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Life ‘Not As We Know It’ Possible on Saturn’s Moon Titan

A representation of a 9-nanometer azotosome, about the size of a virus, with a piece of the membrane cut away to show the hollow interior. James Stevenson

A representation of a 9-nanometer azotosome, about the size of a virus, with a piece of the membrane cut away to show the hollow interior. James Stevenson

A new type of methane-based, oxygen-free life form that can metabolize and reproduce similar to life on Earth has been modeled by a team of Cornell University researchers.

Taking a simultaneously imaginative and rigidly scientific view, chemical engineers and astronomers offer a template for life that could thrive in a harsh, cold world – specifically Titan, the giant moon of Saturn. A planetary body awash with seas not of water, but of liquid methane, Titan could harbor methane-based, oxygen-free cells.

Their theorized cell membrane, composed of small organic nitrogen compounds and capable of functioning in liquid methane temperatures of 292 degrees below zero, is published in Science Advances, Feb. 27. The work is led by chemical molecular dynamics expert Paulette Clancy and first author James Stevenson, a graduate student in chemical engineering. The paper’s co-author is Jonathan Lunine, director for Cornell’s Center for Radiophysics and Space Research.

Download study and images: https://cornell.box.com/azotosome

Lunine is an expert on Saturn’s moons and an interdisciplinary scientist on the Cassini-Huygens mission that discovered methane-ethane seas on Titan. Intrigued by the possibilities of methane-based life on Titan, and armed with a grant from the Templeton Foundation to study non-aqueous life, Lunine sought assistance about a year ago from Cornell faculty with expertise in chemical modeling. Clancy, who had never met Lunine, offered to help.

“We’re not biologists, and we’re not astronomers, but we had the right tools,” Clancy said. “Perhaps it helped, because we didn’t come in with any preconceptions about what should be in a membrane and what shouldn’t. We just worked with the compounds that we knew were there and asked, ‘If this was your palette, what can you make out of that?'”

Graduate student James Stevenson, astronomer Jonathan Lunine and chemical engineer Paulette Clancy, with a Cassini image of Titan in the foreground of Saturn, and an azotosome, the theorized cell membrane on Titan. Jason Koski/University Photography

Graduate student James Stevenson, astronomer Jonathan Lunine and chemical engineer Paulette Clancy, with a Cassini image of Titan in the foreground of Saturn, and an azotosome, the theorized cell membrane on Titan. Jason Koski/University Photography

On Earth, life is based on the phospholipid bilayer membrane, the strong, permeable, water-based vesicle that houses the organic matter of every cell. A vesicle made from such a membrane is called a liposome.

Thus, many astronomers seek extraterrestrial life in what’s called the circumstellar habitable zone, the narrow band around the sun in which liquid water can exist. But what if cells weren’t based on water, but on methane, which has a much lower freezing point?

The engineers named their theorized cell membrane an “azotosome,” “azote” being the French word for nitrogen. “Liposome” comes from the Greek “lipos” and “soma” to mean “lipid body;” by analogy, “azotosome” means “nitrogen body.”

The azotosome is made from nitrogen, carbon and hydrogen molecules known to exist in the cryogenic seas of Titan, but shows the same stability and flexibility that Earth’s analogous liposome does. This came as a surprise to chemists like Clancy and Stevenson, who had never thought about the mechanics of cell stability before; they usually study semiconductors, not cells.

The engineers employed a molecular dynamics method that screened for candidate compounds from methane for self-assembly into membrane-like structures. The most promising compound they found is an acrylonitrile azotosome, which showed good stability, a strong barrier to decomposition, and a flexibility similar to that of phospholipid membranes on Earth. Acrylonitrile – a colorless, poisonous, liquid organic compound used in the manufacture of acrylic fibers, resins and thermoplastics – is present in Titan’s atmosphere.

Excited by the initial proof of concept, Clancy said the next step is to try and demonstrate how these cells would behave in the methane environment – what might be the analogue to reproduction and metabolism in oxygen-free, methane-based cells.

Lunine looks forward to the long-term prospect of testing these ideas on Titan itself, as he put it, by “someday sending a probe to float on the seas of this amazing moon and directly sampling the organics.”

Stevenson said he was in part inspired by science fiction writer Isaac Asimov, who wrote about the concept of non-water-based life in a 1962 essay, “Not as We Know It.”

Said Stevenson: “Ours is the first concrete blueprint of life not as we know it.”

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First Detailed Microscopy Evidence of Bacteria at the Lower Size Limit of Life

This cryo-electron tomography image reveals the internal structure of an ultra-small bacteria cell like never before. The cell has a very dense interior compartment and a complex cell wall. The darker spots at each end of the cell are most likely ribosomes. The image was obtained from a 3-D reconstruction. The scale bar is 100 nanometers. (Credit: Berkeley Lab)

This cryo-electron tomography image reveals the internal structure of an ultra-small bacteria cell like never before. The cell has a very dense interior compartment and a complex cell wall. The darker spots at each end of the cell are most likely ribosomes. The image was obtained from a 3-D reconstruction. The scale bar is 100 nanometers. (Credit: Berkeley Lab)

Scientists have captured the first detailed microscopy images of ultra-small bacteria that are believed to be about as small as life can get. The research was led by scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and the University of California, Berkeley. The existence of ultra-small bacteria has been debated for two decades, but there hasn’t been a comprehensive electron microscopy and DNA-based description of the microbes until now.

The cells have an average volume of 0.009 cubic microns (one micron is one millionth of a meter). About 150 of these bacteria could fit inside an Escherichia coli cell and more than 150,000 cells could fit onto the tip of a human hair.

The scientists report their findings Friday, Feb. 27, in the journal Nature Communications.

The diverse bacteria were found in groundwater and are thought to be quite common. They’re also quite odd, which isn’t a surprise given the cells are close to and in some cases smaller than several estimates for the lower size limit of life. This is the smallest a cell can be and still accommodate enough material to sustain life. The bacterial cells have densely packed spirals that are probably DNA, a very small number of ribosomes, hair-like appendages, and a stripped-down metabolism that likely requires them to rely on other bacteria for many of life’s necessities.

The bacteria are from three microbial phyla that are poorly understood. Learning more about the organisms from these phyla could shed light on the role of microbes in the planet’s climate, our food and water supply, and other key processes.

“These newly described ultra-small bacteria are an example of a subset of the microbial life on earth that we know almost nothing about,” says Jill Banfield, a Senior Faculty Scientist in Berkeley Lab’s Earth Sciences Division and a UC Berkeley professor in the departments of Earth and Planetary Science and Environmental Science, Policy and Management.

“They’re enigmatic. These bacteria are detected in many environments and they probably play important roles in microbial communities and ecosystems. But we don’t yet fully understand what these ultra-small bacteria do,” says Banfield.

Banfield is a co-corresponding author of the Nature Communications paper with Birgit Luef, a former postdoctoral researcher in Banfield’s group who is now at the Norwegian University of Science and Technology, Trondheim.

“There isn’t a consensus over how small a free-living organism can be, and what the space optimization strategies may be for a cell at the lower size limit for life. Our research is a significant step in characterizing the size, shape, and internal structure of ultra-small cells,” says Luef.

A lifeline to other cells? Cryo-transmission electron microscopy captured numerous hairlike appendages radiating from the surface of this ultra-small bacteria cell. The scientists theorize the pili-like structures enable the cell to connect with other microbes and obtain life-giving resources. The scale bar is 100 nanometers. (Credit: Berkeley Lab)

A lifeline to other cells? Cryo-transmission electron microscopy captured numerous hairlike appendages radiating from the surface of this ultra-small bacteria cell. The scientists theorize the pili-like structures enable the cell to connect with other microbes and obtain life-giving resources. The scale bar is 100 nanometers. (Credit: Berkeley Lab)

The scientists set out to study bacteria from phyla that lack cultivated representatives. Some of these bacteria have very small genomes, so the scientists surmised the bacteria themselves might also be very small.

To concentrate these cells in a sample, they filtered groundwater collected at Rifle, Colorado through successively smaller filters, down to 0.2 microns, which is the size used to sterilize water. The resulting samples were anything but sterile. They were enriched with incredibly tiny microbes, which were flash frozen to -272 degrees Celsius in a first-of-its-kind portable version of a device called a cryo plunger. This ensured the microbes weren’t damaged in their journey from the field to the lab.

The frozen samples were transported to Berkeley Lab, where Luef, with the help of Luis Comolli of Berkeley Lab’s Life Sciences Division, characterized the cells’ size and internal structure using 2-D and 3-D cryogenic transmission electron microscopy. The images also revealed dividing cells, indicating the bacteria were healthy and not starved to an abnormally small size.

The bacteria’s genomes were sequenced at the Joint Genome Institute, a DOE Office of Science User Facility located in Walnut Creek, California, under the guidance of Susannah Tringe. The genomes were about one million base pairs in length. In addition, metagenomic and other DNA-based analyses of the samples were conducted at UC Berkeley, which found a diverse range of bacteria from WWE3, OP11, and OD1 phyla.

This combination of innovative fieldwork and state-of-the-art microscopy and genomic analysis yielded the most complete description of ultra-small bacteria to date.

Among their findings: Some of the bacteria have thread-like appendages, called pili, which could serve as “life support” connections to other microbes. The genomic data indicates the bacteria lack many basic functions, so they likely rely on a community of microbes for critical resources.

The scientists also discovered just how much there is yet to learn about ultra-small life.

“We don’t know the function of half the genes we found in the organisms from these three phyla,” says Banfield.

The scientists also used the Advanced Light Source, a DOE Office of Science User Facility located at Berkeley Lab, where Hoi-Ying Holman of the Earth Sciences Division helped determine the majority of the cells in the samples were bacteria, not Archaea.

The research is a significant contribution to what’s known about ultra-small organisms. Recently, scientists estimated the cell volume of a marine bacterium at 0.013 cubic microns, but they used a technique that didn’t directly measure the cell diameter. There are also prior electron microscopy images of a lineage of Archaea with cell volumes as small as 0.009 cubic microns, similar to these bacteria, including results from some of the same researchers. Together, the findings highlight the existence of small cells with unusual and fairly restricted metabolic capacities from two of the three major branches of the tree of life.

The research was supported by the Department of Energy’s Office of Science.

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New NASA Earth Science Missions Expand View of Our Home Planet

Over the past 12 months NASA has added five missions to its orbiting Earth-observing fleet – the biggest one-year increase in more than a decade. Image Credit: NASA

Over the past 12 months NASA has added five missions to its orbiting Earth-observing fleet – the biggest one-year increase in more than a decade. Image Credit: NASA

Four new NASA Earth-observing missions are collecting data from space – with a fifth newly in orbit – after the busiest year of NASA Earth science launches in more than a decade.

On Feb. 27, 2014, NASA and the Japan Aerospace Exploration Agency (JAXA) launched the Global Precipitation Measurement (GPM) Core Observatory into space from Japan. Data from GPM and the other new missions are making observations and providing scientists with new insights into global rain and snowfall, atmospheric carbon dioxide, ocean winds, clouds, and tiny airborne particles called aerosols.

“This has been a phenomenally productive year for NASA in our mission to explore our complex planet from the unique vantage point of space,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate in Washington. “Combined with data from our other Earth-observing spacecraft, these new missions will give us new insights into how Earth works as a system.”

With these missions, including two instruments mounted on the exterior of the International Space Station, NASA now has 20 Earth-observing space missions in operation. Observations from these missions, like all NASA data, will be freely available to the international scientific community and decision makers in the United States and abroad.

“The highly accurate measurements from these new missions will help scientists around the world tackle some of the biggest questions about how our planet is changing,” said Peg Luce, deputy director of the Earth Science Division at NASA Headquarters in Washington. “These new capabilities will also be put to work to help improve lives here on Earth and support informed decision-making by citizens and communities.”

The Global Precipitation Measurement mission produced its first global map of rainfall and snowfall, from April to September 2014. The data map combines measurements from 12 satellites and the GPM Core Observatory, launched Feb 27, 2014, covers 87 percent of the globe and is updated every half hour. Image Credit: NASA’s Goddard Space Flight Center

Last month, NASA released the agency’s most comprehensive global rain and snowfall product to date from the GPM mission made with data from a network of 12 international satellites and the Core Observatory. The Core Observatory acts as a tuner to bring together measurements of other satellites, providing a nearly global picture of rain and snow called the Integrated Multi-satellite Retrievals for GPM, or IMERG. The first global visualization of the initial IMERG data was released Thursday.

“The IMERG data gives us an unprecedented view of global precipitation every 30 minutes,” said Gail Skofronick-Jackson, GPM project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Knowing where, when and how much it rains and snows is vital to understanding Earth’s water cycle.”

The Orbiting Carbon Observatory-2, launched on July 2, 2014, is providing preliminary global maps of carbon dioxide concentrations and a related phenomenon known as solar-induced chlorophyll fluorescence. OCO-2 data will let scientists better understand how carbon dioxide is distributed around the globe and changes with the seasons. The data will be used to identify the sources and storage places, or sinks, of carbon dioxide, the most significant human-produced greenhouse gas driving global climate change.

A preliminary global map based on observations from November and December 2014 shows carbon dioxide concentrations largely driven by the seasons, with higher levels in the northern hemisphere winter and lower in the southern hemisphere summer. The data show levels unprecedented in recorded history, according to Ralph Basilio, OCO-2 project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California.

“The ultimate goal is to collect data to advance carbon cycle science, improve understanding of the global climate change process, and make better-informed decisions,” Basilio said.

In addition to these two free-flying satellite missions, NASA deployed two Earth-observing instruments to the International Space Station: ISS-RapidScat, a scatterometer that measures wind speeds and direction over the ocean, and the Cloud-Aerosol Transport System (CATS), a lidar that measures the altitude of clouds and airborne particles.

Launched Sept. 21, 2014, ISS-RapidScat’s ocean wind measurements continue observations made by the agency’s QuikScat satellite, according to Bryan Stiles, the mission’s science processing lead at JPL. These measurements already are being used in weather forecast models used by the United States Navy, the National Oceanic and Atmospheric Administration, and by European and Indian scientists.

The ISS-RapidScat team also is using the wind measurements to better understand how ocean winds differ, on average, during the day and night.

CATS, which was launched to the space station on Jan. 10, has released its first data image: a slice of the atmosphere over Africa showing clouds and dust particles on Feb. 11. Clouds and aerosols remain two of the biggest question marks in terms of impact on future potential climate change.

CATS was built by a team at Goddard as a way to demonstrate new lidar technology capable of accurate cloud and aerosol measurements, according to Matt McGill, CATS principal investigator at Goddard.

NASA’s newest Earth-observing satellite, the Soil Moisture Active Passive (SMAP), was launched Jan. 31 to begin its mission to map global soil moisture and detect whether soils are frozen or thawed. Currently in its checkout phase, the observatory completed a key milestone Tuesday with the deployment of its 20-foot-wide (6-meter) reflector antenna, which in about a month will begin rotating at approximately 15 revolutions per minute. The antenna will produce a 620-mile-wide (1,000-kilometers) measurement swath, mapping the entire globe every two to three days.

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Improved Vision for James Webb Space Telescope

James Webb Space Telescope. Copyright: Northrop Grumman

James Webb Space Telescope. Copyright: Northrop Grumman

Key science elements of the James Webb Space Telescope have been upgraded ahead of the observatory’s launch in 2018.

The telescope, also known as JWST, is a joint project of NASA, ESA and the Canadian Space Agency. It carries a 6.5 m-diameter telescope and four state-of-the-art science instruments optimised for infrared observations. Europe has led the development of two of the instruments.

As a general-purpose observatory, it will tackle a wide range of topics, including detecting the first galaxies in the Universe and following their evolution over cosmic time, witnessing the birth of new stars and their planetary systems, and studying planets in our Solar System and around other stars.

Installation of the four instruments in the telescope’s Integrated Science Instrument Module, or ISIM, was completed last April. Since then, the module has undergone extensive testing to ensure it can withstand the stresses of launch and operation in space.

A critical part of this process saw the instruments complete cryogenic testing in a round-the-clock campaign running for 116 days last summer.

Following the campaign, several months were dedicated to replacing key components of some of the instruments already known to require additional work before the next stages.

Europe’s ‘NIRSpec’, the near-infrared multi-object spectrograph, was one of the instruments upgraded. NIRSpec will split infrared light from distant stars and galaxies into its colour components – a spectrum – providing scientists with vital information on their chemical composition, age and distance.

Mission accomplished. The final taping of the protective cover is applied and the James Webb Space Telescope NIRSpec instrument is in its final flight configuration and ready to go back into the Integrated Science Instrument Module. From left to right: Ralf Ehrenwinkler (Airbus DS), Frank Merkle (Airbus DS), Kai Hoffmann (Airbus DS), Robert Eder (Airbus DS), Max Speckmaier (Airbus DS) and Maurice te Plate (ESA). Copyright: NASA–C. Gunn

Mission accomplished. The final taping of the protective cover is applied and the James Webb Space Telescope NIRSpec instrument is in its final flight configuration and ready to go back into the Integrated Science Instrument Module.
From left to right: Ralf Ehrenwinkler (Airbus DS), Frank Merkle (Airbus DS), Kai Hoffmann (Airbus DS), Robert Eder (Airbus DS), Max Speckmaier (Airbus DS) and Maurice te Plate (ESA). Copyright: NASA–C. Gunn

The first generation of JWST’s highly sensitive near-infrared detectors were found to suffer from a design flaw that resulted in a progressive degradation of their performance. New detectors have now been installed in all three near-infrared instruments.

“Excellent detectors are crucial to the outstanding instrument performance needed when you want to look at the extremely distant and faint early stars and galaxies that formed when our Universe was still young, and the new detectors secure this top priority of NIRSpec and JWST,” says Pierre Ferruit, ESA’s JWST project scientist.

Another crucial component of NIRSpec are its microshutter arrays, a new technology developed for JWST by NASA.

One of the defining and pioneering features of NIRSpec is its ability to analyse the light from more than 100 astronomical objects at the same time. This is made possible by an assembly of four microshutter arrays, totalling almost a quarter of a million individual shutters.

Armed with a pre-selected list of interesting targets, each shutter can be programmed to open or close individually. The light from the chosen targets passes through the selected open shutters before entering the next stage of the instrument, where it is split into a spectrum and projected onto the detectors for analysis.

But after testing in 2012 designed to simulate the extreme acoustic environment experienced during launch, it was discovered that several thousand microshutters in NIRSpec were jammed closed and could no longer open.

Low light test on micro-shutter array. Copyright: NASA Goddard/Chris Gunn

Low light test on micro-shutter array. Copyright: NASA Goddard/Chris Gunn

A thorough investigation performed with an engineering model of NIRSpec, including tests at NASA’s acoustic facility, found the root cause of the problem and new arrays were built.

The overall performance of the new microshutter assembly was found to be superior to the old system in many ways, and the delicate replacement operation was completed last month.

“This required the instrument’s outer cover to be opened and therefore an exceptionally strict cleanliness regime was needed to avoid contamination,” says Maurice te Plate, ESA’s JWST system integration and test manager.

“In particular, the microshutters are very sensitive to material such as small polyester fibres that can get stuck inside and prevent them from fully closing.

“We just completed our final checks and we are now ready to install NIRSpec back in to the Module.”

“NIRSpec is in its final flight configuration,” adds Peter Jensen, ESA’s JWST project manager. “We have now completed the endeavour we started 11 years ago – it has not been easy, but through skill, persistence, and dedication, the team has made it.”

Later this year, the module and instruments will resume the extensive programme of environmental tests to reproduce the conditions endured during launch and in space. The module will later be integrated into the JWST observatory for full-scale cryogenic optical and system testing before launch on an Ariane 5 from Europe’s Spaceport in Kourou, French Guiana.

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‘Bright Spot’ on Ceres Has Dimmer Companion

These images of dwarf planet Ceres, processed to enhance clarity, were taken on Feb. 19, 2015, from a distance of about 29,000 miles (46,000 kilometers), by NASA's Dawn spacecraft. Dawn observed Ceres completing one full rotation, which lasted about nine hours. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

These images of dwarf planet Ceres, processed to enhance clarity, were taken on Feb. 19, 2015, from a distance of about 29,000 miles (46,000 kilometers), by NASA’s Dawn spacecraft. Dawn observed Ceres completing one full rotation, which lasted about nine hours. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dwarf planet Ceres continues to puzzle scientists as NASA’s Dawn spacecraft gets closer to being captured into orbit around the object. The latest images from Dawn, taken nearly 29,000 miles (46,000 kilometers) from Ceres, reveal that a bright spot that stands out in previous images lies close to yet another bright area.

“Ceres’ bright spot can now be seen to have a companion of lesser brightness, but apparently in the same basin. This may be pointing to a volcano-like origin of the spots, but we will have to wait for better resolution before we can make such geologic interpretations,” said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles.

Using its ion propulsion system, Dawn will enter orbit around Ceres on March 6. As scientists receive better and better views of the dwarf planet over the next 16 months, they hope to gain a deeper understanding of its origin and evolution by studying its surface. The intriguing bright spots and other interesting features of this captivating world will come into sharper focus.

This image was taken by NASA's Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 kilometers). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

This image was taken by NASA’s Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 kilometers). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“The brightest spot continues to be too small to resolve with our camera, but despite its size it is brighter than anything else on Ceres. This is truly unexpected and still a mystery to us,” said Andreas Nathues, lead investigator for the framing camera team at the Max Planck Institute for Solar System Research, Gottingen, Germany.

Dawn visited the giant asteroid Vesta from 2011 to 2012, delivering more than 30,000 images of the body along with many other measurements, and providing insights about its composition and geological history. Vesta has an average diameter of 326 miles (525 kilometers), while Ceres has an average diameter of 590 miles (950 kilometers). Vesta and Ceres are the two most massive bodies in the asteroid belt, located between Mars and Jupiter.

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Water-World Earths Could Host Life, Even If They’re Askew

Artist's conception of GJ1214b, a super-Earth that could have a surface dominated by ocean, orbiting its red dwarf star. Observations with the Hubble Space Telescope revealed a thick atmosphere. Credit: NASA, ESA, and D. Aguilar (Harvard-Smithsonian Center for Astrophysics)

Artist’s conception of GJ1214b, a super-Earth that could have a surface dominated by ocean, orbiting its red dwarf star. Observations with the Hubble Space Telescope revealed a thick atmosphere. Credit: NASA, ESA, and D. Aguilar (Harvard-Smithsonian Center for Astrophysics)

Life could be habitable on an Earth-sized waterworld tilted on its side if the oceans aren’t too shallow, a new study reveals.

As long as the entire world was covered in oceans of at least 50 meters (165 feet) deep, temperatures would be moderate enough at the poles to support life. Even at the equator, which would be the chilliest part of that world since it only would receive a bit of sunlight in spring and fall, life could still exist.

But if you were to shrink the ocean’s depth to something like 20 meters (66 feet), then the risk of a runaway cold effect becomes much greater. Should a thin veneer of ice develop in the ocean, it’s possible the climate system would collapse into an ice block in just a few hundred years. That short timeline would be tough for life to develop a foothold.

“That’s a bad outcome for life,” said lead author David Ferreira, who was with the Massachusetts Institute of Technology when the study was conducted. “With deeper oceans, a collapse into a global snowball is possible, but a bit harder. It feeds into the idea that if you have an extensive, big, deep ocean, your chances to find life or a climate that is habitable are higher.”

Ferreira’s paper, titled “Climate at high-obliquity,” was published in the journal Icarus in November. It forms part of his greater research interest in the role of oceans on climate. That research interest led Ferreira to the United Kingdom’s University of Reading, where he is a lecturer (professor) in the department of meteorology.

Hot poles, cold equator

The traditional view of “habitable” planets came from looking at those that are in the “Goldilocks zone” of their parent stars. This is the point where water can exist above the freezing point, but it’s not so hot that the water begins to boil away.

The conditions for life, however, are more complicated than that. For example, if the planet is too large, the pressure of the gas will likely make it too tough for life to survive. If the planet is too small, its gravity could be too low to hold on to an atmosphere. Therefore, many researchers say habitable planets in the Goldilocks zone must be close to Earth’s size.

An infographic of Europa, an icy “waterworld” moon of Jupiter that could also be host to life. Credit: NASA Jet Propulsion Laboratory

An infographic of Europa, an icy “waterworld” moon of Jupiter that could also be host to life. Credit: NASA Jet Propulsion Laboratory

Other factors can also come into play, such as the presence or absence of an ocean. As those who live in coastal California or the south of Italy know, the proximity of water can make temperatures over nearby land much more steady and mild. On a planet-size scale, a global ocean would also do this trick as long as it is deep enough, the research reveals.

For simplicity’s sake, the simulation assumed an Earth-sized planet orbiting a sun-like star at the same distance our planet does (93 million miles, or 150 million kilometers). The researchers, however, changed two major parameters.

The first was the planet’s tilt. Earth’s axis is tilted at 23.5 degrees, which produces enough of a difference across the planet to produce the seasons. The simulation instead made the tilt 90 degrees so that the planet was spinning on its side.

The second variable was the presence of oceans. While the Earth is covered in oceans by about 70 percent, the simulation assumed 100 percent cover with different depths, ranging from 10 meters (33 feet) to about 3,000 meters (657 feet). It was the threshold of 50 meters that interested researchers the most, as this was considered a minimum depth to have a stable climate suitable for life.

The poles would seem to be the toughest place to live on this theoretical world. During the summer, they would face the sun directly, while in the winter they would face away. Even in the coldest part of the year, the surface temperature in those zones would be no less than 10 to 15 degrees Celsius (50 to 59 degrees Fahrenheit.)

“It’s a bit like the Earth’s Arctic in the summer,” Ferreira said.

The summer, by contrast, would see temperatures soar to 35 to 40° Celsius (95 to 104° Celsius). That’s hot, but by no means hot enough to discourage life from surviving. Meanwhile, the equators would be the coldest parts of the planet, but would remain above freezing, at 2 to 4° Celsius (36 to 39° Fahrenheit.)

“Even there, those are not harsh conditions. Liquid water would survive there,” Ferreira pointed out.

While waves were not simulated on this water world — they’re too small for the scale of the simulation — what was examined was the role of thermal currents. The researchers found similar current systems to Earth’s, which are driven by temperature differences in the ocean and atmospheric winds. There is, for example, a well-known circulation pattern on Earth that brings water from the Southern Hemisphere to the North Atlantic.

“It’s typical of what people would do with climate simulations for future global warming. It’s on this level of complexity,” Ferreira said.

Mapping for future planet-hunters

There are other kinds of worlds where habitability could be possible, in the case of a global ocean. Other systems ripe for consideration include “super-Earths” — those planets that are slightly larger than our own — and “mini-Neptunes,” or planets that are a bit smaller than the gas-swaddled Outer Solar System planet.

What the researchers are considering next, however, is a “tidally locked” planet. This is a planet that perpetually has one side facing its star, and another facing away. This kind of configuration is common in our own solar system. Earth’s moon is tidally locked to our planet. Jupiter and Saturn also have small moons (relative to the gas giants’ size) that keep one side facing the planet.

Planets close in to their stars, such as this Jupiter-sized one in an artist's illustration, are more likely to be detected. Credit: ESO

Planets close in to their stars, such as this Jupiter-sized one in an artist’s illustration, are more likely to be detected. Credit: ESO

It’s too early to make predictions as to how habitable those worlds could be, but Ferreira said if habitability is possible, this increases researchers’ chances of finding life beyond the Solar System. Tidally locked worlds are actually among the easiest kinds of exoplanets for researchers to find. This is because of the methods astronomers use to seek out new worlds. One of them relies on measuring the gravitational “wobble” a planet produces on its parent star. If the planet is closer to its star, it will have a stronger pull, which makes it easier to be detected.

Another method looks for the disc of a planet passing across the disc of its star. Planets with close-in orbits would make those crossings more frequently than planets that don’t, which again increases the odds of them being detected with current technology.

Earth-sized worlds, however, are hard to find due to their tiny size. That said, NASA’s Kepler space telescope has detected at least two in the habitable regions of their parent stars. Future telescopes could make the search easier, since they could be more sensitive to smaller planets. Upcoming planet-hunters include NASA’s James Webb Space Telescope (slated for launch in 2018), and the candidate European mission, PLATO (PLAnetary Transits and Oscillations of stars), which would launch in 2024.

Ferreira’s research, however, will continue in the direction of oceans on newfound worlds.

“Oceans on the Earth are the big regulator of the climate system,” he said. “Naturally, the question is how you would apply that knowledge to the planets that are in a different astronomical state than Earth. One would expect oceans in such planets would be a strong regulator on the climate as well, and a factor in habitability.”

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NASA’s Curiosity Mars Rover Drills at ‘Telegraph Peak’

This hole, with a diameter slightly smaller than a U.S. dime, was drilled by NASA's Curiosity Mars rover into a rock target called "Telegraph Peak." Credit: NASA/JPL-Caltech/MSSS

This hole, with a diameter slightly smaller than a U.S. dime, was drilled by NASA’s Curiosity Mars rover into a rock target called “Telegraph Peak.” Credit: NASA/JPL-Caltech/MSSS

NASA’s Curiosity Mars rover used its drill on Tuesday, Feb. 24 to collect sample powder from inside a rock target called “Telegraph Peak.” The target sits in the upper portion of “Pahrump Hills,” an outcrop the mission has been investigating for five months.

The Pahrump Hills campaign previously drilled at two other sites. The outcrop is an exposure of bedrock that forms the basal layer of Mount Sharp. Curiosity’s extended mission, which began last year after a two-year prime mission, is examing layers of this mountain that are expected to hold records of how ancient wet environments on Mars evolved into drier environments.

The rover team is planning to drive Curiosity away from Pahrump Hills in coming days, exiting through a narrow valley called “Artist’s Drive,” which will lead the rover along a strategically planned route higher on the basal layer of Mount Sharp.

The Telegraph Peak site was selected after the team discussed the large set of physical and chemical measurements acquired throughout the campaign. In particular, measurements of the chemistry of the Telegraph Peak site, using the Alpha Particle X-ray Spectrometer (APXS) on the rover’s arm, motivated selection of this target for drilling before the departure from Pahrump Hills.

Compared to the chemistry of rocks and soils that Curiosity assessed before reaching Mount Sharp, the rocks of Pahrump Hills are relatively enriched in the element silicon in proportion to the amounts of the elements aluminum and magnesium. The latest drilling site exhibits that characteristic even more strongly than the earlier two, which were lower in the outcrop.

“When you graph the ratios of silica to magnesium and silica to aluminum, ‘Telegraph Peak’ is toward the end of the range we’ve seen,” said Curiosity co-investigator Doug Ming, of NASA Johnson Space Center, Houston. “It’s what you would expect if there has been some acidic leaching. We want to see what minerals are present where we found this chemistry.”

The rock-powder sample from Telegraph Peak goes to the rover’s internal Chemistry and Mineralogy (CheMin) instrument for identification of the minerals. After that analysis, the team may also choose to deliver sample material to Curiosity’s Sample Analysis at Mars (SAM) suite of laboratory instruments.

The sample-collection drilling at Telegraph Peak was the first in Curiosity’s 30 months on Mars to be conducted without a preliminary “mini drill” test of the rock’s suitability for drilling. The team judged full-depth drilling to be safe for the drill based on similarities of the target to the previous Pahrump Hills targets. The rover used a low-percussion-level drilling technique that it first used on the previous drilling target, “Mojave 2.”

Curiosity reached the base of Mount Sharp after two years of examining other sites inside Gale Crater and driving toward the mountain at the crater’s center.

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Texas Has New Big, Bright Webb STTARS

A big, bright James Webb Space Telescope “STTARS” is now deep in the heart of Texas. The Space Telescope Transporter for Air Road and Sea (STTARS) is a giant white shipping container with a very important cargo: a test model of part of the Webb telescope, called the “Pathfinder Backplane.” This new NASA video shows its arrival at NASA’s Johnson Space Center in Houston on Feb. 5, 2015.

The Pathfinder Backplane is a practice section of the James Webb Space Telescope. To ensure the telescope will operate at its frigid destination 1 million miles out in space, it must complete cryogenic tests. The biggest cryogenic test occurs at Chamber A at Johnson, the same vacuum chamber where Apollo spacecraft were tested.

The James Webb Space Telescope’s giant shipping container, called the Space Telescope Transporter for Air Road and Sea (STTARS), arrived at NASA’s Johnson Space Center in Houston on Feb. 5, 2015, with important cargo: a test model of part of the telescope, called the Pathfinder Backplane. Image Credit: NASA’s Goddard Space Flight Center

“The James Webb Space Telescope is the biggest telescope for space that’s ever been built,” said Andrew Booth, pathfinder lead optical engineer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

But its enormous size means special accommodations to move it halfway across the country. Enter STTARS.

“The major challenge in this transport is the size,” said Adam Carpenter, one of the mechanical integration engineers on the STTARS team. “The container weighs 165,000 pounds. There is a tremendous amount of planning going through this move.”

The journey began in a clean room at Goddard. The massive shipping container entered the clean room floating on air pads, like a puck on an air hockey table. Then engineers lifted and lowered the 3,000-pound honeycombed Pathfinder Backplane by crane into the container.

Once the container exited the clean room, hydraulic adjustable wheels were attached, and the whole thing was hooked up to a semitruck engine. By midnight, the STTARS was on its way to Joint Base Andrews in Maryland – very, very slowly. Traveling at 5 mph, the STTARS team walked alongside the container making adjustments along its seven hour-long journey.

Once the massive container reached Andrews, it was loaded up into a C-5 Charlie military transport plane, the largest cargo plane in the U.S. fleet, which was designed to carry tanks. The container slid inside with very little clearance on all sides.

Rare glimpse into the mouth of a C-5 Charlie military transport plane, the largest cargo plane in the U.S. fleet, which was designed to carry tanks, just before STTARS (the Space Telescope Transporter for Air Road and Sea) was loaded for transport from Joint Base Andrews, Maryland, to Houston. Image Credit: NASA/Desiree Stover

Rare glimpse into the mouth of a C-5 Charlie military transport plane, the largest cargo plane in the U.S. fleet, which was designed to carry tanks, just before STTARS (the Space Telescope Transporter for Air Road and Sea) was loaded for transport from Joint Base Andrews, Maryland, to Houston. Image Credit: NASA/Desiree Stover

“What’s so significant about this move is that this is the first payload for Webb leaving Goddard,” said Carpenter, who flew with the Pathfinder Backplane to Houston. “When the flight unit leaves Goddard, we’ll be doing this move with the Integrated Science Instrument Module (ISIM) and all four instruments and all 18 primary mirror segments, based off what we learned here. With this project, everything is so big and we are doing so many firsts. During this process we are all working long hours to be sure everything is done right.”

When the C-5 landed at Ellington airport in Houston, the Pathfinder Backplane was carefully unloaded and trucked to Johnson. In the coming weeks it will be prepared for a key cryogenic test that will help the team check out testing methods for the Webb telescope.

After landing at Ellington Airport, the James Webb Space Telescope’s STTARS was unloaded and readied for its route to NASA’s Johnson Space Center in Houston. STTARS is a giant white shipping container with a very important cargo: a test model of part of the telescope called the Pathfinder Backplane. Image Credit: NASA/Chris Gunn

After landing at Ellington Airport, the James Webb Space Telescope’s STTARS was unloaded and readied for its route to NASA’s Johnson Space Center in Houston. STTARS is a giant white shipping container with a very important cargo: a test model of part of the telescope called the Pathfinder Backplane. Image Credit: NASA/Chris Gunn

“We’ve got to test the test,” Booth said. “That’s why this pathfinder is so valuable because it will ensure the testing on the actual telescope is accurate.”

“The Pathfinder Backplane is a key step to the next phase of Webb testing,” said Bethany Selna, Optical Telescope Element and the Integrated Science Instrument Module (OTIS) mechanical integration and test lead. ”The Pathfinder demonstrates the ability to test the full-scale structure with optics at cryogenic temperatures. We will then repeat the tests with the flight hardware.”

The James Webb Space Telescope is the scientific successor to NASA’s Hubble Space Telescope. It will be the most powerful space telescope ever built. Webb is an international project led by NASA with its partners, ESA (the European Space Agency) and the Canadian Space Agency.

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Scientific Spring in Isolated Antarctica

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ESA-sponsored medical doctor Beth Healey at the Concordia station in Antarctica. Copyright: ESA/IPEV/PNRA–B. Healy

In Antarctica, the crew of the French–Italian Concordia research station are preparing for the winter. They have to survive six months of complete isolation – four in darkness because the Sun never rises above the horizon – while they perform science in one of the most barren places on Earth.

This year, ESA-sponsored medical doctor Beth Healey will monitor five experiments that are helping to prepare for long-duration missions to explore our Solar System. Living in Concordia is similar in many ways to living in space, where crew are cut off from the world without normal sunlight and live in reduced pressure – Concordia station lies 3200 m above sea level.

From searching for life that could survive in these extreme conditions to monitoring how the crew of 13 interact and cope with living in close quarters, Beth will have her hands full as the crew maintain the station and perform Antarctic science for the French and Italian polar institutes.

Checking the data nearer to the sea at Halley

The British Antarctic Survey station Halley VI. Halley is built on the Brunt Ice Shelf, a floating area of ice that is flowing off the Antarctic Plateau some 50 km south of the station’s current location. Copyright: BAS–Sam Burrell

The British Antarctic Survey station Halley VI. Halley is built on the Brunt Ice Shelf, a floating area of ice that is flowing off the Antarctic Plateau some 50 km south of the station’s current location. Copyright: BAS–Sam Burrell

Scientific experiments often compare results taken from different places and time periods. ESA signed an agreement this month with the British Antarctic Survey to perform two of the five Concordia experiments at their Halley VI station. If this pilot season runs well, ESA will extend the cooperation.

Concordia offers ESA scientists a place to investigate how humans adapt to living in isolation and at high altitudes. The crew at Halley experience the same isolation and lack of daylight but live at sea level. Performing the same investigations at Halley will allow researchers to cross one factor off the list that might influence data: air pressure.

Collaborative science

Over the next six months, volunteers at Halley and Concordia will record themselves in a video diary and have their social interactions monitored. This is working towards  objective computer software that will give clues to an astronaut’s state of mind.

Concordia research base in the Antarctic. Copyright: ESA/IPEV/PNRA–E. Kaimakamis

Concordia research base in the Antarctic. Copyright: ESA/IPEV/PNRA–E. Kaimakamis

Ask anybody how they feel and most will reply ‘fine’ but, for mission controllers planning a complex spacewalk or spacecraft docking, having an objective second-opinion could be a lifesaver.

The system works by analysing small changes in intonation and grammar, as well as charting how often people talk to each other, to develop an idea of how people feel.

The second experiment being run at both sites will test how our eyes adapt to four months of outside darkness and artificial lighting.

David Vaughan, British Antarctic Survey’s director of science, concludes: “We are committed to supporting excellent science in Antarctica in all disciplines. We are hugely excited to be hosting these new experiments that may help prepare for, perhaps, the biggest adventure in history, a manned flight to Mars.”

Click here for a full list of ESA’s research at Concordia this year and follow the Concordia blogfor updates from the station.

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Could Ionized Gas Do A Better Job of Sterilizing Spacecraft?

Spacecraft arriving at other planets, such as Mars, need to have sterilization done beforehand to ensure they will not contaminate their new environment. Credit: NASA

Spacecraft arriving at other planets, such as Mars, need to have sterilization done beforehand to ensure they will not contaminate their new environment. Credit: NASA

Earth’s microbes are a hardy bunch. They can survive in extreme environments, such as inside hot springs at the bottom of the ocean. Some have even remained alive despite being exposed to the ultraviolet and ionizing radiation, extreme low temperatures, and vacuum of space.

This is why planetary protection advocates are so concerned about our exploration of other planets in the Solar System. Concerns about the contamination of the icy moon Europa, for example, prompted controllers of the Galileo mission to crash the spacecraft into Jupiter in 2003 so that microbes wouldn’t accidentally take seed on what could be a habitable moon.

Nevertheless, despite the best efforts of spacecraft cleaners, some microbes seem to survive conventional cleaning processes. This is why a new method is emerging that uses ionized gas to kill the microbes.

The method was presented at the European Astrobiology Meeting in October, in an effort led by Ralf Moeller, a space microbiologist at the German Aerospace Center (DLR) and Katharina Stapelmann, a plasma researcher at Ruhr-University Bochum in Germany.

“Plasma sterilization is a process not only compatible with modern spacecraft, but it also enables successful removal and inactivation of most resistant microbial species isolated in spacecraft assembly facilities,” wrote Moeller in an e-mail to Astrobiology Magazine.

“It is in the best interest of all spacefaring nations and research agencies, such as NASA and the European Space Agency (ESA), to characterize spacecraft-assembly inhibiting microorganisms thoroughly in order to assess their potential for forward contamination, and development of more effective reduction, cleaning, and sterilization technologies.”

Cleanroom menaces

When a NASA mission leaves Earth, it is designed to meet internationally accepted standards for planetary protection established by the Committee on Space Research (COSPAR). This is a committee that was created in 1958 by the International Council for Science, a non-governmental organization with members from most of the countries of the world.

The standards for missions vary depending on what the goal of a particular spacecraft, noted Moeller. Perhaps a spacecraft is put on a trajectory that won’t put it near the planet or moon’s environment. Other standards address how it is assembled in a “clean room” on Earth, and how it is sterilized.

Another reason to avoid spacecraft contamination is to better characterize environments on other planets and moons. The Curiosity rover is seeking evidence of habitability on Mars, for example. Credit: NASA/JPL-Caltech/MSSS

Another reason to avoid spacecraft contamination is to better characterize environments on other planets and moons. The Curiosity rover is seeking evidence of habitability on Mars, for example. Credit: NASA/JPL-Caltech/MSSS

For most Mars missions — including fairly recent ones, such as Europe’s Mars Express and NASA’s Mars Exploration Rovers (Spirit and Opportunity) — scientists examined the microbial diversity of organisms that were left over after these steps.

“In most cases, spore-forming bacteria constituted a dominant fraction of those microorganisms cultivated after heat-shock treatment,” Moeller said.

The standard protocol is to cook the microbes to 80 degrees Celsius (176 degrees Fahrenheit) for 15 minutes, he said. But there are highly resistant bacteria that can survive these treatments. In 2013, astrobiologists from Germany and the United States found a new bacterial variant called Tersicoccus phoenicis in two clean rooms on different continents.

“The presence of Tersicoccus phoenicis and other (spore- and non-spore forming) microbial species isolated from space craft assembly facilities exclusively in the cleanroom environments suggests selective adaptation and a significant role for these microorganisms in these environments,” Moeller noted.

“Microbes residing in the clean rooms during the spacecraft assembly process could gain access to a spacecraft, and possibly survive en route to extraterrestrial systems.”

Plasma purging

Last year, the researchers presented a newer form of sterilization at the European Astrobiology Meeting. The method involves using plasma — an ionized gas — at low pressure on the spacecraft.

“The method is very fast. Full spore inactivation of 100 million of bacterial spores was achieved in five minutes, even with spores of Bacillus pumilus SAFR-032, a space craft assembly facility isolate, which encounters the highest resistance to UV radiation and further sterilization methods,” wrote Stapelmann in the same e-mail.

There are other benefits to using plasma. The method doesn’t require using toxic or possibly cancer-causing substances such as ethylene oxide; it can be used in small doses; and it appears to be effective against spores from bacteria, fungi and prions (an infectious kind of protein).

There are some species of microbes that seem to exist only in cleanrooms, the zones where spacecraft are prepared for flight. Credit: NRL/NASA/Chris Gunn

There are some species of microbes that seem to exist only in cleanrooms, the zones where spacecraft are prepared for flight. Credit: NRL/NASA/Chris Gunn

“So far, the method is not used for spacecraft in development yet. Another method based on plasma but operated under atmospheric pressure is planned to be used on the International Space Station, if a recent proposal is accepted,” Stapelmann said.

Stapelmann’s and Moeller’s method may take some time to gain acceptance, given that there are already established procedures in place. The current methods of sterilizing surfaces in general (not spacecraft) involve high pressure, high temperature, and radiation through ultraviolet or gamma rays, Moeller pointed out. There are drawbacks to these methods, namely they can damage the underlying material, leave residues and create microbial resistances.

On spacecraft, there are only two accepted methods so far: dry heat (cooking the surface at 111.7 degrees Celsius, or 233 degrees Fahrenheit for 30 hours) or using hydrogen peroxide.

“Both methods, either through elevated temperatures or aggressive chemical reaction, are likely to introduce damage to advanced materials, such as electronics and other heat-sensitive equipment,” Moeller said. “Plasma sterilization is emerging as an alternative to commonly used sterilization techniques, due to many advantages. It’s cost-effective, fast, efficient, and safe in terms of thermal, chemical, or irradiation damage.”

Applications beyond space

Moeller and Stapelmann are part of a growing community looking at plasma for spacecraft sterilization. Research on using plasma sterilization of Planetary Protection purposes includes a January 2014 article in the journal Planetary and Space Science called “Cold atmospheric plasma – A new technology for spacecraft component decontamination,” led by Satoshi Shimizu at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. In their study, Shimizu et. al. are using solely the indirect effects of plasma, such as long-living reactive oxygen species.

While both methods are based on sterilizing with plasma, Stapelmann said, they propose using it in direct contact with the spores. The reported results for Stapelmann and Moeller’s method are an 8-logarithmic reduction of bacterial spores in five minutes, as opposed to a 5-6 log reduction of spores in 90 minutes with Shimizu et. al.

Some of Earth's microbes can survive the harsh environment of space, even in a vacuum. Credit: NASA

Some of Earth’s microbes can survive the harsh environment of space, even in a vacuum. Credit: NASA

Stapelmann argues that their sterilization process — which relies on more direct contact with the spacecraft — is more efficient than Shimizu’s, as it kills more spores in a shorter treatment time. However, the treatment is harsh on electronics because the electronics are exposed directly to the electric field of the plasma, so Shimizu’s treatment would be preferable to Stapelmann’s.

Still, Stapelmann said their methods could use improvement as it is considered for use on spacecraft. In general, it is hard to treat a spacecraft because it is small and tends to have metal jutting out in odd ways. Also, low-pressure plasma systems require plasma chambers and vacuum pumps to get the job done, which can add some cost to the project. For using plasma sterilization on the ISS, an atmospheric-pressure plasma is planned, reducing the costs and the footprint of the system.

Beyond space exploration, Stapelmann points out that there are other uses as well.

“The plasma sterilization system was initially built for the sterilization of medical instruments. Our group has a lot of experience with low-pressure plasma sterilization systems. A first commercial plasma sterilization system was developed and built in cooperation with our institute.”

Read more details about the commercial use in this paper from Plasma Processes and Polymers, called “Plasma Sterilization of Pharmaceutical Products: From Basics to Production.” It was led by Ruhr-University Bochum’s Benjamin Denis.

By monitoring the color of reflected light via satellite, scientists can determine how successfully plant life is photosynthesizing (or using the sun's energy). A measurement of photosynthesis is essentially a measurement of successful growth, and growth means successful use of ambient carbon. Until now, scientists have only had a continuous record of photosynthesis on land. But following three years of continual data collected by the SeaWiFS instrument, NASA has gathered the first record of photosynthetic productivity in the oceans. Credit: NASA Scientific Visualization Studio)

Fotossíntese Infravermelha: Uma Fonte Potencial Para a Vida Alienígena em Lugares Sem Sol

This News Exclusive was originally posted in English on Jun 6, 2013. This translation for the Portuguese edition of Astrobiology magazine was provided by Bruno Martini. The original article is available here.


A "black smoker" hydrothermal vent in the Atlantic Ocean

Uma ´´fumarola negra´´ no Oceano Atlântico. Crédito: OAR/ National Undersea Research Program (NURP); NOAA

Fotossíntese – a coleta de luz solar para produzir energia – é o condutor definitivo de virtualmente toda a vida do nosso planeta. A maioria das criaturas fotossintéticas dependem da luz óptica, do tipo que vemos, para energizar sua maquinaria biológica. Ainda que alguns possam fazer uso da luz infravermelha de menor energia (e invisível aos nossos olhos). E no caso de um tipo de bactéria – descoberta anos atrás, em águas profundas próximas a uma fonte hidrotermal – esta luz não precisa nem vir do Sol.

Um novo estudo explora o potencial para a vida fotossintética persistir em tais condições de ausência de Sol. A pesquisa visa lançar luz, por assim dizer, sobre como organismos poderiam viver das turvas emissões infravermelhas de fontes hidrotermais em mundos alienígenas. Atormentadoramente, tais fontes teoricamente devem existir sob a superfície da lua oceânica coberta de gelo de Júpiter, chamada Europa.

´´Quando nos tornamos conscientes de bactérias usando luz infravermelha para fotossintetizar, nos sentimos muito curiosos para checar o potencial fotossintético com esta luz porque esta é uma avaliação sobre se a vida seria capaz de prosperar ao redor de fontes hidrotermais´´, disse Rolando Cardenas, um físico da Central University ´´Marta Abreu´´ de Las Villas em Santa Clara, Cuba, e co-autor do artigo publicado na edição de maio da Astrophysics and Space Science.

As novas descobertas sugerem que a vida fotossintética, como a conhecemos, iria sofrer para florescer dada a pequena quantidade de luz disponível em ambientes de fontes hidrotermais. Mas organismos que podem fazer uso de luz infravermelha de menor energia podem ter o bastante para se manter em circunstâncias sem Sol.

Vida florescendo no escuro profundo

Nos oceanos, fontes hidrotermais se formam próximas a vulcões submarinos onde placas tectônicas estão se distanciando em cordilheiras meso-oceânicas. O magma quente que borbulha para cima do assoalho oceânico superaquece a água que passa ao redor, que então é cuspida para fora do fundo oceânico, carregada com minerais. Os minerais precipitam da pluma, construindo estruturas como chaminés, conhecidas como fumarolas negras.

Apesar destas fontes hidrotermais de mar profundo não soarem como lugares particularmente hospitaleiros, os vagalhões escaldantes são de fato pontos quentes (hot spots) biológicos.

Green sulfur bacteria growing in a nutrient-filled container

Um exemplo de espécies de bactérias verdes sulfurosas crescendo em um recipiente cheio de nutrientes. Crédito: kOchstudiO/Wikipedia

Vários tipos de bactéria “jantam” materiais como ferro, sulfeto de hidrogênio e amônia “arrotados” pelas fontes hidrotermais. Estas bactérias por sua vez, suportam ecossistemas completos ao redor das fumarolas negras, mais famosamente caracterizadas por vermes tubulares, mas também lares de estranhas lesmas, caranguejos e muito mais.

Oito anos atrás, pesquisadores liderados por J. Thomas Beaty da University of British Columbia (Universidade da Colúmbia Britânica), descobriram uma bactéria de fonte hidrotermal cujo sustento requer muito mais do que apenas aprisionar químicos da água destas fontes. A bactéria, identificada como pertencendo à família das verdes sulfurosas, precisa de luz para obter energia através de uma reação química com enxofre. Esta espécie de bactéria verde sulfurosa, no entanto, foi encontrada em águas a uns 2.400 metros (7.875 pés) de profundidade no Oceano Pacífico, fora da costa do México. Fótons de luz solar não podem irradiar muito mais abaixo dos 200 metros (660 pés) na coluna d´água antes de serem completamente absorvidos. Consequentemente, a bactéria tem de usar a escassa porção de luz geotermal gerada por fontes hidrotermais para sobreviver. Esta luz geotermal é emitida quando águas superaquecidas em erupção rapidamente resfriam nos arredores do ambiente aquático do fundo marinho, pouco acima da temperatura de congelamento da água.

A espécie de bactéria possui uma estrutura semelhante a uma antena que lhe permite capturar a luz eficientemente. ´´É o único exemplo de um organismo que se acredita viver de luz geotermal´´, diz Robert Blankenship, um professor de biologia e química na Washington University (Universidade Washington) em St. Louis, EUA, que estava envolvido no estudo de 2005. ´´O organismo usa um complexo de antena gigante que o permite sobreviver sob condições de luminosidade extremamente baixa – é provavelmente o melhor candidato que se poderia ter para viver em uma fonte hidrotermal através da absorção de fótons.

Siga a luz

Estudando a vida dura e privada de luz em áreas remotas como as fontes hidrotermais é infelizmente um empreendimento difícil e custoso – a bactéria em questão não foi re-isolada desde então. O novo estudo de Cardenas e seus colegas, portanto, se volta para um modelo matemático para estimar o potencial fotossintético ao redor das fumarolas.

Os pesquisadores começaram como uma fumarola conceitual que emite uma quantidade similar de luz daquelas descritas no artigo de Beatty. Uma quantidade negligenciável desta luz vem na forma de alta energia, comprimentos de onda ópticos; bem acima de noventa e nove por cento da luz disponível, ao contrário, flui adiante como luz infravermelha de baixa energia.

Some bacteria can make use of long-wavelength, lower-energy light in the infrared portion of the electromagnetic spectrum

A porção óptica do espectro eletromagnético do visível para os nossos olhos vai de aproximadamente 400 a 700 nanômetros em comprimento de onda de fóton. Algumas bactérias fazem uso da luz de baixa energia e longo comprimento de onda da porção infravermelha do espectro. Crédito: NOAA

´´Os fótons de alta energia não contribuem de uma forma significativa para o balanço da coleta de energia total para organismos fotossintéticos de mar profundo´´ disse o co-autor do artigo Osmel Martin Gonzalez, também da Central University ´´Marta Abreu´´ de Las Villas.

A equipe de pesquisa incluiu equações que descrevem as taxas de fotossíntese, refinando-as porque a luz ultravioleta que pode danificar o fitoplâncton e assim impedir a fotossíntese, não alcança profundidades oceânicas. A variação dos níveis de irradiância foi modelada, assim como temperaturas da água se estendendo de aproximadamente 390 graus Fahrenheit (200 graus Celsius) até uns 750 graus Fahrenheit (400 graus Celsius), consistente com as emissões de fumarolas negras.

Não é uma vida fácil

No total, as taxas de fotossíntese calculadas para a as criaturas coletoras de luz infravermelha não foram muito altas, significando que relativamente pouca energia utilizável foi extraída de emissões de fontes hidrotermais.

Os resultados desta forma concordam com a descoberta de Beatty e Blankenship de que a bactéria verde sulfurosa não pareceu ser um membro dominante de sua comunidade ou uma espécie particularmente robusta. ´´Quanto aos organismos que encontramos nas fontes hidrotermais da Terra, estou convencido de que eles estavam se ´´segurando pelas unhas´´ e apenas gritando por suas vidas´´, disse Blankenship.

De fato, para a vida alienígena subterrânea ou submersa obter suficiente energia através da fotossíntese infravermelha, ela poderia requerer meios fundamentalmente diferentes, ou no mínimo uma significante expansão dos comprimentos de onda que se sabe serem utilizados.

Cardenas e seus colegas ampliaram os horizontes ao considerar organismos hipotéticos que poderiam absorver luz com um comprimento de onda tão longo quanto 1.300 nanômetros (bilionésimos de um metro). Tal comprimento de onda é consideravelmente mais longo (e então menos energético) que da luz que espécies terrestres podem acomodar. O alcance do infravermelho é considerado como iniciando nos 700 nanômetros e organismos foram documentados coletando esta luz invisível até uns 1.000 nanômetros, disse Blankenship.

Ainda, Cardenas disse que ao ir um pouco além da biologia terrestre, ele considera que micróbios fotossintéticos poderiam viver da luz de fontes hidrotermais submersas. ´´Mesmo com a fotossíntese apenas até 1.100 nanômetros, bactérias verdes sulfurosas poderiam fazer fotossíntese em alguma extensão em um ambiente similar em Europa ou outros corpos planetários´´, afirmou Cardenas.

Blankenship é um pouco mais cético. Ele apontou que a água ao redor de fontes hidrotermais provavelmente absorveria muito da luz infravermelha disponível, deixando apenas um ´´estreito retalho de moradias´´ disponível para as criaturas fotossintéticas ocuparem, e um deles as colocaria perigosamente próximas da própria água superaquecida.

´´A quantidade de luz que vem das fontes hidrotermais, pelo menos aqui na Terra, é muito, muito baixa.´´, afirmou Blankenship. ´´Ainda assim, é sempre bom pensar sobre estas coisas.´´

Sob o gelo de Europa

Neste ponto, as características das fontes hidrotermais em Europa, seu calor contínuo e sua produção de luz são pura especulação. ´´Modelos internos detalhados de Europa ainda estão sob alguma controvérsia.´´, disse Cardenas.

Europa possui uma grossa crosta de gelo que os cientistas têm quase certeza que cobre um oceano mantido líquido pelo efeito de maré enquanto a gravidade de Júpiter espreme e comprime a lua. Este efeito de maré poderia também instigar processos do tipo tectônicos no manto de Europa, gerando fontes hidrotermais no assoalho oceânico subsuperficial.

´´Se isto for verdade´´, disse Cardenas, ´´então podemos esperar fontes hidrotermais lá e – por que não? – formas de vida confiando em princípios similares àquelas das fontes hidrotermais da Terra.´´

The puzzling, fascinating surface of Jupiter's icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA's Galileo spacecraft in the late 1990s. Image credit: NASA/JPL-Caltech/SETI Institute

Sob uma espessa crosta de gelo, Europa pode ter um oceano aquecido por interações de maré com Júpiter. Este efeito de maré também poderia produzir um núcleo geologicamente ativo que poderia por sua vez, criar fontes hidrotermais no fundo oceânico. Crédito: NASA/JPL/Ted Stryk

No momento, fotossíntese infravermelha como um meio solo ou complementar para produção de energia por micróbios extraterrestres ao redor de fontes hidrotermais se parece com um tiro a distância; o uso de minerais, como praticado com grande sucesso em nossas abissais oceânicas faz mais sentido. Mas novamente, ninguém esperava encontrar uma abundância de vida ao redor das fumarolas negras quando elas foram descobertas em 1977.

´´A vida parece encontrar uma forma.´´, afirmou Cardenas. ´´´Nós pretendemos continuar avançando no estudo da fotossíntese infravermelha e suas implicações para a vida em habitats terrestres menos convencionais.

Veja mais em: http://www.astrobio.net/news-exclusive/infrared-photosynthesis-a-potential-power-source-for-alien-life-in-sunless-places/#sthash.0xvn5LSp.dpuf

Tradutor: Bruno Martini

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NASA Announces Winning Ideas for Mars Balance Mass Challenge

The Mars Balance Mass Challenge asked for design ideas for small science and technology payloads that could potentially provide dual purpose as ejectable balance masses on spacecraft entering the Martian atmosphere. Image Credit: NASA

The Mars Balance Mass Challenge asked for design ideas for small science and technology payloads that could potentially provide dual purpose as ejectable balance masses on spacecraft entering the Martian atmosphere.
Image Credit: NASA

A member of the public with an idea to study the Martian atmosphere and a team with a way to study Martian weather are the winners of NASA’s Mars Balance Mass Challenge.

Ted Ground of Rising Star, Texas, was awarded $20,000 for his idea to study the Martian atmosphere by releasing material that could be seen and studied by other Martian spacecraft in orbit and on the ground.

A team of engineers, Brian Kujawski, Louis Olds, and Leslie Hall, from Grand Rapids, Michigan, received an honorable mention and $5,000 for their idea to study Martian weather by looking at wind patterns near the planet’s surface.

“The 219 submissions from 43 countries to the Mars Balance Mass Challenge show the interest the public has in directly engaging with NASA,” said NASA Chief Technologist David Miller. “And the two winning ideas highlight how effective these activities can be at helping NASA bring innovative ideas into our missions.”

Ted Ground of Rising Star, Texas, was awarded $20,000 for his idea to study the Martian atmosphere by releasing material that could be seen and studied by other Martian spacecraft in orbit and on the ground. Image Credit: Ted Ground

Ted Ground of Rising Star, Texas, was awarded $20,000 for his idea to study the Martian atmosphere by releasing material that could be seen and studied by other Martian spacecraft in orbit and on the ground. Image Credit: Ted Ground

The Mars Balance Mass Challenge, announced in September 2014 at the World Maker Faire in New York City, sought design ideas for small science and technology payloads that could potentially provide dual purpose as ejectable balance masses on spacecraft entering the Martian atmosphere. The payloads would serve two roles: perform scientific or technology functions that help us learn more about the Red Planet, and provide the necessary weight to balance planetary landers.

“We want citizens to join us on the Journey to Mars,” said George Tahu, program executive for Mars Exploration at NASA Headquarters in Washington. “Challenges such as this invite innovative design ideas and creative solutions that will support our science and technology planning processes as well as encourage science, technology, engineering and math (STEM) education.”

Submissions to the challenge ranged from analyzing Martian weather or the Martian surface, to demonstrating new technologies such as 3D printing or parachutes, to pre-positioning supplies for future human missions on the planet’s surface.

Ground’s concept would release trace elements such as barium or strontium during the main spacecraft’s entry and decent into the Martian atmosphere, while other spacecraft in orbit and on the surface of the planet observed the patterns made by the tracer elements in the atmosphere. A similar process is used to study Earth’s atmosphere by sending sounding rockets along a parabolic path anywhere from 30 to 800 miles above the Earth.

Louis Olds, Leslie Hall, and Brian Kujawski (left to right), a team of engineers from Grand Rapids, Michigan, received an honorable mention and $5,000 for their idea to study Martian weather by looking at wind patterns near the planet’s surface. Image Credit: Brian Kujawski

Louis Olds, Leslie Hall, and Brian Kujawski (left to right), a team of engineers from Grand Rapids, Michigan, received an honorable mention and $5,000 for their idea to study Martian weather by looking at wind patterns near the planet’s surface. Image Credit: Brian Kujawski

The challenge selection team also evaluated a number of concepts using balloon-carried payloads. The best of these was chosen as an honorable mention for its realistic approach to delivering the payloads and for its possible benefit to future human missions to Mars.

All four selectees are new to the world of NASA prizes and challenges, but are now eager to work on upcoming NASA challenges.

Kujawski said, “I now tell everyone that these sorts of challenges are worth giving a shot – you get an opportunity to learn more about something that you’re passionate about, and the satisfaction of coming up with a solution to a tough problem.”

Ground, who was inspired to pursue other NASA challenges, agrees, “I think there are lots of skilled, creative, and educated citizens that could contribute, to help ‘shape’ the contents or overall goals of NASA missions, perhaps more closely than they have in the past.”

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NASA’s MAVEN Spacecraft Completes First Deep Dip Campaign

This image shows an artist concept of NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission. Image Credit: NASA's Goddard Space Flight Center

This image shows an artist concept of NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission. Image Credit: NASA’s Goddard Space Flight Center

NASA’S Mars Atmosphere and Volatile Evolution has completed the first of five deep-dip maneuvers designed to gather measurements closer to the lower end of the Martian upper atmosphere.

“During normal science mapping, we make measurements between an altitude of about 150 km and 6,200 km (93 miles and 3,853 miles) above the surface,” said Bruce Jakosky, MAVEN principal investigator at the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder. “During the deep-dip campaigns, we lower the lowest altitude in the orbit, known as periapsis, to about 125 km (78 miles) which allows us to take measurements throughout the entire upper atmosphere.”

The 25 km (16 miles) altitude difference may not seem like much, but it allows scientists to make measurements down to the top of the lower atmosphere. At these lower altitudes, the atmospheric densities are more than ten times what they are at 150 km (93 miles).

“We are interested in the connections that run from the lower atmosphere to the upper atmosphere and then to escape to space,” said Jakosky. “We are measuring all of the relevant regions and the connections between them.”

The first deep dip campaign ran from Feb. 10 to 18. The first three days of this campaign were used to lower the periapsis. Each of the five campaigns lasts for five days allowing the spacecraft to observe for roughly 20 orbits.  Since the planet rotates under the spacecraft, the 20 orbits allow sampling of different longitudes spaced around the planet, providing close to global coverage.

This month’s deep dip maneuvers began when team engineers fired the rocket motors in three separate burns to lower the periapsis. The engineers did not want to do one big burn, to ensure that they didn’t end up too deep in the atmosphere.  So, they “walked” the spacecraft down gently in several smaller steps.

“Although we changed the altitude of the spacecraft, we actually aimed at a certain atmospheric density,” said Jakosky. “We wanted to go as deep as we can without putting the spacecraft or instruments at risk.”

Even though the atmosphere at these altitudes is very tenuous, it is thick enough to cause a noticeable drag on the spacecraft.  Going to too high an atmospheric density could cause too much drag and heating due to friction that could damage spacecraft and instruments.

At the end of the campaign, two maneuvers were conducted to return MAVEN to normal science operation altitudes. Science data returned from the deep dip will be analyzed over the coming weeks. The science team will combine the results with what the spacecraft has seen during its regular mapping to get a better picture of the entire atmosphere and of the processes affecting it.

One of the major goals of the MAVEN mission is to understand how gas from the atmosphere escapes to space, and how this has affected the planet’s climate history through time. In being lost to space, gas is removed from the top of the upper atmosphere. But it is the thicker lower atmosphere that controls the climate.  MAVEN is studying the entire region from the top of the upper atmosphere all the way down to the lower atmosphere so that the connections between these regions can be understood.

MAVEN is the first mission dedicated to studying the upper atmosphere of Mars. The spacecraft launched Nov. 18, 2013, from Cape Canaveral Air Force Station in Florida. MAVEN successfully entered Mars’ orbit on Sept. 21, 2014.

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Planets Can Alter Each Other’s Climates over Eons

A crowded solar system chock-full of planets. Credit: NASA/Tim Pyle

A crowded solar system chock-full of planets. Credit: NASA/Tim Pyle

A new study sheds light on how exoplanets in tightly-packed solar systems interact with each other gravitationally by affecting one another’s climates and their abilities to support alien life.

Because the exoplanets are so close to one another in these compact solar systems, they have tidal influence, much like the Earth and the Moon have on each other. The tides modify the spin rates, axial tilts and orbits of these planets over time, and therefore alter their climates.

The study examines two exo-solar systems — Kepler-62 and Kepler-186 — that have made headlines for hosting worlds orbiting in the “habitable zone,” the potentially life-friendly band where water can remain liquid on a planetary surface. The findings show that tidal evolution can profoundly impact a world’s climate.

“We wanted to investigate the question of the influence of tidal dynamics on the climate of ‘habitable’ planets,” said lead author Emeline Bolmont, a post-doctoral research scientist at the University of Bordeaux in France at the time when the research was conducted, and now at the University of Namur in Belgium.

The findings can help astrobiologists understand how habitability is affected by the complex gravitational interplay of neighboring planets. The paper will be published in March 2015 in the book “Complex Planetary Systems (IAU S310),” a publication of the International Astronomical Union (IAU).

The big picture factors for climate

Almost half of the 1,100-plus exoplanetary systems now known contain multiple planets in the manner of our solar system. Because our ability to discover exoplanets is still at an early stage, our instruments are biased towards detecting planets that closely orbit their host stars. As a result, many of these multi-planet systems we know of look like scrunched-up versions of our solar system. These compact solar systems often have several planets whirling around in orbits within the same distance as Mercury is to the Sun.

Earth's axial tilt of 23.44 degrees gives our planet its seasons and moderates the climate. Credit: NASA

Earth’s axial tilt of 23.44 degrees gives our planet its seasons and moderates the climate. Credit: NASA

The proximity of these planets causes them to exert tidal influences on each other, modifying their rotations and axial tilts. The Moon’s gravity has similarly acted like a brake on Earth’s rotation, slowing it from a primordial six hour day to the just-shy of the 24 hours we set our clocks to in modern times. The Moon’s stabilizing mass also helps maintain Earth’s axial tilt of 23.44 degrees, which gives us our seasons and moderates the planet’s overall temperature, much to life’s benefit.

In the solar systems Kepler-62 and Kepler-186, tidal effects from their various planets and host stars similarly impact the planets’ rotation and axial tilt. The general effect is slowed-down planetary spin rates, as well as axial tilts that are regularized in such a way as to spin perpendicular to the plane of their orbits (they have zero axial tilt).

The new study evaluated how the gravity of closely interacting exoplanets might modify these two climate-determining parameters over billions of years. The study also briefly assessed the bigger-picture factors of planets’ orbital shapes and distances to see how stable these would remain in compact multi-planet solar systems. Both variables, of course, have a fundamental impact on a planet’s climatic characteristics.

“The presence of liquid water on a planet’s surface depends on many different parameters, some of which are the orbital distance, the shape of the orbit, the direction of the rotation axis of the planet and the rotation period of the planet,” said Bolmont. “All these quantities are influenced by dynamics and in particular by tidal dynamics.”

Alien solar system models

The study ran computer simulations of the Kepler-62 and Kepler-186 solar systems using to the best data available. Each system’s star is a red dwarf, which is smaller and dimmer than the Sun, and hosts at least five planets. The exoplanets Kepler-62e and Kepler-62f, both super-Earths, orbit in the habitable zone. Kepler-186f, meanwhile, is the first approximately Earth-sized exoplanet discovered in a habitable zone. It is therefore widely considered among the best candidates yet spotted for harboring extraterrestrial life.

The computer simulations focused on how the gravitational push-and-pull of the overall system affected these three exoplanets of interest. For the masses of the exoplanets in their models—which determines the planets’ gravitational attraction—Bolmont and her colleagues assumed Earth-like compositions for all five Kepler-62 worlds. For the Kepler-186 system, the researchers played with the compositions to get different masses to see what would happen. The compositions ranged from pure, low-density ice to pure, high-density iron (higher density packs in more mass to the same volume).

A comparison of the Kepler-62 solar system and our own. Credit: NASA Ames/JPL-Caltech

A comparison of the Kepler-62 solar system and our own. Credit: NASA Ames/JPL-Caltech

An innovative aspect to the computer simulations is a new code developed by Bolmont and colleagues. The code calculates the gravitational interactions between the stars and the planets in Kepler-62 and Kepler-168, computing the resulting orbital evolution of the planets.

The code is more sophisticated physics-wise than those that have powered prior simulations. It adds to the key tidal effects previously discussed, as well as rotational flattening (spinning bodies bulge at their centers, influencing their orbital evolution) and even Einstein’s general relativity, a more accurate description of gravitation than simple Copernican physics, often used in similar simulations.

“We try to take into account the most important dynamical processes for the evolution of a system,” said Bolmont.

The code will be publicly released soon so other scientists can run simulations and tinker with it.

Keeping it all together

The Bolmont simulations showed that tidal effects in general can help make compact, multi-planet solar systems more stable. The gravitational interplay in simpler runs of the model, without the added-in, relevant physics, worked in setting planets on wild orbits. The system would destabilize, with planets colliding or getting flung right out of the solar system. A destabilization scenario would almost surely be lethal for whatever life might have gotten going in tight, multi-planet systems.

But the addition of tidal effects and the other physics previously mentioned kept the worlds snugly in their respective orbital lanes, at least for the simulation’s duration. The additional gravitational checks and balances help preserve a solar system, it would appear.

That’s a good sign for life if compressed multi-planet systems can remain together for long periods. Life took several hundred million years to develop on Earth, and a few billion to develop complexity.

Changes over time

Individually, the axial tilts and spin rates of Kepler-62e and Kepler-62f did evolve considerably, and in varying ways, over the course of seven billion years.

“We found that Kepler-62e and f are likely to have different climates,” said Bolmont,

Artist's impressions about Kepler-62 solar system worlds. Kepler-62e and Kepler-62f are likely to have differing climates, according to a new study. Credit: PHL @ UPR Arecibo (phl.upr.edu) April, 2013

Artist’s impressions about Kepler-62 solar system worlds. Kepler-62e and Kepler-62f are likely to have differing climates, according to a new study. Credit: PHL @ UPR Arecibo (phl.upr.edu) April, 2013

Kepler-62e, according to the simulation, is likely to have a very small axial tilt, thanks to the braking as well as accelerative effects from the other planets in its solar system. Lacking much tilt, Kepler-62e would not experience seasons and its poles would be quite cold. Earth, with its seasons, has cold poles too, of course, when compared to its hot equatorial regions. But the difference in temperature on Kepler-62e between its equator and poles would be far more pronounced.

The exoplanet’s rotation would possibly slow to a day-length equivalent of 125 or so Earth days. A planet’s rotation also contributes to moderating its surface temperatures, like a roast turned on a spit, such that one portion of the meat does not singe black while the rest is merely warmed. In the case of Kepler-62e, with its very slow turning, the side of the planet facing its star heats up considerably more than the night side, plunged into darkness for a third of an Earth-year.

Kepler-62f, on the other hand, is located farther out in the exo-solar system than planet ‘e.’ The gravitational perturbation from the star and inner planets would not be as strong in the outer reaches. Even after seven billion years, Kepler-62f would not have had its axial tilt abolished by the solar system’s other bodies. Kepler-62f should therefore still have an axial tilt, and thus seasons, and a day length perhaps broadly similar to Earth’s.

“Kepler-62f is located farther and wouldn’t have had time to tidally evolve,” said Bolmont.

Fingers crossed for Kepler-186f?

The case for Kepler-186f is less clear-cut. We know the age of the Kepler-62 solar system, but do not know it yet for Kepler-186. That data is important because the tidal evolution dynamics require long time scales to bring about significant changes in a planet’s parameters. By making some assumptions, though, the Kepler-186 system model can still offer insight.

Assuming that the whole system is older than four billion years, as a separate recent study has suggested, then the four innermost planets in Kepler-186, being located so close to their star, will likely have had any axial tilt to be erased. In the case of Kepler-186f, the outermost planet and the one of interest in its potential habitability, an old solar system would mean it, too, has little to no axial tilt and a day-length of approximately 125 Earth-days.

An artist's conception of Kepler-186f. Credit: NASA Ames/SETI Institute/JPL-Caltech

An artist’s conception of Kepler-186f. Credit: NASA Ames/SETI Institute/JPL-Caltech

If the Kepler-186 system is less than a billion years, Kepler-186f might still have a high axial tilt and a fast spin rate, more like Earth’s. The axial tilt might be so high, the models showed, on the order of 80 degrees, that the planet could be spinning on its “side,” as it were, like Uranus in our solar system. (Uranus is thought to have been knocked on its side by a collision at some point in its planetary lifetime. The world is too isolated for the Sun or other planets to tidally “right” the planet back up.) Under that scenario, Kepler-186f would develop a very cold hemisphere that is pointed away from the star, and a possibly too-warm hemisphere facing the star.

Given the holes in the data, the jury is very much still out on how much Kepler-186f’s evolution is tidally influenced.

“We don’t have enough data, such as the age of the system,” said Bolmont.

The overall takeaway from the study is that planets can indeed gravitationally influence each other in compact solar systems in ways that heavily influence climate and therefore habitability. Much more work needs to be done in this area, said Bolmont, to better learn how orbital shapes and distances change over time.

“These are still open questions,” said Bolmont. “There is a lot of diversity in the orbits of the habitable zone planets, and thus in the climate of habitable worlds.”

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Does dark matter cause mass extinctions and geologic upheavals?

The Milky Way. Credit: Serge Brunier

The Milky Way. Credit: Serge Brunier

Research by New York University Biology Professor Michael Rampino concludes that Earth’s infrequent but predictable path around and through our Galaxy’s disc may have a direct and significant effect on geological and biological phenomena occurring on Earth.

In a new paper in Monthly Notices of the Royal Astronomical Society, he concludes that movement through dark matter may perturb the orbits of comets and lead to additional heating in the Earth’s core, both of which could be connected with mass extinction events.

The Galactic disc is the region of the Milky Way Galaxy where our solar system resides. It is crowded with stars and clouds of gas and dust, and also a concentration of elusive dark matter–small subatomic particles that can be detected only by their gravitational effects.

Previous studies have shown that Earth rotates around the disc-shaped Galaxy once every 250 million years. But the Earth’s path around the Galaxy is wavy, with the Sun and planets weaving through the crowded disc approximately every 30 million years. Analyzing the pattern of the Earth’s passes through the Galactic disc, Rampino notes that these disc passages seem to correlate with times of comet impacts and mass extinctions of life. The famous comet strike 66 million ago that led to the extinction of the dinosaurs is just one example.

What causes this correlation between Earth’s passes through the Galactic disc, and the impacts and extinctions that seem to follow?

While traveling through the disc, the dark matter concentrated there disturbs the pathways of comets typically orbiting far from the Earth in the outer Solar System, Rampino observes. This means that comets that would normally travel at great distances from the Earth instead take unusual paths, causing some of them to collide with the planet.

Core of the Earth

With each dip through the disc, the dark matter can apparently accumulate within the Earth’s core.

But even more remarkably, with each dip through the disc, the dark matter can apparently accumulate within the Earth’s core.

Eventually, the dark matter particles annihilate each other, producing considerable heat. The heat created by the annihilation of dark matter in Earth’s core could trigger events such as volcanic eruptions, mountain building, magnetic field reversals, and changes in sea level, which also show peaks every 30 million years.

Rampino therefore suggests that astrophysical phenomena derived from the Earth’s winding path through the Galactic disc, and the consequent accumulation of dark matter in the planet’s interior, can result in dramatic changes in Earth’s geological and biological activity.

His model of dark matter interactions with the Earth as it cycles through the Galaxy could have a broad impact on our understanding of the geological and biological development of Earth, as well as other planets within the Galaxy.

“We are fortunate enough to live on a planet that is ideal for the development of complex life,” Rampino says. “But the history of the Earth is punctuated by large scale extinction events, some of which we struggle to explain. It may be that dark matter – the nature of which is still unclear but which makes up around a quarter of the universe – holds the answer. As well as being important on the largest scales, dark matter may have a direct influence on life on Earth.”

In the future, he suggests, geologists might incorporate these astrophysical findings in order to better understand events that are now thought to result purely from causes inherent to the Earth. This model, Rampino adds, likewise provides new knowledge of the possible distribution and behaviour of dark matter within the Galaxy.