Tag Archives: exoplanet

Time to Move to Trappist-1

Those bright women and men at NASA have done it again. This time they’ve discovered 7 exoplanets all revolving around the same distant star. The cool news is that on the cosmological distance scale it’s relatively close, only around 40-light years away — a mere 230 trillion miles or so. And, even more fascinating, three of the system’s planets are within the so-called “Goldilocks” habitable zone.

The system is named TRAPPIST-1 (Transiting Planets and Planetesimals Small Telescope). The TRAPPIST telescope in Chile originally discovered 3  exoplanets. Now, using NASA’s Spitzer Space Telescope and the European Southern Observatory’s Very Large Telescope, researchers have upped the total to 7 exoplanets.

I’m ready. Now, just need a spacecraft, and a quick one at that.

From NASA:

NASA’s Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water.

The discovery sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system. All of these seven planets could have liquid water – key to life as we know it – under the right atmospheric conditions, but the chances are highest with the three in the habitable zone.

“This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life,” said Thomas Zurbuchen, associate administrator of the agency’s Science Mission Directorate in Washington. “Answering the question ‘are we alone’ is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.”

Read more here.

Image: An illustration of seven Earth-sized planets observed by NASA’s Spitzer Space Telescope around a tiny, nearby, ultra-cool dwarf star called TRAPPIST-1. Three of these planets are firmly in the habitable zone. Courtesy: NASA.

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Can We Move There?

Pale Red Dot is an international search for an Earth-like exoplanet around the closest star to us, Proxima Centauri. It will use HARPS, attached to ESO’s 3.6-metre telescope at La Silla Observatory, as well as the Las Cumbres Observatory Global Telescope Network (LCOGT) and the Burst Optical Observer and Transient Exploring System (BOOTES). It will be one of the few outreach campaigns allowing the general public to witness the scientific process of data acquisition in modern observatories. The public will see how teams of astronomers with different specialities work together to collect, analyse  and interpret data, which may or may not be able to confirm the presence of an Earth-like planet orbiting our nearest neighbour . The outreach campaign consists of blog posts and social media updates on the Pale Red Dot Twitter account and using the hashtag #PaleRedDot. For more information visit the Pale Red Dot website: http://www.palereddot.org

I’ve been toying with the idea of uprooting and moving to Canada should a certain orange-haired bigot win the US presidential election. But, no offense to Canadians, scientists have just discovered an Earth-like planet a mere 4.25 light-years away, our nearest celestial neighbor.

Can anyone convince Elon Musk (of SpaceX) to get cracking on a suitable spacecraft that will get us there, or at least help us leave, before November 8, 2016? Forget Mars, Proxima Centauri here I come!

From Space.com

The star closest to the sun hosts a planet that may be very much like Earth, a new study reports.

Astronomers have discovered a roughly Earth-size alien world around Proxima Centauri, which lies just 4.2 light-years from our own solar system. What’s even more exciting, study team members said, is that the planet, known as Proxima b, circles in the star’s “habitable zone” — the range of distances at which liquid water could be stable on a world’s surface.

“We hope these findings inspire future generations to keep looking beyond the stars,” lead author Guillem Anglada-Escude, a physics and astronomy lecturer at Queen Mary University of London, said in a statement.”The search for life on Proxima b comes next.” [In Pictures: The Discovery of Planet Proxima b]

The discovery of Proxima b was a long time in the making.

Astronomers have been hunting intensively for planets around Proxima Centauri for more 15 years, using instruments such as the Ultraviolet and Visual Echelle Spectrograph (UVES) and the High Accuracy Radial velocity Planet Searcher (HARPS), both of which are installed on telescopes run by the European Southern Observatory in Chile.

UVES, HARPS and other instruments like them allow researchers to detect the slight wobbles in a star’s movement caused by the gravitational tugs of orbiting planets.

Astronomers found hints of such a wobble back in 2013, but the signal was not convincing, Anglada-Escude said. So he and a number of other researchers launched a campaign to ferret out the planet. They called this effort the Pale Red Dot — a nod to Carl Sagan’s famous description of Earth as a “pale blue dot,” and the fact that Proxima Centauri is a small, dim star known as a red dwarf.

The Pale Red Dot team focused HARPS on Proxima Centauri every night from Jan. 19, 2016, through March 31 of this year. After they combined this new data with UVES observations from 2000 through 2008 and HARPS observations from 2005 through early 2014, the signal of a possible planet came through loud and clear.

Then, after analyzing observations of the star’s brightness made by several other telescopes, Anglada-Escude and his colleagues ruled out the possibility that this signal could be caused by the variable activity of Proxima Centauri.

“The conclusion: We have found a planet around Proxima Centauri,” Anglada-Escude said Tuesday (Aug. 23) during a news conference.

Read the entire story here.

Image: Pale Red Dot, an international search for an Earth-like exoplanet around the closest star to us, Proxima Centauri. It will use HARPS, attached to ESO’s 3.6-metre telescope at La Silla Observatory, as well as the Las Cumbres Observatory Global Telescope Network (LCOGT) and the Burst Optical Observer and Transient Exploring System (BOOTES). It will be one of the few outreach campaigns allowing the general public to witness the scientific process of data acquisition in modern observatories. The public will see how teams of astronomers with different specialities work together to collect, analyse and interpret data, which may or may not be able to confirm the presence of an Earth-like planet orbiting our nearest neighbour. The outreach campaign consists of blog posts and social media updates on the Pale Red Dot Twitter account and using the hashtag #PaleRedDot. For more information visit the Pale Red Dot website : http://www.palereddot.org. Courtesy: ESO/Pale Red Dot – http://www.eso.org/public/images/ann16002a/

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Searching for Signs of Life

Gliese 581 c

Surely there is intelligent life somewhere in the universe. Cosmologists estimate that the observable universe contains around 1,000,000,000,000,000,000,000,000 planets. And, they calculate that our Milky Way galaxy alone contains around 100 billion planets that are hospitable to life (as we currently know it).

These numbers boggle the mind and beg a question: how do we find evidence for life beyond our shores? The decades long search for extraterrestrial intelligence (SETI) pioneered the use of radio telescope observations to look for alien signals from deep space. But, the process has remained rather rudimentary and narrowly focused. The good news now is that astronomers and astrobiologists have a growing toolkit of techniques that allow for much more sophisticated detection and analysis of the broader signals of life — not just potential radio transmissions from an advanced alien culture.

From Quanta:

Huddled in a coffee shop one drizzly Seattle morning six years ago, the astrobiologist Shawn Domagal-Goldman stared blankly at his laptop screen, paralyzed. He had been running a simulation of an evolving planet, when suddenly oxygen started accumulating in the virtual planet’s atmosphere. Up the concentration ticked, from 0 to 5 to 10 percent.

“Is something wrong?” his wife asked.

“Yeah.”

The rise of oxygen was bad news for the search for extraterrestrial life.

After millennia of wondering whether we’re alone in the universe — one of “mankind’s most profound and probably earliest questions beyond, ‘What are you going to have for dinner?’” as the NASA astrobiologist Lynn Rothschild put it — the hunt for life on other planets is now ramping up in a serious way. Thousands of exoplanets, or planets orbiting stars other than the sun, have been discovered in the past decade. Among them are potential super-Earths, sub-Neptunes, hot Jupiters and worlds such as Kepler-452b, a possibly rocky, watery “Earth cousin” located 1,400 light-years from here. Starting in 2018 with the expected launch of NASA’s James Webb Space Telescope, astronomers will be able to peer across the light-years and scope out the atmospheres of the most promising exoplanets. They will look for the presence of “biosignature gases,” vapors that could only be produced by alien life.

They’ll do this by observing the thin ring of starlight around an exoplanet while it is positioned in front of its parent star. Gases in the exoplanet’s atmosphere will absorb certain frequencies of the starlight, leaving telltale dips in the spectrum.

As Domagal-Goldman, then a researcher at the University of Washington’s Virtual Planetary Laboratory (VPL), well knew, the gold standard in biosignature gases is oxygen. Not only is oxygen produced in abundance by Earth’s flora — and thus, possibly, other planets’ — but 50 years of conventional wisdom held that it could not be produced at detectable levels by geology or photochemistry alone, making it a forgery-proof signature of life. Oxygen filled the sky on Domagal-Goldman’s simulated world, however, not as a result of biological activity there, but because extreme solar radiation was stripping oxygen atoms off carbon dioxide molecules in the air faster than they could recombine. This biosignature could be forged after all.

The search for biosignature gases around faraway exoplanets “is an inherently messy problem,” said Victoria Meadows, an Australian powerhouse who heads VPL. In the years since Domagal-Goldman’s discovery, Meadows has charged her team of 75 with identifying the major “oxygen false positives” that can arise on exoplanets, as well as ways to distinguish these false alarms from true oxygenic signs of biological activity. Meadows still thinks oxygen is the best biosignature gas. But, she said, “if I’m going to look for this, I want to make sure that when I see it, I know what I’m seeing.”

Meanwhile, Sara Seager, a dogged hunter of “twin Earths” at the Massachusetts Institute of Technology who is widely credited with inventing the spectral technique for analyzing exoplanet atmospheres, is pushing research on biosignature gases in a different direction. Seager acknowledges that oxygen is promising, but she urges the astrobiology community to be less terra-centric in its view of how alien life might operate — to think beyond Earth’s geochemistry and the particular air we breathe. “My view is that we do not want to leave a single stone unturned; we need to consider everything,” she said.

As future telescopes widen the survey of Earth-like worlds, it’s only a matter of time before a potential biosignature gas is detected in a faraway sky. It will look like the discovery of all time: evidence that we are not alone. But how will we know for sure?

Read the entire article here.

Image: Artist’s Impression of Gliese 581 c, the first terrestrial extrasolar planet discovered within its star’s habitable zone. Courtesy: Hervé Piraud, Latitude0116, Xhienne. Creative Commons Attribution 2.5.

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The Curious Case of the Strange Transit Signal

Something very strange is happening over at KIC 8462852. But, it may not be an alien intelligence.

KIC-8462852–Where-is-the-flux

NASA’s extrasolar, planet-hunting space telescope, found some odd changes in the luminosity of a star — KIC 8462852— located in the constellation of Cygnus, about 1,400 light-years from Earth. In a recent paper submitted to the Royal Astronomical Society, astronomers reported that:

“Over the duration of the Kepler mission, KIC 8462852 was observed to undergo irregularly shaped, aperiodic dips in flux down to below the 20 percent level.”

But despite several years of monitoring, astronomers have yet to come up with a feasible, natural explanation. And, this has conspiracy theorists, alien hunters and SciFi enthusiasts very excited. Could it be a massive alien structure shielding the star, or is there simpler and natural, but less amazing possibility? Occam’s razor could well prevail again, but I certainly hope not in this case.

From Wired:

Last week, astronomers—amateur and pro—got excited about some strange results from the Kepler Space Telescope, the NASA observatory tasked with searching for Earth-like planets. As those planets orbit their own distant suns, periodically blocking light from Kepler’s view, the telescope documents the flickers. But over the last several years, it has picked up a strange pattern of blips from one star in particular, KIC 8462852.

Light from that star dramatically plunges in irregular intervals—not the consistent pattern you’d expect from an orbiting planet. But what could possibly cause such a thing? Gotta be aliens, right? Clearly someone—something—has assembled a megastructure around its sun, like that hollow Celestial head in Guardians of the Galaxy. Or maybe it’s a solar array, collecting energy-giving radiation and preventing light from reaching NASA’s telescope.

This, of course, is almost certainly poppycock. When you’re searching the vast expanse of space, lots of things look like they could be signs of extraterrestrial life. Astronomical observers are constantly looking for tiny glimmers of information in the mess of noise that streams through space toward Earth, and often, things that at first look like signals end up being mirages. This has all happened before; it will all happen again. For example:

Pulsars

In 1967, astronomer Jocelyn Bell was monitoring signals from the Mullard Radio Astronomy Observatory, trying to analyze the behavior of quasars, energy-spewing regions surrounding supermassive black holes within distant galaxies. What she found, though, was a series of regular pulses, always from the same part of the sky, that she labeled LGM-1: Little Green Men. Soon, though, she found similar signals coming from another part of the sky, and realized that she wasn’t seeing messages from two different alien civilizations: It was radiation from a spinning, magnetized neutron star—the first measured pulsar.

Sparks at Parkes

In 1998, astronomers at the 64-meter Parkes radio telescope in Australia started noticing mysterious radio signals called perytons—unexplained, millisecond-long bursts. The researchers there didn’t immediately cry alien, though; they could tell that the radio signals were terrestrial in origin, because they showed up across the entire spectrum monitored by the telescope. They didn’t know until this year, however, exactly where those emissions came from: a microwave oven on the observatory’s campus, which released a short, powerful radio signal when staffers opened its door in the middle of heating.

Read the entire story here.

Image: Flux time series for KIC 8462852 showing different portions of the 4-year Kepler observations. Courtesy: T. S. Boyajian et al, Planet Hunters X. KIC 8462852 – Where’s the flux?

 

 

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The Big Breakthrough Listen

If you were a Russian billionaire with money to burn and a penchant for astronomy and physics what would you do? Well, rather than spend it on a 1,000 ft long super-yacht, you might want to spend it on the search for extraterrestrial intelligence. That’s what Yuri Milner is doing. So, hats off to him and his colleagues.

Though, I do hope any far-distant aliens have similar, or greater, sums of cash to throw at equipment to transmit a signal so that we may receive it. Also, I have to wonder what alien oligarchs spend their excess millions and billions on — and what type of monetary system they use (hopefully not Euros).

From the Guardian:

Astronomers are to embark on the most intensive search for alien life yet by listening out for potential radio signals coming from advanced civilisations far beyond the solar system.

Leading researchers have secured time on two of the world’s most powerful telescopes in the US and Australia to scan the Milky Way and neighbouring galaxies for radio emissions that betray the existence of life elsewhere. The search will be 50 times more sensitive, and cover 10 times more sky, than previous hunts for alien life.

The Green Bank Observatory in West Virginia, the largest steerable telescope on the planet, and the Parkes Observatory in New South Wales, are contracted to lead the unprecedented search that will start in January 2016. In tandem, the Lick Observatory in California will perform the most comprehensive search for optical laser transmissions beamed from other planets.

Operators have signed agreements that hand the scientists thousands of hours of telescope time per year to eavesdrop on planets that orbit the million stars closest to Earth and the 100 nearest galaxies. The telescopes will scan the centre of the Milky Way and the entire length of the galactic plane.

Launched on Monday at the Royal Society in London, with the Cambridge cosmologist Stephen Hawking, the Breakthrough Listen project has some of the world’s leading experts at the helm. Among them are Lord Martin Rees, the astronomer royal, Geoff Marcy, who has discovered more planets beyond the solar system than anyone, and the veteran US astronomer Frank Drake, a pioneer in the search for extraterrestrial intelligence (Seti).

Stephen Hawking said the effort was “critically important” and raised hopes for answering the question of whether humanity has company in the universe. “It’s time to commit to finding the answer, to search for life beyond Earth,” he said. “Mankind has a deep need to explore, to learn, to know. We also happen to be sociable creatures. It is important for us to know if we are alone in the dark.”

The project will not broadcast signals into space, because scientists on the project believe humans have more to gain from simply listening out for others. Hawking, however, warned against shouting into the cosmos, because some advanced alien civilisations might possess the same violent, aggressive and genocidal traits found among humans.

“A civilisation reading one of our messages could be billions of years ahead of us. If so they will be vastly more powerful and may not see us as any more valuable than we see bacteria,” he said.

The alien hunters are the latest scientists to benefit from the hefty bank balance of Yuri Milner, a Russian internet billionaire, who quit a PhD in physics to make his fortune. In the past five years, Milner has handed out prizes worth tens of millions of dollars to physicists, biologists and mathematicians, to raise the public profile of scientists. He is the sole funder of the $100m Breakthrough Listen project.

“It is our responsibility as human beings to use the best equipment we have to try to answer one of the biggest questions: are we alone?” Milner told the Guardian. “We cannot afford not to do this.”

Milner was named after Yuri Gagarin, who became the first person to fly in space in 1961, the year he was born.

The Green Bank and Parkes observatories are sensitive enough to pick up radio signals as strong as common aircraft radar from planets around the nearest 1,000 stars. Civilisations as far away as the centre of the Milky Way could be detected if they emit radio signals more than 10 times the power of the Arecibo planetary radar on Earth. The Lick Observatory can pick up laser signals as weak as 100W from nearby stars 25tn miles away.

Read the entire story here.

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Earth 2.0: Kepler 452b

452b_artistconcept_beautyshot

On July 23, 2015 NASA announced discovery of Kepler 452b, an Earth-like exoplanet, which they dubbed Earth 2.0. Found following a four-year trawl through data from the Kepler exoplanet-hunting space telescope, Kepler 452b is the closest exoplanet yet in its resemblance to Earth. It revolves around its sun-like home star in 380 days at a distance similar to that between Earth and our sun (93 million miles).

Unfortunately, Kepler 452b is a “mere” 1,400 light years away — so you can forget trying to strike up a real-time conversation with any of its intelligent inhabitants. If it does harbor life I have to hope that any sentient lifeforms have taken better care of their home than we earthlings do of our own. Then again, it may be better that the exoplanet hosts only non-intelligent life!

Here’s NASA’s technical paper.

Check out NASA’s briefing here.

Image: Artist rendition of Kepler 452b. Courtesy of NASA. Public Domain.

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Exotic Exoplanets Await Your Arrival

NASA_kepler16b_poster

Vintage travel posters from the late 1890s through to the 1950s colorfully captured the public’s imagination. Now, not to be outdone by the classic works from the Art Nouveau and Art Deco periods, NASA has published a series of its own. But, these posters go beyond illustrating alpine ski resorts, sumptuous hotels and luxurious cruises. Rather, NASA has its sights on exotic and very distant travels — from tens to hundreds of millions of light-years. One such spot is the destination Kepler-16.

Kepler-16 A/B is a binary star system in the constellation of Cygnus that was targeted for analysis by the Kepler exoplanet hunting spacecraft. The star system is home to a Saturn-sized planet Kepler 16b orbiting the red dwarf star, Kepler 16-B, and  is 196 light-years from Earth.

See more of NASA’s travel posters here.

 

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European Extremely Large Telescope

Rendering_of_the_E-ELT

When it is cited in the high mountains in the Chilean coastal desert the European Extremely Large Telescope (or E-ELT) will be the biggest and the baddest telescope to date.  With a mirror having a diameter of around 125 feet, the E-ELT will give observers unprecedented access to the vast panoramas of the cosmos. Astronomers are even confident that when it is fully operational, in about 2030, the telescope will be able to observe exo-planets directly, for the first time.

From the Observer:

Cerro Armazones is a crumbling dome of rock that dominates the parched peaks of the Chilean Coast Range north of Santiago. A couple of old concrete platforms and some rusty pipes, parts of the mountain’s old weather station, are the only hints that humans have ever taken an interest in this forbidding, arid place. Even the views look alien, with the surrounding boulder-strewn desert bearing a remarkable resemblance to the landscape of Mars.

Dramatic change is coming to Cerro Armazones, however – for in a few weeks, the 10,000ft mountain is going to have its top knocked off. “We are going to blast it with dynamite and then carry off the rubble,” says engineer Gird Hudepohl. “We will take about 80ft off the top of the mountain to create a plateau – and when we have done that, we will build the world’s biggest telescope there.”

Given the peak’s remote, inhospitable location that might sound an improbable claim – except for the fact that Hudepohl has done this sort of thing before. He is one of the European Southern Observatory’s most experienced engineers and was involved in the decapitation of another nearby mountain, Cerro Paranal, on which his team then erected one of the planet’s most sophisticated observatories.

The Paranal complex has been in operation for more than a decade and includes four giant instruments with eight-metre-wide mirrors – known as the Very Large Telescopes or VLTs – as well as control rooms and a labyrinth of underground tunnels linking its instruments. More than 100 astronomers, engineers and support staff work and live there. A few dozen metres below the telescopes, they have a sports complex with a squash court, an indoor football pitch, and a luxurious 110-room residence that has a central swimming pool and a restaurant serving meals and drinks around the clock. Built overlooking one of the world’s driest deserts, the place is an amazing oasis. (See box.)

Now the European Southern Observatory, of which Britain is a key member state, wants Hudepohl and his team to repeat this remarkable trick and take the top off Cerro Armazones, which is 20km distant. Though this time they will construct an instrument so huge it will dwarf all the telescopes on Paranal put together, and any other telescope on the planet. When completed, the European Extremely Large Telescope (E-ELT) and its 39-metre mirror will allow astronomers to peer further into space and look further back into the history of the universe than any other astronomical device in existence. Its construction will push telescope-making to its limit, however. Its primary mirror will be made of almost 800 segments – each 1.4 metres in diameter but only a few centimetres thick – which will have to be aligned with microscopic precision.

It is a remarkable juxtaposition: in the midst of utter desolation, scientists have built giant machines engineered to operate with smooth perfection and are now planning to top this achievement by building an even more vast device. The question is: for what purpose? Why go to a remote wilderness in northern Chile and chop down peaks to make homes for some of the planet’s most complex scientific hardware?

The answer is straightforward, says Cambridge University astronomer Professor Gerry Gilmore. It is all about water. “The atmosphere here is as dry as you can get and that is critically important. Water molecules obscure the view from telescopes on the ground. It is like trying to peer through mist – for mist is essentially a suspension of water molecules in the air, after all, and they obscure your vision. For a telescope based at sea level that is a major drawback.

“However, if you build your telescope where the atmosphere above you is completely dry, you will get the best possible views of the stars – and there is nowhere on Earth that has air drier than this place. For good measure, the high-altitude winds blow in a smooth, laminar manner above Paranal – like slabs of glass – so images of stars remain remarkably steady as well.”

The view of the heavens here is close to perfect, in other words – as an evening stroll around the viewing platform on Paranal demonstrates vividly. During my visit, the Milky Way hung over the observatory like a single white sheet. I could see the four main stars of the Southern Cross; Alpha Centauri, whose unseen companion Proxima Centauri is the closest star to our solar system; the two Magellanic Clouds, satellite galaxies of our own Milky Way; and the Coalsack, an interstellar dust cloud that forms a striking silhouette against the starry Milky Way. None are visible in northern skies and none appear with such brilliance anywhere else on the planet.

Hence the decision to build this extraordinary complex of VLTs. At sunset, each one’s housing is opened and the four great telescopes are brought slowly into operation. Each machine is made to rotate and swivel, like football players stretching muscles before a match. Each housing is the size of a block of flats. Yet they move in complete silence, so precise is their engineering.

Read the entire article here.

Image: Architectural rendering of ESO’s planned European Extremely Large Telescope (E-ELT) shows the telescope at work, with its dome open and its record-setting 42-metre primary mirror pointed to the sky. Courtesy of the European Southern Observatory (ESO) / Wikipedia.

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Revisiting Drake

In 1960 radio astronomer Frank Drake began the first systematic search for intelligent signals emanating from space. He was not successful, but his pioneering efforts paved the way for numerous other programs, including SETI (Search for Extra-Terrestrial Intelligence). The Drake Equation is named for him, and put simply, gives an estimate of the number of active, extraterrestrial civilizations with methods of communication in our own galaxy. Drake postulated the equation as a way to get the scientific community engaged in the search for life beyond our home planet.

The Drake equation is:

N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

where:

N = the number of civilizations in our galaxy with which communication might be possible (i.e. which are on our current past light cone); and

R* = the average number of star formation per year in our galaxy

fp = the fraction of those stars that have planets

ne = the average number of planets that can potentially support life per star that has planets

fl = the fraction of planets that could support life that actually develop life at some point

fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)

fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space

L = the length of time for which such civilizations release detectable signals into space

Now, based on recent discoveries of hundreds of extra-solar planets, or exoplanets (those beyond our solar system), by the Kepler space telescope and other Earth-bound observatories, researchers are fine-tuning the original Drake Equation for the 21st century.

From the New Scientist:

An iconic tool in the search for extraterrestrial life is getting a 21st-century reboot – just as our best planet-hunting telescope seems to have died. Though the loss of NASA’s Kepler telescope is a blow, the reboot could mean we find signs of life on extrasolar planets within a decade.

The new tool takes the form of an equation. In 1961 astronomer Frank Drake scribbled his now-famous equation for calculating the number of detectable civilisations in the Milky Way. The Drake equation includes a number of terms that at the time seemed unknowable – including the very existence of planets beyond our solar system.

But the past two decades have seen exoplanets pop up like weeds, particularly in the last few years thanks in large part to the Kepler space telescope. Launched in 2009Movie Camera, Kepler has found more than 130 worlds and detected 3000 or so more possibles. The bounty has given astronomers the first proper census of planets in one region of our galaxy, allowing us to make estimates of the total population of life-friendly worlds across the Milky Way.

With that kind of data in hand, Sara Seager at the Massachusetts Institute of Technology reckons the Drake equation is ripe for a revamp. Her version narrows a few of the original terms to account for our new best bets of finding life, based in part on what Kepler has revealed. If the original Drake equation was a hatchet, the new Seager equation is a scalpel.

Seager presented her work this week at a conference in Cambridge, Massachusetts, entitled “Exoplanets in the Post-Kepler Era”. The timing could not be more prescient. Last week Kepler suffered a surprise hardware failure that knocked out its ability to see planetary signals clearly. If it can’t be fixed, the mission is over.

“When we talked about the post-Kepler era, we thought that would be three to four years from now,” co-organiser David Charbonneau of the Harvard-Smithsonian Center for Astrophysics said last week. “We now know the post-Kepler era probably started two days ago.”

But Kepler has collected data for four years, slightly longer than the mission’s original goal, and so far only the first 18 months’ worth have been analysed. That means it may have already gathered enough information to give alien-hunters a fighting chance.

The original Drake equation includes seven terms, which multiplied together give the number of intelligent alien civilisations we could hope to detect (see diagram). Kepler was supposed to pin down two terms: the fraction of stars that have planets, and the number of those planets that are habitable.

To do that, Kepler had been staring unflinchingly at some 150,000 stars near the constellation Cygnus, looking for periodic changes in brightness caused by a planet crossing, or transiting, a star’s face as seen from Earth. This method tells us a planet’s size and its rough distance from its host star.

Size gives a clue to a planet’s composition, which tells us whether it is rocky like Earth or gassy like Neptune. Before Kepler, only a few exoplanets had been identified as small enough to be rocky, because other search methods were better suited to spotting larger, gas giant worlds.

“Kepler is the single most revolutionary project that has ever been undertaken in exoplanets,” says Charbonneau. “It broke open the piggybank and rocky planets poured out.” A planet’s distance from its star is also crucial, because that tells us whether the temperature is right for liquid water – and so perhaps life – to exist.

But with Kepler’s recent woes, hopes of finding enough potentially habitable planets, or Earth twins, to satisfy the Drake equation have dimmed. The mission was supposed to run for three-and-a-half years, which should have been enough to pinpoint Earth-sized planets with years of a similar length. After the telescope came online, the mission team realised that other sun-like stars are more active than ours, and they bounce around too much in the telescope’s field of view. To find enough Earths, they would need seven or eight years of data.

Read the entire article here.

Image courtesy of the BBC. Drake Equation courtesy of Wikipedia.

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Idyllic Undeveloped Land: Only 1,200 Light Years Away

Humans may soon make their only home irreversibly uninhabitable. Fortunately, astronomers have recently discovered a couple of exo-planets capable of sustaining life. Unfortunately, they are a little too distant — using current technology it would take humans around 26 million years. But, we can still dream.

From the New York Times:

Astronomers said Thursday that they had found the most Earth-like worlds yet known in the outer cosmos, a pair of planets that appear capable of supporting life and that orbit a star 1,200 light-years from here, in the northern constellation Lyra.

They are the two outermost of five worlds circling a yellowish star slightly smaller and dimmer than our Sun, heretofore anonymous and now destined to be known in the cosmic history books as Kepler 62, after NASA’s Kepler spacecraft, which discovered them. These planets are roughly half again as large as Earth and are presumably balls of rock, perhaps covered by oceans with humid, cloudy skies, although that is at best a highly educated guess.

Nobody will probably ever know if anything lives on these planets, and the odds are that humans will travel there only in their faster-than-light dreams, but the news has sent astronomers into heavenly raptures. William Borucki of NASA’s Ames Research Center, head of the Kepler project, described one of the new worlds as the best site for Life Out There yet found in Kepler’s four-years-and-counting search for other Earths. He treated his team to pizza and beer on his own dime to celebrate the find (this being the age of sequestration). “It’s a big deal,” he said.

Looming brightly in each other’s skies, the two planets circle their star at distances of 37 million and 65 million miles, about as far apart as Mercury and Venus in our solar system. Most significantly, their orbits place them both in the “Goldilocks” zone of lukewarm temperatures suitable for liquid water, the crucial ingredient for Life as We Know It.

Goldilocks would be so jealous.

Previous claims of Goldilocks planets with “just so” orbits snuggled up to red dwarf stars much dimmer and cooler than the Sun have had uncertainties in the size and mass and even the existence of these worlds, said David Charbonneau of the Harvard-Smithsonian Center for Astrophysics, an exoplanet hunter and member of the Kepler team.

“This is the first planet that ticks both boxes,” Dr. Charbonneau said, speaking of the outermost planet, Kepler 62f. “It’s the right size and the right temperature.” Kepler 62f is 40 percent bigger than Earth and smack in the middle of the habitable zone, with a 267-day year. In an interview, Mr. Borucki called it the best planet Kepler has found.

Its mate, known as Kepler 62e, is slightly larger — 60 percent bigger than Earth — and has a 122-day orbit, placing it on the inner edge of the Goldilocks zone. It is warmer but also probably habitable, astronomers said.

The Kepler 62 system resembles our own solar system, which also has two planets in the habitable zone: Earth — and Mars, which once had water and would still be habitable today if it were more massive and had been able to hang onto its primordial atmosphere.

The Kepler 62 planets continue a string of breakthroughs in the last two decades in which astronomers have gone from detecting the first known planets belonging to other stars, or exoplanets, broiling globs of gas bigger than Jupiter, to being able to discern smaller and smaller more moderate orbs — iceballs like Neptune and, now, bodies only a few times the mass of Earth, known technically as super-Earths. Size matters in planetary affairs because we can’t live under the crushing pressure of gas clouds on a world like Jupiter. Life as We Know It requires solid ground and liquid water — a gentle terrestrial environment, in other words.

Kepler 62’s newfound worlds are not quite small enough to be considered strict replicas of Earth, but the results have strengthened the already strong conviction among astronomers that the galaxy is littered with billions of Earth-size planets, perhaps as many as one per star, and that astronomers will soon find Earth 2.0, as they call it — our lost twin bathing in the rays of an alien sun.

“Kepler and other experiments are finding planets that remind us more and more of home,” said Geoffrey Marcy, a longtime exoplanet hunter at the University of California, Berkeley, and Kepler team member. “It’s an amazing moment in science. We haven’t found Earth 2.0 yet, but we can taste it, smell it, right there on our technological fingertips.”

Read the entire article following the jump.

Image: The Kepler 62 system: homes away from home. Courtesy of JPL-Caltech/Ames/NASA.

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Looking for Alien Engineering Work

We haven’t yet found any aliens inhabiting exoplanets orbiting distant stars. We haven’t received any intelligently manufactured radio signals from deep space. And, unless you subscribe to the conspiracy theories surrounding Roswell Area 51, it’s unlikely that we’ve been visited by an extra-terrestrial intelligence.

Most reasonable calculations suggest that the universe should be teeming with life beyond our small, blue planet. So, where are all the aliens and why haven’t we been contacted yet? Not content to wait, some astronomers believe we should be looking for evidence of distant alien engineering projects.

From the New Scientist:

ALIENS: where are you? Our hopes of finding intelligent companionship seem to be constantly receding. Mars and Venus are not the richly populated realms we once guessed at. The icy seas of the outer solar system may hold life, but almost certainly no more than microbes. And the search for radio signals from more distant extraterrestrials has so frustrated some astronomers that they are suggesting we shout out an interstellar “Hello”, in the hope of prodding the dozy creatures into a response.

So maybe we need to think along different lines. Rather than trying to intercept alien communications, perhaps we should go looking for alien artefacts.

There have already been a handful of small-scale searches, but now three teams of astronomers are setting out to scan a much greater volume of space (see diagram). Two groups hope to see the shadows of alien industry in fluctuating starlight. The third, like archaeologists sifting through a midden heap on Earth, is hunting for alien waste.

What they’re after is something rather grander than flint arrowheads or shards of pottery. Something big. Planet-sized power stations. Star-girdling rings or spheres. Computers the size of a solar system. Perhaps even an assembly of hardware so vast it can darken an entire galaxy.

It might seem crazy to even entertain the notion of such stupendous celestial edifices, let alone go and look for them. Yet there is a simple rationale. Unless tool-users are always doomed to destroy themselves, any civilisation out there is likely to be far older and far more advanced than ours.

Humanity has already covered vast areas of Earth’s surface with roads and cities, and begun sending probes to other planets. If we can do all this in a matter of centuries, what could more advanced civilisations do over many thousands or even millions of years?

In 1960, the physicist Freeman Dyson pointed out that if alien civilisations keep growing and expanding, they will inevitably consume ever more energy – and the biggest source of energy in any star system is the star itself. Our total power consumption today is equivalent to about 0.01 per cent of the sunlight falling on Earth, so solar power could easily supply all our needs. If energy demand keeps growing at 1 per cent a year, however, then in 1000 years we’d need more energy than strikes the surface of the planet. Other energy sources, such as nuclear fusion, cannot solve the problem because the waste heat would fry the planet.

In a similar position, alien civilisations could start building solar power plants, factories and even habitats in space. With material mined from asteroids, then planets, and perhaps even the star itself, they could really spread out. Dyson’s conclusion was that after thousands or millions of years, the star might be entirely surrounded by a vast artificial sphere of solar panels.

The scale of a Dyson sphere is almost unimaginable. A sphere with a radius similar to that of Earth’s orbit would have more than a hundred million times the surface area of Earth. Nobody thinks building it would be easy. A single shell is almost certainly out, as it would be under extraordinary stresses and gravitationally unstable. A more plausible option is a swarm: many huge power stations on orbits that do not intersect, effectively surrounding the star. Dyson himself does not like to speculate on the details, or on the likelihood of a sphere being built. “We have no way of judging,” he says. The crucial point is that if any aliens have built Dyson spheres, there is a chance we could spot them.

A sphere would block the sun’s light, making it invisible to our eyes, but the sphere would still emit waste heat in the form of infrared radiation. So, as Carl Sagan pointed out in 1966, if infrared telescopes spot a warm object but nothing shows up at visible wavelengths, it could be a Dyson sphere.

Some natural objects can produce the same effect. Very young and very old stars are often surrounded by dust and gas, which blocks their light and radiates infrared. But the infrared spectrum of these objects should be a giveaway. Silicate minerals in dust produce a distinctive broad peak in the spectrum, and molecules in a warm gas would produce bright or dark spectral lines at specific wavelengths. By contrast, waste heat from a sphere should have a smooth, featureless thermal spectrum. “We would be hoping that the spectrum looks boring,” says Matt Povich at the California State Polytechnic University in Pomona. “The more boring the better.”

Our first good view of the sky at the appropriate wavelengths came when the Infrared Astronomical Satellite surveyed the skies for 10 months in 1983, and a few astronomers have sifted through its data. Vyacheslav Slysh at the Space Research Institute in Moscow made the first attempt in 1985, and Richard Carrigan at Fermilab in Illinois published the latest search in 2009. “I wanted to get into the mode of the British Museum, to go and look for artefacts,” he says.

Carrigan found no persuasive sources, but the range of his search was limited. It would have detected spheres around sunlike stars only within 1000 light years of Earth. This is a very small part of the Milky Way, which is 100,000 light years across.

One reason few have joined Carrigan in the hunt for artefacts is the difficulty of getting funding for such projects. Then last year, the Templeton Foundation – an organisation set up by a billionaire to fund research into the “big questions” – invited proposals for its New Frontiers programme, specifically requesting research that would not normally be funded because of its speculative nature. A few astronomers jumped at the chance to look for alien contraptions and, in October, the programme approved three separate searches. The grants are just a couple of hundred thousand dollars each, but they do not have to fund new telescopes, only new analysis.

One team, led by Jason Wright at Pennsylvania State University in University Park, will look for the waste heat of Dyson spheres by analysing data from two space-based infrared observatories, the Wide-field Infrared Survey Explorer (WISE) and the Spitzer space telescope, launched in 2009 and 2003. Povich, a member of this team, is looking specifically within the Milky Way. Thanks to the data from Spitzer and WISE, Povich should be able to scan a volume of space thousands of times larger than previous searches like Carrigan’s. “For example, if you had a sun-equivalent star, fully enclosed in a Dyson sphere, we should be able to detect it almost anywhere in the galaxy.”

Even such a wide-ranging hunt may not be ambitious enough, according to Wright. He suspects that interstellar travel will prove no harder than constructing a sphere. An alien civilisation with such a high level of technology would spread out and colonise the galaxy in a few million years, building spheres as they go. “I would argue that it’s very hard for a spacefaring civilisation to die out. There are too many lifeboats,” says Wright. “Once you have self-sufficient colonies, you will take over the galaxy – you can’t even try to stop it because you can’t coordinate the actions of the colonies.”

If this had happened in the Milky Way, there should be spheres everywhere. “To find one or a few Dyson spheres in our galaxy would be very strange,” says Wright.

Read the entire article after the jump.

Image: 2001: A Space Odyssey, The Monolith. Courtesy of Daily Galaxy.

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Exoplanet Exploration

It wasn’t too long ago that astronomers found the first indirect evidence of a planet beyond our solar system. They inferred the presence of an exoplanet (extrasolar planet) from the periodic dimming or wiggle of its parental star, rather than much more difficult direct observation. Since the first confirmed exoplanet was discovered in 1995 (51 Pegasi b), researchers have definitively  catalogued around 800, and identified another 18,000 candidates. And, the list seems to now grow daily.

If that wasn’t amazing enough researchers now have directly observed several exoplanets and even measured their atmospheric composition.

From ars technica:

The star system HR 8799 is a sort of Solar System on steroids: a beefier star, four possible planets that are much bigger than Jupiter, and signs of asteroids and cometary bodies, all spread over a bigger region. Additionally, the whole system is younger and hotter, making it one of only a few cases where astronomers can image the planets themselves. However, HR 8799 is very different from our Solar System, as astronomers are realizing thanks to two detailed studies released this week.

The first study was an overview of the four exoplanet candidates, covered by John Timmer. The second set of observations focused on one of the four planet candidates, HR 8799c. Quinn Konopacky, Travis Barman, Bruce Macintosh, and Christian Marois performed a detailed spectral analysis of the atmosphere of the possible exoplanet. They compared their findings to the known properties of a brown dwarf and concluded that they don’t match—it is indeed a young planet. Chemical differences between HR 8799c and its host star led the researchers to conclude the system likely formed in the same way the Solar System did.

The HR 8799 system was one of the first where direct imaging of the exoplanets was possible; in most cases, the evidence for a planet’s presence is indirect. (See the Ars overview of exoplanet science for more.) This serendipity is possible for two major reasons: the system is very young, and the planet candidates orbit far from their host star.

The young age means the bodies orbiting the system still retain heat from their formation and so are glowing in the infrared; older planets emit much less light. That makes it possible to image these planets at these wavelengths. (We mostly image planets in the Solar System using reflected sunlight, but that’s not a viable detection strategy at these distances). A large planet-star separation means that the star’s light doesn’t overwhelm the planets’ warm glow. Astronomers are also assisted by HR 8799’s relative closeness to us—it’s only about 130 light-years away.

However, the brightness of the exoplanet candidates also obscures their identity. They are all much larger than Jupiter—each is more than 5 times Jupiter’s mass, and the largest could be 35 times greater. That, combined with their large infrared emission, could mean that they are not planets but brown dwarfs: star-like objects with insufficient mass to engage in hydrogen fusion. Since brown dwarfs can overlap in size and mass with the largest planets, we haven’t been certain that the objects observed in the HR 8799 system are planets.

For this reason, the two recent studies aimed at measuring the chemistry of these bodies using their spectral emissions. The Palomar study described yesterday provided a broad, big-picture view of the whole HR 8799 system. By contrast, the second study used one of the 10-meter Keck telescopes for a focused, in-depth view of one object: HR 8799c, the second-farthest out of the four.

The researchers measured relatively high levels of carbon monoxide (CO) and water (H2O, just in case you forgot the formula), which were present at levels well above the abundance measured in the spectrum of the host star. According to the researchers, this difference in chemical composition indicated that the planet likely formed via “core accretion”— the gradual, bottom-up accumulation of materials to make a planet—rather than a top-down fragmentation of the disk surrounding the newborn star. The original disk in this scenario would have contained a lot of ice fragments, which merged to make a world relatively high in water content.

In many respects, HR 8799c seemed to have properties between brown dwarfs and other exoplanets, but the chemical and gravitational analyses pushed the object more toward the planet side. In particular, the size and chemistry of HR 8799c placed its surface gravity lower than expected for a brown dwarf, especially when considered with the estimated age of the star system. While this analysis says nothing about whether the other bodies in the system are planets, it does provide further hints about the way the system formed.

One final surprise was the lack of methane (CH4) in HR 8799c’s atmosphere. Methane is a chemical component present in all the Jupiter-like planets in our Solar System. The authors argued that this could be due to vigorous mixing of the atmosphere, which is expected because the exoplanet has higher temperatures and pressures than seen on Jupiter or Neptune. This mixing could enable reactions that limit methane formation. Since the HR 8799 system is much younger than the Solar System—roughly 30 million years compared with 4.5 billion years—it’s uncertain how much this chemical balance may change over time.

Read the entire article after the jump.

One of the discovery images of the system obtained at the Keck II telescope using the adaptive optics system and NIRC2 Near-Infrared Imager. The rectangle indicates the field-of-view of the OSIRIS instrument for planet C. Courtesy of NRC-HIA, C. Marois and Keck Observatory.

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The Habitable Exoplanets Catalog

The Habitable Exoplanets Catalog is a fascinating resource for those who dream of starting a new life on a distant world. Only into its first year, the catalog now lists 7 planets outside of our solar system and within our own Milky Way galaxy that could become a future home for adventurous humans — complaints from existing inhabitants notwithstanding. Although, the closest at the moment at a distance of just over 20 light years — Gliese 581g — would take around 200,000 years to reach using current technology.

From the Independent:

An ambitious project to catalogue every habitable planet has discovered seven worlds inside the Milky Way that could possibly harbour life.

Marking its first anniversary, the Habitable Exoplanets Catalog said it had far exceeded its expectation of adding one or two new planets this year in its search for a new earth.

In recent years scientists from the Puerto Rico-based Planetary Habitability Laboratory that runs the catalogue have sharpened their techniques for finding new planets outside our solar system.

Chile’s High Accuracy Radial Veolocity Planet Searcher and the orbiting Kepler Space Telescope are two of the many tools that have increased the pace of discoveries.

The Planetary Habitability Laboratory launched the Habitable Exoplanets Catalog last year to measure the suitability for life of these emerging worlds and as a way to organise them for the public.

It has found nearly 80 confirmed exoplanets with a similar size to Earth but only a few of those have the right distance from their star to support liquid surface water – the presence of which is considered essential to sustain life.

Seven potentially habitable exoplanets are now listed by the Habitable Exoplanets Catalog, including the disputed Gliese 581g, plus some 27 more from NASA Kepler candidates waiting for confirmation.

Although all these exoplanets are superterrans are considered potentially habitable, scientists have not yet found a true Earth analogue.

Read the entire article following the jump.

Image: Current Potential Habitable Exoplanets. Courtesy of CREDIT: PHL @ UPR Arecibo.

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