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Does Proxima Centauri b Have A Shiny Green Tint

October 17, 2017 by  
Filed under Around The Net

A world orbiting the sun’s closest stellar neighbor may have a shiny green tint to it — and not necessarily because it’s covered in leafy plants. 

Researchers have found a way to characterize potential auroras on the nearby exoplanet Proxima Centauri b and found that, if the planet sports oxygen in its atmosphere, the auroras may give the atmosphere a greenish cast. 

“The northern and southern lights [on Proxima Centauri b] would be at least 100 times brighter than on Earth,” Rodrigo Luger, a postdoctoral student at the University of Washington, who led the study of how the planet’s auroras could be spotted from Earth, told Space.com by email. Luger said the auroras might be so bright as to be visible with very powerful telescopes.

The active star Proxima Centauri lies only 4.2 light-years from the solar system. A small world orbits in the star’s habitable zone, the region where liquid water could survive on the surface. Its radius remains a mystery. However, scientists know it is about 1.3 times as massive as the Earth, which its initial discovers said suggests a rocky planet. 

Proxima Centauri is a small star, dimmer than Earth’s sun, so its habitable zone is closer to the star than the habitable zone of the sun. As a result, Proxima Centauri b is 20 times closer to its star than Earth is to the sun, and completes an orbit every 11.2 Earth-days. The red dwarf star is more active than Earth’s sun, firing off far more frequent flares that may douse the planet in radiation that could be harmful for potential life. 

Those same flares may help scientists better understand the planet. If Proxima Centauri b has a magnetic field, it may capture the charged particles in the flares and funnel them toward the poles, creating brilliant auroral displays. 

Observing the auroras can help researchers characterize the planet’s atmosphere. On Earth, the different color glow of the northern and southern lights corresponds to reactions with different molecules in the atmosphere. According to Luger, who presented the results at the Astrobiology Science Conference in Mesa, Arizona, in April, if Proxima Centauri b is a terrestrial world with an Earth-like atmosphere and a magnetic field, the green light of the oxygen auroras would grow 100 times stronger than on Earth.

Because of the potential for green light, the researchers dubbed such a world “the pale green dot,” a nod to Carl Sagan’s categorization of Earth as a pale blue dot.

Periods of intense stellar activity could make the auroras even brighter. While coronal mass ejections and flares have the strongest impact on generating auroras, Luger said, they aren’t really predictable in advance.

“But the sun certainly has periodic activity cycles, so if we understand those of Proxima Centauri, we might be able to use that to our advantage,” he said.

He went on to say that the extreme activity of the star may make such knowledge unnecessary — astronomers could simply count on a high likelihood that the star would flare and cause the auroras to brighten.

While several studies have described searches for auroras on gas giant exoplanets that orbit close to their parent stars, none have been spotted on worlds beyond the solar system. But Luger remains confident.

“Proxima Centauri b is optimal for auroral detection,” he said.

He gave several reasons that auroras may be soon spotted on Proxima Centauri b. The planet is nearby — it’s the closest known exoplanet to Earth — making it easier for instruments to collect detailed observations. The extreme magnetic activity of the star, coupled with the planet’s close orbit, means Proxima Centauri b is bombarded with solar particles far more vigorously than Earth. At the same time, the star is faint, so a glowing green planet would show up more easily than it would around a sun-like star. Finally, the short orbit means that the world moves around its sun at a rapid clip; when a light source is moving toward or away from an observer, this motion can be observed through a phenomenon called redshift, or Doppler shift. Luger said the Doppler shift of the auroras’ light waves would be significantly larger than they would be on their own, making lines that would otherwise be hard to see more visible. That would make it easier to identify any oxygen in the atmosphere.

Unfortunately, this “pale green dot” won’t be spotted with current telescopes. NASA’s upcoming powerhouse telescope ― the James Webb Space Telescope ― will hunt for infrared light, so Luger said it won’t be able to detect the green oxygen aurora, which is in the visible light range.

“Our best bet for detection is the [Thirty-Meter Telescope] or similar next-generation extremely large telescopes,” he said.

The Thirty-Meter Telescope (TMT) — so-named because its primary mirror would be 30 meters (98 feet) wide — began construction on Hawaii’s Mauna Kea peak before it was halted in 2015 after protests over the sacred nature of the land. The project remains at a halt today, though some astronomers have lauded the benefits of moving the telescope to Spain’s Canary Islands.

But even TMT would take some time to identify the signature of oxygen from the auroras, with Luger estimating “tens of hours” of observation. The same is true for the Large UV/Opitcal/Infrared Survey (LUVOIR), a proposed design for a telescope with a primary mirror between 9 and 15 meters (30 and 50 feet). With telescope time extremely competitive, it could be hard to study the system so extensively.

In order to produce auroras, a planet must have a magnetic field. Out of the four terrestrial planets in Earth’s solar system, only two have a worldwide field — Earth and Mercury. Mars has a patchy field, and Venus has none. If Proxima Centauri b is similarly lacking, it might not produce auroras.

However, the planet may get a brightness boost from airglow, the faint emission of light from the atmosphere that keeps nighttime on Earth from ever being completely dark.

“The planet is likely also to have strong airglow, which is planetwide,” Luger said. “Airglow is not generated by magnetic fields, and is typically weaker than aurorae, so we did not calculate it. But it should be quite strong on Proxima Centauri b, and could cause the entire planet to glow green.”

Courtesy-Space

Astronomers Discover Water Mystery On Mars

October 9, 2017 by  
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A new examination of old data suggests that there might be ice hiding in the Martian equator, even though scientists previously thought that the substance couldn’t exist there.

Scientists uncovered an unexpected amount of hydrogen when looking at older data from NASA’s Mars Odyssey spacecraft dating back to between 2002 and 2009. At higher latitudes, hydrogen generally indicates buried water ice, but this was not believed possible at the equator, according to a statement from NASA.

If there is indeed water there, this would help with a future human mission to Mars, because it could mean the astronauts wouldn’t need to bring the substance with them for drinking, cooling equipment or watering plants, researchers said in the statement. Instead, the astronauts could live off the land to an extent, reducing the number of resources that need to be trucked (at higher cost) from Earth

Mars Odyssey’s first major discovery, in 2002, was also linked to water; the spacecraft found buried hydrogen at high latitudes, and the 2008 landing of the Phoenix Mars lander confirmed that there was water ice. However, at lower latitudes, measurements of hydrogen were explained as hydrated minerals (which other spacecraft have also observed). Researchers didn’t think water ice was thermodynamically stable in those areas.

For this new study, the researchers analyzed data collected using Mars Odyssey’s neutron spectrometer. The instrument is not designed to directly detect water, but by measuring neutrons, it can detect signatures of hydrogen, which can mark the presence of water or other hydrogen-bearing substances. 

The science team reduced the blurring or “noise” in Odyssey’s data using image-reconstruction techniques based on those used for other spacecraft and for medicine, according to the statement. This improved the spatial resolution of the data to 180 miles (290 kilometers), twice the previous resolution of 320 miles (520 km).

“It was as if we’d cut the spacecraft’s orbital altitude in half, and it gave us a much better view of what’s happening on the surface,” Jack Wilson, the study’s principal investigator and a postdoctoral researcher at the Johns Hopkins University Applied Physics Laboratory.

Their work focused on equatorial areas, particularly in zones around the Medusae Fossae formation, an area that includes material that is easy to erode. Previous observations from NASA’s Mars Reconnaissance Orbiter and the European Space Agency’s Mars Express orbiter suggested there might be volcanic deposits or water ice just below the surface. Scientists, however, were skeptical that it was water ice, because “if the detected hydrogen were buried ice within the top meter [3.3 feet] of the surface, there would be more than would fit into pore space in soil,” Wilson said.

The study’s scientists emphasized that more evidence is needed to conclude that the signature indeed comes from water ice. They’re not too sure how the water was preserved, they said; perhaps ice and dust flowing from the poles moved through the atmosphere when Mars had a steeper axis tilt than today. However, it’s been at least hundreds of thousands of years since those conditions existed, and the water ice deposited back then shouldn’t be around anymore, the researchers said. (This would be true even if, somehow, dust or a crust at the surface trapped the humidity underground, the scientists added.)

“Perhaps the signature could be explained in terms of extensive deposits of hydrated salts, but how these hydrated salts came to be in the formation is also difficult to explain,” Wilson said. “So, for now, the signature remains a mystery worthy of further study, and Mars continues to surprise us.”

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Astronomers Find Carbon Star With Red Glowing Bubble

September 28, 2017 by  
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Gorgeous new imagery shows the enormous, glowing bubble that a strange, dying red star has blown around itself.

The huge star, known as U Antliae, lies about 900 light-years from Earth, in the southern constellation Antlia (the Air Pump). U Antliae has burned all the hydrogen and helium in its core and has therefore moved on to the “asymptotic giant branch” (AGB), the last major step in the life cycle of a sun-like star before it becomes superdense white dwarf. 

AdvertisementA few millennia ago, U Antliae erupted in a spasm of activity that generated a big bubble, a surprisingly thin structure that astronomers have now studied using the European Southern Observatory’s Atacama Large Millimeter/submillimeter Array (ALMA), a network of radio telescopes in northern Chile.

“Around 2,700 years ago, U Antliae went through a short period of rapid mass loss,” ESO officials wrote in a statement. “During this period of only a few hundred years, the material making up the shell seen in the new ALMA data was ejected at high speed. Examination of this shell in further detail also shows some evidence of thin, wispy gas clouds known as filamentary substructures.”

ALMA captured the bubble in multiple wavelengths of light, producing a 3D “data cube” that researchers have mined in detail. For example, the imagery shows gases in the bubble moving toward or away from the observer at different speeds, ESO officials said.

This image was created from ALMA data on the red carbon star U Antliae and its surrounding shell of material. The colors show the motion of the glowing material in the shell along the line of sight to the Earth. Blue material lies between us and the central star, and is moving toward us. Red material around the edge is moving away from the star, but not toward Earth. (For clarity, this view does not include the material on the far side of the star, which is receding from us in a symmetrical manner.)

Analyzing such stellar bubbles could help astronomers better understand the evolution of stars and galaxies, ESO officials added.

“Shells such as the one around U Antliae show a rich variety of chemical compounds based on carbon and other elements,” the officials wrote in the same statement. “They also help to recycle matter and contribute up to 70 percent of the dust between stars.”

The new ALMA imagery is part of a study, led by Franz Kerschbaum of the University of Vienna, that has been accepted for publication in the journal Astronomy & Astrophysics.

Courtesy-Space 

Does The Asteroid Belt Hold Key To The Building Blocks Of Planets

September 27, 2017 by  
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The asteroid belt may have started out empty, later becoming a “cosmic refugee camp” taking on leftovers of planetary formation from across the solar system, a new study finds.

The main asteroid belt, located between the orbits of Mars and Jupiter, makes up 0.05 percent the mass of Earth. The asteroids there can range greatly in mass, with the four largest ones — Ceres, Vesta, Pallas and Hygiea — holding more than half the belt’s mass.

To explain the dramatic range of sizes in the asteroid belt, previous models suggested that the primordial asteroid belt originally possessed a mass equal to at least that of Earth, and that its members had less disparity in mass. The gravitational pulls of the planets later helped whittle down this primordial belt, depleting asteroids of certain sizes more than others.  

However, these prior models of asteroid formation raised a question: how the belt could have lost more than 99.9 percent of its mass without losing all of it, said study lead author Sean Raymond, an astronomer at the University of Bordeaux in France.

“Our approach is the opposite. We asked the question, ‘Could the asteroid belt have been born empty?’,” Raymond told Space.com. “The answer is yes, effortlessly.”

The scientists developed computer models of an empty primordial asteroid belt to see whether leftovers from planetary formation could explain the belt’s current composition. The inner belt is dominated by dry S-type, or silicaceous, asteroids, which appear to be made of silicate materials and nickel iron and account for about 17 percent of known asteroids. The outer belt is dominated by water-rich C-type, or carbonaceous, asteroids, which consist of clay and stony silicate rocks and make up more than 75 percent of known asteroids.

The researchers found that an empty primordial asteroid belt could explain the mass and compositions of the current members of the asteroid belt. This model suggests that this zone between Mars and Jupiter is a repository of planetary leftovers, “a refugee camp housing objects that were kicked out of their homes and left to brave interplanetary space, finally settling onto stable orbits in the asteroid belt,” Raymond told Space.com. 

In this new model, the inner belt consists largely of rocky leftovers from the formation of the terrestrial planets — Earth, Mars, Venus and Mercury. In contrast, the outer belt is made up of remnants of the formation of the gas giant planets, such as Jupiter and Saturn.

“In terms of composition, Jupiter and Saturn grew in a region that was much colder than where the rocky planets grew,” Raymond said. “Being colder, their cores could incorporate ice and other volatiles. The C-types are about 10 percent water, whereas the S-types are much drier, having started off in the much hotter terrestrial planet zone.”

These findings suggest that the asteroid belt “is a treasure trove — it must contain relics of the building blocks of all the planets,” Raymond said. “There must be pieces of terrestrial building blocks out in the asteroid belt, as well as leftovers from building the giant planets’ cores.”

Future research can further test how well the various models of asteroid-belt formation match reality. Raymond hopes the team’s new concept “will help keep people’s minds open to potentially drastically different origins stories for the solar system, and for extra-solar planets, too.”

Raymond and his colleague Andre Izidoro at the University of Bordeaux detailed their findings online Sept. 13 in the journal Science Advances.

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Astronomers Ponder The Role Of Physics In Life

September 25, 2017 by  
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Understanding the origin of life is arguably one of the most compelling quests for humanity. This quest has inevitably moved beyond the puzzle of life on Earth to whether there’s life elsewhere in the universe. Is life on Earth a fluke? Or is life as natural as the universal laws of physics?

Jeremy England, a biophysicist at the Massachusetts Institute of Technology, is trying to answer these profound questions. In 2013, he formulated a hypothesis that physics may spontaneously trigger chemicals to organize themselves in ways that seed “life-like” qualities.

Now, new research by England and a colleague suggests that physics may naturally produce self-replicating chemical reactions, one of the first steps toward creating life from inanimate substances.

This might be interpreted as life originating directly from the fundamental laws of nature, thereby removing luck from the equation. But that would be jumping the gun.

Life had to have come from something; there wasn’t always biology. Biology is born from the raw and lifeless chemical components that somehow organized themselves into prebiotic compounds, created the building blocks of life, formed basic microbes and then eventually evolved into the spectacular array of creatures that exist on our planet today.  

“Abiogenesis” is when something nonbiological turns into something biological and England thinks thermodynamics might provide the framework that drives life-like behavior in otherwise lifeless chemicals. However, this research doesn’t bridge life-like qualities of a physical system with the biological processes themselves, England said.

“I would not say I have done anything to investigate the ‘origin of life’ per se,” England told Live Science. “I think what’s interesting to me is the proof of principle – what are the physical requirements for the emergence of life-like behaviors?”

Self-organization in physical systems

When energy is applied to a system, the laws of physics dictate how that energy dissipates. If an external heat source is applied to that system, it will dissipate and reach thermal equilibrium with its surroundings, like a cooling cup of coffee left on a desk. Entropy, or the amount of disorder in the system, will increase as heat dissipates. But some physical systems may be  sufficiently out of equilibrium that they “self-organize” to make best use of an external energy source, triggering interesting self-sustaining chemical reactions that prevent the system from reaching thermodynamic equilibrium and thus maintaining an out-of-equilibrium state, England speculates. (It’s as if that cup of coffee spontaneously produces a chemical reaction that sustains a hotspot in the center of the fluid, preventing the coffee from cooling to an equilibrium state.) He calls this situation “dissipation-driven adaptation” and this mechanism is what drives life-like qualities in England’s otherwise lifeless physical system.

A key life-like behavior is self-replication, or (from a biological viewpoint) reproduction. This is the basis for all life: It starts simple, replicates, becomes more complex and replicates again. It just so happens that self-replication is also a very efficient way of dissipating heat and increasing entropy in that system.

In a study published July 18 in the journal Proceedings of the National Academy of Sciences,  England and co-author Jordan Horowitz tested their hypothesis. They carried out computer simulations on a closed system (or a system that doesn’t exchange heat or matter with its surroundings) containing a “soup” of 25 chemicals. Although their setup is very simple, a similar type of soup may have pooled on the surface of a primordial and lifeless Earth. If, say, these chemicals are concentrated and heated by an external source – a hydrothermal vent, for example – the pool of chemicals would need to dissipate that heat in accordance with the second law of thermodynamics. Heat must dissipate and the entropy of the system will inevitably increase.

Under certain initial conditions, he found that these chemicals may optimize the energy applied to the system by self-organizing and undergoing intense reactions to self-replicate. The chemicals fine-tuned themselves naturally. These reactions generate heat that obeys the second law of thermodynamics; entropy will always increase in the system and the chemicals would self-organize and exhibit the life-like behavior of self-replication.

“Essentially, the system tries a bunch of things on a small scale, and once one of them starts experiencing positive feedback, it does not take that long for it to take over the character of organization in the system,” England told Live Science.

This is a very simple model of what goes on in biology: chemical energy is burned in cells that are – by their nature – out of equilibrium, driving the metabolic processes that maintain life. But, as England admits, there’s a big difference between finding life-like qualities in a virtual chemical soup and life itself.

Sara Imari Walker, a theoretical physicist and astrobiologist at Arizona State University who was not involved in the current research, agrees.

“There’s a two-way bridge that needs to be crossed to try to bridge biology and physics; one is to understand how you get life-like qualities from simple physical systems and the other is to understand how physics can give rise to life,” Imari Walker told Live Science. “You need to do both to really understand what properties are unique to life and what properties are characteristic of things that you consider to be almost alive […] like a prebiotic system.”

Emergence of life beyond Earth?

Before we can even begin to answer the big question of whether these simple physical systems may influence the emergence of life elsewhere in the universe, it would be better to understand where these systems exist on Earth first.

“If, when you say ‘life,’ you mean stuff that is as stunningly impressive as a bacterium or anything else with polymerases and DNA, my work doesn’t yet tell us anything about how easy or difficult it is to make something that complex, so I shouldn’t speculate about what we’d be likely to find elsewhere than Earth,”  England said. (Polymerases are proteins that assemble DNA and RNA.)

This research doesn’t specifically identify how biology emerges from nonbiological systems, only that in some complex chemical situations, surprising self-organization occurs. These simulations do not consider other life-like qualities – such as adaptation to environment or reaction to stimuli. Also, this thermodynamics test on a closed system does not consider the role of information reproduction in life’s origins, said Michael Lässig, a statistical physicist and quantitative biologist at the University of Cologne in Germany.

“[This] work is indeed a fascinating result on non-equilibrium chemical networks but it is still a long way from a physics explanation of the origins of life, which requires the reproduction of information,” Lässig, who was not involved in the research, told Live Science.

There’s a critical role for information in living systems, added Imari Walker. Just because there appears to be natural self-organization exhibited by a soup of chemicals, it doesn’t necessarily mean living organization.

“I think there’s a lot of intermediate stages that we have to get through to go from simple ordering to having a full-on information processing architecture like a living cell, which requires something like memory and hereditary,” said Imari Walker. “We can clearly get order in physics and non-equilibrium systems, but that doesn’t necessarily make it life.”

To say England’s work could be the “smoking gun” for the origin of life is premature, and there are many other hypotheses as to how life may have emerged from nothing, experts said. But it is a fascinating insight into how physical systems may self-organize in nature. Now that researchers have a general idea about how this thermodynamic system behaves, it would be a nice next step to identify sufficiently out-of-equilibrium physical systems that naturally occur on Earth, England said.

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Astronomers Find Titanium Oxide On Aline Planet

September 22, 2017 by  
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For the first time ever, titanium oxide has been spotted in an exoplanet’s skies, a new study reports.

Astronomers using the European Southern Observatory’s Very Large Telescope (VLT) in Chile detected the substance in the atmosphere of WASP-19b, a huge, scorching-hot planet located 815 light-years from Earth.

The presence of titanium oxide in the atmosphere of WASP-19b can have substantial effects on the atmospheric temperature structure and circulation,” study co-author Ryan MacDonald, an astronomer at the University of Cambridge in England, said in a statement.  

One possible effect is “thermal inversion.” If enough titanium oxide is present, the stuff can keep heat from entering or exiting an atmosphere, causing upper layers to be hotter than lower layers, researchers said. (This phenomenon occurs in Earth’s stratosphere, but the culprit is ozone, not titanium oxide.)

Artist’s illustration showing the exoplanet WASP-19b, whose atmosphere contains titanium oxide. In large enough quantities, titanium oxide can prevent heat from entering or escaping an atmosphere, leading to a “thermal inversion” in which temperatures are higher in the upper atmosphere than lower down.

WASP-19b is a bizarre world about the mass of Jupiter. The alien planet lies incredibly close to its host star, completing one orbit every 19 hours. As a result, WASP-19b’s atmospheric temperatures are thought to hover around 3,600 degrees Fahrenheit (2,000 degrees Celsius).

The research team — led by Elyar Sedaghati of the European Southern Observatory, the German Aerospace Center and the Technical University of Berlin — studied WASP-19b for more than a year using the VLT’s refurbished FORS2 instrument. These observations allowed them to determine that small amounts of titanium oxide, along with water and wisps of sodium, swirl around in the exoplanet’s blistering air.

“Detecting such molecules is, however, no simple feat,” Sedaghati said in the same statement. “Not only do we need data of exceptional quality, but we also need to perform a sophisticated analysis. We used an algorithm that explores many millions of spectra spanning a wide range of chemical compositions, temperatures, and cloud or haze properties in order to draw our conclusions.”

In addition to shedding new light on WASP-19b, the new study — which was published online today (Sept. 13) in the journal Nature — should improve researchers’ modeling of exoplanet atmospheres in general, team members said.

“To be able to examine exoplanets at this level of detail is promising and very exciting,” said co-author Nikku Madhusudhan, also of the University of Cambridge. 

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With Boron On Mars Prove Life Once Existed

September 21, 2017 by  
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NASA’s Mars rover Curiosity has discovered boron in Gale Crater — new evidence that the Red Planet may have been able to support life on its surface in the ancient past.

Boron is a very interesting element to astrologists; on Earth, it’s thought to stabilize the sugary molecule ribose. Ribose is a key component of ribonucleic acid (RNA), a molecule that’s present in all living cells and drives metabolic processes. But ribose is notoriously unstable, and to form RNA, it is thought that boron is required to stabilize it. When dissolved in water, boron becomes borate, which, in turn, reacts with ribose, making RNA possible.

In a new study published in the journal Geophysical Research Letters, researchers analyzed data gathered by Curiosity’s ChemCam (Chemistry and Camera) instrument, which zaps rocks with a powerful laser to see what minerals they contain. ChemCam detected the chemical fingerprint of boron in calcium-sulfate mineral veins that have been found zigzagging their way through bedrock in Gale Crater, the 96-mile-wide (154 kilometers) crater that the rover is exploring. These veins were formed by the presence of ancient groundwater, meaning the water contained borate.

The find raises exciting possibilities, the researchers said.

“Because borates may play an important role in making RNA — one of the building blocks of life — finding boron on Mars further opens the possibility that life could have once arisen on the planet,” study lead author Patrick Gasda, a postdoctoral researcher at Los Alamos National Laboratory in New Mexico, said in a statement. 

“Borates are one possible bridge from simple organic molecules to RNA,” he added. “Without RNA, you have no life. The presence of boron tells us that, if organics were present on Mars, these chemical reactions could have occurred.”

Scientists have long hypothesized that the earliest “proto-life” on Earth emerged from an “RNA World,” where individual RNA strands containing genetic information had the ability to copy themselves. The replication of information is one of the key requirements for basic lifelike systems. Therefore, the detection of boron on Mars, locked in calcium-sulfate veins that we know were deposited by ancient water, shows that borates were present in water “0 to 60 degrees Celsius (32 to 140 degrees Fahrenheit) and with neutral-to-alkaline pH,” the researchers said.

“We detected borates in a crater on Mars that’s 3.8 billion years old, younger than the likely formation of life on Earth,” Gasda added. “Essentially, this tells us that the conditions from which life could have potentially grown may have existed on ancient Mars, independent from Earth.”

Since landing on Mars in 2012, Curiosity has uncovered compelling evidence that the planet used to be a far wetter place than it is now. For example, the rover has found evidence of a lake-and-stream system inside Gale Crater that lasted for long stretches in the distant past. And, by climbing the slopes of Mount Sharp — the 3.4-mile-high (5.5 km) mountain in the crater’s center — Curiosity has been able to examine various layers of sedimentary minerals that formed in the presence of ancient water. 

These studies are helping scientists gain a better understanding of how long these minerals were dissolved in the water, where they were deposited and, ultimately, how they impacted the habitability of the Red Planet. The detection of boron is another strand of evidence supporting the idea that ancient life might have existed on our neighboring planet.

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Can The James Webb Telescope Find Life In Our Solar System

September 18, 2017 by  
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The soon-to-launch James Webb Space Telescope will turn its powerful eye on two of the solar system’s top candidates for hosting alien life: the icy moons Enceladus and Europa, the agency confirmed in a statement this month.

Both Europa (a moon of Jupiter) and Enceladus (a moon of Saturn) are thought to possess subsurface oceans of liquid water beneath thick outer layers of ice. Both moons have also shown evidence of enormous plumes of liquid shooting up through cracks in the surface ice; these plumes could be caused by subsurface geysers, which could provide a source of heat and nutrients to life-forms there, scientists have said.

“We chose these two moons because of their potential to exhibit chemical signatures of astrobiological interest,” said Heidi Hammel, executive vice president of the Association of Universities for Research in Astronomy (AURA), who is leading an effort to use the telescope to study objects in Earth’s solar system.  

The James Webb Space Telescope, nicknamed “Webb,” will capture infrared light, which can be used to identify objects that generate heat but are not hot enough to radiate light (including humans, which is why many night-vision systems utilize infrared light). Researchers are hoping that Webb can help to identify regions on the surfaces of these moons where geologic activity, such as plume eruptions, are taking place. 

Enceladus’ plumes were studied in detail by the Cassini probe at Saturn. The spacecraft spotted hundreds of plumes, and even flew through some of them and sampled their composition. Europa’s plumes were spotted by the Hubble Space Telescope, and researchers know far less about them than those on Europa.

“Are they made of water ice? Is hot water vapor being released? What is the temperature of the active regions and the emitted water?” Geronimo Villanueva, lead scientist on the Webbobservation of Europa and Enceladus, said in the statement. “Webb telescope’s measurements will allow us to address these questions with unprecedented accuracy and precision.”

Webb’s observations will help pave the way for the Europa Clipper mission, a $2 billion orbital mission to the icy moon. Scheduled to launch in the 2020s, Europa Clipper will search for signs of life on Europa. The observations with Webb could identify areas of interest for the Europa Clipper mission to investigate, according to the statement.

As seen by Webb, the Saturn moon Enceladus will appear about 10 times smaller than Europa, so scientists will not be able to capture high-resolution views of Enceladus’ surface, according to the statement. However, Webb can still analyze the molecular composition of Enceladus’ plumes. 

But it’s also possible that the observations won’t catch a plume erupting from Europa’s surface; scientists don’t know how frequently these geysers erupt, and the limited observing time with Webb may not coincide with one of them. The telescope can detect organics — elements such as carbon that are essential to the formation of life as we know it — in the plumes. However, Villanueva cautioned that Webb does not have the power to directly detect life-forms in the plumes.

Webb is set to launch in 2018 and will orbit the sun at the L2 Lagrange point, which is about one million miles (1.7 million km) farther from the sun than the Earth’s orbit around the sun. The telescope will provide high-resolution views of both the very distant and very nearby universe. Scientists have already begun submitting ideas for objects or regions that should be observed using Webb’s powerful eye, and Europa and Enceladus are among the objects that are now guaranteed observing time.

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Project Blue Telescope Goes CrowdFunding

September 15, 2017 by  
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The private space telescope initiative Project Blue launched a new crowdfunding campaign Sept. 6 in a second attempt to raise money for its mission to directly image Earth-like exoplanets. 

The initiative aims to launch a small space telescope into low-Earth orbit. The telescope will spy on our interstellar neighbor Alpha Centauri and image any Earth-like planets that might orbit the star system.

In support of Project Blue, BoldlyGo Institute and numerous organizations, including the SETI (Search for Extraterrestrial Intelligence) Institute, the University of Massachusetts Lowell and Mission Centaur, launched an IndieGoGo campaign to raise $175,000 over the next two months. The funds will be used to establish mission requirements, design the initial system architecture and test its capability for detecting exoplanets. Project leaders will also begin looking for potential partners who could manufacture parts of the space telescope, representatives said in a statement. 

“We’re very excited to pursue such an impactful space mission and, as a privately-funded effort, to include a global community of explorers and space science advocates in Project Blue from the beginning,” Jon Morse, CEO of BoldlyGo Institute, said in the statement.

Last year, Project Blue organizers attempted to raise $1 million through the crowdfunding platform Kickstarter, but the campaign was canceled after only $335,597 was contributed and Project Blue received none of the funds (as is Kickstarter’s policy). 

With the IndieGoGo campaign, however, the organizers have a more flexible goal and will be able to keep all contributions from supporters, even if the initial goal of $175,000 is not reached. So far, more than $45,000 has been raised through the campaign.

The neighboring star system Alpha Centauri is located only 4.37 light-years from Earth, making it a target for scientific research. Project Blue estimates it will take about $50 million to build the special-purpose telescope, which is planned to launch in 2021. 

The small space telescope will use a specialized coronagraph to block the bright glare of Alpha Centauri’s stars and detect planets that may be orbiting there. One planet, Proxima b, has already been detected around Proxima Centauri. 

However, Proxima b was discovered indirectly, by measuring the planet’s gravitational effect on its host star. Instead, the Project Blue telescope will be designed to directly image Earth-like planets in Alpha Centauri’s neighborhood.

 

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After 40 Years Voyager Still Moving Through The Galaxy

September 14, 2017 by  
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NASA’s Voyager 1 probe lifted off on Sept. 5, 1977, a few weeks after its twin, Voyager 2. Together, the two Voyager spacecraft performed an epic “Grand Tour” of the solar system’s giant planets, flying by Jupiter, Saturn, Uranus and Neptune.

But their work didn’t stop there. Both spacecraft kept flying, pushing farther and farther into the dark, cold and little-known realms far from the sun. [Voyager: 40 Epic Photos from NASA’s Grand Tour]

Then, on Aug. 25, 2012, Voyager 1 popped free into interstellar space, becoming the first human-made object ever to do so. Voyager 2, which took a different route through the solar system, will likely exit the sun’s sphere of influence in the next few years as well, mission team members have said.

And both spacecraft still have their eyes and ears open, all these decades later.

“It’s amazing that the two spacecraft are still working after 40 years,” said Ed Stone, who has been a Voyager project scientist since the mission’s inception in 1972. [Voyager at 40: An Interview with Ed Stone]

“When we launched, the Space Age itself was only 20 years old, so this is an unparalleled journey, and we’re still in the process of seeing what’s out there,” Stone, who’s based at the California Institute of Technology in Pasadena, told Space.com.

As of Friday (Sept. 1), Voyager 1 was a whopping 12.97 billion miles (20.87 billion kilometers) from Earth — more than 139 times the distance from our planet to the sun. Voyager 2 was about 10.67 billion miles (17.17 billion km) from its home planet.

Voyager 1 cruised by Jupiter in March 1979 and Saturn in November 1980. This latter encounter also included a close flyby of Saturn’s huge moon Titan. [Voyager at 40: NASA Retrospective Videos Look Back]

Voyager 2 pulled off its own Jupiter-Saturn double, flying by those two planets in July 1979 and August 1981, respectively. Then, the spacecraft had encounters with Uranus, in January 1986, and Neptune, in August 1989.

During this Grand Tour, both spacecraft beamed home data that surprised and excited scientists.

For example, before the Voyagers launched, the only known active volcanoes were here on Earth. But Voyager 1 spotted eight erupting volcanoes on the Jupiter moon Io, showing that the little world is far more volcanically active than our own planet. [More Photos from the Voyager 1 and Voyager 2 Probes]

The mission also determined that Titan has a nitrogen-dominated atmosphere, just as Earth does.

“It may, in some important ways, resemble what the Earth’s atmosphere was like before life evolved and created the oxygen that we all breathe,” Stone said.

Furthermore, Voyager observations suggested that the Jupiter moon Europa may harbor an ocean of water beneath its icy crust — a notion that subsequent NASA missions have pretty much confirmed.

“I think what Voyager has done is reveal how diverse the planets and the moons and the rings, and the magnetic fields of the planets, are,” Stone said. “Our terracentric view was just much narrower than, in fact, reality.”

Interstellar ambassadors

Voyager 1 has found that cosmic radiation is incredibly intense beyond the sun’s protective bubble, Stone said. The probe is also revealing how the “wind” of charged particles from the sun interact with the winds of other stars. [5 Surprising Facts About NASA’s Voyager Probes]

Meanwhile, Voyager 2 is studying the environment near the solar system’s edge. After it enters interstellar space, Voyager 2 will make its own measurements, revealing more about this mysterious region.

But this work cannot go on forever.

The Voyagers are powered by radioisotope thermoelectric generators, which convert the heat produced by the radioactive decay of plutonium-238 into electricity. And that heat is waning.

“We have about 10 years or so of power remaining until we have only enough to power the spacecraft itself, without any of the instruments,” Stone said.

But even after the probes power down, they’ll continue speeding through the cosmos for eons, making one lap around the Milky Way every 225 million years.

What if intelligent aliens intercept the Voyagers during this journey? Well, the probes’ makers planned for this unlikely scenario: Both Voyagers carry a copy of the “Golden Record,” which is full of images and sounds of Earth, as well as directions to our planet.

In the far future, the Voyagers will “be our silent ambassadors, with messages about where the place was that sent them so many billions of years earlier,” Stone said.

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Do Trappist-1 Planets Have Enough Water For Alien Life

September 11, 2017 by  
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The new study looks at how much ultraviolet (UV) radiation is received by each of the planets, because this could affect how much water the worlds could sustain over billions of years, according to the study. Lower-energy UV light can break apart water molecules into hydrogen and oxygen atoms on a planet’s surface, while higher-energy UV light (along with X-rays from the star) can heat a planet’s upper atmosphere and free the separated hydrogen and oxygen atoms into space, according to the study. (It’s also possible that the star’s radiation destroyed the planets’ atmospheres long ago.)

The researchers measured the amount of UV radiation bathing the TRAPPIST-1 planets using NASA’s Hubble Space Telescope, and in their paper they estimate just how much water each of the worlds could have lost in the 8 billion years since the system formed.

It’s possible that the six innermost planets (identified by the letters b, c, d, e, f and g), pelted with the highest levels of UV radiation, could have lost up to 20 Earth-oceans’ worth of water, according to the paper. But it’s also possible that the outermost four planets (e, f, g and h — the first three of which are in the star’s habitable zone) lost less than three Earth-oceans’ worth of water.

If the planets had little or no water to start with, the destruction of water molecules by UV radiation could spell the end of the planets’ habitability. But it’s possible that the planets were initially so rich in liquid water that, even with the water loss caused by UV radiation, they haven’t dried up,  according to one of the study’s authors, Michaël Gillon, an astronomer at the University of Liège in Belgium. Gillon was also lead author on two studies that first identified the seven TRAPPIST-1 planets.

“It is very likely that the planets formed much farther away from the star [than they are now] and migrated inwards during the first 10 million years of the system,” Gillon told Space.com in an email.

Farther away from their parent star, the planets might have formed in an environment rich in water ice, meaning the planets could have initially had very water-rich compositions.

“We’re talking about dozens, and maybe even hundreds of Earth-oceans, so a loss of 20 Earth-oceans wouldn’t matter much,” Gillon said. “What our results show is that even if the outer planets were initially quite water-poor like the original Earth, they could still have some water on their surfaces.”

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Was Proxima b Stripped Of It’s Atmosphere Eons Ago

September 7, 2017 by  
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The nearby alien planet Proxima b may have lost the ability to support life long ago, a new study suggests.

If Earth had formed where Proxima b orbits — quite close to a red dwarf star — our planet’s atmosphere would likely have been stripped away by intense stellar radiation fairly quickly, the study found.

“Things can get interesting if an exoplanet holds on to its atmosphere, but Proxima b’s atmospheric loss rates here are so high that habitability is implausible,” co-author Jeremy Drake, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, said in a statement. “This questions the habitability of planets around such red dwarfs in general.”

Proxima b circles the red dwarf Proxima Centauri, which lies just 4.2 light-years from the sun. The roughly Earth-size exoplanet completes one lap around its host star once every 11 Earth days. But, because Proxima Centauri is much dimmer than the sun, this tight orbit puts Proxima b within the habitable zone — the region where liquid water could exist on a planet’s surface. 

This proximity also puts the planet in danger, however. Red dwarfs tend to be quite active, especially in their youths. Charged particles pour out from these stars into space, and the closer a planet orbits to such a star, the more intensely it gets hit by damaging radiation. 

High-energy UV light can knock electrons off molecules in a planet’s atmosphere, producing charged particles (also known as ions). Some of these newly liberated electrons can be energetic enough to escape the planet’s gravity, pulling particles of the opposite charge with them into space.

This atmosphere-stripping stellar activity is one reason many scientists argue that most planets around red dwarfs are not habitable. Because red dwarfs make up roughly three-quarters of the stars in the Milky Way, most of the galaxy’s rocky planets may receive too much radiation for life to evolve.

Planets can have a variety of shields against radiation. One possibility is a thick atmosphere, which can absorb the bulk of radiation hitting a planet. Another is a magnetic field, which can funnel charged particles away from the planet. But magnetic fields aren’t always helpful. 

“The magnetic poles of a planet can be connected to the stellar wind, which provides a pathway for the upper, ionized region of the atmosphere to escape,” said Katherine Garcia-Sage, lead author of the new study and a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

“Energy from the stellar wind is also redirected to the magnetic poles, providing extra energy for escape at these same regions where ions and electrons are able to leave the planet and enter interplanetary space,” told Space.com via email.

So, the same magnetic field that shields a planet can also help funnel away part of its atmosphere.  

To investigate what might be happening with Proxima b, Garcia-Sage and her colleagues did some computer modeling. Their models put an Earth twin — an Earth-size world with an Earth-like magnetic field — at Proxima b’s spot and then buffeted the planet with the appropriate radiation (levels of which were determined using nearly 40 years of observations of Proxima Centauri).

“This was a simple calculation based on average activity from the host star,” Garcia-Sage said in the same statement. “It doesn’t consider variations like extreme heating in the star’s atmosphere or violent stellar disturbances to the exoplanet’s magnetic field — things we’d expect to provide even more ionizing radiation and atmospheric escape.”

Despite the relatively conservative radiation dose, the modeled planet didn’t fare well, the researchers found. Assuming high atmospheric temperatures and a completely open magnetic field, Proxima b could lose an Earth-equivalent atmosphere in only 100 million years, an eye-blink in the 4-billion-year lifetime of the planet, the researchers said. Even with the lowest temperatures and a closed magnetic field, the atmosphere would be stripped in 2 billion years.

Of course, these results assume an Earth-like magnetic field. A stronger or weaker magnetic field could produce different timescales, the scientists said.

“It is not immediately obvious which quantities contribute to a planetary magnetic field and to its strength,” said Chuanfei Dong, a researcher at Princeton University. Dong, who was not involved in the project, studies exoplanet atmospheres.

Candidate contributors include a planet’s radius, conductivity, density and core rotation rate, Dong said, and none of these quantities are known for Proxima b. Because of how the planet was detected, scientists have direct measurements of its mass but not its radius. That means they cannot directly calculate Proxima b’s density, which would yield insights about the planet’s core. Instead, researchers rely on previous studies that link a planet’s mass with its radius.

“The radius of the planet can affect the radius of the electrically conducting fluid core, so it can affect the development and strength of its magnetic field,” Dong told Space.com.

The distance between a planet and its star, and the time the planet takes to orbit, can also play important roles in determining the magnetic field strength, Dong said. That’s due in part to the phenomenon called tidal locking, in which one side of a world permanently faces its star — a common feature of tightly orbiting worlds such as those in the habitable zones of red dwarfs.

Though the new results — which were published last month in The Astrophysical Journal Letters — don’t bode well for the prospect of life on Proxima b, not all hope is lost, Dong said. Geological processes such as volcanic activity could help replenish a planet’s atmosphere, he said. 

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Astronomers Capture First Star Beyond The Sun

August 31, 2017 by  
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A new photo of the red “supergiant”Antares is the best ever captured of a star other than the sun, researchers said.

The image shows Antares’ tumultuous surface and reveals unexpected turbulence in its atmosphere, hinting at some mysterious process that is churning away violently inside the stellar mass, the scientists added.

Located nearly 620 light-years from Earth in the constellation of Scorpio, Antares is a puffy stellar monster, with a mass and diameter 12 times and 700 times that of our sun, respectively. Antares is therefore one of the largest and brightest stars known in our galaxy. It is also nearing the end of its life; astronomers estimate that it will explode as a supernova in just a few thousand years.

Now, using the European Southern Observatory’s Very Large Telescope Interferometer (VLTI) in Chile, astronomers have resolved the turbulent structure in the star’s outermost layers, revealing, for the first time, detail on a distant star’s surface and, possibly, filling in the gaps of our knowledge as to how massive stars die.

“How stars like Antares lose mass so quickly in the final phase of their evolution has been a problem for over half a century,” Keiichi Ohnaka, of the Universidad Católica del Norte in Chile, said in a statement. 

“The VLTI is the only facility that can directly measure the gas motions in the extended atmosphere of Antares — a crucial step towards clarifying this problem,” added Ohnaka, detailing the new finds that waslast week “The next challenge is to identify what’s driving the turbulent motions.”

The VLTI consists of up to four telescopes — a combination of 26.9-foot (8.2 meters) “Unit Telescopes” and smaller 5.9-foot (1.8 m) “Auxiliary Telescopes” — that combine their collected infrared light via interferometry to create a “virtual” telescope 660 feet (200 m) wide. Very high angular resolution of distant objects can therefore be attained, allowing the dramatic, bubbling surface of Antares to be studied in detail. 

Using an instrument called AMBER (Astronomical Multi-BEam combineR), Ohnaka’s team was able to measure the speed of plasma bubbling up from Antares’ interior at different positions and compare these speeds with the average speed of plasma across the whole of the star. From these data, a map of the relative speed of atmospheric gases over the star’s disk could be created. This is the first time that such a map has been created for any star apart from the sun, study team members said.

Immediately, the researchers uncovered a surprise: There appears to be turbulent, low-density gas erupting much farther out from the star than theoretical models predict. Usually, in stars like our sun, convection flows of superheated gases bubble up from near the stars’ cores to the surface, much like the convection flow of water in a boiling kettle. But convection cannot explain Antares’ strange atmosphere, and the researchers conclude that, for the atmospheres of red supergiants, there must be another — as yet unknown — process that drives the motion of material.

Ohnaka is hopeful that the observational techniques demonstrated on Antares may be applied to other stars to see how their atmospheres are structured, perhaps revealing the mystery that drives these turbulent motions. 

“Our work brings stellar astrophysics to a new dimension and opens an entirely new window to observe stars,” he said.

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Astronomers Celebrate 40 Years Of Voyager

August 18, 2017 by  
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Nearly 40 years after lifting off, NASA’s historic Voyager mission is still exploring the cosmos.

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The twin spacecraft launched several weeks apart in 1977 — Voyager 2 on Aug. 20 and Voyager 1 on Sept. 5 — with an initial goal to explore the outer solar system. Voyager 1 flew by Jupiter and Saturn, while its twin took advantage of an unusual planetary alignment to visit Jupiter, Saturn, Uranus and Neptune.

And then the spacecraft kept on flying, for billions and billions of miles. Both remain active today, beaming data home from previously unexplored realms. Indeed, in August 2012, Voyager 1 became the first human-made object ever to reach interstellar space. [Photos from Voyager 1 and 2’s Grand Tour]

The mission’s legacy reached into film, art and music with the inclusion of a “Golden Record” of Earth messages, sounds and pictures designed to give any prospective alien who encountered it an idea of what humanity and our home planet are like. This time capsule is expected to last billions of years.

“I believe that few missions can ever match the achievements of the Voyager spacecraft during their four decades of exploration,” Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA headquarters in Washington, D.C., said in a statement. “They have educated us to the unknown wonders of the universe and truly inspired humanity to continue to explore our solar system and beyond.”

Voyager 2 launched atop a Titan/Centaur rocket on Aug. 20, 1977, from NASA’s Kennedy Space Center in Florida.

The spacecraft are now flying through space far away from any planet or star; their next close encounter with a cosmic object isn’t expected to occur for 40,000 years. Their observations, however, are giving scientists more insight into where the sun’s influence diminishes in our solar system, and where interstellar space begins.

Voyager 1 is nearly 13 billion miles (21 billion kilometers) from Earth and has spent five years in interstellar space. This zone is not completely empty; it contains material left over from stars that exploded as supernovas millions of years ago. The “interstellar medium” (as the space in this region is called) is not a threat to Voyager 1. Rather, it’s an interesting environment that the spacecraft is studying.

Voyager 1’s observations show that the huge bubble of the sun’s magnetic influence, which is known as the heliosphere, protects Earth and other planets from cosmic radiation. Cosmic rays (atomic nuclei traveling almost at the speed of light) are four times less abundant near Earth than they are in interstellar space, Voyager 1 has found.

Voyager 2 is nearly 11 billion miles (18 billion km) from Earth and will likely enter interstellar space in a few years, NASA officials have said. Its observations from the edge of the solar system help scientists make comparisons between interstellar space and the heliosphere. When Voyager 2 crosses the boundary, the two spacecraft can sample the interstellar medium from two different locations at the same time.

“None of us knew, when we launched 40 years ago, that anything would still be working, and continuing on this pioneering journey,” Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena, said in the same statement. “The most exciting thing they find in the next five years is likely to be something that we didn’t know was out there to be discovered.”

Mission designers made the spacecraft robust to make sure they could survive the harsh radiation environment at Jupiter. This included so-called redundant systems — meaning the spacecraft can switch to backup systems if needed — and power supplies that have lasted well beyond the spacecraft’s primary mission.

Each of the spacecraft is powered by three radioisotope thermoelectric generators, which convert the heat produced by the radioactive decay of plutonium-238 into electricity. The power available to each Voyager, however, decreases by about 4 watts per year. This requires engineers to dig into 1970s documentation (or to speak with former Voyager personnel) to operate the spacecraft as its power diminishes.

Even with an eye to efficiency, the last science instrument will have to be shut off around 2030, mission team members have said. But even after that, the Voyagers will continue their journey (albeit without gathering data), flying at more than 30,000 mph (48,280 km/h) and orbiting the Milky Way every 225 million years.

In their four decades in space, the spacecraft have set many records and made key discoveries about the outer solar system and interstellar space. These include:

First and only spacecraft to enter interstellar space (Voyager 1).

First and only spacecraft to fly by all four outer planets (Voyager 2).

First active volcanoes seen beyond Earth, on Jupiter’s moon Io (both Voyagers).

Finding evidence of a subsurface ocean on Jupiter’s moon Europa (both Voyagers).

Discovering an early-Earth-like atmosphere on Saturn’s moon Titan (both Voyagers).

Imaging the chaotic terrain of Uranus’ moon Miranda (Voyager 2).

Imaging icy geysers on Neptune’s moon Triton (Voyager 2).

 

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Will The James Webb Telescope Easily Find Earth Like Planets

August 17, 2017 by  
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The James Webb Space Telescope (JWST), billed as “NASA’s premier observatory of the next decade,” could search for signs of an atmosphere on Proxima b. When it launches next year, JWST will be the most powerful space-based observatory yet, and the largest ever contrcuted. Its 6.5-meter mirror (nearly three times the size of the Hubble Space Telescope’s mirror) is expected to yield insights into the entire universe, ranging from the formation of planets and galaxies to peering at exoplanets in higher resolution than ever before.

There is only so much telescope time for JWST, however, and as with Hubble observations, astronomers will receive access on a competitive basis. Among the many proposals for the telescope that have emerged in recent months following NASA’s solicitation of science projects, a paper accepted for publication in the Astrophysical Journal (a draft version of which is available on Arxiv) suggests using the JWST to probe Proxima b’s atmosphere.

If such observations go forward, the telescope will provide an unparalleled view of Proxima b. JWST is optimized for infrared wavelengths, which can be used to examine a planet’s heat emissions. Because JWST will be orbiting the sun, it won’t be peering through Earth’s atmosphere, whose warmth can interfere with observations.

“Other telescopes are not able to do this,” Ignas Snellan, an astronomy researcher at the University of Leiden in the Netherlands and the paper’s lead author, told Seeker in an email. “Hubble is too small and works in the wrong wavelength range. Current ground-based telescopes cannot touch the mid-infrared because of very high thermal backgrounds, and are in a not enough stable environment, in contrast to JWST, which operates from space.”

The astronomers hope to use JWST to determine whether or not Proxima b has an atmosphere. Snellan said this will be very difficult, because the planet is very faint compared to its parent star. The research team therefore proposes looking for carbon dioxide.

The team’s method “looks for a striking signature that is expected from this molecule at 15 micron, that varies strongly from one wavelength to the next,” Snellan explained. “It will be very challenging, but we think doable.”

Finding carbon dioxide isn’t necessarily a sign of life as we know it. The gas is only found in trace amounts in Earth’s atmosphere (which is mostly made up of nitrogen and oxygen), even though carbon is the primary basis for life on our planet.

But carbon dioxide is a common gas on both Venus, which has a hellishly thick atmosphere, and Mars. Though the Red Planet once had a much thicker atmosphere long ago, today it is very thin. Scientists are still investigating how this atmospheric loss occurred, but suggest that the sun might have pushed light molecules out of Mars’ upper atmosphere that could not be held in by the planet’s gravity. Life may have existed on Mars in the ancient past, but scientists aren’t sure if that was possible then — or even now.

Might Proxima b be hospitable to life? Scientists are eager to look at the exoplanet in more detail, but Snellen notes that even better telescopes will be needed to answer that question. He suggests that the European Extremely Large Telescope could do the job after construction of the massive observatory is completed in the next decade. It would be able to probe for oxygen, which is a more definitive sign of life.

Meanwhile, the Breakthrough Starshot Initiative, which aims to one day send ultra-fast nanoprobes to the Alpha Centauri star system, is planning to soon begin examining the system’s three stars. The initiative recently partnered with the European Southern Observatory’s Very Large Telescope to look for worlds that could be habitable.

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