Life may have Evolved thanks to an Extraterrestrial Supply of vitamin B3

Ancient Earth might have had an extraterrestrial supply of vitamin B₃ delivered by carbon-rich meteorites, according to a new analysis by NASA-funded researchers. The result supports a theory that the origin of life may have been assisted by a supply of key molecules created in space and brought to Earth by comet and meteor impacts.

"It is always difficult to put a value on the connection between meteorites and the origin of life; for example, earlier work has shown that vitamin B₃ could have been produced non-biologically on ancient Earth, but it's possible that an added source of vitamin B₃ could have been helpful," said Karen Smith of Pennsylvania State University in University Park, Pa. "Vitamin B₃, also called nicotinic acid or niacin, is a precursor to NAD (nicotinamide adenine dinucleotide), which is essential to metabolism and likely very ancient in origin." Smith is lead author of a paper on this research, along with co-authors from NASA's Goddard Space Flight Center in Greenbelt, Md., now available online in the journal Geochimica et Cosmochimica Acta.

This is not the first time vitamin B₃ has been found in meteorites. In 2001 a team led by Sandra Pizzarello of Arizona State University, in Tempe discovered it along with related molecules called pyridine carboxylic acids in the Tagish Lake meteorite.

In the new work at Goddard's Astrobiology Analytical Laboratory, Smith and her team analyzed samples from eight different carbon-rich meteorites, called "CM-2 type carbonaceous chondrites" and found vitamin B₃ at levels ranging from about 30 to 600 parts-per-billion. They also found other pyridine carboxylic acids at similar concentrations and, for the first time, found pyridine dicarboxylic acids.

"We discovered a pattern – less vitamin B₃ (and other pyridine carboxylic acids) was found in meteorites that came from asteroids that were more altered by liquid water. One possibility may be that these molecules were destroyed during the prolonged contact with liquid water," said Smith. "We also performed preliminary laboratory experiments simulating conditions in interstellar space and showed that the synthesis of vitamin B₃ and other pyridine carboxylic acids might be possible on ice grains."

Scientists think the solar system formed when a dense cloud of gas, dust, and ice grains collapsed under its own gravity. Clumps of dust and ice aggregated into comets and asteroids, some of which collided together to form moon-sized objects or planetesimals, and some of those eventually merged to become planets.

Space is filled with radiation from nearby stars as well as from violent events in deep space like exploding stars and black holes devouring matter. This radiation could have powered chemical reactions in the cloud (nebula) that formed the solar system, and some of those reactions may have produced biologically important molecules like vitamin B₃.

Asteroids and comets are considered more or less pristine remnants from our solar system's formation, and many meteorites are prized samples from asteroids that happen to be conveniently delivered to Earth. However, some asteroids are less pristine than others. Asteroids can be altered shortly after they form by chemical reactions in liquid water. As they grow, asteroids incorporate radioactive material present in the solar system nebula. If enough radioactive material accumulates in an asteroid, the heat produced as it decays will be sufficient to melt ice inside the asteroid. Researchers can determine how much an asteroid was altered by water by examining chemical and mineralogical signatures of water alteration in meteorites from those asteroids.

When asteroids collide with meteoroids or other asteroids, pieces break off and some of them eventually make their way to Earth as meteorites. Although meteorites are valued samples from asteroids, they are rarely recovered immediately after they fall to Earth. This leaves them vulnerable to contamination from terrestrial chemistry and life.

The team doubts the vitamin B₃ and other molecules found in their meteorites came from terrestrial life for two reasons. First, the vitamin B₃ was found along with its structural isomers – related molecules that have the same chemical formula but whose atoms are attached in a different order. These other molecules aren't used by life. Non-biological chemistry tends to produce a wide variety of molecules -- basically everything permitted by the materials and conditions present -- but life makes only the molecules it needs. If contamination from terrestrial life was the source of the vitamin B₃ in the meteorites, then only the vitamin should have been found, not the other, related molecules.

Second, the amount of vitamin B₃ found was related to how much the parent asteroids had been altered by water. This correlation with conditions on the asteroids would be unlikely if the vitamin came from contamination on Earth.

The team plans to conduct additional interstellar chemistry experiments under more realistic conditions to better understand how vitamin B₃ can form on ice grains in space. "We used pyridine-carbon dioxide ice in the initial experiment," said Smith. "We want to add water ice (the dominant component of interstellar ices) and start from simpler organic precursors (building-block molecules) of vitamin B₃ to help verify our result."

Smith performed the research at Goddard as a graduate student at Pennsylvania State University, University Park, Pa. Funding came from the Penn State Astrobiology Research Center and the Goddard Center for Astrobiology via the NASA Astrobiology Institute. The research was also funded by the NASA Pennsylvania Space Grant Consortium and the NASA Cosmochemistry Program.

For more information about the Tagish Lake meteorite, visit:

http://www.nasa.gov/centers/goddard/news/features/2011/tagish-lake.html

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New Super Material Claimed to be Thinnest Possible Membrane

Thinnest feasible membrane produced

17.04.2014 | Fabio Bergamin | Research

A new nano-membrane made out of the “super material” graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The membrane produced by the researchers at ETH Zurich is as thin as is technologically possible.

Artist’s rendering of the two-layered graphene membrane (grey honeycomb structure) with molecules (blue) being able – as a function of their size – to pass the pores. (Illustration: Ben Newton / ETH Zurich)

Researchers have produced a stable porous membrane that is thinner than a nanometre. This is a 100,000 times thinner than the diameter of a human hair. The membrane consists of two layers of the much exalted ”super material” graphene, a two-dimensional film made of carbon atoms, on which the team of researchers, led by Professor Hyung Gyu Park at the Department of Mechanical and Process Engineering at ETH Zurich, etched tiny pores of a precisely defined size.

The membrane can thus permeate tiny molecules. Larger molecules or particles, on the other hand, can pass only slowly or not at all. “With a thickness of just two carbon atoms, this is the thinnest porous membrane that is technologically possible to make,” says PhD student Jakob Buchheim, one of the two lead authors of the study, which was conducted by ETH-Zurich researchers in collaboration with scientists from Empa and a research laboratory of LG Electronics. The study has just been published in journal Science.

The ultra-thin graphene membrane may one day be used for a range of different purposes, including waterproof clothing. “Our membrane is not only very light and flexible, but it is also a thousand fold more breathable than Goretex,” says Kemal Celebi, a postdoc in Park’s laboratory and also one of the lead authors of the study. The membrane could also potentially be used to separate gaseous mixtures into their constituent parts or to filter impurities from fluids. The researchers were able to demonstrate for the first time that graphene membranes could be suitable for water filtration. The researchers also see a potential use for the membrane in devices used for the accurate measurement of gas and fluid flow rates that are crucial to unveiling the physics around mass transfer at nanoscales and separation of chemical mixtures.

Breakthrough in nanofabrication

Part of a graphene membrane with a multiplicity of pores (black) of precisely defined size (in this case with a diameter of 50 nanometres; photomicrograph). (Photo: Celebi K. et al. Science 2014)

The researchers not only succeeded in producing the starting material, a double-layer graphene film with a high level of purity, but they also mastered a technique called focused ion beam milling to etch pores into the graphene film. In this process, which is also used in the production of semiconductors, a beam of helium or gallium ions is controlled with a high level of precision in order to etch away material. The researchers were able to etch pores of a specified number and size into the graphene with unprecedented precision. This process, which could easily take days to complete, took only a few hours in the current work. “This is a breakthrough that enables the nanofabrication of the porous graphene membranes,” explains Ivan Shorubalko, a scientist at Empa that also contributed to the study.

In order to achieve this level of precision, the researchers had to work with double-layer graphene. “It wouldn’t have been possible for this method to create such a membrane with only one layer because graphene in practice isn't perfect,” says Park. The material can exhibit certain irregularities in the honeycomb structure of the carbon atoms. Now and again, individual atoms are missing from the structure, which not only impairs the stability of the material but also makes it impossible to etch a high-precision pore onto such a defect. The researchers solved this problem by laying two graphene layers on top of each other. The probability of two defects settling directly above one another is extremely low, explains Park.

Fastest possible filtration

A key advantage of the tiny dimensions is that the thinner a membrane, the lower its permeation resistance. The lower the resistance, the higher the energy-efficiency of the filtration process. “With such atomically thin membranes we can reach maximal permeation for a membrane of a given pore size and we believe that they allow the fastest feasible rate of permeation,” says Celebi. However, before these applications are ready for use on an industrial scale or for the production of functional waterproof clothing, the manufacturing process needs to be further developed. To investigate the fundamental science, the researchers worked with tiny pieces of membrane with a surface area of less than one hundredth of a square millimetre. Objectives from now on will be to produce larger membrane surfaces and impose various filtering mechanisms.

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Literature reference

Celebi K, Buchheim J, Wyss RM, Droudian A, Gasser P, Shorubalko I, Kye JI, Lee C, Park HG: Ultimate Permeation across Atomically Thin Porous Graphene. Science, 2014, 344: 289-344, doi:10.1126/science.1249097 

First Habitable Earth Sized Exoplanet, Kepler-186f, Confirmed

Editor: we have discussed exoplanets and the search for extra-terrestrial life several times on Photonic Positive (e.g. here): this discovery seems to be an incremental step towards the goal.  

The first Earth-sized exoplanet orbiting within the habitable zone of another star has been confirmed by observations with both the W. M. Keck Observatory and the Gemini Observatory. The initial discovery, made by NASA's Kepler Space Telescope, is one of a handful of smaller planets found by Kepler and verified using large ground-based telescopes. It also confirms that Earth-sized planets do exist in the habitable zone of other stars.

The artistic concept of Kepler-186f is the result of scientists and artists collaborating to help imagine the appearance of these distant worlds.Credit: NASA Ames/SETI Institute/JPL-CalTech.

"What makes this finding particularly compelling is that this Earth-sized planet, one of five orbiting this star, which is cooler than the Sun, resides in a temperate region where water could exist in liquid form," says Elisa Quintana of the SETI Institute and NASA Ames Research Center who led the paper published in the current issue of the journal Science. The region in which this planet orbits its star is called the habitable zone, as it is thought that life would most likely form on planets with liquid water.

Steve Howell, Kepler's Project Scientist and a co-author on the paper, adds that neither Kepler (nor any telescope) is currently able to directly spot an exoplanet of this size and proximity to its host star. "However, what we can do is eliminate essentially all other possibilities so that the validity of these planets is really the only viable option."

credit NASA Ames/SETI Institute/JPL-CalTech

With such a small host star, the team employed a technique that eliminated the possibility that either a background star or a stellar companion could be mimicking what Kepler detected. To do this, the team obtained extremely high spatial resolution observations from the eight-meter Gemini North telescope on Mauna Kea in Hawai`i using a technique called speckle imaging, as well as adaptive optics (AO) observations from the ten-meter Keck II telescope, Gemini's neighbor on Mauna Kea. Together, these data allowed the team to rule out sources close enough to the star's line-of-sight to confound the Kepler evidence, and conclude that Kepler's detected signal has to be from a small planet transiting its host star.

"The Keck and Gemini data are two key pieces of this puzzle," says Quintana. "Without these complementary observations we wouldn't have been able to confirm this Earth-sized planet."

The Gemini "speckle" data directly imaged the system to within about 400 million miles (about 4 AU, approximately equal to the orbit of Jupiter in our solar system) of the host star and confirmed that there were no other stellar size objects orbiting within this radius from the star. Augmenting this, the Keck AO observations probed a larger region around the star but to fainter limits. According to Quintana, "These Earth-sized planets are extremely hard to detect and confirm, and now that we've found one, we want to search for more. Gemini and Keck will no doubt play a large role in these endeavors."

The host star, Kepler-186, is an M1-type dwarf star relatively close to our solar system, at about 500 light years and is in the constellation of Cygnus. The star is very dim, being over half a million times fainter than the faintest stars we can see with the naked eye. Five small planets have been found orbiting this star, four of which are in very short-period orbits and are very hot. The planet designated Kepler-186f, however, is earth-sized and orbits within the star's habitable zone. The Kepler evidence for this planetary system comes from the detection of planetary transits. These transits can be thought of as tiny eclipses of the host star by a planet (or planets) as seen from the Earth. When such planets block part of the star's light, its total brightness diminishes. Kepler detects that as a variation in the star's total light output and evidence for planets. So far more than 3,800 possible planets have been detected by this technique with Kepler.

The Gemini data utilized the Differential Speckle Survey Instrument (DSSI) on the Gemini North telescope. DSSI is a visiting instrument developed by a team led by Howell who adds, "DSSI on Gemini Rocks! With this combination, we can probe down into this star system to a distance of about 4 times that between the Earth and the Sun. It's simply remarkable that we can look inside other solar systems." DSSI works on a principle that utilizes multiple short exposures of an object to capture and remove the noise introduced by atmospheric turbulence producing images with extreme detail.

Observations with the W.M. Keck Observatory used the Natural Guide Star Adaptive Optics system with the NIRC2 camera on the Keck II telescope. NIRC2 (the Near-Infrared Camera, second generation) works in combination with the Keck II adaptive optics system to obtain very sharp images at near-infrared wavelengths, achieving spatial resolutions comparable to or better than those achieved by the Hubble Space Telescope at optical wavelengths. NIRC2 is probably best known for helping to provide definitive proof of a central massive black hole at the center of our galaxy. Astronomers also use NIRC2 to map surface features of solar system bodies, detect planets orbiting other stars, and study detailed morphology of distant galaxies.

"The observations from Keck and Gemini, combined with other data and numerical calculations, allowed us to be 99.98% confident that Kepler-186f is real," says Thomas Barclay, a Kepler scientist and also a co-author on the paper. "Kepler started this story, and Gemini and Keck helped close it," adds Barclay.

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Eye of the beholder -- improving the human-robot connection

Researchers are programming robots to communicate with people using human-like body language and cues, an important step toward bringing robots into homes.

Researchers at the University of British Columbia enlisted the help of a human-friendly robot named Charlie to study the simple task of handing an object to a person. Past research has shown that people have difficulty figuring out when to reach out and take an object from a robot because robots fail to provide appropriate nonverbal cues.

"We hand things to other people multiple times a day and we do it seamlessly," says AJung Moon, a PhD student in the Department of Mechanical Engineering. "Getting this to work between a robot and a person is really important if we want robots to be helpful in fetching us things in our homes or at work."

Moon and her colleagues studied what people do with their heads, necks and eyes when they hand water bottles to one another. They then tested three variations of this interaction with Charlie and the 102 study participants.

[NB: Video available at: http://youtu.be/5AQ-E3njViw]

Programming the robot to use eye gaze as a nonverbal cue made the handover more fluid. Researchers found that people reached out to take the water bottle sooner in scenarios where the robot moved its head to look at the area where it would hand over the water bottle or looked to the handover location and then up at the person to make eye contact.

"We want the robot to communicate using the cues that people already recognize," says Moon. "This is key to interacting with a robot in a safe and friendly manner."

This paper won best paper at the IEEE International Conference on Human-Robot Interaction.


Contact: Heather Amos
heather.amos@ubc.ca
604-822-3213
University of British Columbia 

Photonic Space: You may recall that the robot android in the film Prometheus aimed for empathy using the persona of Lawrence of Arabia, but that didn't quite work out in a safe and friendly manner! Interesting idea though. ed.

Lessons of hope: Indigenous societies' 'first contact' typically brings collapse, but rebounds are possible.

Photonic Progress:

The story of indigenous peoples suffering in Brazil is undoubtedly tragic and shouldn't be trivialized. For the future, the parallels with first contact with an advanced alien society, a likelihood we face as a species, can't be overlooked. There seems to me some encouragement in this report:

 It was disastrous when Europeans first arrived in what would become Brazil -- 95 percent of its population, the majority of its tribes, and essentially all of its urban and agricultural infrastructure vanished. The experiences of Brazil's indigenous societies mirror those of other indigenous peoples following "first contact."

A new study of Brazil's indigenous societies led by SFI researcher Marcus Hamilton paints a grim picture of their experiences, but also offers a glimmer of hope to those seeking ways to preserve indigenous societies.

Even among the indigenous societies contacted in just the last 50 years, says Hamilton, “all of them went through a collapse, and for the majority of them it was disastrous,” with disease and violence responsible in most cases, and with lasting detrimental effects. “That’s going on today -- right now.”

Brazil is “a tragic natural experiment,” Hamilton says: several hundred native tribes contacted by outsiders remain, according to Instituto Socioambiental, a non-governmental organization that reports census data on 238 of those societies going back a half-century or more. That volume of data makes possible a detailed analysis of the health and prospects of the surviving contacted -- and uncontacted -- societies, an analysis that wouldn’t be possible any where else in the world.

Using a method called population viability analysis, the researchers found that contact by outsiders is typically catastrophic, yet survivable. While first contacts in Brazil led to population declines of 43 percent on average, that decline bottomed out an average of eight or nine years after contact, following which population numbers grew as much as four percent a year -- about as much as possible. Projecting those results into the future suggests that contacted and as-yet uncontacted populations could recover from a low of just 100 individuals.

Hamilton and co-authors Robert Walker and Dylan Kesler of the University of Missouri describe their analysis in a paper published this week in Scientific Reports.

While their analysis paints a hopeful picture, Hamilton notes that deforestation, the breakdown of interactions between tribes, and assimilation with the outside world pose ongoing threats to indigenous societies.

“Demographically they’re healthy,” Hamilton says, but as for their long-term survival, “it’s very up in the air.”

Read the paper in Scientific Reports (April 1, 2014)

one of my favorite films on this theme (other than star-trek 'first-contact' : ed.

NASA find hidden ocean on Enceladus, a strong candidate for Extraterrestrials

NASA's Cassini spacecraft and Deep Space Network have uncovered evidence Saturn's moon Enceladus harbors a large underground ocean of liquid water, furthering scientific interest in the moon as a potential home to extraterrestrial microbes.

Gravity measurements by NASA's Cassini spacecraft and Deep Space Network suggest that Saturn's moon Enceladus, which has jets of water vapor and ice gushing from its south pole, also harbors a large interior ocean beneath an ice shell, as this illustration depicts. Image credit: NASA/JPL-Caltech

Researchers theorized the presence of an interior reservoir of water in 2005 when Cassini discovered water vapor and ice spewing from vents near the moon's south pole. The new data provide the first geophysical measurements of the internal structure of Enceladus, consistent with the existence of a hidden ocean inside the moon. Findings from the gravity measurements are in the Friday, April 4 edition of the journal Science.

"The way we deduce gravity variations is a concept in physics called the Doppler Effect, the same principle used with a speed-measuring radar gun," said Sami Asmar of NASA's Jet Propulsion Laboratory in Pasadena, Calif., a coauthor of the paper. "As the spacecraft flies by Enceladus, its velocity is perturbed by an amount that depends on variations in the gravity field that we're trying to measure. We see the change in velocity as a change in radio frequency, received at our ground stations here all the way across the solar system."

The gravity measurements suggest a large, possibly regional, ocean about 6 miles (10 kilometers) deep, beneath an ice shell about 19 to 25 miles (30 to 40 kilometers) thick. The subsurface ocean evidence supports the inclusion of Enceladus among the most likely places in our solar system to host microbial life. Before Cassini reached Saturn in July 2004, no version of that short list included this icy moon, barely 300 miles (500 kilometers) in diameter.

"This then provides one possible story to explain why water is gushing out of these fractures we see at the south pole," said David Stevenson of the California Institute of Technology, Pasadena, one of the paper's co-authors.

Cassini has flown near Enceladus 19 times. Three flybys, from 2010 to 2012, yielded precise trajectory measurements. The gravitational tug of a planetary body, such as Enceladus, alters a spacecraft's flight path. Variations in the gravity field, such as those caused by mountains on the surface or differences in underground composition, can be detected as changes in the spacecraft's velocity, measured from Earth.

NASA Image of Enceladus

The technique of analyzing a radio signal between Cassini and the Deep Space Network can detect changes in velocity as small as less than one foot per hour (90 microns per second). With this precision, the flyby data yielded evidence of a zone inside the southern end of the moon with higher density than other portions of the interior.

The south pole area has a surface depression that causes a dip in the local tug of gravity. However, the magnitude of the dip is less than expected given the size of the depression, leading researchers to conclude the depression's effect is partially offset by a high-density feature in the region, beneath the surface.

"The Cassini gravity measurements show a negative gravity anomaly at the south pole that however is not as large as expected from the deep depression detected by the onboard camera," said the paper's lead author, Luciano Iess of Sapienza University of Rome. "Hence the conclusion that there must be a denser material at depth that compensates the missing mass: very likely liquid water, which is seven percent denser than ice. The magnitude of the anomaly gave us the size of the water reservoir."

There is no certainty the subsurface ocean supplies the water plume spraying out of surface fractures near the south pole of Enceladus, however, scientists reason it is a real possibility. The fractures may lead down to a part of the moon that is tidally heated by the moon's repeated flexing, as it follows an eccentric orbit around Saturn.

Much of the excitement about the Cassini mission's discovery of the Enceladus water plume stems from the possibility that it originates from a wet environment that could be a favorable environment for microbial life.

"Material from Enceladus' south polar jets contains salty water and organic molecules, the basic chemical ingredients for life," said Linda Spilker, Cassini's project scientist at JPL. "Their discovery expanded our view of the 'habitable zone' within our solar system and in planetary systems of other stars. This new validation that an ocean of water underlies the jets furthers understanding about this intriguing environment."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for NASA's Science Mission Directorate in Washington. For more information about Cassini, visit:

http://www.nasa.gov/cassini

and

http://saturn.jpl.nasa.gov