Grounded: The End of a Love Affair

A vintage 1940s J-3 Piper Cub sits on the tarmac at Sterling.

By Mark Zastrow
BU News Service

One hour west of Boston, past the Wachusett reservoir and farms draped on rolling hills lies a little strip of tarmac in a big grass field, surrounded by the central Massachusetts forest. A dozen small airplanes sit on the cracked asphalt next to rusted-out hangars with oil-stained floors. This is Sterling Airport, and as you walk to the door, a big green sign greets you, saying: LEARN TO FLY HERE.

The weather on this Saturday afternoon: clear skies, 50 ºF, over 10 miles visibility—more than enough to see Mt. Wachusett on the northwest horizon. It’s a spring day in February, and a beautiful one for flying. But the only thing up there now is a hawk, making lazy circles over the sun-beat tarmac, soaring on the rising air.

Inside the airport operator’s building it smells like old couches, and three greying white men are sitting on them. Hangar talk. Hanging on the wall are the T-shirts worn by student pilots on their first solo, signed with the date and the plane’s tail number. They end at 2007. One of them bears the slogan: “Sterling Airport: Grass roots aviation at its finest!”

Seems the grass has stopped growing. General aviation—that is, personal, non-airline flying—in the United States is in a nosedive. In 1980, according to FAA numbers, there were more than 200,000 student pilots in the process of earning their private pilot’s license. In 2009, there were 73,000. The number of active pilots has fallen from 827,000 to fewer than 600,000.

Rising fuel and insurance costs and the inexorable demographic of war-swollen generations of pilots are part of the reason. But there’s also been a cultural shift: flying simply isn’t cool. When I was a kid, Popular Mechanics still published cover stories about flying cars. But this afternoon at Sterling, the personal airplane seems a thing of the past, not the future.

Even on a warm spring day, there can be more sitting around than flying.

After me, the next youngest person in the room is Renee, a woman in her mid-40s with brown hair and a lilting Midwestern accent. She’s been a tow pilot with Sterling’s gliding club for 12 years. I ask how many kids are training here these days. “It’s…a reasonable number,” she says. “A lot less than a few years ago.” She glances at the rates written on the wall: $88/hr to rent the Cessna 150 two-seater, plus $45 for the instructor. It’s double what I paid to get my license a decade ago growing up in Wisconsin. “Not many can afford it anymore.”

As a child, I heard small airplanes pass over my yard every day. I always looked up. It wasn’t the freedom that I craved, to feel the “tumbling mirth of sun-split clouds in footless halls of air” that John Gillespie Magee, Jr. immortalized in his sonnet “High Flight.” No, more than anything else, I wanted to fly because I wanted to look down. I wanted perspective. I wanted to know what my house looked like from above—to find out where I was, to place myself amongst my surroundings. The year after I got my pilot’s license, I came across a site called Google Maps. And eventually, I stopped looking up.

Final approach to the grass strip at Sterling in a glider. Mt. Wachusett is just left of center on the horizon.

I remember to look up now as I walk back to my car. The skies are still clear; even the hawk is gone. From the south end of the strip, Mt. Wachusett rises from the treeline, seven miles distant as the hawk flies. On a good summer day, when the ground is warm, you can hop in a glider, get a 3,000 foot tow, and soar all the way there to dance across its slopes on the uplift off the ridges and glide back to Sterling—or so I’m told. Since I arrived, I haven’t see a single plane take off or land, nor heard a single engine fired.

But I’ll be back. I forgot to pay for my coffee.

Hot Times for Cool Stars

By Mark Zastrow
BU News Service

Alien worlds may be even more alien than we thought.

Artist’s impression of sunset on the super-Earth world Gliese
The M dwarf Gliese 667 C hovers on the horizon with its two companion stars in this artist’s impression of a sunset on the potentially habitable planet Gliese 667 Cc. (ESO/L. Calçada)

For decades, astronomers’ visions of a habitable planet circling distant stars were like holding up a mirror to our own: it had to be rocky (not gaseous like Jupiter), at just the right distance from its star to support liquid water (not too hot, not too cold), and orbiting a friendly yellow star like our own.

But within the last two years, scientists analyzing data from NASA’s planet-hunting Kepler space telescope have overturned that last assumption. It seems we were blinded by our biases; it turns out that the stars that hold the most rocky planets with just the right temperature are not like the Sun. Instead, they are a long-overlooked class of stars, the most common in the Galaxy: the diminutive M dwarfs. Now, astronomers are paying attention to them. If these systems harbor alien life, we might be able to detect them in less than ten years.

Compared to the Sun, M dwarfs are puny, with half the mass and half the diameter at most. They’re cooler, with surface temperatures that max out at 6700º F, compared to the Sun’s 10,000 ºF.  They give off a faint red glow much dimmer than the Sun’s fiery yellow. To be warm enough to support liquid water, any planet orbiting such a star would have to be close. The star would loom large in the sky, causing tides so great, they would stop the planet’s rotation. One side would be locked into perpetual day, the other in eternal night.

Until recently, astronomers had no reason to think there would be many of these planets around M dwarfs. To be honest, M dwarfs were kind of an afterthought,” says Andrew Howard, who coauthored an August 2012 study of Kepler’s first batch of data when he was a postdoctoral fellow at the University of California–Berkeley. NASA had launched the space telescope in 2009 specifically to find habitable worlds around stars like the Sun. But when Howard and his team ran the numbers on Kepler’s first 1200 exoplanets, they found a surprise: there were many more Earth-like planets around small stars than around those that resembled our sun. They had overturned the very assumptions that begat the satellite’s conception.

These miniature M-dwarf systems filled with rocky planets were an entirely new species of solar system—and highly prized by planet hunters who began to refocus their efforts. “This is where it starts,” says Andrew West, an astronomer at Boston University who specializes in M dwarfs. “When this came out, I was just like, ‘Holy crap. That is awesome.’”

Confirmation soon followed. In January 2013, a Caltech team led by astronomer Jonathan Swift published another analysis of the Kepler data showing that planets seemed to be everywhere—on average, one for each of the 300 billion M dwarfs in the galaxy. The next month, Courtney Dressing and David Charbonneau of the Harvard–Smithsonian Center for Astrophysics announced they’d found an error in the Kepler database that had been overestimating the size of most M dwarfs. This was even better news because astronomers measure the sizes of Kepler’s planets relative to the size of their host stars. If the stars were actually smaller, then so were their planets, meaning a lot more of them are Earth-sized.

With these revised figures, Dressing and Charbonneau concluded there’s a 95% chance that an Earth-sized planet that could support water around an M dwarf is less than 17 light years away, a tiny distance on a galactic scale. If the Milky Way’s diameter of 100,000 light years were shrunk to the size of the United States, that planet would be just a stroll across Central Park.

Artist's impression of the Gliese 667C system
In this artist’s impression of a vista on Gliese 667Cd, the three stars of the triple system are visible, as well as the planet Gliese 667Ce, a crescent to the left of Gliese 667C.

There’s no consensus yet as to why M dwarfs have so many rocky planets. One leading theory is that since stars and their planets are born out of the same cloud of gas, a small star simply doesn’t have enough leftover material to make large gaseous planets such as Saturn and Jupiter.

Whatever the reason M dwarfs produce rocky planets, it’s a lucky break for astronomers. With the limits of today’s technology, it’s also much easier to find Earth-like planets around M dwarfs than around stars like the Sun. That’s because it’s hard to find planets just by looking—they tend to hide in the glare of their bright stars. Instead, astronomers search for signs of the planets’ influence on their host stars.

They use two main methods. The first is to detect the gravitational wobble of the star as its planet pulls on it ever so slightly. As the star rocks toward and away from us, its light shifts between bluer and redder colors due to the same effect that causes the sound waves of a train’s whistle to shift pitch as it rushes past us. It’s easier to detect this shift in a tiny M dwarf because it gets yanked around harder than a more massive star. Plus, any habitable planets produce an even larger wobble because they are so close to their M dwarfs.

The other method for finding planets is to monitor a star’s brightness, hoping for a planet to wander in front of it, blocking some of its light and temporarily dimming it each time it “transits” its host star. NASA’s Kepler mission exploited this to great effect, using it to discover thousands of likely exoplanets. This, too, is easier with a small M dwarf because the planet blocks out a greater fraction of the star’s light.

GJ1214b (Artist’s impression)
Transit observations revealed the planet GJ 1214b around its M dwarf host, shown here in an artist’s impression.

Astronomers salivate at the sight of transits for another reason: it gives them the opportunity to detect life. A planet that transits also disappears behind its host star on the other side of its orbit. This allows astronomers to measure the star’s light alone. Then, they can subtract the starlight from their previous measurements, isolating the effects of the planet and its atmosphere.

After NASA’s next-generation James Webb Space Telescope (JWST) launches in 2018, one of its projects will be using this technique in an attempt to find the chemical footprints of organic molecules in exoplanet atmospheres. According to Jonathan Lunine, a planetary scientist at Cornell and member of the JWST science team, it will focus almost entirely on M dwarfs to maximize their chances.

Despite these advantages, any claim that a planet around an M dwarf is truly “habitable” comes with caveats. One is that the stars’ strong magnetic fields twist and writhe, releasing enough UV radiation to sterilize the planet. Life on Earth copes with similar flares from our own Sun, which occasionally disrupt satellite communications, but they’re much weaker—“microscopic in comparison,” says Howard.

Another worry is that when a star is born from its nebulous nursery of gas and dust, all that coalescing material keeps the young stars hot well into middle age. In an M dwarf, this period lasts much longer than a sun-like star—so long, that it could boil away a young planet’s oceans. “You basically get a Venus scenario,” says Gibor Basri, an astronomer at UC–Berkeley and an early proponent of M dwarf studies.

If there are oceans on planets around M dwarfs in which life can spawn and flourish, there is one thing working in its favor: time. As the M dwarf ages its rotation slows down, weakening its magnetic field and reducing the amount of UV radiation. So even if James Webb doesn’t discover any life around M dwarfs in our epoch, West is optimistic that life will have a chance in the future. Unlike our Sun, which will run out of fuel, sputter itself away, and die within 4 billion years, M dwarfs are “the VW Beetles of the galaxy,” says West. They can last for up to trillions of years—thousands of times older than the current age of the universe. “It may just be we haven’t been around long enough to really see M dwarf habitability,” he says. “You could imagine that when the first round of M dwarfs’ [magnetic fields] really shut off, then maybe life sets up. … We might be at the wrong time.”

Life might survive a meteoric fall to Earth

Phytoplankton: foundation of the ocean's food web...and possibly of life's origins? Photo courtesy of NOAA via flickr Creative Commons.
Phytoplankton: foundation of the ocean’s food web…and possibly of life’s origins? Photo courtesy of NOAA via flickr Creative Commons.

by Mark Zastrow
BU News Service

Are we the aliens we’ve been looking for?

The notion that the seeds of life originated in outer space and fell to Earth on a meteorite may seem like science fiction. After all, the theory, known as panspermia supposes that life could survive the violent impact. But now, that survival act looks possible, according to research presented last month at a conference in London.

To test life’s resilience, the researchers froze phytoplankton—the microscopic organisms that permeate the ocean—into pellets, as if stuck on a rock sailing through interstellar space. They loaded the ice-bound algae into a powerful gas gun, which shot them into water at over 13,500 miles per hour. Then they thawed the samples and left them to culture.

But despite the violent impact, a small portion of plankton survived. “This sort of impact velocity would be what you would expect if a meteorite hit a planet similar to the Earth,” Dina Pasini, a scientist at University College London and the study’s lead author, said in a statement.

Panspermia has recently received a boost of media coverage. A study published September 15 in the journal Nature Geoscience suggested that comets smashing into primordial Earth could have formed amino acids, the building blocks of life. And in late August, a team of scientists claimed that Mars, not Earth, was the best place in the early Solar System to find molybdenum, a key element in enzymes required by complex life.

Pasini notes that a round of headlines doesn’t mean the theory is proven. But she says that her research shows that questions like whether we fell from the sky, or if aliens out there are our distant relatives, are “not as farfetched as one might assume.”

On Stage, Science Stories Take the Spotlight

Erin Barker and Ben Lillie take the stage at Story Collider. Photo by Mark Zastrow.
Erin Barker and Ben Lillie take the stage at Story Collider. Photo by Mark Zastrow.


By Mark Zastrow 
BU News Service

Cambridge, MA — “I’m so nervous!” cried Emily Graslie, pacing in a dark wing of the basement of the Middle East Club in Cambridge, Mass., as she waited to take the blue-lit stage behind her.

On her YouTube channel, Graslie regularly takes people behind the scenes of natural history museums, cheerfully explaining their dynamics. But she and the other science communicators in the lineup—including Pulitzer Prize-winning journalist Deborah Blum and MIT physicist/novelist Alan Lightman—weren’t there to lecture and break down science in the regular way.

“You are not going to learn anything,” producer and host Erin Barker assured the crowd. “That is the Story Collider promise. If you feel yourself about to learn, make your way to the bar, order a couple shots, you’ll be fine. Don’t panic.”

Instead, the performers were telling true, personal stories—live, without notes, and about science.

When Graslie took the stage moments later, she held the audience captive, recounting her self-discovery of a passion for zoology as an undergraduate. It led to volunteering at her college museum in Montana, a series of YouTube videos, and eventually being hired by the Field Museum in Chicago under the whimsical title “Chief Curiosity Correspondent.”

She was followed on stage by Kishore Hari, the director of the San Francisco-based Bay Area Science Festival, who related colorful anecdotes from a cross-country trip. Later, physicist and novelist Alan Lightman recounted a childhood tale of a homemade model rocket and its passenger, an unfortunate lizard.

The Sept 22, 2013, event was all part of a growing, four-year-old effort to put a new spin on science – and to embed the effort more deeply in the research-centric Cambridge-Greater Boston community.

It may sound a bit like the shows put on by the New York City-based storytelling startup The Moth, with an added dose of science. And Story Collider’s cofounder Ben Lillie isn’t offended by the comparison—he is himself a winner at the Moth’s “story slam” competitions. But Lillie – a former physicist who worked at the Large Hadron Collider in Europe – and his fellow physicist friend Brian Wecht, founded the Story Collider in 2010 in Brooklyn with an additional motivation: to change the way people think about science.

From the outset, Lillie has said that the Story Collider’s goal is “to humanize science.” It’s about “not just humanizing scientists, but showing how science itself is part of us, both in the everyday experiences, and the extraordinary ones,” he told Scientific American in 2011, after the series had just got under way.

Audience member Jason Makhlouta, a software engineer, said he thought the effort succeeded. “You’ve got these people who give it a human face and a personality,” he said. “It makes all the difference.”

This means a Story Collider event isn’t your typical science lecture, of which you can find dozens on any week night across the labs and campuses of science-crazy

Boston. “It’s definitely a little more, you know, rough-edged,” said science writer Carl Zimmer, “and a little more, you know, alcohol-infused.” He smiled. “Which is good.”

The September Story Collider show in Cambridge also drew people from outside the science community.

Zimmer, who has performed at the Story Collider before, points out that the show’s podcast reaches an audience far beyond the hall. “They’re searchable on Google, and people just find them,” he said. “And lots of people find them. So it’s not just the crowd that’s here, it’s thousands, hundreds of thousands of people who hear it.”

Although sporadic Story Collider events have been held in Greater Boston since its inception, the show is ramping up its presence here, its organizers say. The goal is monthly events. “Boston is a great town to do this show in,” producer Erin Barker said.

“It’s totally a science town…. We’ve never done a show in Boston that didn’t sell out. They love it.”

After the show, a relieved and amped-up Graslie greeted her fans and thanked them for their support. She continues to marvel at the whole phenomenon: “That I can make some kind of contribution to the scientific community that gets other people excited about science, and then they’re going to come out on a weeknight to come see us tell stories in a crowded bar? It’s amazing to me.”

Humans Really Can Read Dog’s Faces

This image shows examples of the facial expressions of dogs and infants used in the study. On the left are the before and after images (labelled "baseline" and "experimental," respectively) of dogs and humans being rewarded. On the right are before and after images of them being isolated from their owners or parents.
This image shows examples of the facial expressions of dogs and infants used in the study. On the left are the before and after images (labelled “baseline” and “experimental,” respectively) of dogs and humans being rewarded. On the right are before and after images of them being isolated from their owners or parents.


By Mark Zastrow
BU News Service

It’s often said that a dog is a human’s best friend. It’s also said that communication is the key to any relationship. So how do we manage to communicate emotion across species? A new study suggests it might be in our hunter-gatherer genes: we appear to be born with the ability to read dogs’ faces.

The findings, published in September in the online journal PLOS ONE, shed light on the evolutionary dawn of our interspecies friendship by asking: Do dogs’ faces convey actual emotion, or are we just convincing ourselves that we can see feelings in their cute, cuddly faces?

“If I speculated on this with dog owners, they would insist that their dogs smile,” says Annett Schirmer, a psychologist at the National University of Singapore and the study’s lead author. “However, if I talked to colleagues, they would be skeptical and suggest that we likely just anthropomorphize dog expressions.”

While previous studies have tried to distinguish a range of emotions in dogs based on praise, reprimands, and the dreaded sight of nail clippers, Schirmer and her colleagues took a simpler approach, considering only positive and negative feelings. To obtain the equivalent of a smile, they snapped pictures of 24 dogs of various breeds just as their owners gave them a toy or treat; for a sad face, they took pictures again after their owners left the room and the dogs began to show signs of negative feelings like whimpering.

The researchers then asked over 60 people to evaluate the dogs’ facial expressions in two ways. One was simply rating them as a positive or negative. The other was more subtle: the researchers observed how quickly people could identify positive and negative words after seeing the canines’ faces. This exercise attempted to recreate the snap judgments of emotions that we make when looking at human faces. The team found that not only could dog owners identify whether the dog was in a positive or negative emotional state, but so could people who had never interacted with dogs.

Harris Friedman, a psychologist at the University of Florida who coauthored a previous study of how we recognize dogs’ emotions,  was impressed by the experiment’s focus. “It simplified our study, reducing looking at six emotions to two (positive and negative), which I think was a really good way to try to…get a better handle on it.”

But what intrigues him most is what such innate communication says about the roots of our species, tens of thousands of years ago. While still speculative, he agrees that it provides “additional evidence” that dogs may have evolved facial expressions to emote to our nomadic ancestors as they learned to coexist, cooperate, and get ahead.

But both Schirmer and Friedman note that there could be another explanation dating back even further: humans and dogs may simply have inherited the same facial expressions from our common mammalian ancestors.

The answer could be a combination. Schirmer notes that studies have shown that non-domesticated canines make positive facial expressions that humans can recognize, but not sad faces. Perhaps humans and dogs could always read the joy on our faces, but had to coevolve to share sadness.

To settle it, Friedman thinks an improved archeological record of dog domestication will provide clues. He also notes that most people who’ve never played with dogs still have cultural knowledge of them: “People watch TV and are exposed to dogs in a myriad of ways.” A logical next step is to study indigenous cultures with no experience with dogs.