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Does Oumuamua Change Planetary Science For Researchers

December 29, 2017 by  
Filed under Around The Net

Our solar system’s first-known visitor from another star, the recently discovered object called ‘Oumuamua, could be a bonanza for researchers. With only a brief window of time to observe the cigar-shaped wanderer before it zooms beyond the reach of our best telescopes, astronomers have crammed in observations with the hopes of learning more about this interstellar interloper. Not only is the fast-moving object intriguing in its own right; it may also provide insights about how planetary systems evolve.

‘Oumuamua caught the eyes of astronomers on October 19 this year. Calculations revealed the space rock was traveling at 26 kilometers per second relative to the sun, a rapid clip that along with its extremely elongated orbital trajectory suggested it came from outside the solar system. Telescopes swiftly targeted the object, with most researchers expecting to see a cometary tail trailing from an icy visitor as it approached the sun. But to their surprise, ‘Oumuamua showed none. Instead, it looked more like an asteroid. “It does not a resemble a comet—it had no tail whatsoever,” says Karen Meech, who studies comets at the University of Hawai’i at Mnoa. Meech used NASA’s Hubble Space Telescope and other observatories to examine the mysteriously inert space tourist.

Asteroid or comet—why does it matter? The answer ties into our understanding of how planetary systems grow over time in their natal “protoplanetary” disks around young stars. Newborn giant planets can jostle one another, using their gravity to push each other around. They also lord their size over their smaller neighboring worlds—and especially over the kilometer-scale objects called “planetesimals” left behind as debris from the planet-forming process. When a giant planet throws its weight around, more than half of these planetesimals can wind up hurled from the system. Because most of a typical protoplanetary disk is icy—in 2016 Meech used solar system observations to estimate there were as many as 10,000 icy objects for every rocky object—icy objects should dominate the ejecta.

Location also makes a difference in what gets thrown out. Most gas giants lie on the other side of the “snow line,” a demarcation in a protoplanetary disk where its composition shifts from mostly rock to mostly ice. Objects on the star side are baked dry by starlight and thus predominantly rocky whereas objects on the darker outer side are colder and tend to retain more ice. In our solar system the snow line lies between the orbits of Mars and Jupiter, and astronomers believe that distance is roughly where it started out for other sunlike stars. As outlying gas giants shift their orbits, they become more likely to interact with nearby ices than the more distant rocky material closer-in to the star, adding fuel to the idea that most of the interstellar visitors we observe should be icy—including ‘Oumuamua.

“The population of planetesimals floating in space should be dominated by comets, not by asteroids,” says Sean Raymond, an astronomer at the Laboratory of Astrophysics of Bordeaux in France who models the early solar system. In a recent paper Raymond argues the extrasolar visitor is more like a defunct comet than an asteroid, based on how the exoplanets we’ve observed so far are laid out. “It’s kind of weird that this object ‘Oumuamua doesn’t have any signs of activity.”

‘Oumuamua’s oddball spin could be related to its origins as well. According to new research posted on the preprint server arXiv.org, the visitor is tumbling willy-nilly rather than smoothly rotating on its axis. The researchers, who declined to comment due to embargo concerns, state in their paper “1I/’Oumuamua was likely set tumbling within its parent planetary system, and will remain tumbling well after it has left ours.” ‘Oumuamua’s motion, they speculate, could be due to a long-ago collision with another body or the extreme tidal torqueing it may have experienced during its ejection from its parent planetary system. Alternatively, its spin could come from the jetlike outgassing of icy material vaporizing in sunlight—the process that creates a cometary tail.

But, again, the object did not appear to sprout a tail when it closely approached our sun. If indeed ‘Oumuamua is an icy body, how did it avoid growing a cometary tail? David Jewitt, an astronomer at the University of California, Los Angles, suspects any ice might be buried under a layer of material damaged by the charged particles known as cosmic rays that bombarded ‘Oumuamua while it traveled through space. “The prolonged exposure will toast the surface,” forming a protective crust, he says.

A crust of only half a meter could be enough to shield the ice, Jewitt adds. He calculated how heat could have moved through the object, using solar system analogues because its surface composition is unknown, and found it would not make it very far. “You’d only have to go a meter or two into the surface,” he says, “to reach the ‘interstellar temperature,'”—which is only a few degrees above absolute zero.

Not everyone thinks ‘Oumuamua could be a crusty comet. “I would not expect that volatiles would be sealed up in any particular way,” Meech notes. David Trilling, who studies asteroids at Northern Arizona University, says that although it is possible to strongly irradiate primitive material in the solar system, “it’s not obvious that you can get that irradiated goop on an interstellar object.”

Unfortunately, we are unlikely to ever know what materials comprise ‘Oumuamua because it is moving far too fast on its way out of the solar system for us to have a realistic chance of catching up to it with even our speediest spacecraft. But it left astronomers excited about the next one; they anticipate spotting about one interstellar visitor a year in the near future. If those objects all wind up being rocky, that could mean bad news for our understanding of planet formation. “If the first 10 [objects] were all rocky, then it would mean we’re really off on something important,” Raymond says. Most likely, it would mean the rocky material makes up a far larger portion of the natal disks than expected by the models. “We’d have to be way off on where planetesimals form,” he says.

In a separate paper U.C. Santa Cruz astrophysicist Greg Laughlin estimates that an abundance of rocky interstellar voyagers would require about 200 Earth-masses of debris to be ejected from every planet-hosting star, rather than the 10 Earth-masses current models call for. “It just doesn’t really work,” he says. “It’s just a little too much to ask for.”

If ‘Oumuamua is icy, Laughlin thinks it has important implications for Neptune-size worlds in the outer reaches of other planetary systems, which have been a challenge to observe. Because distant Jupiter-size worlds are only found around roughly one out of every 10 stars, he thinks the ejection of ‘Oumuamua-like objects might need a boost from an as-yet-undiscovered population of icy Neptune-like worlds in Jupiter-free systems.

For now, scientists are waiting for the more tourists from other solar systems to visit—hopefully streaming long tails behind them. “It’s not hopeless,” Jewitt says. “We just have to wait for the next 10 or so to be discovered. If none look like a comet, that would be interesting. It would tell us a little more than just seeing one object.”

Courtesy-Space

Did Rocks Doom Mars

December 27, 2017 by  
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Mars’ destiny as a cold, dry world may have been etched in stone at the planet’s birth.

Much of the water that flowed and sloshed on the Martian surface billions of years ago was sponged up by thirsty rocks and then buried deep underground, in the Red Planet’s mantle, a new study suggests.

This drying-out mechanism was so potent that it likely would have transformed Mars even if the planet hadn’t lost some of its liquid water to space and some to the near subsurface, where it’s locked away as ice, study team members said. 

“We’re suggesting that, irrespective of these two factors, Mars, by virtue of its chemistry, was doomed from the start,” lead author Jon Wade, a geologist at the University of Oxford in England, told Space.com via email. “It was likely inevitable that its water would have been sucked back into its mantle.”

Shortly after its formation, Mars was a relatively warm and wet world, complete with a thick atmosphere, rivers, lakes and likely even oceans. But this life-friendly environment didn’t last: By 3.7 billion years ago, most of the Red Planet’s atmosphere, and pretty much all of its surface water, was gone.

Scientists think the key development in this transition was the shutdown of Mars’ internal dynamo, which led to the loss of the planet’s global magnetic field. This field had protected the Red Planet’s atmosphere from the solar wind, the stream of charged particles flowing from the sun. With the field gone, Mars’ atmosphere was stripped away, and the planet became much colder and drier. (Earth is about 10 times more massive than Mars and, as a result, still has a functioning dynamo and magnetic field.)

Some of Mars’ surface water went underground, where it remains today as ice deposits. And some was split into its constituent hydrogen and oxygen atoms by solar radiation and then lost to space, as happened to the majority of the planet’s air.

But a portion of the Red Planet’s original surface water is still missing, even after these two processes are taken into account. Now, Wade and his team think they know what happened to it.

The researchers modeled how liquid water interacted with lava on the surfaces of ancient Earth and Mars. They determined that, on the Red Planet, these reactions led to the formation of denser, more iron-rich hydrous minerals — a consequence of the fact that Mars’ mantle is more than twice as iron-rich as that of Earth.

This difference has had significant consequences, Wade said.

“On early Earth, hydrated surface rocks would tend to ‘float’ on the surface until they dehydrate, providing a return path of water to the surface,” he said. “However, on [ancient] Mars, these hydrated rocks, bearing dense minerals, may sink into the mantle and act to lock up the water, removing it for good.”

If these rock-water reactions were efficient, they could have sequestered huge amounts of water — the equivalent volume of a global Mars ocean at least 1.9 miles (3 kilometers) deep, Wade added.

The new study, which was published online today (Dec. 20) in the journal Nature, could help researchers better understand why Earth remained capable of supporting surface life, whereas Mars and Venus veered off on their own divergent paths, Wade said. And it could prove helpful to astrobiologists investigating planetary habitability in general, he added.

“It’s perhaps not just a question of ‘about the right place, right size and right-ish chemistry’ when assessing a planet’s long-term suitability for life to evolve,” Wade said. “It’s also important to explore the subtleties, like accretionary history and mantle-rock chemistry. These subtleties may play a significant role on whether the planet’s surface can ‘hang on’ to water for lengths of time that are relevant to the evolution of complex life.”

Courtesy-Space

Astronomers Discover Evaporating Planet With Weird Orbit

December 26, 2017 by  
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Astronomers already knew that the Neptune-mass exoplanet is evaporating; a few years back, a research team spotted the huge, comet-like tail of gas that streams behind GJ 436b as it orbits its small, dim host star. 

Now, a new study reveals there’s something very off about that orbit: It’s highly elliptical and takes the alien world over the star’s poles. (The “normal” case, exhibited by all eight officially recognized planets in Earth’s solar system, is a relatively circular path in line with the star’s equatorial plane.)

“This planet is under enormous tidal forces because it is incredibly close to its star, barely 3 percent of the Earth-sun distance,” study lead author Vincent Bourrier, an astronomer at the University of Geneva in Switzerland, said in a statement. 

“The star is a red dwarf whose lifespan is very long,” Bourrier added. “The tidal forces it induces should have since circularized the orbit of the planet, but this is not the case!”

Bourrier and his colleagues figured this out after analyzing spectrographic observations of GJ 436b, which lies 33 light-years from Earth in the constellation Leo. These observations were made by the High Accuracy Radial velocity Planet Searcher (HARPS) instrument at the European Southern Observatory’s La Silla Observatory in Chile, and HARPS-N (for Northern Hemisphere), which is installed at the Roque de los Muchachos Observatory in the Canary Islands.

The team’s calculations also suggest that GJ 436b did not always sport its peculiar tail. The alien world probably once orbited much farther away from its parent star but was pushed inward at some point, likely by an as-yet-undiscovered sibling planet, study team members said.

“Our next goal is to identify the mysterious planet that has upset this planetary system,” Bourrier said.

The new study was published online Monday (Dec. 18) in the journal Nature.

Courtesy-Space

Were Uranus Moon’s Caused By Uranus Impact

December 22, 2017 by  
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The giant impact from an Earth-size rock that knocked Uranus sideways may have also helped create the tilted planet’s moons, a new study finds.

The poles along which Earth spins are mostly pointed the same way as the poles of the sun and nearly all the other planets of the solar system. However, Uranus is an oddball in that its axis of spin is tilted by a whopping 98 degrees (relative to the plane of the solar system), meaning it essentially spins on its side. No other planet in the solar system is tilted as much — Jupiter is tilted by about 3 degrees, for example, and Earth by about 23 degrees.

Now, researchers in Japan suggest a giant cosmic impact may not only have knocked Uranus on its side, but also created most of the planet’s moons.

Uranus possesses 27 known moons. Eighteen of these moons orbit around the planet’s equator, and these “regular” moons make up 98 percent of the total mass of Uranus’ moons, said study lead author Yuya Ishizawa at Kyoto University in Japan. The other nine moons are “irregular” in that their orbits are skewed away from Uranus’ equator, and prior work suggested these moons were captured after Uranus formed.

In computer simulations, the researchers found that an Earth-size rock striking a newborn Uranus could have helped give the planet its current tilt. At the same time, the simulations found that the rubble from the impact could go on to collapse and form moons with orbits and masses similar to those of Uranus’ actual moons.

“Material from the two bodies is ejected in a debris disk, and finally satellites are formed from the debris disk,” Ishizawa told Space.com. “It is possible to explain the axial tilt and the formation of the regular satellites of Uranus simultaneously.”

Ishizawa noted that the researchers’ initial simulations did predict the formation of a number of moons that would orbit Uranus at distances closer than planet’s actual moons do today. He suggested that further research should investigate how the orbit of such moons might decay over time and potentially end up destroying these moons, explaining their current absence around Uranus.

Ishizawa and his colleagues detailed their findings Dec. 13 at the annual meeting of the American Geophysical Union in New Orleans.

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Are Astronomers On The Verge Of Finding Earth-Like Planets

December 20, 2017 by  
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The art of exoplanet detection is on the upswing, and scientists are perhaps at the cusp of a watershed moment — detecting life on other worlds.

To date, ground- and space-based telescopes have discovered more than 3,500 confirmed planets circling stars other than Earth’s sun. And that number is destined to grow.

Indeed, the discovery of extrasolar planets that are about the same size and mass as Earth has opened the door to scientific debate about the probability that such worlds may be habitable.

Exoplanet finds over the last few years have sparked lots of news stories with terms such as “most habitable planet” or “Earth twin” in the headlines. However, the reality is that we currently have no way to quantitatively assess a planet’s ability to support life, said Elizabeth Tasker, an associate professor in the Department of Solar System Sciences for the Japan Aerospace Exploration Agency and its Institute of Space and Astronautical Science.

“We need to change how we discuss habitability. We talk about habitable planets, but the bottom line is, at the moment, we don’t know,” Tasker told Space.com during the Habitable Worlds 2017 workshop, which was held in Laramie, Wyoming, from Nov. 13 to Nov. 17. The workshop was staged by the Nexus for Exoplanet System Science (NExSS), a NASA research-coordination network dedicated to the study of planetary habitability.

By implying that scientists can measure the degree to which a planet is able to support life, Tasker said, “we undermine future projects” to explore factors such as atmospheric conditions of newly found worlds. She suggested changing both the language and the metrics used in exoplanet exploration, turning toward detectability rather than habitability.

During the workshop, Tasker showed off a “Watch Your Language!” poster that read, in part, “We need to change how we discuss exoplanet metrics. Unless we want to risk destroying our chance to find out if the Earth is unique, we need to stop pretending we already know.”

Tasker said she often winces when she hears the term “Goldilocks zone,” which refers to the region of space around a star where the temperature on a planet’s surface is just right for liquid water (and, by extension, life as we know it).

“People get very excited when they hear ‘Earth-sized’ planet and ‘in the habitable zone,'” Tasker said. “Therefore, they think it must be habitable, but that’s absolutely wrong.”

All it means, she explained, is that you have a planet the same size as Earth that receives a similar level of radiation. But we don’t know if it has a magnetic field. Does it have the kind of rock [necessary] to have a carbon-silicate cycle? Does it even have water at all?

“The term ‘Earth-like’ conjures up images of rolling hills [and] glistening lakes, and some might even start seeing Starbucks,” Tasker said. “We need to emphasize that this does not mean that the planet is definitely Earth-like or habitable. I feel it would just take one sentence of clarification, and everyone would get the idea.”

A key issue is that exoplanet science cuts across diverse research fields.

“It’s interdisciplinary. We don’t use the same jargon when we talk across each other,” Tasker said. “Getting planetary [scientists], Earth scientists and astrophysicists to talk in the same room is one of the most exciting, but challenging areas of exoplanet studies at the moment. Let’s get on the same page. We need to be careful in all areas. I think clarity is going to be the big name of the game for the next few years.”

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Does Pluto Have Buried Oceans

December 7, 2017 by  
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Our solar system may harbor many more potentially habitable worlds than scientists had thought.

Subsurface oceans could still slosh beneath the icy crusts of frigid, faraway worlds such as the dwarf planets Pluto and Eris, kept liquid by the heat-generating tug of orbiting moons, according to a new study. 

“These objects need to be considered as potential reservoirs of water and life,” lead author Prabal Saxena, of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement. “If our study is correct, we now may have more places in our solar system that possess some of the critical elements for extraterrestrial life.”  

Underground oceans are known, or strongly suspected, to exist on a number of icy worlds, including the Saturn satellites Titan and Enceladus and the Jovian moons Europa, Callisto and Ganymede. These oceans are kept liquid to this day by “tidal heating”: The powerful gravitational pull of these worlds’ giant parent planets stretches and flexes their interiors, generating heat via friction.

The new study suggests something similar may be going on with Pluto, Eris and other trans-Neptunian objects (TNOs).

Many of the moons around TNOs are thought to have coalesced from material blasted into space when objects slammed into their parent bodies long ago. That’s the perceived origin story for the one known satellite of Eris (called Dysnomia) and for Pluto’s five moons (as well as for Earth’s moon). 

Such impact-generated moons generally begin their lives in relatively chaotic orbits, team members of the new study said. But over time, these moons migrate to more-stable orbits, and as this happens, the satellites and the TNOs tug on each other gravitationally, producing tidal heat.

Saxena and his colleagues modeled the extent to which this heating could warm up the interiors of TNOs — and the researchers got some intriguing results.

“We found that tidal heating can be a tipping point that may have preserved oceans of liquid water beneath the surface of large TNOs like Pluto and Eris to the present day,” study co-author Wade Henning, of NASA Goddard and the University of Maryland, said in the same statement.

As the term “tipping point” implies, there’s another factor in play here as well. It’s been widely recognized that TNOs could harbor buried oceans thanks to the heat produced by the decay of the objects’ radioactive elements. But just how long such oceans could persist has been unclear. This type of heating peters out eventually, as more and more radioactive material decays into stable elements. And the smaller the object, the faster it cools down.

Tidal heating may do more than just lengthen subsurface oceans’ lives, researchers said.Next Up

“Crucially, our study also suggests that tidal heating could make deeply buried oceans more accessible to future observations by moving them closer to the surface,” said study co-author Joe Renaud, of George Mason University in Virginia. “If you have a liquid-water layer, the additional heat from tidal heating would cause the next adjacent layer of ice to melt.” 

The new study was published online last week in the journal Icarus

Courtesy-Space

Does Space Dust Transport Life Around The Galaxy

November 29, 2017 by  
Filed under Around The Net

It may not take an asteroid strike to transport life from one planet to another.

Fast-moving dust could theoretically knock microbes floating high up in a world’s atmosphere out into space, potentially sending the bugs on a trip to another planet — perhaps even one orbiting a different star, according to a new study.

“The proposition that space-dust collisions could propel organisms over enormous distances between planets raises some exciting prospects of how life and the atmospheres of planets originated,” study author Arjun Berera, a professor in the School of Physics and Astronomy at the University of Edinburgh in Scotland, said in a statement.  

“The streaming of fast space dust is found throughout planetary systems and could be a common factor in proliferating life,” Berera added.

Berera isn’t the first person to propose that organisms could hop from world to world throughout the cosmos. That basic idea, known as panspermia, has been around for thousands of years. It has received renewed interest recently, however, as scientists have demonstrated that some organisms — such as certain bacteria, and micro-animals known as tardigrades — can survive for extended periods in space.

But researchers have generally regarded comet or asteroid impacts as the only viable way to get simple life-forms off a planet and into space, whence they could perhaps blunder their way to a different habitable world. (We won’t consider here the “directed panspermia” idea, which posits that intelligent aliens have seeded the galaxy with life or its building blocks.)

Comet or asteroid impacts do indeed blast rocks from planet to planet. Scientists have found numerous meteorites here on Earth that were once part of Mars — including one known as ALH84001, which some scientists think may preserve signs of ancient Red Planet life.

In the new study, Berera examined what likely happens when bits of interplanetary dust hit molecules and particles in Earth’s atmosphere. This space stuff rains down on us every day, hitting the planet at speeds of between 22,400 mph and 157,000 mph (36,000 to 253,000 km/h).

He calculated that small particles floating at least 93 miles (150 kilometers) above Earth’s surface could theoretically get knocked into space by this wandering dust. It’s unclear if microbes could survive such violent collisions; that’s an area ripe for future research, Berera wrote in the new paper, which has been accepted for publication in the journal Astrobiology. (You can read the study for free at the online preprint site arXiv.org.)

And even if these micro-impacts are invariably fatal, they could still help life get a foothold on other worlds by sending its building blocks — the complex molecules that make up a microbe corpse, for example — out into space, he added.

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Astronomers Find New Alien Planet Suitable For Life

November 21, 2017 by  
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A newfound exoplanet may be one of the best bets to host alien life ever discovered — and it’s right in Earth’s backyard, cosmically speaking.

Astronomers have spotted a roughly Earth-mass world circling the small, dim star Ross 128, which lies just 11 light-years from the sun. The planet, known as Ross 128b, may have surface temperatures amenable to life as we know it, the researchers announced in a new study that will appear in the journal Astronomy & Astrophysics.

Ross 128b is 2.6 times more distant from Earth than Proxima b, the potentially habitable planet found in the nearest solar system to the sun. But Proxima b’s parent star, Proxima Centauri, blasts out a lot of powerful flares, potentially bathing that planet in enough radiation to stunt the emergence and evolution of life, scientists have said. [10 Exoplanets That Could Host Alien Life]

Radiation is likely much less of an issue for Ross 128b, because its parent star is not an active flarer, said discovery team leader Xavier Bonfils, of the Institute of Planetology and Astrophysics of Grenoble and the University of Grenoble Alpes in France.

“This is the closest Earth-mass planet potentially in the habitable zone that orbits a quiet star,” Bonfils told Space.com

Bonfils and his colleagues found Ross 128b using the High Accuracy Radial velocity Planet Searcher (HARPS), an instrument at the European Southern Observatory’s La Silla Observatory in Chile.

As its name suggests, HARPS employs the “radial velocity” method, noticing the wobbles in a star’s movement induced by the gravitational tugs of orbiting planets. (NASA’s prolific Kepler space telescope, by contrast, uses the “transit” technique, spotting tiny brightness dips caused when a planet crosses its host star’s face from the spacecraft’s perspective.)

The HARPS observations allowed Bonfils and his team to determine that Ross 128b has a minimum mass 1.35 times that of Earth, and that the planet orbits its host star once every 9.9 Earth days.

Such a tight orbit would render Ross 128b uninhabitable in our own solar system. But Ross 128 is much cooler than the sun, so the newfound world is likely temperate, the researchers said. Determining whether  the planet is actually capable of supporting life as we know it, however, would require a better understanding of its atmosphere, Bonfils said.

“Ross 128b receives 1.38 times [more] irradiation than Earth from our sun,” he said. “Some models made by theorists say that a wet Earth-size planet with such irradiation would form high-altitude clouds. Those clouds would reflect back to space a large fraction of the incident light, hence preventing too much greenhouse heating. With those clouds, the surface would remain cool enough to allow liquid water at the surface. Not all models agree, though, and others predict this new planet is rather like Venus.

Though both Ross 128 and Proxima Centauri are red dwarfs — the most common type of star in the Milky Way galaxy — they are very different objects.

“Proxima Centauri is particularly active, with frequent, powerful flares that may sterilize (if not strip out) its atmosphere,” Bonfils said. “Ross 128 is one of the quietest stars of our sample and, although it is a little further away from us (2.6x), it makes for an excellent alternative target.”

And the star may indeed be targeted in the not-too-distant-future — by giant ground-based instruments such as the European Extremely Large Telescope, the Giant Magellan Telescope and the Thirty Meter Telescope, all of which are scheduled to be up and running by the mid-2020s.

Such megascopes should be able to resolve Ross 128b and even search its atmosphere for oxygen, methane and other possible signs of life, Bonfils said. (NASA’s $8.9 billion James Webb Space Telescope, which is scheduled to launch in early 2019, probably won’t be able to perform such a biosignature search, the researchers said in their discovery paper. If Ross 128b transited its host star from Webb’s perspective, it would likely be a different story, they added.)

Earlier this year, by the way, radio astronomers detected a strange signal that seemed to be emanating from Ross 128. But further investigation revealed that the signal most likely came from an Earth-orbiting satellite, not an alien civilization.

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Is Another Mission To Pluto Being Planned

October 31, 2017 by  
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A grassroots movement seeks to build momentum for a second NASA mission to the outer solar system, a generation after a similar effort helped give rise to the first one.

That first mission, of course, was New Horizons, which in July 2015 performed the first-ever flyby of Pluto and is currently cruising toward a January 2019 close encounter with a small object known as 2014 MU69.

New Horizons got its start with letter-writing campaigns in the late 1980s, and the new project hopes to duplicate that success, said campaign co-leader Kelsi Singer, a New Horizons team member who’s based at the Southwest Research Institute (SwRI) in Boulder, Colorado.   

Nearly three dozen scientists have drafted letters in support of a potential return mission to Pluto or to another destination in the Kuiper Belt, the ring of icy bodies beyond Neptune’s orbit, Singer told Space.com.Next Up

These letters have been sent to NASA planetary science chief Jim Green, as well as to the chairs of several committees that advise the agency, she added.

“We need the community to realize that people are interested,” Singer said. “We need the community to realize that there are important, unmet goals. And we need the community to realize that this should have a spot somewhere in the Decadal Survey.”

That would be the Planetary Science Decadal Survey, a report published by the National Academy of Sciences that lays out the nation’s top exploration priorities for the coming decade.

“This is the way it normally works,” said New Horizons principal investigator Alan Stern, who’s also based at SwRI.

“First it bubbles up in the community and then, when there’s enough action, the agency starts to get behind it,” Stern, who has been the driving force behind New Horizons since the very beginning, told Space.com. “Then it lets the Decadal Survey sort things out.”

Stern contributed a letter to the new campaign, and he has voiced support for a dedicated Pluto orbiter. Singer would also be happy if NASA went back to the dwarf planet.

“Pluto just has so much going on,” she said.

But there are other exciting options available as well, Singer said. For example, NASA could do a flyby of a different faraway dwarf planet — Eris, perhaps — to get a better idea of the variety and diversity of these intriguing worlds.

Or the agency could target Kuiper Belt objects (KBOs) that have diameters of a few hundred kilometers or so, she added. New Horizons has flown by one “big” KBO (Pluto) and will soon see a small one — 2014 MU69 is just 20 miles (32 km) or so across — but there are no plans at the moment to study anything of an intermediate size up close.

The last Decadal Survey was put out in 2011, and it covers the years 2013 to 2022. The next one is due out in five years, and it will help map out NASA’s plans for the 2020s and early 2030s. So Singer knows she and her colleagues must be patient, even if their letter-writing campaign ultimately bears fruit.

“I would say 25 years is the longest I think about,” she said, referring to how long it may be before another Kuiper Belt mission gets to its destination. “And I hope it may be more like 15 years.”

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Astronomers Discover Prehistoric Lake On Mars Could Have Supported Life

October 6, 2017 by  
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An up-close view of Mars’ rocky deposits by NASA’s Curiosity rover shows a changing climate in the planet’s ancient past that would have left the surface warm and humid enough to support liquid water — and possibly life. Evidence of an ancient lake points to the prospect of two unique habitats within its shores; the lower part of the lake was devoid of oxygen compared to an oxygen-rich upper half. 

In a recent paper published in the journal Science, Redox stratification of an ancient lake in Gale crater,” Stony Brook University geoscientist Joel Hurowitz and his colleagues used more than three years of data retrieved from the rover to paint a picture of ancient conditions at Gale Crater, the lowest point in a thousand kilometers. The site, a 150-mile kilometer crater formed during an impact around 3.8 billion years ago, once flowed with rivers ending in a lake. The sedimentary rocks laid down by these rivers and onto the lakebed tell the story of how the environment changed over time.

Curiosity landed on a group of sedimentary rocks known as the Bradbury group. The rover sampled a part of this group called the Sheepbed mudstones, as well as rocks from the Murray formation at the base of the 5-kilometer high peak at the center of the crater known as Mount Sharp. Both types of rocks were deposited in the ancient lake, but the Sheepbed rocks are older and occur lower in the stratigraphic layers of rocks. Comparing the two types of rocks can lead to interesting revelations about the paleoenvironment. 

Rocks that form at the same time in the same area can nevertheless display differences in composition and other characteristics. These different groupings are known as “facies” and the Murray formation is split into two facies. One is comprised mainly of hematite and phyllosilicate, and given the name HP, while the other is the magnetite-silicate facies, known as MS. 

“The two Murray facies were probably laid down at about the same time within different parts of the lake,” explained Hurowitz. “The former laid down in shallow water, and the latter in deeper water.”

The near-shore HP facies have thicker layers in the rocks compared to the thin layers of the deeper water MS facies. This difference in layer thickness is because the river flowing into the lake would have slowed down and dumped some of its sedimentary material at the lake shore. The flow would then have spread into the lake and dropped finer material into the deeper parts of the lake. 

Curiosity landed on rocks known as the Bradbury group. The Murray formation consist of younger rocks at the base of Mount Sharp. The height is exaggerated in the diagram.

The different mineralogy of the two facies was caused by the lake becoming separated into two layers. Ultraviolet (UV) radiation along with low levels of atmospheric oxygen penetrated the upper part of the lake and acted as oxidants on molecules in the water. These ions of iron (Fe2+) and manganese (Mn2+) were brought to the lake via seepage of groundwater through the lake floor.

When the UV and oxygen interacted with these, they lost electrons, meaning that they had become “oxidized.” The oxidized iron and manganese precipitated into minerals — hematite and manganese oxide — that eventually made up the rocks sampled by Curiosity in the HP facies. However, the UV and oxygen didn’t reach all the way to the lake floor, so the iron and manganese wasn’t oxidized in the deeper part of the lake, and instead became the mineral known as magnetite, making up the MS facies. 

The difference in oxidation of the two facies in the Murray formation due to differences in layers of the lake is known as redox stratification. Identifying redox stratification in the ancient lake shows that there were two completely different types of potential habitat available to any microbial life that might have been present.

The researchers also discovered that the Murray formation has a high concentration of salts, which provide clues relating to evaporation of the lake, and thus the end of the potential habitat. High salinity is a result of water evaporating and leaving salts behind. However, evaporation leaves other tell-tale signs such as desiccation cracks — similar to what you see when mud dries and cracks — and none of these signs appear in the Murray formation. This indicates that the evaporation occurred at a later period of time and that the salts seeped through layers overlying the Murray formation before becoming deposited in the Murray rocks. 

“Curiosity will definitely be able to examine the rocks higher up in the stratigraphy to determine if lake evaporation influenced the rocks deposited in it,” said Hurowitz. “In fact, that’s exactly what the rover is doing as we speak at the area known as Vera Rubin Ridge.”

Once Curiosity examines these rocks, it will be able to confirm that the salts found in the Murray formation came from a later period of evaporation, and therefore no significant evaporation occurred during the time that the Murray formation was deposited, meaning the environment would have been stable enough to support possible life forms.

The inflowing river deposits thicker material (clastics) close to the lake shore, and finer material towards the deeper part of the lake. The incoming UV and O2 oxidizes the iron and manganese in the upper part

Another result of the research is evidence of climate change. The older Sheepbed formation shows very little evidence of chemical weathering compared to the Murray formation. The change to substantial chemical weathering in the younger rocks indicates that the climate likely changed from cold, arid conditions to a warm, wet one. 

“The timing of this climate shift is not something we can tell for sure because we haven’t seen the Sheepbed member and the Murray formation in contact with each other,” said Hurowitz. “If we had, then we might be able to tell if the change in their chemical and mineralogical properties were abrupt (indicating rapid climate change) or gradual. At best, what we can say is that the rocks that we examined were likely deposited over a timespan of tens of thousands of years to as much as around 10 million years.”

The cause of the climate change on Mars is still a matter of debate. If the climate changed in a short period of time, it could have been due to short-term variations or an asteroid impact. A slower change in climate could have been the result of changes in the obliquity cycle of the planet.

The climate change indicated in the rocks shows that the ancient Martian environment would have been warm and humid enough to sustain liquid water on the surface. The redox stratification of the lake as revealed by the different mineralogy in the Murray formation shows that there would have been two different environments within the lake itself. If microbial life was present on Mars at this time, the different potentially habitable niches could have encouraged diversity with anaerobic forms possibly living in the lower depths of the lake. 

“I’m not sure that this was something we would have predicted if we hadn’t had the opportunity to examine Gale’s rock record up close and personal,” adds Hurowitz.

Courtesy-Space

 

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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