite transaction.” A giant storm could disrupt our GPS systems, communication with planes in flight and other crucial satellite-based technologies.
But the biggest concern, experts say, would be disruptions to our power grid—as a 2011 OECD report (PDF) on the impacts of solar storms points out, “Electric power is modern society’s cornerstone technology on which virtually all other infrastructures and services depend.” A surge in solar wind can blow out power transformers by melting their copper windings, and especially in highly interconnected regions (such as the East Coast), transformer failures can trigger cascading effects, spreading power outages over wide areas.
One analysis looked at a 1921 storm—which was ten times more powerful than the 1989 event—and estimated that if it occurred today, it would leave some 130 million people without power, potentially affecting water and food distribution, heating and air conditioning, sewage disposal and a host of other aspects of the infrastructure we take for granted daily. The total cost of an even larger storm, such as the 1859 event, could be enormous: an estimated $1 to $2 trillion in the first year alone, and a total recovery that could take 4 to 10 years in total.
The good news is that CMEs large enough to trigger a disruptions like the 1859 storm are rare–for the most severe damage to occur, a CME has to be directed in such away that Earth receives the brunt of the blast. Fortunately, solar activity occurs in a cycle with a duration of roughly 11 years, during which all kinds of solar activity (including the number of sunspots, the frequency of flares and the level of mass ejections) fluctuate from high to low and back to high again. However, we’re near the peak of the cycle, which NASA predicts will occur this fall.
Both NASA and the National Weather Service’s Space Weather Prediction Center monitor solar activity and issue warnings when CMEs and other alterations in the solar wind occur. The SWPC’s current 3-day forecast predicts no storms over the weekend, despite this new enormous sunspot.
If a massive CME were spotted, such 3-day forecasts give us some lead time: there are some measures electric utilities could take to protect their equipment, such as quickly disconnecting transformers. Polar flights, which travel at the highest altitudes, could be rerouted to avoid contact with damaging solar particles, and some satellites could be switched into a safe mode to minimize damage. Here on Earth, at the very least, we’d have some time to prepare for potential power blackouts and other problems.