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.
January 3, 2013
Last year, noted meteorite collector Jay Piatek traveled to Morocco and bought a single stone, less than a pound in weight, that had been discovered in the country some time earlier. When he passed it on to researchers at the University of New Mexico to perform a mineral analysis, they found something unexpected.
The meteor seemed to have originated on Mars, but the rock’s composition didn’t exactly match any of the well-studied meteorites from there found previously. When the researchers compared it to data from soil and rock samples obtained by Curiosity and other recent Martian rovers, though, they realized that rather than originating in the planet’s mantle, as the others had, it appeared to have come from the Martian crust.
Most intriguingly, when they analyzed the basaltic breccia rock even more closely, they discovered it contained a large quantity of water molecules locked in its crystalline structure. While previous studies of Martian meteorites have suggested the presence of water on the red planet, this sample’s analysis, published today in Science, revealed that it contained 10 times more water than any Martian meteorite examined before.
The discovery of the water molecules in the rock at concentrations of 6000 parts per million could indicate the presence of liquid water sometime during Mars’ history. “The high water content could mean there was an interaction of the rocks with surface water either from volcanic magma, or from fluids from impacting comets during that time,” study co-author Andrew Steele of the Carnegie Institute said in a statement.
Apart from the presence of water, the researchers say that information they’ve gleaned over the course of a year-long analysis of the meteor—the first ever linked to the Martian crust—could significantly impact our understanding of the planet’s geology as a whole. The meteorite is primarily composed of chunks of basalt cemented together, indicating that it formed from rapidly cooling lava, likely on the planet’s crust. While we’ve found meteorites from the Moon that match this composition, we haven’t seen anything like it from Mars previously.
Already, the researchers determined that the specimen is roughly 2.1 billion years-old, formed during Mars’ Amazonian epoch, a time period from which we had no previous rock samples. “It is the richest Martian meteorite geochemically,” Steele said. “Further analyses are bound to unleash more surprises.”
December 14, 2012
The year 2012 was a major one for science. We saw scientists develop a new type of drug to combat HIV, figure out how to store digital data in DNA—fitting an astonishing 700 terabytes of information into a single gram of it—and even invent a coating for the inside of condiment bottles that could eliminate our stuck-ketchup-headaches once and for all (though, admittedly, this one is a little less groundbreaking than the others). Yet a few milestones in particular—discoveries, technological feats, realizations, and inventions—stand out:
1. The Higgs Boson: The landmark discovery by the European Organisation for Nuclear Research (CERN) of the once-mythical particle might be the most significant scientific discovery of our lifetimes, but it’s also one of the most surprising. Stephen Hawking, the Einstein of our time, famously bet Michigan physicist Gordon Kane $100 that it would never be found.
In an interview with The Atlantic, physicist Lawrence Krauss explained why so many experts had agreed with Hawking, arguing that the existence of the Higgs—a particle (and associated field) that makes certain types of elementary particles behave as though they had mass—was just too convenient, as it was originally posited simply to explain away an apparent difficulty in an otherwise appealing theory in theoretical physics.
The theory seeks to unite all physical forces under the same set of rules. But how can electromagnetic forces–governed by massless photons–fit under the same theoretical umbrella as the weak force, which is governed by bosons with discernible mass that control radioactive decay? Efforts to answer this conundrum gave birth to the Higgs boson. Krauss noted,”It seemed too easy…It seemed to me that introducing an invisible field to explain stuff is more like religion than science…Great, I invented invisible hobgoblins to make things right.”
Incredibly, in this case, it turned out the hobgoblins were real.
2. Earth-Like Planets: 2012 featured a ton of exoplanet discoveries, but the sighting of HD 40307g was without a doubt the most unexpected and exciting. The planet, bigger than earth but not so large as to be a gas giant, seems to orbit in its sun’s “goldilocks zone” (not too hot and not too cold), making it potentially capable of hosting liquid water, considered a prerequisite for life as we know it.
Even better, it’s just 42 light-years away: distant by human standards, but fairly close by compared many of the astronomical objects, making future projects to observe the planet much more feasible.
3. Curiosity Reaches Mars: Okay, the mission itself wasn’t too surprising—it’s been in the works since 2004—but what was so astonishing was the sudden surge of public interest in the rover and in space exploration as a whole. For decades following the manned Apollo missions of the 1960s and 70s, general enthusiasm for space science had slowly ebbed. After Curiosity’s successful landing, though, it surged. Among other things, video of NASA engineers celebrating the feat went viral and the official Curiosity twitter account garnered some 1.2 million followers.
People are so interested in Curiosity‘s exploits, in fact, that even an engineer’s throwaway line about “a discovery for the history books” pumped up expectations so much that we were bound to be disappointed by the actual finding: that early Martian soil samples seem to be representative of what we know of the planet as a whole, and that its chemistry is complex enough to have potentially once supported life. Bigger news might come over the next few years, but as project scientist John Grotzinger said, “Curiosity’s middle name is patience.”
4. Climate Change Is Even Worse Than We Thought: After decades of warnings from scientists that our greenhouse gas emissions will soon wreak havoc with the climate, we’re now starting to see the consequences—and they sure aren’t pretty. As a whole, experts are saying that the even the most frightening climate scenarios have proved to be too conservative in their analysis of how rising carbon dioxide concentrations will alter precipitation patterns, drive ocean acidification, lead to more powerful storms and, in general, make most parts of the planet grow warmer.
One silver lining might be that the public is now starting to acknowledge climate change as a present-day problem, rather than a hypothetical trend that could take effect in the future. Sadly, this has come only after record-breaking heat waves, droughts and the tragic impacts of Hurricane Sandy. Although the most recent international climate talks in Doha accomplished little, there are hopes that this shift in opinion could lead to a long-awaited change in policy sometime soon.
5. A New Way to Desalinate Seawater: With world populations expected to keep growing and potable water projected to grow more scarce over the coming century, a practical and cheap means of desalinating sea water is one of materials science’s holy grails. In July, MIT researchers announced the development of a new method of desalinization using one-atom-thick sheets of graphene, a pure carbon substance. Their method could be far cheaper and less energy-intensive than existing systems—potentially providing a way to solve many of the world’s water problems once and for all.
December 7, 2012
We all have science nerds in our lives (if you’re reading this blog, in fact, you probably are one yourself). But when the wintertime gift-giving holidays roll around, picking out gifts for this crowd can be more difficult than for others. A sweater just won’t cut it. With this in mind, here some fascinating (if sometimes impractical) gift ideas for science nerds:
Glass anatomical models: as detailed by Wired, master glassblower Gary Farlow and his team of artists make exquisitely detailed full-scale anatomical models of the human body’s vascular systems (above), from the arteries of the brain to the vessels that feed our internal organs. These stunning creations aren’t just for show—designed with the help of cardiologists, the see-through systems are used for training medical students. You might want to reserve them as gifts for the extra-special bio-nerds on your list, though, as a full-body model costs up to $25,000.
3-D Printers: Once restricted to professionals, 3-D printers are rapidly coming down enough in price to enter the consumer market in earnest. Much like a normal printer takes digital images and puts them on a piece of paper, a 3-D printer can convert plans for 3-D objects and carve them into plastic or other materials. They are beloved by engineers, inventors and tinkerers of all types. At the low end of the market is the Printbot jr., a $399 machine that requires some self-assembly, and the $480 Portabee 3D Printer, billed as the world’s first portable 3-D printing device.
Retro Adding Machines: The age of the artisan calculator is upon us. As he desribes on his website, Andy Aaron makes fully functional Victorian-inspired adding machines, using old-fashioned tools like switches, cranks and levers, all mounted in a handsome wood casing. The handcrafted devices each take roughly a year to produce—and all the ones posted on Aaron’s website are already marked “SOLD”—so you might went to get in touch with him pronto if you want to buy one this holiday season.
Electronic Field Guides: In the past, nature lovers roamed forests and countrysides with a trusty field guide at hand to help identify plant and wildlife species. Now all you need is your smart phone. Leafsnap is one of the first in a series of field guide apps being developed by researchers from a group of institutions (including the Smithsonian) that automatically identify a plant species based on a picture you take of a leaf. Even better, it’s entirely free.
Martian Meteorites: As Curisoity explores Mars, you can buy yourself a small piece of it. MeteoriteMarket.com sells a variety of meteorites, including pieces of Martian Shergottite rock that crashed into the Oman desert and were discovered in 1999. While the many of the smallest pieces are already long gone, a handful remain, ranging from $1067 to $14,500 in price.