alien life

Will NASA’s Next Super Telescope Finally Find Alien Life?

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Following in the footsteps of the James Webb Space Telescope, NASA’s next super telescope in space would be the first specifically designed to search for signs of life on planets orbiting other stars.

Now that the James Webb Space Telescope is fulfilling its mission, NASA has a roadmap for its next massive undertaking: the Habitable Worlds Observatory, with which it hopes to take a picture of an Earth-like planet (and then some).

It takes time to put together a space-based super-observatory. The James Webb, the largest and most complex space telescope ever built, was first conceived in the late 1990s, and was originally targeted for launch by 2010. But because it was so complex, with its series of origami-like folding mirrors and heat shields, development and testing took much longer than expected. It wasn’t until Christmas day of 2021 that the observatory finally launched.

In many ways, the James Webb marks the end of an era—and the beginning of a new one. Throughout the 1990s, NASA launched a series of “Great Observatories,” massive telescopes targeting a specific wavelength range and set of science targets. The James Webb’s predecessor, the Hubble, focused on visible wavelengths of light, while the Spitzer Space Telescope worked with infrared, and the Chandra X-ray Observatory conducted x-rays, of course.

james webb space telescope in deep space research far galaxies jwst and gaalxy space observatory sci fi collage elements of this image furnished by nasa

The James Webb Space Telescope is situated about 9.32 million miles from Earth, peering into the distant universe.

The James Webb, itself, is focused mainly on infrared light from the wider universe, but it has no Great Observatory companion in other wavelength ranges. Plus, because the James Webb needs to actively cool itself to work, in roughly a decade it will run out of fuel and have to power down. These are weaknesses that the astronomical community quickly realized as soon as the telescope’s schedule began to slip.

The Habitable Worlds Observatory, or HWO, is the first step toward filling that gap, complementing the work of the James Webb, and leading the next generation of Great Observatories.

How to Find an Alien, Habitable World

The primary goal of the HWO (which will surely get a better name as time goes on) is exactly what’s on its eponymous label: to observe habitable worlds.

As of the writing of this article, there is no evidence whatsoever of any kind of life— intelligent, or single-celled, or anything in between—existing in the universe. As far as we know, we are completely and utterly alone. But it’s a big universe out there, and we’ve only just started looking in earnest. Our Milky Way galaxy alone is home to roughly 300 billion stars, and at least as many planets (with some estimates suggesting that there are trillions of worlds out there).

Most of those worlds are inhospitable and uninhabitable, just like most of the worlds in the solar system. But a certain fraction of them will be very similar to Earth, with just the right mass and density, and just the right distance from its parent star, to host liquid water on their surfaces—and potentially life. This is a very rough guess, but astronomers believe there are 5–10 billion Earth-like planets orbiting sun-like stars in our galaxy alone.

But if we want to show that any of those planets are full of life, then we have our work cut out for us. The nearest potentially habitable planet will be hundreds, if not thousands, of light years away. We can’t possibly go to those planets and poke around for ourselves, so we’re going to have to find evidence for life remotely.

This is what HWO plans to do, and it will combine two critical pieces of technology to make it happen. One is a giant mirror, at least 18 feet across, comparable to the James Webb’s impressive array. This will allow the HWO to peer into the distant universe and have high enough resolution to take pictures of alien planets.

But those alien planets orbit stars, and the stars themselves give off so much light that the planets will be hiding in their glare. So, the designers of the HWO are exploring options to reduce that glare. One option is a free-flying sunshade, a giant structure resembling a metallic flower that will orbit in tandem with the HWO. The sunshade will block the light of a parent star, allowing the observatory to directly image the target planet.

Another option is a coronagraph, a smaller device built into the main body of the HWO itself that accomplishes a similar function. The James Webb carries a coronagraph, as does the Nancy Grace Roman telescope, an upcoming space mission that will work to survey large portions of the wider universe.

nancy grace roman space telescope in a clean room during assembly

Once it is launched, the Nancy Grace Roman Space Telescope will survey the infrared universe from L2, a vantage point about 930,000 miles from Earth, in the direction opposite the sun.

Either way, the plans for the HWO call for it to directly image at least 25 planets outside the solar system, with the list of candidates provided by the James Webb and complementary ground-based observatories. The HWO will examine the light reflected from the atmospheres of those planets in search of signs of life.

Those signs of life will be anything that throws an atmosphere out of equilibrium. For example, Earth’s atmosphere has way more oxygen than it normally would without life. That’s because oxygen is a byproduct of photosynthesis. Earth also has extra levels of methane, a byproduct of many biological processes, and carbon dioxide, a result of animal respiration. Without life, our atmosphere would look completely different.

The hope is that the HWO will find these kinds of “biosignatures,” the telltale signs of life, in the chemical makeup of the atmospheres of its target worlds through a technique known as spectroscopy. With spectroscopy, astronomers break up light from the target into all of its different wavelengths, known as a spectrum. Individual elements and molecules give off “fingerprints” of specific wavelengths of light. By looking for those fingerprints in the spectrum, astronomers can determine what elements are present in the target, and the relative amounts of those elements. This allows them to figure out what an alien atmosphere is made of all from the comfort of their home (or office).

A Step Forward for Humanity

Currently, the HWO is in the design and planning stages. Astronomers from across the United States have come together to form various working groups to narrow down the science goals, find the best fits in terms of technology, and provide a roadmap for getting the instrument designed, built, and launched. It will be quite a while—perhaps as long as two decades—before the instrument is launched.

But it will be worth it.

Beside its search for life, the HWO will be a premiere astronomical observatory, a successor to the James Webb in the same way that Webb was a successor to Hubble. Astronomers will use the HWO to study the properties of galaxies on the far side of the universe, to watch as cosmic explosions twinkle in the night sky, and to peer into the hearts of nebulae, star-forming regions, and more

And honestly, whichever way it goes will be a step forward for humanity. Either way, we will find definitive signs of life, and we will know we are not alone in the universe (even if the alien world is populated solely by single-celled organisms, we will know that life is possible in the wider cosmos).

Or, we will find nothing, and we will confirm that our fragile world that we call home is that much more rare, precious, and worth preserving.

Old Stars May Be Prime Locations for Finding Alien Life.

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Astronomers have discovered that stars like the Sun experience a significant reduction in magnetic braking as they age, altering our understanding of star evolution and the potential for habitable environments around older stars. Credit: SciTechDaily.com

New studies reveal that older stars have weaker magnetic braking, suggesting that they might be prime locations for finding alien life.

Once upon a cosmic time, scientists assumed that stars apply an eternal magnetic brake, causing an endless slowdown of their rotation. With new observations and sophisticated methods, they now peeked into a star’s magnetic secrets and found it wasn’t what they expected.

The cosmic hotspots for finding alien neighbors might be around stars hitting their midlife crisis and beyond. This groundbreaking study, shedding light on magnetic phenomena and habitable environments, has been published in the Astrophysical Journal Letters.

Discovery of Exoplanets and 51 Pegasi

In 1995, Swiss astronomers Michael Mayor and Didier Queloz announced the first discovery of a planet outside our solar system, orbiting a distant Sun-like star known as 51 Pegasi. Since then, more than 5500 so-called exoplanets have been found orbiting other stars in our galaxy, and in 2019 the two scientists shared a Nobel Prize in Physics for their pioneering work. This week, an international team of astronomers published new observations of 51 Pegasi, suggesting that the current magnetic environment around the star may be particularly favorable for the development of complex life.

Composite image illustrating 51 Pegasi system and its measured magnetic field. The detected “Weak Magnetic Braking” of 51 Peg represents a relatively sudden change that makes the magnetic environment more stable. The current study suggests that the Sun has already made this transition, supporting the development of more complex life. Credit: AIP/J. Fohlmeister, edited

Rethinking Magnetic Braking in Stars

Stars like the Sun are born spinning rapidly, which creates a strong magnetic field that can erupt violently, bombarding their planetary systems with charged particles and harmful radiation. Over billions of years, the rotation of the star gradually slows as its magnetic field drags through a wind flowing from its surface, a process known as magnetic braking. The slower rotation produces a weaker magnetic field, and both properties continue to decline together with each feeding off the other. Until recently, astronomers assumed that magnetic braking continues indefinitely, but new observations have started to challenge this assumption.

New Insights From Advanced Observations

“We are rewriting the textbooks on how rotation and magnetism in older stars like the Sun change beyond the middle of their lifetimes,” says team leader Travis Metcalfe, a senior research scientist at White Dwarf Research Corporation in Golden, Colorado, USA. “Our results have important consequences for stars with planetary systems, and their prospects for developing advanced civilizations.”

Klaus Strassmeier, director at the Leibniz-Institute for Astrophysics in Potsdam, Germany and co-author of the study, adds “This is because weakened magnetic braking also throttles the stellar wind and makes devastating eruptive events less likely.”

Evidence From NASA’s Kepler and TESS Missions

The team of astronomers from the United States and Europe combined observations of 51 Pegasi from NASA’s Transiting Exoplanet Survey Satellite (TESS) with cutting-edge measurements of its magnetic field from the Large Binocular Telescope (LBT) in Arizona using the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI).

Although the exoplanet that orbits 51 Pegasi does not pass in front of its parent star as seen from Earth, the star itself shows subtle brightness variations in the TESS observations that can be used to measure the star’s radius, mass, and age — a technique known as asteroseismology. Meanwhile, the magnetic field of the star imprints a tiny amount of polarization on the starlight, allowing PEPSI on the LBT to create a magnetic map of the stellar surface as the star rotates – a technique known as Zeeman-Doppler Imaging. Together, these measurements allowed the team to evaluate the current magnetic environment around the star.

Previous observations from NASA’s Kepler space telescope already suggested that magnetic braking might weaken substantially beyond the age of the Sun, severing the close relationship between rotation and magnetism in older stars. However, the evidence for this change was indirect, relying on measurements of the rotation rate for stars with a wide range of ages. It was clear that rotation stopped slowing down somewhere near the age of the Sun (4.5 billion years), and that weakened magnetic braking in older stars could reproduce this behavior. However, only direct measurements of a star’s magnetic field can establish the underlying causes, and the targets observed by Kepler were too faint for LBT observations. The TESS mission began collecting measurements in 2018 — similar to Kepler’s observations but for the nearest and brightest stars in the sky, including 51 Pegasi.

Over the past few years, the team began using PEPSI on the LBT to measure the magnetic fields for several TESS targets, gradually building a new understanding of how magnetism changes in stars like the Sun as they grow older. The observations revealed that magnetic braking changes suddenly in stars that are slightly younger than the Sun, becoming more than 10 times weaker at that point, and diminishing further as the stars continue to age. The team attributed these changes to an unexpected shift in the strength and complexity of the magnetic field, and the influence of that shift on the stellar wind. The newly measured properties of 51 Pegasi show that — just like our own Sun — it has already gone through this transition to weakened magnetic braking.

Implications for the Search for Extraterrestrial Life

“It is very gratifying that the LBT and PEPSI were able to reveal a new perspective on this planetary system which played such a pivotal role in exoplanet astronomy,” says Klaus Strassmeier, principal investigator of the PEPSI spectrograph. “This research is an important step forward in the search for life in our galaxy.”

In our own solar system, life’s transition from the oceans onto land occurred several hundred million years ago, coinciding with the time that magnetic braking began to weaken in the Sun. Young stars bombard their planets with radiation and charged particles that are hostile to the development of complex life, but older stars appear to provide a more stable environment. According to Travis Metcalfe, the team’s findings suggest that the best places to look for life outside of our solar system might be around stars that are middle-aged and older.

Will an AI be the first to discover alien life?

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SETI, the search for extraterrestrial intelligence, is deploying machine-learning algorithms that filter out Earthly interference and spot signals humans might miss.

The alien from the 1982 film E.T. the Extra-Terrestrial.
Machine learning is good at picking out unconventional signals that might have come from an E.T.

From the hills of West Virginia to the flats of rural Australia, some of the world’s largest telescopes are listening for signals from distant alien civilizations. The search for extraterrestrial intelligence, known as SETI, is an effort to find artificial-looking electromagnetic-radiation signals that might have come from a technologically advanced civilization in a far-away solar system. A study published today1 describes one of several efforts to use machine learning, a subset of artificial intelligence (AI), to help astronomers sift quickly through the reams of data such surveys yield. As AI reshapes many scientific fields, what promise does it hold for the search for life beyond Earth?

“It is a new era for SETI research that is opening up thanks to machine-learning technology,” says Franck Marchis, a planetary astronomer at the SETI Institute in Mountain View, California.

The problem of big data is relatively new for SETI. For decades, the field was constrained by having hardly any data at all. Astronomer Frank Drake pioneered SETI in 1960, when he pointed a telescope in Green Bank, West Virginia, towards two stars and listened for radio transmissions. Most of the SETI searches that followed were also limited to a small number of stars.

But in 2015, billionaire Yuri Milner funded the biggest SETI programme ever, in Berkeley, California: the Breakthrough Listen project to search one million stars for signs of intelligent life. Using telescopes in West Virginia, Australia and South Africa, the project looks for radio emissions that come from the direction of a star and that change steadily in frequency, as would happen if an alien transmitter were on a planet moving with respect to Earth.

Data blizzard

The trouble is that these searches yield a blizzard of data — including false positives produced by Earthly interference from mobile phones, GPS and other aspects of modern life.

“The biggest challenge for us in looking for SETI signals is not at this point getting the data,” says Sofia Sheikh, an astronomer at the SETI Institute. “The difficult part is differentiating signals from human or Earth technology from the kind of signals we’d be looking for from technology somewhere else out in the Galaxy.”

A radio telescope against a cloudy sky.
The Robert C. Byrd Green Bank Telescope in West Virginia is one of several helping to look for alien civilizations.

Going through millions of observations manually isn’t practical. A common alternative approach is to use algorithms that look for signals matching what astronomers think alien beacons could look like. But those algorithms can overlook potentially interesting signals that are slightly different from what astronomers are expecting.

Enter machine learning. Machine-learning algorithms are trained on large amounts of data and can learn to recognize features that are characteristic of Earthly interference, making them very good at filtering out the noise.

Overlooked signals

Machine learning is also good at picking up candidate extraterrestrial signals that don’t fall into conventional categories and so might have been missed by earlier methods, says Dan Werthimer, a SETI scientist at the University of California, Berkeley.

Peter Ma, a mathematician and physicist at the University of Toronto, Canada, and lead author of today’s paper, agrees. “We can’t always be anticipating what ET might send to us,” he says.

Ma and his colleagues sifted through Breakthrough Listen observations of 820 stars, made using the 100-metre Robert C. Byrd Green Bank Telescope. They built machine-learning software to analyse the data; this netted nearly three million signals of interest but discarded most as Earth-based interference. Ma then manually reviewed more than 20,000 signals and narrowed them down to 8 intriguing candidates.

The search ultimately came up empty — all eight signals disappeared when the team listened again. But the methods could be used on other data, such as a flood of observations from the MeerKAT array of 64 radio telescopes in South Africa, which Breakthrough Listen began using in December. The machine-learning algorithms could also be used on archived SETI data, says Ma, to seek signals that might previously have been overlooked.

Citizen SETI

Machine learning is also at the heart of a separate SETI effort that will launch next month. On 14 February, astronomers at the University of California, Los Angeles (UCLA), will launch a community-science project in which volunteers from the public will sort through images of radio signals and classify them as potential types of interference, to train a machine-learning algorithm to search SETI data from Green Bank.

And AI can help with other stages of the SETI process. Werthimer and his colleagues have used machine learning to come up with a ranking of stars to be observed in an ongoing SETI project that uses the world’s largest single-dish telescope, the 500-metre FAST radio telescope in China.

Still, SETI will probably continue to use a mixture of classical and machine-learning approaches to sort through data, says Jean-Luc Margot, an astronomer at UCLA. Classical algorithms remain excellent at picking up candidate signals, and machine learning is “not a panacea”, he says.

“The machines can’t do it all, yet,” agrees Werthimer.

Source: Nature

Which planets could be ‘possible homes for alien life’? Here’s what research says.

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Scientists Debate Signatures of Alien Life

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Searching for signs of life on faraway planets, astrobiologists must decide which telltale biosignature gases to target.

 

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.

Filming by Tom Hurwitz and Richard Fleming. Editing and motion graphics by Ryan Griffin. Other graphics and images from NASA, the European Southern Observatory and Creative Commons. Music by Podington Bear.

In Theory Video: David Kaplan explores the best ways to search for alien life on distant planets.

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?

Scientists must quickly hone their models and address the caveats if they are to select the best exoplanets to target with the James Webb telescope. Because of the hundreds of hours it will take to examine the spectrum for each planetary atmosphere and the many competing demands on its time, the telescope will likely only observe between one and three earthlike worlds in the habitable “Goldilocks” zones of nearby stars. In choosing from a growing list of known exoplanets, the scientists want to avoid planetary circumstances in which oxygen false positives arise. “We’re looking at maybe putting our eggs, if not all in one basket, at least in only a couple of baskets,” Meadows said, “so it’s important to try and figure out what we should be looking for there. And in particular, how we might get fooled.”

Breath of Life

Oxygen has been regarded as the gold standard since the chemist James Lovelock first contemplated biosignature gases in 1965, while working for NASA on methods of detecting life on Mars. As Frank Drake and other pioneers of astrobiology sought to detect radio signals coming from distant alien civilizations — an ongoing effort called the search for extraterrestrial intelligence (SETI) — Lovelock reasoned that the presence of life on other planets could be deduced by looking for incompatible gases in their atmospheres. If two gases that react with each other can both be detected, then some lively biochemistry must be continually replenishing the planet’s atmospheric supplies.

In Earth’s case, though it readily reacts with hydrocarbons and minerals in the air and ground to produce water and carbon dioxide, diatomic oxygen (O2) comprises a steady 21 percent of the atmosphere. Oxygen persists because it is poured into the sky by Earth’s photosynthesizers — plants, algae and cyanobacteria. They enlist sunlight to strip hydrogen atoms off water molecules, building carbohydrates and releasing the oxygen byproduct as waste. If photosynthesis ceased, the existing oxygen in the sky would react with elements in the crust and drop to trace levels in 10 million years. Eventually, Earth would resemble Mars, with its carbon dioxide-filled air and rusty, oxidized surface — evidence, Lovelock argued, that the Red Planet does not currently harbor life.

But while oxygen is a trademark of life on Earth, why should that be true elsewhere? Meadows argues that photosynthesis offers such a clear evolutionary advantage that it is likely to become widespread in any biosphere. Photosynthesis puts the biggest source of energy on any planet, its sun, to work on the most commonplace of planetary raw materials: water and carbon dioxide. “If you want to have the uber-metabolism you will try and evolve something that will allow you to use sunlight, because that’s where it’s at,” Meadows said.

Diatomic oxygen also boasts strong absorption bands in the visible and near-infrared — the exact sensitivity range of both the $8 billion James Webb telescope and the Wide Field Infrared Survey Telescope (WFIRST), a mission planned for the 2020s. With so many imminent hopes riding on oxygen, Meadows is determined to know “where the gotchas are likely to be.” So far, her team has identified three major nonbiological mechanisms that can flood an atmosphere with oxygen, producing false positives for life. On planets that formed around small, young M-dwarf stars, for instance, intense ultraviolet sunlight can in certain cases boil down the planet’s oceans, creating an atmosphere thick with water vapor. At high altitudes, as VPL scientists reported in the journal Astrobiology last year, intense UV radiation splinters off the lightweight hydrogen atoms. These atoms then escape to space, leaving behind a veil of oxygen thousands of times denser than Earth’s atmosphere.

Because the smallness of M-dwarf stars makes it easier to detect much smaller, rocky planets passing in front of them, they are the intended targets for NASA’s Transiting Exoplanet Survey Satellite (TESS), a planet-finding mission scheduled to launch next year. The earthlike planets that will be studied by the James Webb telescope will be selected from among TESS’s finds. With these candidates on the way, astrobiologists must learn how to distinguish between alien photosynthesizers and runaway ocean boiling. In work that is now being prepared for publication, Meadows and her team show that a spectral absorption band from tetraoxygen (O4) loosely forms when O2 molecules collide. The denser the O2 in an atmosphere, the more molecular collisions occur and the stronger the tetraoxygen signal becomes. “We can look for the [O4] to give us the telltale sign that we’re not just looking at a 1-bar atmosphere with 20 percent oxygen” — an earthlike atmosphere suggestive of photosynthesis — Meadows explained, “we’re looking at something that just has massive amounts of oxygen in it.”

A strong carbon monoxide signal will identify the false positive that Domagal-Goldman first encountered that drizzly morning in 2010. Now a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., he says he isn’t worried about oxygen’s long-term prospects as a reliable biosignature gas. Oxygen false positives only happen in rare cases, he said, “and the planet that has those certain cases is also going to have observational properties that we should be able to detect, as long as we think about it in advance, which is what we’re doing right now.”

He and other astrobiologists are also mindful, though, of oxygen false negatives — planets that harbor life but have no detectable oxygen in their atmospheres. Both the false positives and false negatives have helped convince Sara Seager of the need to think beyond oxygen and explore quirkier biosignatures.

Encyclopedia of Gases

If the diverse exoplanet discoveries of the past decade have taught us anything, it’s that planetary sizes, compositions and chemistries vary dramatically. By treating oxygen as the be-all, end-all biosignature gas, Seager argues, we might miss something. And with a personal dream of discovering signs of alien life, the 44-year-old can’t abide by that.

Even on Earth, Seager points out, photosynthesizers were pumping out oxygen for hundreds of millions of years before the process overwhelmed Earth’s oxygen sinks and oxygen started accumulating in the sky, 2.4 billion years ago. Until about 600 million years ago, judged from a distance by its oxygen levels alone, Earth might have appeared lifeless.

Meadows and her collaborators have studied some alternatives to oxygenic photosynthesis. But Seager, along with William Bains and Janusz Petkowski, are championing what they call the “all-molecules” approach. They’re compiling an exhaustive database of molecules — 14,000 so far — that could plausibly exist in gas form. On Earth, many of these molecules are emitted in trace amounts by exotic creatures huddled in ocean vents and other extreme milieus; they don’t accumulate in the atmosphere. The gases might accrue in other planetary contexts, however. On methane-rich planets, as the researchers argued in 2014, photosynthesizers might harvest carbon from methane (CH4) rather than CO2 and spew hydrogen rather than oxygen, leading to an abundance of ammonia. “The ultimate, long-term goal is [to] look at another world and make some informed guesses as to what life might produce on that world,” said Bains, who splits his time between MIT and Rufus Scientific in the United Kingdom.

Domagal-Goldman agrees that thinking both deeply about oxygen and broadly about all the other biochemical possibilities is important. “Because all these surprises have happened in our detections of the masses and radii and orbital properties of these other worlds,” he said, “[astronomers] are going to keep pushing on the people like me who come from an earth sciences background, saying, ‘Let’s think further outside the box.’ That is a healthy and necessary pressure.”

Meadows, however, questions the practicality of the all-molecules approach. In a 3,000-word email critiquing Seager’s ideas, she wrote, “After you build this exhaustive database, how do you identify those molecules that are most likely to be produced by life? And how do you identify their false positives?” She concluded: “You will still have to be guided by life on Earth, and our understanding of planetary environments and how life interacts with those environments.”

In contemplating what life might be like, it’s exasperatingly difficult to escape the only data point we have — for now.

Uncertain Odds

At a 2013 symposium, Seager presented a revised version of the Drake equation, Frank Drake’s famous 1961 formula for gauging the odds that SETI would succeed. Whereas the Drake equation multiplied a string of mostly unknown factors to estimate the number of radio-broadcasting civilizations in the galaxy, Seager’s equation estimates the number of planets with detectable biosignature gases. With the modern capacity to look for any life regardless of whether it’s intellectually capable of beaming messages into space, the calculation of our chances of success no longer depends on uncertainties like the rareness of intelligence as an evolutionary outcome or the galactic popularity of radio technology. However, one of the biggest unknowns remains: the probability that life will arise in the first place on a rocky, watery, atmospheric planet like ours.

“Abiogenesis,” as the mystery event is called, seems to have occurred not long after Earth accumulated liquid water, leading some to speculate that life might start up readily, even inevitably, under favorable conditions. But if so, then shouldn’t abiogenesis have happened multiple times in Earth’s 4.5-billion-year history, spawning several biochemically distinct lineages rather than a monoculture of DNA-based life? John Baross, a microbiologist at the University of Washington who studies the origins of life, explained that abiogenesis might well have happened repeatedly, creating a menagerie of genetic codes, structures and metabolisms on early Earth. But gene-swapping and Darwinian selection would have merged these different upstarts into a single lineage, which has since colonized virtually every environment on Earth, preventing new upstarts from gaining ground. In short, it’s virtually impossible to tell whether abiogenesis was a fluke event, or a common occurrence — here, or elsewhere in the universe.

Scheduled to speak last at the symposium, Seager set a light-hearted tone for the after party. “I put it all in our favor,” she said, positing that life has a 100 percent chance of arising on Earth-like planets, and that half of these biospheres will produce detectable biosignature gases — another uncertainty in her equation. Crunching these wildly optimistic numbers yielded the prediction that two signs of alien life would be found in the next decade. “You’re supposed to laugh,” Seager said.

Meadows, Seager and their colleagues agree that the odds of such a detection this decade are slim. Though the prospects will improve with future missions, the James Webb telescope would have to get extremely lucky to pick a winner in its early attempts. And even if one of its targeted planets does harbor life, spectral measurements are easily foiled. In 2013, the Hubble Space Telescope monitored the starlight passing through the atmosphere of a midsized planet called GJ 1214b, but the spectrum was flat, with no chemical fingerprints at all. Seager and her collaborators reported in Nature that a high-altitude layer of clouds appeared to have obscured the planet’s sky from view.

Finding Alien Life May Require Giant Telescopes Built in Orbit

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Influential astrophysicists, roboticists and astronauts say that orbital construction could spark a renaissance in space science and exploration

Finding Alien Life May Require Giant Telescopes Built in Orbit
Astronauts repair and upgrade the Hubble Space Telescope during the first servicing mission to that orbital observatory, in 1993. NASA is now studying how telescopes far larger than Hubble might someday be assembled and serviced in space by astronauts or robots. Credit: NASA

After snapping the final piece into place with a satisfying “click” she feels through her spacesuit gloves, the astronaut pauses to appreciate the view. Her reflection swims before her in a silvery disk the size of three tennis courts; for a moment she feels like a bug floating on a darkened pond. Composed of hundreds of interlocking metallic hexagons like the one she has just installed, the disk is a colossal mirror 30 meters wide, the starlight-gathering eye of the largest space telescope ever built. From her perch on the robotic arm of a small space station, Earth is a tiny blue and white orb she could cover with an outstretched thumb, dwarfed by the bright and silent moon spinning thousands of kilometers below her feet.

Although this scene remains the stuff of science fiction, an ad hoc assemblage of scientists, engineers and technocrats now say it is well on its way to becoming reality. Under the auspices of a modest NASA-sponsored initiative, this diverse group is gauging how the space agency might build bigger, better space telescopes than previously thought possible—by constructing and servicing them in space. The effort, formally known as the “in-Space Assembled Telescope” study (iSAT), is part of a long trend in which science advances by piggybacking on technologies created for more practical concerns.

For example, the development of surveillance satellites and warhead-carrying rockets during the 20th-century cold war also catalyzed the creation of robotic interplanetary probes and even NASA’s crewed Apollo lunar missions. Similarly, in the 21st century a soaring military and industrial demand for building and servicing satellites in orbit could lead to dramatically enhanced space telescopes capable of definitively answering some of science’s biggest questions—such as whether or not we are alone. “The iSAT is a program that can be NASA’s next Apollo,” says study member Matt Greenhouse, an astrophysicist at the space agency’s Goddard Space Flight Center. “And the science enabled by the iSAT would likely include discovery of extraterrestrial life—an achievement that would eclipse Apollo in terms of impact on humanity.”

Ready for Prime Time

In some respects, building and repairing spacecraft in space is a revolution that has already arrived, merely kept under the radar by a near-flawless track record that makes it seem deceptively routine. Two of NASA’s pinnacle projects—the International Space Station (ISS) and the Hubble Space Telescope—owe their existence to orbital construction work. Assembled and resupplied in orbit over two decades, the ISS is now roughly as big as a football field and has more living space than a standard six-bedroom house. And only space-based repairs allowed Hubble to become the world’s most iconic and successful telescope, after a space shuttle crew on a first-of-its-kind servicing mission in 1993 fixed a crippling defect in the observatory’s primary mirror. Astronauts have since conducted four more Hubble servicing missions, replacing equipment and upgrading instruments to leave behind an observatory reborn.

An artist’s rendition of the upcoming Dragonfly mission, a collaboration between NASA and Space Systems Loral to demonstrate technologies required for orbital construction. Dragonfly’s robotic arm (inset) will assemble and deploy reflectors to create a large radio antenna when the mission launches sometime in the 2020s. Credit: NASA and SSL

Today multiple projects are carrying the momentum forward from those pioneering efforts, cultivating powerful new capabilities. Already NASA and the Pentagon’s Defense Advanced Research Projects Agency (DARPA) as well as private-sector companies such as Northrop Grumman and Space Systems Loral (SSL) are building robotic spacecraft for launch in the next few years on lengthy missions to refuel, repair, re-position and upgrade governmental and commercial satellites. Those spacecraft—or at least the technologies they demonstrate—could also be used to assemble telescopes and other large structures in space such as those associated with NASA’s perennial planning (pdf) for human missions to the moon and Mars. Last year—under the auspices of a “partnership forum” between NASA, the U.S. Air Force and National Reconnaissance Office—the space agency took the lead on crafting a national strategy for further public and private development of in-space assembly in the 2020s and beyond.

These trends could end what some experts see as a “dark age” in space science and exploration. “Imagine a world where once your car runs low on fuel, instead of driving to the gas station you take it to the junkyard and abandon it. Imagine a world where once you’ve moved into your house for the first time you have no way of ever getting more groceries inside, having a plumber come to fix a leaky pipe or any way to bring in and install a new TV. Imagine a world where we all live in tents that we can carry on our backs and no one thinks to build anything larger or more permanent. That seems crazy, doesn’t it?” says iSAT study member Joe Parrish, a program manager for DARPA’s Tactical Technology Office who helms its Robotic Servicing of Geosynchronous Satellites (RSGS) mission. “But that’s exactly the world we live in right now with our $1-billion–class assets in space. … I think we will look back on the era before on-orbit servicing and assembly the way we now look back on the era when leeches were used to treat diseases.”

Bigger Is Better

The fundamental reality behind the push for in-space assembly is easy to understand: Anything going to space must fit within the rocket taking it there. Even the very biggest—the mammoth 10-meter rocket fairing of NASA’s still-in-development Space Launch System (SLS)—would be unable to hold something like the ISS or even the space agency’s smaller “Gateway,” a moon-orbiting space station proposed for the 2020s. Launching such megaprojects piece by piece, for orbital assembly by astronauts or robots, is literally the only way to get them off the ground. And coincidentally, even though massive “heavy lift” rockets such as the SLS remain ruinously expensive, the midsize rockets that could support orbital assembly with multiple launches are getting cheaper all the time.

The forces demanding supersize space telescopes are straightforward, too: The larger a scope’s light-collecting mirror is, the deeper and finer its cosmic gaze. Simply put, bigger is better when it comes to telescopes—especially ones with transformative objectives such as tracking the coalescence of galaxies, stars and planets throughout the universe’s 13.8-billion-year history, learning the nature of dark matter and dark energy, and seeking out signs of life on habitable worlds orbiting other stars. Most of today’s designs for space telescopes pursuing such alluring quarry cap out with mirrors as wide as 15 meters—but only because that is the approximate limit of what could be folded to fit within a heavy-lift rocket like the SLS.

Astronomers have long fantasized about building space observatories even bigger, with mirrors 30 meters wide or more—rivaling the sizes of ground-based telescopes already under construction for the 2020s. Assembled far above our planet’s starlight-scattering atmosphere, these behemoths could perform feats the likes of which ground-based observers can only dream, such as taking pictures of potentially Earth-like worlds around a huge sample of other stars to determine whether those worlds are actually habitable—or even inhabited. If our own Earth is any example to go by, life is a planetary phenomenon that can transform the atmosphere and surface of its home world in clearly recognizable ways; provided, that is, one has a telescope big enough to see such details across interstellar distances.

A recent “Exoplanet Science Strategy” report from the National Academies of Sciences, Engineering and Medicine said NASA should take the lead on a major new space telescope that begins to approach that grand vision—something capable of surveying hundreds (or at least dozens) of nearby stars for snapshots of potential exo-Earths. That recommendation (itself an echo from several previous prestigious studies) is reinforced by the core conclusion of another new Academies report which calls for the agency to make the search for alien life a more fundamental part of its future space exploration activities. These reports build on the growing consensus that our galaxy likely holds billions of potentially habitable worlds, courtesy of statistics from NASA’s recently deceased Kepler space telescope and the space agency’s newly launched Transiting Exoplanet Survey Satellite. Whether viewed through the lens of scientific progress, technological capability or public interest, the case for building a life-finding space telescope is stronger than ever before—and steadily strengthening. Sooner or later it seems NASA will find itself tasked with making this longed-for giant leap in the search for life among the stars.

How big such a telescope must be to offer a reasonable chance of success in that interstellar quest depends on life’s still-unknown cosmic prevalence. With a bit of luck, one with a four-meter mirror might suffice to hit the jackpot, locating an inhabited exo-Earth around one of our sun’s nearest neighboring stars. But if the cosmos is less kind and the closest life-bearing worlds are much farther away, something in excess of the 15-meter limit imposed by near-future rockets could be necessary to sniff out any living planets within our solar system’s corner of the galaxy. In short, in-space assembly may offer the only viable path to completing the millennia-long effort to end humanity’s cosmic loneliness.

An artist’s rendition of the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR), a concept for a future life-finding space telescope under investigation by NASA. The largest version of LUVOIR would boast a primary mirror 15 meters wide, bringing it to the limit of what could fit within the world’s largest rockets. Credit: NASA and GSFC

Decadal Dreams

“Scientists have already hit a design constraint to achieve the science they want to advance,” says Nick Siegler, an astrophysicist at NASA’s Jet Propulsion Laboratory (JPL) and chief technologist of the space agency’s Exoplanet Exploration Program. “What if that particular constraint did not exist? This is what in-space assembly offers—the opportunity to push the boundaries, both in scientific discoveries and human exploration.” Along with Harley Thronson, a senior scientist at NASA Goddard, and Rudra Mukherjee, a JPL roboticist, Siegler formed what would become the Future Assembly and Servicing Study Team (FASST) in late 2016, organizing the group’s inaugural meeting at an astrophysics conference in Texas in early 2017.

The iSAT study is the first NASA-funded FASST activity, but probably not the last. The team aims to be more than just another group of cloistered academics proffering pie-in-the-sky ideas. Its membership includes level-headed spaceflight veterans such as John Grunsfeld, a former astronaut and head of NASA’s science programs who served as an orbital repairman on three of the five Hubble servicing missions. The team’s intention, Grunsfeld and other participants say, is less to persuade the space agency to champion in-space telescope assembly, and more to clarify the approach’s potential benefits and drawbacks. “Assembly of telescopes in space will clearly yield bigger telescopes, but answers to the why, what, how, risk, cost and when to do in-space assembly do not yet exist,” says team member Ron Polidan, a now-retired expert in space technology development at NASA and Northrop.

What is already certain, though, is time is running out for the group to have a meaningful impact on NASA’s near-future plans. The team is now conducting frequent teleconferences, sprinting to complete a “proof of concept” study examining the in-space assembly of a hypothetical telescope with a 20-meter mirror. What would such a telescope’s modular components be, where in space would it be built and operated, which rockets and spacecraft would support it and how many launches would be required? Would the telescope’s pieces be assembled by astronauts or by robots? And, perhaps most importantly, could in-space assembly become a cost-competitive approach to building smaller space telescopes that would otherwise follow the tradition of being stowed and deployed from a single rocket? The iSAT team’s report will address such questions when it appears in the spring of next year.

A schematic illustration of the iSAT study’s “proof of concept” design, a hypothetical telescope with a 20-meter mirror designed for space-based robotic assembly and servicing. A starlight-blocking, telescope-cooling “sunshade” is shown behind the honeycomb-like segmented primary mirror as well as beneath the truss-mounted instrument bay. Such an observatory could be built in increments, progressively increasing in capability as new instruments and additional primary mirror segments are launched from Earth and installed. Credit: NASA, JPL-Caltech and R. Mukherjee et al.

That timing is important for potentially influencing the final design of NASA’s proposed lunar Gateway, which could be used as a deep-space construction platform. The iSAT study’s timing also overlaps with the onset of the astrophysics “Decadal Survey,” a once-every-10-year process in which the U.S. research community creates a prioritized list of recommended future projects for NASA and Congress to follow. The Decadal Survey’s most impactful recommendation would be a multibillion-dollar space telescope for the 2030s—a “flagship” project, the largest class of science mission the space agency undertakes.

Four NASA-sponsored Science and Technology Definition Team (STDT) studies are presently underway in anticipation of the Decadal Survey, each developing a unique flagship concept and associated suite of science objectives based on scientific, technological and budgetary considerations. According to Siegler and other NASA officials, the largest designs from two of the four STDT studies—both with exoplanet-imaging as a foremost goal—have already reached either the size or weight limitations of the most powerful version of NASA’s nascent SLS heavy-lift rocket. But as of yet none of the four studies have incorporated meaningful considerations of in-space assembly techniques.

Siegler, for one, is not surprised. “The STDTs are all doing a great job coming up with compelling science while also trying to minimize their mission cost,” he says. “[In-space assembly] has not yet shown how it can reduce cost, and from their perspective it may appear as an increase in complexity. The onus is on our study to show where the benefits are, if they actually exist.”

Polidan offers a blunter assessment. “A few community members have suggested to me personally that we wait and do the iSAT study until after the Decadal Survey,” he says. “All these comments are due to the current lack of a detailed definition of assembling telescopes in space, and a fear that it will look ‘too good,’ and somehow influence the Decadal committee to go down a path that is too risky or too costly for astrophysics.”

Webb’s Cautionary Tale

A new very large space telescope might be a hard sell for many in the U.S. astrophysics community, regardless of whether it is built on the ground or in space. Either approach could prove a bridge too far for NASA, based on the space agency’s problem-plagued flagship next in line to launch: the James Webb Space Telescope, which seeks to glimpse the universe’s very first stars and galaxies. “People are still traumatized by what happened with Webb, and rightfully so—they are worried that something similar will happen again,” says Scott Gaudi, an astronomer at The Ohio State University and co-author of the “Exoplanet Science Strategy” report.

The project hinges on the nail-biting self-deployment of a foldable 6.5-meter mirror and an even larger “sunshield”—each the largest ever launched—as the observatory travels to a dark, quiet point past the moon and beyond ready repair or servicing by NASA’s astronaut corps. Ensuring all will go as planned has proved enormously expensive. From a notional projected budget of $1.6 billion in 1996 and a potential launch date as early as 2007, Webb’s actual price tag has ballooned to nearly $10 billion, and the telescope’s launch is now slated for no earlier than 2021. The funds to pay for Webb’s overruns have come in part from cannibalizing many other worthy projects, to the overall detriment of NASA’s space-science portfolio and near-universal consternation of researchers.

The James Webb Space Telescope’s scientific instruments and optical elements—including its gold-plated 6.5-meter primary mirror—emerge from cryogenic testing at NASA Johnson Space Center in Houston on December 1, 2017. Credit: NASA

“Going into the Decadal Survey, my fear is that the Decadal committee will be so frightened of cost that they won’t recommend any flagship,” says one prominent astrophysicist who asked to remain anonymous. “And if the Decadal—the community, really—is too shy and doesn’t recommend a large strategic mission, then it becomes a self-fulfilling prophecy that there simply will not be one.” That, in turn, could lead to the U.S. ceding its preeminence in the field of space-based astronomy to competing nations, namely China, which has plans of its own for in-space assembly—including taikonaut-tended orbital observatories. The resulting exodus of scientists and engineers for fairer international shores could devastate U.S. space science for generations, with far-reaching consequences for the nation’s continuance as a global superpower.

“A Damn Good Reason to Do It”

Whether all this makes Webb a testament for or against in-space assembly and servicing is a matter of debate. Any hiccups in the mirror’s or sunshield’s postlaunch deployments could render Webb a $10-billion hunk of inoperative space junk—and that assumes, of course, the telescope escapes Earth at all rather than falling victim to an unlikely-but-possible malfunction of its launch vehicle. In principle, building and testing the telescope in orbit could have reduced or nullified these and other threats—albeit potentially with a greater price tag. “In-space assembly would have completely relieved the requirement to fold and deploy Webb, and furthermore, a launch failure would not necessarily be a mission failure,” Siegler notes.

And even if all goes as planned with Webb, it has not been designed with servicing in mind (unlike its predecessor Hubble—or, for that matter, its successor, a planned post-Webb flagship called WFIRST). Within about a decade of reaching its deep-space destination Webb will run out of fuel, presumably sealing its space-junk fate. “That is astonishing,” says iSAT study member Gordon Roesler, the former head of DARPA’s RSGS program. “Wouldn’t it be nice if Webb could last a lot longer? The general thinking of [iSAT] is that something like Webb makes more sense as a 50-year mission, where we can plan from the outset to visit it, replenish consumables, replace parts and install new instruments with better technology.”

For all those reasons, despite Webb’s status as the premier facility for space-based astronomy in the 2020s and its associated wealth of new technologies that can feed in to even more advanced future observatories, many iSAT team members team see the project as an unsustainable “evolutionary dead end” whose time has in some respects already passed. Whatever arises from its fantastic-but-flawed legacy will depend not only on the outcomes of the iSAT study and the Decadal Survey, but also on the courage of scientists and policy makers to embrace bold, paradigm-shifting new approaches.

“The scientific community is sometimes its own worst enemy when it comes to understanding what it is that’s possible,” says Ken Sembach, director of the Space Telescope Science Institute. “Some of us now have the preconceived idea that it is not possible to build another telescope that is bigger and, yes, maybe more expensive than Webb. But I talk all the time to younger researchers, Congress and the public, and they all ask, ‘Why aren’t we thinking bigger?’ People want to support ambitious things. So it is possible—provided there is a damn good reason to do it.”

This Cloaking Device Could Hide Us From Alien Life

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IN BRIEF

Emitting a continuous 30 MW laser for about 10 hours, once a year, would be enough to hide us from aliens, at least in visible light.

OFFERING A CHOICE

Stephen Hawking has often cautioned humanity against broadcasting our presence to alien life. He noted that any civilization with which humanity could communicate is likely to be much older and much more technologically advanced than ours.

In short, they could easily kill us and strip-mine our planet for parts, if they chose to do so.

Photo Credit: ESO / G. Hüdepohl

Hawking isn’t the only scientist to share this concern. However, now, astronomers at Columbia University in New York could have the answer to staying hidden from potential other-worldly threats. Professor David Kipping and graduate student Alex Teachey suggest humanity could use lasers to conceal the Earth from the searches of advanced extraterrestrial civilizations.

To help clarify, astronomers try to find other Earth-like planets by looking for the dip in light when a planet moves directly in front of the star it orbits. If a far-off extraterrestrial is using the same method, our visibility could be masked by controlled laser emission, with the beam directed at the star where the aliens might live. When the Earth moves in front of the Sun, the laser would be switched on to compensate for the dip in light.

“There is an ongoing debate as to whether we should advertise ourselves or hide from advanced civilizations. Our work offers humanity a choice,” says Kipping.

KEEPING UP APPEARANCES

According to the authors, in order to mask our presence, emitting a continuous 30 MW laser for about 10 hours, once a year, would be enough to eliminate the dip, at least in visible light. A chromatic cloak, effective at all wavelengths, is more challenging.

“Alternatively, we could cloak only the atmospheric signatures associated with biological activity. This should make the Earth appear as if life never took hold on our world,” said Teachey.

But what if aliens already know about laser cloaking and are doing it themselves? That might sound a little bit conspiracy-theory heavy, but the scientists have considered this possibility. They propose that the Search for Extraterrestrial Intelligence could be broadened to search for artificial transits in order to help us find alien life.

Which leaves us asking: Would we really want to seek out a civilization that doesn’t want visitors?

Nasa’s ‘holy grail’: Entire new solar system that could support alien life discovered

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It is ‘amazing’ how similar the entire solar system is to Earth.

Scientists have found a new solar system filled with planets that look like Earth and could support life, Nasa has announced.

At least three of the seven planets represent the “holy grail for planet-hunting astronomers”, because they sit within the “temperate zone” and are the right temperature to allow alien life to flourish, the researchers have said. And they are capable of having oceans, again suggesting that life could flourish on them.

No other star system has ever been found to contain so many Earth-sized and rocky planets, of the kind thought to be necessary to contain aliens.

The researchers might soon be able to find evidence of life on the planets, they have said. British astronomer Dr Chris Copperwheat, from Liverpool John Moores University, who was part of the international team, said: “The discovery of multiple rocky planets with surface temperatures which allow for liquid water make this amazing system an exciting future target in the search for life.”

 Any evidence of life is likely to be “strong, very strong or conclusive”, the scientists said. It will be done by looking for what molecules are in the atmosphere – if they were to find things like oxygen, and in the right amounts, then it would probably indicate that there was biological activity.

Co-researcher Dr Amaury Triaud, of the Institute of Astronomy in Cambridge, said: “We hope we will know if there’s life there within the next decade.”

Even if life isn’t ever found near TRAPPIST-1, it might eventually develop there. The star is relatively young – even when our own Sun has run out of fuel and our solar system is destroyed, the newly-discovered one will still be in its early infancy.

TRAPPIST-1 “burns hydrogen so slowly that it will live for another 10 trillion years – more than 700 times longer than the Universe has existed so far, which is arguably enough time for life to evolve”, wrote Ignas AG Snellen from the Leiden Observatory, in an accompanying article about the discovery.How the new solar system that could support life would actually look

All of the planets were found using a method called “transit photometry”. That works by watching out for when a planet passes, or transits, in front of its host star – blocking out a small amount of light, allowing us to see the planet and learn about its size.

Scientists first found the star TRAPPIST-1 in 2010, after monitoring the smallest stars close to the Sun. Since then, they have been watching out for those transits – and after seeing 34 of them clearly, they proposed that they can be attributed to the seven new planets.

They then worked to understand the size and composition of each of the worlds. That work is still continuing, but the researchers believe that the planets have large oceans, are temperate and other conditions that could make way for alien life.

 The Seven Wonders of Trappist-1

Dr Michael Gillon, from the STAR Institute at the University of Liege in Belgium, said: “This is an amazing planetary system – not only because we have found so many planets, but because they are all surprisingly similar in size to the Earth.”

If a person were on one of the planets, everything would look a lot darker than usual, the scientists said. The amount of light heading to your eye would be about 200 times less than you get from the sun, and would be comparable to what you can see at sunset.

Despite that relative darkness, everything would still feel warm, the researchers said. That’s because roughly the same amount of energy would be coming from the star as warms our Earth – but it does so infrared.

Because the star is so dim in relative terms, all of the planets are warmed enough to sit in the temperate zone. That’s despite the fact that they are all so close to it – each of them sitting nearer to the star than Mercury, the planet in our solar system that orbits closest to the Sun.

“The spectacle would be beautiful,” said Amaury Triaud, one of the scientists involved in the research. “Every now and then you’d see another planet, about as big as another moon in the sky.”

The sun would also look about 10 times bigger than our own does from Earth, Dr Triaud said, despite the fact that it is in fact only 8 per cent as big. And it would be a sort of salmon pink, said Dr Triaud, who noted that the scientists initially thought it would be a deep reddish crimson but most of that red light would be infrared and so invisible.

pia21425.jpg
This chart shows, on the top row, artist conceptions of the seven planets of TRAPPIST-1 with their orbital periods, distances from their star, radii and masses as compared to those of Earth. The bottom row shows data about Mercury, Venus, Earth and Mars

It’s unlikely that any possible life that is on the planet would actually see this way, the scientists noted, since they would probably have evolved entirely different eyes – or perhaps none at all.

The researchers hope that they can do more work to watch the planets and learn more about their character. They want to look in particular at the seventh, outermost planet because at the moment they are not sure how it interacts with the inner ones.

Nasa’s Hubble Space Telescope is already being used to search for atmospheres around the planets. Future telescopes, including the the European Extremely Large Telescope and James Webb Space Telescope, may be powerful enough to detect markers of life such as oxygen in the atmospheres of exoplanets.

The first exoplanet was found in 1992. Since then, astronomers have detected more than 3,500 of the worlds, distributed across 2,675 star systems.

About a fifth of the sun-like stars are thought to have Earth-sized planets close enough to them to support life.

 Further details on the 7 newly discovered planets

In all, there might be 40 billion potentially habitable words sitting just in our galaxy, the Milky Way, astronomers estimate.

Scientists have long thought that Earth-sized planets were abundant, but the new research shows just how many of them there might be. Many of those planets might never be seen, because they don’t pass in front of their host star and so aren’t visible.

That might mean that the new system is actually not all that out of the ordinary. Scientists expect that for each planet we find, there are as many as 100 we can’t see – and so the scientists might not actually have been lucky, but rather seen something that wasn’t that unusual.

Stephen Hawking: alien life is out there, scientist warns.

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Stephen Hawking has suggested that aliens almost certainly exist but has warned humanity not to try to contact them.

One of the world’s leading scientists makes the claim in a new television documentary series, beginning on the Discovery Channel next month.

Hawking says that in a universe with 100 billion galaxies, each containing hundreds of millions of stars, it is unlikely that earth is the only place where life has evolved.

“To my mathematical brain, the numbers alone make thinking about aliens perfectly rational,” he said, according to The Sunday Times.

“The real challenge is working out what aliens might actually be like.”

Hawking says that they could be microbes – basic animals such as worms which have been on Earth for millions of years, but suggests that extraterrestrial life could develop much further.

“We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet,” Hawking said.

“I imagine they might exist in massive ships, having used up all the resources from their home planet. Such advanced aliens would perhaps become nomads, looking to conquer and colonise whatever planets they can reach.”

The scientist, who is paralysed by motor neurone disease, warned that contact with alien life could spell disaster for the human race.

“If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn’t turn out very well for the American Indians.”

Alien life, or noise? Russian telescope detects ‘strong signal’ from sun-like star.

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Signal detected a year ago from HD164595, only 95 light years away and with at least one planet, but Seti scientists are scanning the area and have yet to find it

radio telescope
Seti scientists have been scanning the coordinates since Sunday night but have yet to find the signal. 

As David Bowie might have sung: is there life on HD164595b?

A Russian radio telescope scanning the skies has observed “a strong signal” from a nearby star, HD164595, in the constellation Hercules. The star is a scant 95 light years away and 99% of the size of Earth’s own sun. It has at least one planet,HD164595b, which is about the size of Neptune and has a 40-day year.

Seth Shostak of the Search for Extraterrestrial Intelligence Institute (Seti) in Mountain View, California, told the Guardian he was shocked to have learned of the discovery only now – the readings from Russian radio telescope Ratan-600, Shostak said, were taken a year ago.

Seti, a private organization, searches the skies for alien life and has been underwritten by US government divisions as diverse as Nasa and the Department of Energy. Operated by the Russian Academy of Sciences, Ratan-600’s primary area of focus is monitoring the sun, though it has contributed to Seti’s work.

The news came to international attention on Saturday through Claudio Maccone of the University of Turin in Italy, who attended a talk by the scientists who recorded the signal on 15 May 2015. Maccone passed data from the presentation to the science and science-fiction writer Paul Gilster, who maintains a blog about interstellar exploration called Centauri Dreams.

Maccone sent the Guardian his proposed presentation for the International Academy of Astronautics 2016 meeting on the subject of the search for alien life, set for 27 September. He will call for the permanent monitoring of HD164595. “The power of the signal received is not unrealistic for type I civilizations,” he wrote.

The phrase “type I civilization” is a designation on the Kardashev scale, named for Russian astrophysicist Nikolai Kardashev developed in the 1960s and described in English in his 1985 paper On the Inevitability and the Possible Structures of Supercivilizations. A type I civilization would be similar to the current development of technology on earth.

“Could it be an ET?” asked Shostak rhetorically. “Of course, but [Ratan-600] didn’t have a receiver that has any spectral resolution.” The receiver on the Russian radio telescope is very wide, which aids it in its primary mission of monitoring solar activity but also means that, like a terrestrial radio receiving a news station, rock’n’roll station and country station at the same time, it is difficult to discern which band is broadcasting at which frequency. “They have a receiver that would swallow a big chunk of the radio dial at once,” Shostak said.

 Because the receiver covers such a big sweep of the radio dial, it is hard to tell if the signal comes from intelligent life.

If it is being broadcast across a large chunk of the radio spectrum, the noise is probably coming from a quasar or another source of stellar “noise”; if it is over a narrower band but very strong, it is likelier to be the product of intelligence.

Gilster said he was curious about the possibility that the signal could be caused by “microlensing” – a quirk of gravity that occurs when massive objects like stars or quasars are aligned behind another heavenly body.

“My own thought is that this is very possibly a one-time signal, much like the famous WOW! signal some years back,” Gilster said. On 15 August 1977, astronomer Jerry Ehman received a powerful radio signal from a group of stars called Chi Sagittarii; he circled the surprising spot on the readout and wrote “WOW!” The signal never returned.

“If it too doesn’t repeat,” said Gilster, “then we won’t know what it was, including the possibility of some kind of local signal whose source just hasn’t been figured out.”

Shostak said he wished he had been made aware of the signal earlier. “Why is it that we’re hearing about this now because one of the guys gave a talk in Moscow a year ago?” he asked. “Maccone’s explanation is that the Russians are ‘shy’. [But] it’s generally accepted procedure in the Seti community if you find a signal that you think is interesting, you call up people in another observatory and say: ‘Hey, here’s the position in the sky,’ and you see what happens.”

Gilster said his understanding was that the Russian team had spent the past year analyzing and confirming its data.

Shostak told the Guardian that Seti’s own radio telescope was scanning the coordinates in question in search of the promising signal as of Sunday night. That evening, though, everything was quiet.

The Russian radio telescope team and Maccone have been contacted for comment.