Category: Science &Technology

{The world’s attention is now on Proxima Centauri b, a possibly Earth-like planet orbiting the closest star, 4.22 light-years away. The planet’s orbit is just right to allow liquid water on its surface, needed for life. But could it in fact be habitable?}

If life is possible there, the planet evolved very different than Earth, say researchers at the University of Washington-based Virtual Planetary Laboratory (VPL) where astronomers, geophysicists, climatologists, evolutionary biologists and others team to study how distant planets might host life.

Astronomers at Queen Mary University in London have announced discovery of Proxima Centauri b, a planet orbiting close to a star 4.22 light-years away. The find has been called “the biggest exoplanet discovery since the discovery of exoplanets.”

Rory Barnes, UW research assistant professor of astronomy, published a discussion about the discovery at palereddot.org, a website dedicated to the search for life around Proxima Centauri. His essay describes research underway through the UW planetary lab — part of the NASA Astrobiology Institute — to answer the question, is life possible on this world?

“The short answer is, it’s complicated,” Barnes writes. “Our observations are few, and what we do know allows for a dizzying array of possibilities” — and almost as many questions.

The Virtual Planetary Laboratory is directed by Victoria Meadows, UW professor of astronomy. UW-affiliated researchers include Giada Arney, Edward Schwieterman and Rodrigo Luger. Using computer models, the researchers studied clues from the orbits of the planet, its system, its host star and apparent companion stars Alpha Centauri A and B — plus what is known of stellar evolution to begin evaluating Proxima b’s chances.

Relatively little is known about Proxima:

• It’s at least as massive as Earth and may be several times more massive, and its “year” — the time it takes to orbit its star — is only 11 days

• Its star is only 12 percent as massive as our sun and much dimmer (so its habitable zone, allowing liquid water on the surface, is much closer in) and the planet is 25 times closer in than Earth is to our sun

• The star may form a third part of the Alpha Centauri binary star system, separated by a distance of 15,000 “astronomical units,” which could affect the planet’s orbit and history

• The new data hint at the existence of a second planet in the system with an orbital period near 200 days, but this has not been proven

Perhaps the biggest obstacle to life on the planet, Barnes writes, is the brightness of its host star. Proxima Centauri, a red dwarf star, is comparatively dim, but wasn’t always so.

“Proxima’s brightness evolution has been slow and complicated,” Barnes writes. “Stellar evolution models all predict that for the first one billion years Proxima slowly dimmed to its current brightness, which implies that for about the first quarter of a billion years, planet b’s surface would have been too hot for Earth-like conditions.”

Barnes notes that he and UW graduate student Rodrigo Luger recently showed that had modern Earth been in such a situation, “it would have become a Venus-like world, in a runaway greenhouse state that can destroy all of the planet’s primordial water,” thus extinguishing any chance for life.

Next come a host of questions about the planet’s makeup, location and history, and the team’s work toward discerning answers.

• Is the planet “rocky” like Earth? Most orbits simulated by the planetary lab suggest it could be — and thus can host water in liquid form, a prerequisite for life

• Where did it form, and was there water? Whether it formed in place or farther from its star, where ice is more likely, VPL researchers believe it is “entirely possible” Proxima b could be water-rich, though they are not certain.

• Did it start out as a hydrogen-enveloped Neptune-like planet and then lose its hydrogen to become Earth-like? VPL research shows this is indeed possible, and could be a viable pathway to habitability

• Proxima Centauri flares more often than our sun; might such flares have long-since burned away atmospheric ozone that might protect the surface and any life? This is possible, though a strong magnetic field, as Earth has, could protect the surface.

Also, any life under even a few meters of liquid water would be protected from radiation.

Another concern is that the planet might be tidally locked, meaning one side permanently faces its star, as the moon does Earth. Astronomers long thought this to mean a world could not support life, but now believe planetwide atmospheric winds would transport heat around the planet.

“These questions are central to unlocking Proxima’s potential habitability and determining if our nearest galactic neighbor is an inhospitable wasteland, an inhabited planet, or a future home for humanity,” Barnes writes.

Planetary laboratory researchers also are developing techniques to determine whether Proxima b’s atmosphere is amenable to life.

“Nearly all the components of an atmosphere imprint their presence in a spectrum (of light),” Barnes writes. “So with our knowledge of the possible histories of this planet, we can begin to develop instruments and plan observations that pinpoint the critical differences.”

At high enough pressures, he notes, oxygen molecules can momentarily bind to each other to produce an observable feature in the light spectrum.

“Crucially, the pressures required to be detectable are large enough to discriminate between a planet with too much oxygen, and one with just the right amount for life.

As we learn more about the planet and the system, we can build a library of possible spectra from which to quantitatively determine how likely it is that life exists on planet b.”

Our own sun is expected to burn out in about 4 billion years, but Proxima Centauri has a much better forecast, perhaps burning for 4 trillion years longer.

“If Proxima b is habitable, then it might be an ideal place to move. Perhaps we have just discovered a future home for humanity. But in order to know for sure, we must make more observations, run many more computer simulations and, hopefully, send probes to perform the first direct reconnaissance of an exoplanet,” Barnes writes. “The challenges are huge, but Proxima b offers a bounty of possibilities that fills me with wonder.”

Proxima Centauri b may be the first exoplanet to be directly characterized by powerful ground- and space-based telescopes planned for the future, and its atmosphere spectroscopically probed for active biology. The research was funded by the NASA Astrobiology Institute. “Whether habitable or not,” Barnes concludes, “Proxima Centauri b offers a new glimpse into how the planets and life fit into our universe.”

{In the race to discover a proposed ninth planet in our Solar System, Carnegie’s Scott Sheppard and Chadwick Trujillo of Northern Arizona University have observed several never-before-seen objects at extreme distances from the Sun in our Solar System. Sheppard and Trujillo have now submitted their latest discoveries to the International Astronomical Union’s Minor Planet Center for official designations. A paper about the discoveries has also been accepted to The Astronomical Journal.}

The more objects that are found at extreme distances, the better the chance of constraining the location of the ninth planet that Sheppard and Trujillo first predicted to exist far beyond Pluto (itself no longer classified as a planet) in 2014. The placement and orbits of small, so-called extreme trans-Neptunian objects, can help narrow down the size and distance from the Sun of the predicted ninth planet, because that planet’s gravity influences the movements of the smaller objects that are far beyond Neptune. The objects are called trans-Neptunian because their orbits around the Sun are greater than Neptune’s.

In 2014, Sheppard and Trujillo announced the discovery of 2012 VP113 (nicknamed “Biden”), which has the most-distant known orbit in our Solar System. At this time, Sheppard and Trujillo also noticed that the handful of known extreme trans-Neptunian objects all cluster with similar orbital angles. This lead them to predict that there is a planet at more than 200 times our distance from the Sun. Its mass, ranging in possibility from several Earths to a Neptune equivalent, is shepherding these smaller objects into similar types of orbits.

Some have called this Planet X or Planet 9. Further work since 2014 showed that this massive ninth planet likely exists by further constraining its possible properties. Analysis of “neighboring” small body orbits suggest that it is several times more massive than Earth, possibly as much as 15 times more so, and at the closest point of its extremely stretched, oblong orbit it is at least 200 times farther away from the Sun than Earth. (This is over 5 times more distant than Pluto.)

“Objects found far beyond Neptune hold the key to unlocking our Solar System’s origins and evolution,” Sheppard explained. “Though we believe there are thousands of these small objects, we haven’t found very many of them yet, because they are so far away. The smaller objects can lead us to the much bigger planet we think exists out there. The more we discover, the better we will be able to understand what is going on in the outer Solar System.”

Sheppard and Trujillo, along with David Tholen of the University of Hawaii, are conducting the largest, deepest survey for objects beyond Neptune and the Kuiper Belt and have covered nearly 10 percent of the sky to date using some of the largest and most advanced telescopes and cameras in the world, such as the Dark Energy Camera on the NOAO 4-meter Blanco telescope in Chile and the Japanese Hyper Suprime Camera on the 8-meter Subaru telescope in Hawaii. As they find and confirm extremely distant objects, they analyze whether their discoveries fit into the larger theories about how interactions with a massive distant planet could have shaped the outer Solar System.

“Right now we are dealing with very low-number statistics, so we don’t really understand what is happening in the outer Solar System,” Sheppard said. “Greater numbers of extreme trans-Neptunian objects must be found to fully determine the structure of our outer Solar System.”

According to Sheppard, “we are now in a similar situation as in the mid-19th century when Alexis Bouvard noticed Uranus’ orbital motion was peculiar, which eventually led to the discovery of Neptune.”

The new objects they have submitted to the Minor Planet Center for designation include 2014 SR349, which adds to the class of the rare extreme trans-Neptunian objects. It exhibits similar orbital characteristics to the previously known extreme bodies whose positions and movements led Sheppard and Trujillo to initially propose the influence of Planet X.

Another new extreme object they found, 2013 FT28, has some characteristics similar to the other extreme objects but also some differences. The orbit of an object is defined by six parameters. The clustering of several of these parameters is the main argument for a ninth planet to exist in the outer solar system. 2013 FT28 shows similar clustering in some of these parameters (its semi-major axis, eccentricity, inclination, and argument of perihelion angle, for angle enthusiasts out there) but one of these parameters, an angle called the longitude of perihelion, is different from that of the other extreme objects, which makes that particular clustering trend less strong.

Another discovery, 2014 FE72, is the first distant Oort Cloud object found with an orbit entirely beyond Neptune. It has an orbit that takes the object so far away from the Sun (some 3000 times farther than Earth) that it is likely being influenced by forces of gravity from beyond our Solar System such as other stars and the galactic tide. It is the first object observed at such a large distance.

This research was funded by NASA Planetary Astronomy.

{Critics question assumptions in analysis of harsh planet’s past.}

Venus might have once been prime real estate. New computer simulations suggest that the hellish planet next door could have been habitable in the not-too-distant past, with moderate temperatures, plenty of seaside locales and even a few spots for skiing.

Modern Venus is harsh: sulfuric acid rain, crushing atmospheric pressure and a surface temperature around 460° Celsius. But if Venus maintained its glacial rotation rate for much of its history — one day lasts roughly 116 Earth days — then the average temperature could have been around 15° C as recently as 715 million years ago. The findings were published online August 11 in Geophysical Research Letters.

“This is a very speculative, hypothetical paper,” says Mark Bullock, a planetary scientist at Southwest Research Institute in Boulder, Colo. It doesn’t prove that Venus was habitable, he says, but the researchers do show that conditions existed under which Venus could have maintained oceans and a temperate climate for billions of years.

“Rotation rate is really key,” says lead author Michael Way, an astrophysicist at the NASA Goddard Institute for Space Studies in New York City. Venus’ odd rotation — not only is it poky but it’s backwards relative to most other planets in the solar system — has long been an enigma. One idea is that it once spun more swiftly, but gravitational interactions between its atmosphere and the sun slowed it down. Way and colleagues combined climate simulations with Venus topography data from NASA’s Magellan spacecraft, which orbited Venus from 1990 to 1994, to test how rotation rates might have affected the Venusian climate. They find that if Venus has held on to its current spin speed, it could have been more Earth-like for billions of years. And as long as it spun no faster than roughly once every 16 Earth days, and had a shallow global ocean to help regulate temperatures, the planet could have been toasty but habitable.

On Earth, the relatively brisk rotation of the planet breaks the atmosphere into distinct churning cells that help keep the climate in check. Venus doesn’t turn fast enough to whip up its atmosphere. Instead, a long-lasting cloud formation arises over the sun-facing side of the planet, the researchers find. The cloud reflects enough sunlight to keep the surface balmy for a couple of billion years before temperatures escalate, leading to the current suffocating conditions. Some locations could even have seen occasional snow, and the northern highlands of Ishtar Terra could have maintained a year-round snowpack roughly 5 meters deep, the researchers report.

But these conclusions depend on assumptions that might not be reasonable, says Fred Taylor, a physicist at the University of Oxford. The researchers assume, for example, that Venus once had a predominantly nitrogen atmosphere with a pressure similar to Earth’s — a choice that’s not likely, says Taylor. “Venus probably has never been habitable,” he says.

Future missions to Venus can test some of these assumptions. An orbiter or lander could look for evidence of granite, for example, which requires water. “That would really be the smoking gun for this hypothesis that Venus held on to oceans for a long time,” Bullock says. The Japanese Akatsuki probe is currently studying the planet’s climate (SN: 1/9/16, p. 14), and NASA is considering two ideas for sending a spacecraft as early as 2020.

{New noninvasive technique may lead to low-cost therapy for patients with severe brain injury.}

A 25-year-old man recovering from a coma has made remarkable progress following a treatment at UCLA to jump-start his brain using ultrasound. The technique uses sonic stimulation to excite the neurons in the thalamus, an egg-shaped structure that serves as the brain’s central hub for processing information.

“It’s almost as if we were jump-starting the neurons back into function,” said Martin Monti, the study’s lead author and a UCLA associate professor of psychology and neurosurgery. “Until now, the only way to achieve this was a risky surgical procedure known as deep brain stimulation, in which electrodes are implanted directly inside the thalamus,” he said. “Our approach directly targets the thalamus but is noninvasive.”

Monti said the researchers expected the positive result, but he cautioned that the procedure requires further study on additional patients before they determine whether it could be used consistently to help other people recovering from comas.

“It is possible that we were just very lucky and happened to have stimulated the patient just as he was spontaneously recovering,” Monti said.

A report on the treatment is published in the journal Brain Stimulation. This is the first time the approach has been used to treat severe brain injury.

The technique, called low-intensity focused ultrasound pulsation, was pioneered by Alexander Bystritsky, a UCLA professor of psychiatry and biobehavioral sciences in the Semel Institute for Neuroscience and Human Behavior and a co-author of the study. Bystritsky is also a founder of Brainsonix, a Sherman Oaks, California-based company that provided the device the researchers used in the study.

That device, about the size of a coffee cup saucer, creates a small sphere of acoustic energy that can be aimed at different regions of the brain to excite brain tissue. For the new study, researchers placed it by the side of the man’s head and activated it 10 times for 30 seconds each, in a 10-minute period.

Monti said the device is safe because it emits only a small amount of energy — less than a conventional Doppler ultrasound.

Before the procedure began, the man showed only minimal signs of being conscious and of understanding speech — for example, he could perform small, limited movements when asked. By the day after the treatment, his responses had improved measurably. Three days later, the patient had regained full consciousness and full language comprehension, and he could reliably communicate by nodding his head “yes” or shaking his head “no.” He even made a fist-bump gesture to say goodbye to one of his doctors.

“The changes were remarkable,” Monti said.

The technique targets the thalamus because, in people whose mental function is deeply impaired after a coma, thalamus performance is typically diminished. And medications that are commonly prescribed to people who are coming out of a coma target the thalamus only indirectly.

Under the direction of Paul Vespa, a UCLA professor of neurology and neurosurgery at the David Geffen School of Medicine at UCLA, the researchers plan to test the procedure on several more people beginning this fall at the Ronald Reagan UCLA Medical Center. Those tests will be conducted in partnership with the UCLA Brain Injury Research Center and funded in part by the Dana Foundation and the Tiny Blue Dot Foundation.

If the technology helps other people recovering from coma, Monti said, it could eventually be used to build a portable device — perhaps incorporated into a helmet — as a low-cost way to help “wake up” patients, perhaps even those who are in a vegetative or minimally conscious state. Currently, there is almost no effective treatment for such patients, he said.

The study’s other co-authors are Vespa, who holds UCLA’s Gary L. Brinderson Family Chair in Neurocritical Care and is director of neurocritical care at the Ronald Reagan UCLA Medical Center; Caroline Schnakers, a UCLA neurosurgery researcher; and Alexander Korb, a Semel Institute researcher.

{Researchers have combined satellite imagery with AI to predict areas of poverty across the world.}

There’s little reliable data on local incomes in developing countries, which hampers efforts to tackle the problem.

A team from Stanford University were able to train a computer system to identify impoverished areas from satellite and survey data in five African countries.

The results are published in the journal Science.

Neal Jean, Marshall Burke and colleagues say the technique could transform efforts to track and target poverty in developing countries.

“The World Bank, which keeps the poverty data, has for a long time considered anyone who is poor to be someone who lives on below $1 a day,” Dr Burke, assistant professor of Earth system science at Stanford, told the BBC’s Science in Action programme.

“We traditionally collect poverty data through household surveys… we send survey enumerators around to houses and we ask lots of questions about income, consumption – what they’ve bought in the last year – and we use that data to construct our poverty measures.”

{{Night lights}}

However, surveys are costly, infrequent and sometimes impossible to carry out in particular regions of countries because of, for example, armed conflict.

So there is a need for other accurate measures of household consumption and income in the developing world.

The idea of mapping poverty from satellite imagery is not completely new. Recent studies have shown that space-based data that capture night lights can be used to predict wealth in a given area.

But night lights are not such a good indicator at the bottom end of the income distribution, where satellite images are dark across the board.

The latest study looked at daylight images that capture features such as paved roads and metal roofs – markers that can help distinguish different levels of economic wellbeing in developing countries.

They then used a sophisticated computer model to categorise the various indicators in daytime satellite images of Nigeria, Tanzania, Uganda, Rwanda and Malawi.

“If you give a computer enough data it can figure out what to look for. We trained a computer model to find things in imagery that are predictive of poverty,” said Dr Burke.
“It finds things like roads, like urban areas, like farmland, it finds waterways – those are things we recognise. It also finds things we don’t recognise. It finds patterns in imagery that to you or I don’t really look like anything… but it’s something the computer has figured out is predictive of where poor people are.”

The researchers used imagery from countries for which survey data were available to validate the computer model’s findings.

“These things [that the computer model found] are surprisingly predictive of economic livelihoods in these countries,” Dr Burke explained.

The researchers say their ambition is to scale up the technique to cover all of sub-Saharan Africa and, afterwards, the whole of the developing world.

In a perspective article in the same issue of Science, Dr Joshua Blumenstock, an expert in development economics and data science, who was not involved in the study, said there was “exciting potential for adapting machine learning to fight poverty”.

The assistant professor at the University of California, Berkeley, wrote: “For social welfare programmes, some of which already use satellite imagery to identify eligible recipients, higher-fidelity estimates of poverty can help to ensure that resources get to those with the greatest need.”

{The distant planet GJ 1132b intrigued astronomers when it was discovered last year. Located just 39 light-years from Earth, it might have an atmosphere despite being baked to a temperature of around 450 degrees Fahrenheit. But would that atmosphere be thick and soupy or thin and wispy? New research suggests the latter is much more likely.}

The distant planet GJ 1132b intrigued astronomers when it was discovered last year. Located just 39 light-years from Earth, it might have an atmosphere despite being baked to a temperature of around 450 degrees Fahrenheit. But would that atmosphere be thick and soupy or thin and wispy? New research suggests the latter is much more likely.

Harvard astronomer Laura Schaefer (Harvard-Smithsonian Center for Astrophysics, or CfA) and her colleagues examined the question of what would happen to GJ 1132b over time if it began with a steamy, water-rich atmosphere.

Orbiting so close to its star, at a distance of just 1.4 million miles, the planet is flooded with ultraviolet or UV light. UV light breaks apart water molecules into hydrogen and oxygen, both of which then can be lost into space. However, since hydrogen is lighter it escapes more readily, while oxygen lingers behind.

“On cooler planets, oxygen could be a sign of alien life and habitability. But on a hot planet like GJ 1132b, it’s a sign of the exact opposite — a planet that’s being baked and sterilized,” said Schaefer.

Since water vapor is a greenhouse gas, the planet would have a strong greenhouse effect, amplifying the star’s already intense heat. As a result, its surface could stay molten for millions of years.

A “magma ocean” would interact with the atmosphere, absorbing some of the oxygen, but how much? Only about one-tenth, according to the model created by Schaefer and her colleagues. Most of the remaining 90 percent of leftover oxygen streams off into space, however some might linger.

“This planet might be the first time we detect oxygen on a rocky planet outside the solar system,” said co-author Robin Wordsworth (Harvard Paulson School of Engineering and Applied Sciences).

If any oxygen does still cling to GJ 1132b, next-generation telescopes like the Giant Magellan Telescope and James Webb Space Telescope may be able to detect and analyze it.

The magma ocean-atmosphere model could help scientists solve the puzzle of how Venus evolved over time. Venus probably began with Earthlike amounts of water, which would have been broken apart by sunlight. Yet it shows few signs of lingering oxygen. The missing oxygen problem continues to baffle astronomers.

Schaefer predicts that their model also will provide insights into other, similar exoplanets. For example, the system TRAPPIST-1 contains three planets that may lie in the habitable zone. Since they are cooler than GJ 1132b, they have a better chance of retaining an atmosphere.