Dark streaks in images from Mars, seen above, suggest flowing water. (NASA)

During spring months on Earth, the ground thaws and new life abounds. On Mars, scientists have observed activity of a different sort — water that seems to bleed from the ground.

Mars is thought to have been much wetter in the past with oceans, rivers, and even lakes that could have supported life. By now, those bodies of water are long gone. But despite the dry, desolate picture we have of modern Mars, scientists in 2011 spotted what appeared to be seasonal melts of water flowing down gullies. These appear in photographs as dark streaks of what is likely to be water, and while the flows are only a few yards wide, they stretch for over a half a mile. In new research published in Nature Geoscience, scientists have discovered even more of these flowing features in surprising locations, and they say that some of the water might be habitable for microbes. “There is a lot more water near the surface at the equator of Mars than anyone expected or really knows how to explain,” says Alfred McEwen, the lead researcher on the project.

“There is a lot more water … than anyone really knows how to explain.”

The scientists call these features “recurring slope lineae” (RSL). That name is intentionally clunky in an effort to eliminate any tantalizing assumptions about the origins of these features. But despite their caution in naming the flows, researchers feel increasingly confident that RSL indicate flowing water. The RSL are found in warm places and during hotter periods on Mars: they seem to appear in warmer equatorial regions and are active in spring and summer months before fading away when temperatures drop. The flows also only appear on darker surfaces that absorb more heat.

A time lapse of images showing flowing and drying liquid. (Credit: NASA/JPL/University of Arizona)

There’s no way to know the salt content of the flows, but it’s possible that some of it might even be freshwater. As a consequence, scientists are concerned about the protection of these sites. Liquid, fresh water is important for the habitability of these sites — both for Earth-based microbes that may have hitched a ride to Mars and for potential Martian microbes. So if rovers do explore nearby, extra precautions must be taken to ensure the water isn’t inadvertently contaminated.

The source of the water is still a mystery

But the source of the water is still a mystery. When RSL were first spotted, they were in regions where there’s probably shallow ice left over from a more moist climate. But this latest research seems to have found RSL in areas that aren’t likely to have any ice — leading scientists to speculate that the flows come from deep, salty groundwater in the planet’s crust. In fact, these equatorial regions of Mars were thought to be very dry, so any water there is a surprise, and difficult to explain.

For now, the investigations continue. “[The water] still needs some mechanism to replenish, so we haven’t figured all of this out,” McEwen says. In addition to the questions surrounding the origins of RSL, there’s one big asterisk next to this whole discovery — while water is the most likely cause of the flows, scientists don’t have the ability to directly prove it. And in the near term, that’ll remain a challenge: Martian rovers aren’t near any of these sites, which are comprised of tough terrain. “These are very steep, rocky slopes. These are the most difficult places to land,” McEwen says. “We’ve never gone close to landing near one of these kind of sites.”

For now, the best chance to definitively identify water is through monitoring from the Mars Reconnaissance Orbiter, which might one day yield more robust data. “This does not fit anybody’s model of the water cycle on Mars,” McEwen says. “This is a surprise, and we’re still being surprised by what we see on Mars. There’s clearly a lot more that we have to learn.”

The phenomenon of solar flares, as seen above, might be better understood thanks to the discovery of giant cells.

Nearly half a century ago, scientists started to unravel the structure of the sun and determine how solar material flowed on its surface. At the time, they predicted that the star should have massive cell structures, some 16 times the width of Earth, that carry currents across its surface. But these giant cells, despite their size, have remained elusive. Now, a researcher who 30 years ago worked on the problem as an intern has managed to solve the puzzle — moving this phenomenon from theory to reality.

Our sun, like many stars, is in part comprised of a convective layer that transports heat from its core to its surface. This transportation, in turn, creates pockets of solar currents that are constantly evolving (much like currents in the Earth’s atmosphere). Scientists have known about some of the cells carrying these currents for centuries. Namely, they’ve been aware of relatively small “granules,” which are about the size of Texas and only endure for about 10 minutes, as well as so-called “supergranules,” which are about three times the width of Earth and last for about a day. Both discoveries led scientists to think that granules and supergranules were part of a hierarchy of currents, which pointed to the existence of giant cells.

If only those cells were easy to find

If only those cells were easy to find. In large part, they’ve eluded scientists because the motion caused by giant cells is relatively slow, and therefore tough to detect. Granules have flow velocities (a measure of how quickly the material within the cells move) of about 3,000 meters per second (almost double the speed of a X-51A scramjet) and supergranules flow at 500 meters per second. In contrast, giant cells have flow velocities of just 10 meters per second (about the speed of Usain Bolt), meaning the motion is subtle and difficult to tease out.

An illustration of giant-cell flow trajectories in 2010. Credit: Hathaway/NASA

But David Hathaway, a NASA scientist whose new paper in Science confirms the existence of giant cells, was able to find the structures by tracking supergranules over time. Hathaway and fellow researchers used NASA’s Solar Dynamics Observatory to monitor the sun every 45 seconds for a few months. With careful averaging, they were able to determine that large groups of supergranules were being moved by an underlying presence — the long-sought giant cells.

These giant cells have a very visible consequence

They may have been tough to detect, but these giant cells have a very visible consequence: they cause the equatorial region of the sun to rotate faster than the poles. The cells are also important to understanding the sun’s weather. “The analogy with Earth weather systems is very close,” Hathaway says. “The same way weather systems carry moisture in the Earth’s atmosphere, these things are carrying magnetic fields in the sun’s surface and interior.” Both granules and supergranules move magnetic fields around, and Hathaway thinks giant cells won’t be any different. This phenomenon may have an impact on the strength of the magnetic field at the poles of the sun, which determines how intense the 11-year solar cycle of increasing and decreasing sunspots is going to be.

Hathaway also hopes that this finding yields a better understanding of where sunspots form. “The observation we’re dying to get is whether there is any indication in these flows about where new sunspots are going to emerge,” he says. Despite several theories on where sunspots might form with respect to these giants cells, pinning down the connection between won’t be easy.

“Everything interesting about the sun is related to magnetic fields.”

The next step for Hathaway and other experts will be to observe how magnetic fields respond to flows within the giant cells. “Everything interesting about the sun is related to magnetic fields — coronal heating, flares, coronal mass ejections,” Hathaway says. Pinpointing the connection between flow and magnetism would allow scientists to better predict the behavior of solar storms and how they’ll affect the solar system (like stripping away the Martian atmosphere), the Earth, and our satellites. “What does the solar wind look like? If you do produce a flare and a coronal mass ejection, how is it going to move through the interplanetary space? All of that is given by what this magnetic field does at the surface,” Hathaway says. “I think we will get a better hand on that given the fact that we now see these flows.”

When gun violence makes the news, it’s often described as an epidemic, implying that the violence is out of control on a massive scale, akin to a rampant disease. The term is used largely as a buzzword — but new research out of Yale University suggests that there’s more than just a semantic connection between gun violence and the behavior of diseases.

Stray bullets, while tragic, are relatively rare — meaning you can’t exactly “catch a bullet” the way you would an airborne disease, explains study leader Andrew Papachristos, an associate professor of sociology at Yale. Rather, “the vast majority of gun violence, the everyday violence that we see in our streets, is actually passed on person to person, much more like a blood-borne pathogen.” The idea behind Papachristos’ study, essentially, is that if you spend time with people who have been shot, carry a gun, or engage in risky behaviors, your own risk of being shot increases.

You can’t exactly ‘catch a bullet.’

The study, published this week in the American Journal of Public Health, pulled public arrest and homicide records to look at a social network of people who were linked by being arrested together for the same crime — indicating that they tend to be involved in risky activities, and share social connections with others who do the same (you’re more likely to rob a bank with someone you know well, for instance, than a complete stranger). The data was taken from a six-square-mile, high-crime area in Chicago.

The arrest network of the study’s Chicago neighborhood. Homicide victims are shown in black, with many connected in a large cluster.

While it may seem that gun violence and its victims are spread randomly, Papachristos’ network analysis shows that much of the violence is highly concentrated. In Chicago, the homicide rate is around 14.7 deaths per 100,000 people, and the neighborhood in the study has a rate of 55.2. Just being arrested increases the rate of being killed by a gun by almost 50 percent. While these numbers are high, geography and being arrested don’t tell the whole story about one’s risk of being shot. By simply being connected to a homicide victim via this network, a person’s risk of dying at the hand of a gun rockets up 900 percent.

A person’s risk of dying … rockets up 900 percent

Looked at another way, the largest group of people that are connected to one another via this arrest network contains just 4 percent of the people in the neighborhood — and yet represents 41 percent of the homicide victims for the area. Additionally, there are many smaller clusters in the arrest network that also contain homicide victims. The violence in this neighborhood is concentrated to a small fraction of the people who share these particular social connections and risky behaviors. However, the risk for becoming a victim in this network is not uniform. As the degrees of separation between an individual and a homicide victim increase, the risk of becoming a victim decreases: each additional connection separating the two individuals lowers one’s risk by 57 percent.

It seems simple in hindsight: your risk of being shot increases if you know someone else who’s been shot. But according to John Hollywood, a crime researcher at RAND Corporation, the research “could be a really useful contribution” towards preventing gun-related violence. “It was just good to see that some people have an idea and they go outside the box,” Hollywood said. “And in this case, going outside the box really paid off.”

“You’re aware you’re at risk. What are you going to do?”

In fact, the findings are already being used by Chicago law enforcement to track networks of people at risk and offer educational interventions. “The typical reaction is that they are riveted,” Papachristos said of those alerted by the Chicago Police Department. “What it does is it kind of gives them a little warning that says ‘You’ve got to be careful. There’s shooting going on around you, and you should probably be aware of it.'”

For Papachristos, data like this offers the opportunity for proactive interventions — in the same way that public health experts can intervene to mitigate the spread of illness. “You can condemn certain behaviors,” he said, likening the scenario to the spread of HIV. “Or you can figure out how to get clean needles, condoms, and education to the people who are most at risk.” At the very least, Papachristos points out, more information makes people aware of their choices. “You’re aware you’re at risk,” he said. “What are you going to do?”

Gazing up at the stars is something of a shared human experience. We look and we wonder. Are those stars like ours? Do they have planets around them? Are we alone? While ET hasn’t phoned home yet, a new study from astronomers at the University of California at Berkeley and the University of Hawaii at Manoa sheds light on how many planets could resemble our own.

Finding Earth-sized planets that are in an Earthlike orbit is a challenge. The larger a planet is and the closer it is to a star, the easier it is to detect. So it isn’t a surprise that some of the first exoplanets found were gas giants, such as Jupiter, that were fairly close to their star. But scientists have gotten better at spotting planets outside of our solar system. In large part, they do this by detecting when a planet moves in front of its star, which causes the light from that star to dim. A larger planet, or one closer to its host star, will yield a more pronounced drop in light.

Spotting planets outside of our solar system

Unfortunately, Earth-sized planets are relatively small and won’t block much light from a star. And while scientists have just identified an Earth-sized planet with an Earthlike composition, that planet isn’t in what’s known as the habitable zone — it’s too hot for life. The habitable zone is the not-too-hot, not-too-cold distance from a star where water can exist in liquid form.

In their new study, scientists wanted to find out how many planets are the size of Earth and orbit in the habitable zone of their sunlike stars. To do that, they created a computer program to analyze starlight gathered by the Kepler space observatory, in an effort to find the characteristic dimming of planets crossing in front of their stars.

For every planet researchers do see, there could be 100 more

Of the 42,000 stars analyzed, researchers detected only 10 that harbored Earth-sized planets. While this may seem disappointingly small, these few planets actually point to a host of other, undetected ones. As it turns out, most planets will not cross in front of their star, so this dimming is uncommon. For every planet researchers do see, there could be 100 more in orbits that keep them hidden. And that’s not the only way the planets are undercounted.

In an effort to boost the accuracy of their estimation, the team then created a test set of “mock” dimmings — essentially allowing them to distinguish between how many planets their program should find and how many it actually did. They concluded that the program only isolates a small number of dimmings, meaning that the 10 Earthlike planets directly detected may represent over 9,000 similarly sized planets in habitable zones. “The high abundance of Earth-sized planets appears to be a general feature of nature,” says lead study author Erik Petigura. “With about 100 billion stars in our Milky Way galaxy, that’s about 20 billion such planets.”

“The high abundance of Earth-sized planets appears to be a general feature of nature.”

Of course, being both Earth-sized and within the habitable zone aren’t the only factors that matter. “Some significant share of those planets are going to be uninhabitable for lots of different reasons,” says study co-author Andrew Howard. A planet might be uninhabitable because of a gas-giant composition or an elliptical orbit, for instance. This latest research, however, ensures scientists will have plenty of planets to study more closely.

The sci-fi worlds of Star Wars and Star Trek have trained us to think there are rocky, solid planets orbiting far away stars that are so similar to Earth we could walk upright and breathe their atmosphere. In reality, scientists have yet to identify a single planet outside of our solar system that’s comparable to the size and composition of Earth.

Until now, that is.

Two independent research groups, reporting in Nature, have found that a far-off planet, Kepler-78b, has a similar mass and composition to Earth. While previous observations of Kepler-78b had estimated the size of the planet to be 1.2 times wider than Earth, these latest measurements focused on observing the gravitational interactions between the planet and its star. The result? Researchers can combine the previously known size of the planet with the newly measured mass to determine its makeup.

The gravitational interactions between the planet and its star

Of course a star has a strong gravitational pull on a planet — that’s why planets orbit stars. But planets also exert a gravitational force on their host star, causing a small wobble in the star’s position. This wobble can be seen as a change in the wavelength of the light coming from the star, which is analogous to the change in sound of a train passing you — the pitch drops (the wavelength changes) because of the motion of the train. Researchers used this wobble to conclude that Kepler-78b has a mass 1.69 times larger than that of Earth. The combination of the size and mass of the planet yields the planet’s density, allowing researchers to determine what combination of materials comprise the planet. The density of Kepler-78b, they found, corresponds to an Earth-like makeup of rock and iron.

An Earthlike makeup of rock and iron

“Having a planet made largely of rock and iron, like our Earth, means that we have a good surface for life to evolve on,” says Andrew Howard, one of the researchers behind the new findings. Unfortunately, the composition of Kepler-78b doesn’t necessarily make it hospitable to life. “From an Earth-centric perspective, we’d like to have liquid water on the surface [and] this planet is obviously way too hot.”

Indeed, Kepler-78b is about 100 times closer to its star than we are to the sun, and it orbits the star in a blazingly fast 8.5 hours. As a consequence, the planet’s surface temperature is somewhere between 3700 and 5100ºF. That heat, combined with huge amounts of UV radiation, means the planet could not support an Earthlike atmosphere, nor any liquid surface water. “It’s probably a lava planet, so the surface is just red lava flowing. It’s completely different [from Earth],” said Francesco Pepe, lead author of the second study. “The sun would occupy half of the sky.”

“The surface is just red lava flowing.”

Kepler-78b might not be habitable, but scientists aren’t done studying the mysterious planet. “We have now more questions we have to answer,” Pepe says, noting that the particular geometry of this planet–star pair remains puzzling. “Theories cannot really explain why this planet did not fall into the star at some point.”

The planet might also help find answers for broader questions in the search for exoplanets. Scientists continue to wonder, for instance, whether an iron and rock composition is the rule or an exception for Earth-sized planets. To help address these questions, NASA has a planned mission in 2017 that will provide better tools for finding more exoplanets and will help put planets like Kepler-78b and Earth in context.

New materials lead to new innovations. Gorilla Glass is a big selling point for smartphones. Kevlar saves lives and has worked its way into consumer products. Lithium-ion batteries have enabled a host of energy-storage applications, from planes to cars to computers. But there’s a problem.

Actually creating a new, game-changing material is a glacially slow process — especially when compared to the rate at which new products relying on those materials hit the market. It took just under nine years for the Boeing 787 Dreamliner to go from a concept to commercial flight. The development of the iPhone began in 2005; the phone was on store shelves by 2007. In contrast, the creation of new materials moves far more slowly, taking about 20 years for all of the necessary research and development.

An attempt to gain a deeper understanding of how the elements interact

In an effort to overcome this innovation bottleneck, the White House two years ago announced the Materials Genome Initiative. The venture aims to halve development time for new materials and slash the monetary investment required. And if the name sounds familiar, it should: in the same way the Human Genome Project set out to map the underlying structure of human genes, the Materials Genome Initiative is an attempt to gain a deeper understanding of how the elements interact to give us a diverse set of materials and materials properties. With that foundation of knowledge, scientists and engineers will hopefully be able to create new materials tuned to the exact properties needed for a particular application — and be able to do it much, much faster.

A huge number of atomic combinations and arrangements may have useful properties. However, most arrangements won’t be useful, or even able to be synthesized. Trying to explore the vast world of potential materials in a lab would be both impractical and just plain impossible. So to map out that enormous number of possible materials, several research groups working on the Materials Genome Initiative are using computers to model known and unknown materials. They mine the resulting data to find areas that deserve a more careful examination.

In the years since its inception, the initiative has brought together several successful ventures. Among them are the Materials Project at MIT and the Harvard Clean Energy Project. These two projects have similar theoretical underpinnings for different end goals. MIT’s Materials Project is focused on inorganic solids, especially those for battery materials, while the Clean Energy Project is examining molecules for solar cell applications. Both are powered by huge databases that are populated with information gleaned from Density Functional Theory (DFT) calculations. DFT uses quantum mechanics to predict many properties of the real, physical substances being modeled.

A dataset of over 100,000 known and theoretical materials

MIT’s Materials Project started about eight years ago, and was catalyzed by the work of Professor Gerbrand Ceder. As a consultant to several companies, Ceder would screen a large number of materials for particular applications. But working with individual companies left the data siloed and locked up. “People would be able to do really creative things with this if we gave this to the world, and this became Materials Project,” he says. Now, MIT’s dataset consists of over 100,000 known and theoretical materials. To make sense of the data and design new materials, MIT researchers use a combination of human intuition and machine learning designed to understand the laws of chemistry.

Similarly, the Harvard Clean Energy Project has created a huge database that can be explored by man and machine for potential solutions to materials problems. The venture started as a small proof of concept examining potential organic solar cell materials. Researchers calculated the properties of about 15 compounds to predict how well these new substances might perform in the real world without having to synthesize them first. These calculations eventually yielded a new compound with near record-breaking electrical properties. But that success was just from a few chemicals calculated by a single graduate student. What could be discovered if you increased available computing power by distributing the calculations to an army of volunteers?

Researchers have calculated millions of potential solar cell compounds

Today, the Harvard Clean Energy Project is doing just that: anyone across the globe can download a program that performs scientific calculations on their PCs and reports back the results. With this massive resource at their disposal, researchers have calculated millions of potential solar cell compounds — and they’re only getting started. “Right now is an interesting time for the project,” says Dr. Hachmann, a research associate involved in the Harvard project. “We are at the point where we can harvest the fruits of our hard work and hopefully get some nice results.”

Currently, Harvard investigators have released 2.3 million compounds online for anyone to search through. And while these compounds have been calculated with solar cells in mind, other scientists who mine the data will be able to use the information to research other classes of materials. Similarly, researchers working on MIT’s Materials Project have an online portal for anyone to explore their data.

“You cannot anticipate what people will do with it.”

The greater Materials Genome Initiative aims to reduce costs and time for material development, and Ceder hopes to see it accomplish that bold goal. In fact, he’s already seen it work: Ceder is in the process of patenting new materials for use in batteries, a big win for the burgeoning Initiative and the field of materials discovery. And with heaps of data being shared in online databases, those successes are likely to keep coming. Ceder hopes to see the Materials Genome Initiative will lead to big innovations in materials science in the same, unpredictable way the web transformed many facets of modern life. “When you make stuff like this available,” he says, “you cannot anticipate what people will do with it.”