Scientists Debate Signatures of Alien Life

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.


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

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


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.


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.


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

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.”

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.

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.

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.

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.

Planet Hunters Seek New Ways to Detect Alien Life

Astrobiologists debate which chemical signatures would hint at life on other worlds

This artist’s conception illustrates Kepler-22b, a planet known to comfortably circle in the habitable zone of a sun-like star.

In the search for life beyond Earth, false alarms abound. Researchers have generally considered, and rejected, claims ranging from a 1970s report of life on Mars to the 1990s ‘discovery’ of fossilized space microbes in a meteorite.

Now, inspired by the detection of thousands of planets beyond the Solar System, NASA has started a fresh effort to learn how to recognize extraterrestrial life. The goal is to understand what gases alien life might produce—and how Earth-bound astronomers might detect such ‘biosignatures’ in light passing through the atmospheres of planets trillions of kilometres away (see ‘Searching for alien life’).

The agency will convene a workshop this week in Seattle, Washington, with the ultimate goal of advising a NASA exoplanet group on how to avoid embarrassing errors in the future. “We have to come together and determine what good evidence of life on another planet could be,” says Shawn Domagal-Goldman, one of the workshop’s organizers and an astronomer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The exercise comes at a crucial time, as astronomers grapple with how to interpret exoplanet data from the next generation of telescopes. Some scientists are working to understand how nature could produce archetypal biosignature gases, such as oxygen, in the absence of living organisms. Others are trying to think as expansively as possible about the types of biochemistry that could sustain life.

“We could fool ourselves into thinking a lifeless planet has life—or we could be missing life because we don’t really understand the context of what could be produced on another planet,” says Sarah Rugheimer, an astronomer at the University of St Andrews, UK.

Detecting a biosignature gas is just the first step to understanding what could be happening on an exoplanet. Each world has its own combination of physical and chemical factors that may or may not lead to life, says Victoria Meadows, an astronomer at the University of Washington in Seattle. “Planets are hard, and we shouldn’t think they are all going to be the same or reveal their secrets very easily,” she says.

A planet’s environment is key. Some Earth-sized planets orbit M dwarf stars—the most common type of star in the Galaxy—at the right distance to harbour liquid water. But Meadows’ collaborators have shown that photo-chemical reactions can send water into the planet’s atmosphere and then break off its hydrogen, which escapes into space. What’s left is a thick blanket of oxygen that might seem as if it came from living organisms, but results from a run-away greenhouse effect.

There are ways to tell. The runaway greenhouse would create an atmosphere thousands of times denser than Earth’s, in which O2 molecules collide to produce O4. So spotting O4 in a planet’s atmosphere could be a clue that the oxygen does not, in fact, come from life, Meadows’ team reported this year.

Another method is to draw up a list of alternative biosignature gases—things not as obvious as oxygen that might be made by organisms under certain conditions. These include dimethyl sulfide, which is produced by Earthly phytoplankton, or even ammonia. On a cold alien planet, organisms might make the gas using the same chemical process as industrial manufacturers.

At the Massachusetts Institute of Technology in Cambridge, astronomer Sara Seager has begun to examine 14,000 compounds that are stable enough to exist in a planetary atmosphere. She and her colleagues are winnowing down their initial list of molecules using criteria such as whether there are geophysical ways to send the compound into the atmosphere.

“We’re doing a triage process,” says Seager. “We don’t want to miss anything.”

The Seattle meeting aims to compile a working list of biosignature gases and their chemical properties. The information will feed into how astronomers analyse data from NASA’s James Webb Space Telescope, slated for launch in 2018. The telescope will be able to look at only a handful of habitable planets, but it will provide the first detailed glimpse of what gases surround which world, says Nikole Lewis, an astronomer at the Space Telescope Science Institute in Baltimore, Maryland.

No single gas is likely to be a slam-dunk indicator of alien life. But Domagal-Goldman hopes that the workshop will produce a framework for understanding where scientists could trip themselves up. “We don’t want to have a great press release,” he says, “and then a week later have egg on everybody’s faces.”

NASA Openly Admits Alien Life Exists: Get Ready for Disclosure!

Most people ‘in the know’ realize that NASA is just part of the military industrial complex, but a recent open admission on mainstream news that “there are indications of alien life” is likely the beginning of a bid to get your undivided attention before full-forced disclosure ensues.

Most people already believe what NASA Chief Scientist Ellen Stofan states:

“I think we’re going to have strong indications of life beyond Earth within a decade . . .I think we’re going to have definitive evidence within 20-30 years.”

It isn’t going to take that long if we open our eyes.

Stofan goes on to say:

“We’re on the verge of things that people have wondered about for millennia. Within all of our lifetimes we’re going to understand that there is life on other bodies in the solar system. We’re going to understand the implications of that for life here on Earth.”

What we’re going to understand is that our ‘secret’ government has been hiding this fact for ages. In an effort to transition the US and other countries through its reach to a cabal-run oligarchy, our shadow government has been lying about off-planet corporate slavery ringsalien abductions, benevolent beings who can only do so much until our collective consciousness elevates, and much, much more.

William Cooper, among others, tried to disclose the true purpose of NASA, but he was exterminated. His death, among thousands of others, will not be in vain.

We will learn that aside from extraterrestrial beings visiting our planet and many different ET races tinkering with our DNA over millenia, there are ancient humanoid races that are more than 10 million years old.

We will learn that a recent computer hacking retrieved millions of government and corporate personnel records, some say as part of documentation for Nuremburg-like trials, will begin soon against those who have mind-controlled, enslaved and tortured us. Undeniable photos of UFOs were also unearthed.

We will also learn that chemtrails and GMOs were the LEAST of plans made for us ‘sheeple’ and ‘useless eaters’ by a Luciferian cabal, and that President Harry Truman signed a document with certain ETs that allowed the ‘elite’ to conduct highly technological experiments with intelligence gained from these ETs in exchange for looking the other way when certain humans were abducted for ET experiments.

We will learn that we are not helpless, as we have been programmed to believe. We are, in fact, a rare humanoid race that has an incredible range of emotion and creative power. We will learn that our minds and emotions can either fuel chaos on this planet, or restore it to its rightful place of peace and cooperation, of care for others at least as much as ourselves.

We will learn that our ascension into infinitely peaceful beings is indeed possible, and it has been described in countless books, many of which have been suppressed along with UFO information.

NASA is telling us now that the likelihood of alien life is a ruse. Be sure to remember those who have been executed to try to prove this information to us decades ago, and to use discernment when the truth is finally revealed.

Watch the video. discussion. URL:

Starshot scientist says we won’t find alien life on planets

Physicist Stephen Hawking and Russian billionaire Yuri Milner are teaming up with a host of other physics and cosmology luminaries to plan a mission to Alpha Centauri, a star far beyond our own solar system that will take at least two decades to reach if they can make their experimental technology work.

They hope to send miniature robots, smaller than iPhones, to explore the faraway depths of the Milky Way and search for signs of life.

The project, dubbed Breakthrough Starshot, was made public on April 12.

At the official announcement, the physicist and mathematician Freeman Dyson told the assembled crowd that while Starshot’s destination would be Alpha Centauri, what these robots find along the way may be even more interesting.

“The space between here and Alpha Centauri is not empty … there are thousands of objects in between,” he said. “We know that there are billions of planets [in our galaxy] … but we also know that there are trillions of comets and asteroids.”

And he predicts that our focus on planets may have obscured something truly exciting: Some of these smaller objects might be teeming with life.

“I’ve always believed that planets are not the big thing,” he said. “I’ve made a bet that when the first alien life is discovered, it will not be on a planet.”

atacama desert starsesoastronomy/Flickr

This idea is not entirely new. Scientists recently claimed that there was evidence of potential alien life on the comet Philae, but those claims turned out to be unfounded.

Still, it’s entirely possible that life on Earth originated thanks to meteors that pummeled our planet with the elements required for life. If that’s the case, there’s no reason to believe that similar bodies are not still out there. A theory called panspermia suggests that it’s comets and asteroids that spread the building blocks for life all around the universe.

If the Starshot initiative is able to get off the ground, it may not tell us anything for certain about the origins of life on our own planet. But it could provide tantalizing clues about whether alien life is hiding on rocks hurtling across the sky.

The telescope big enough to spot signs of alien life on other planets .

Engineers are about to blast away the top of a Chilean mountain to create a site for the European Extremely Large Telescope. It will allow us, for the first time, to directly observe planets outside the solar system
An artist's impression of the European Extremely Large Telescope (E-ELT).

An artist’s impression of the European Extremely Large Telescope (E-ELT).

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 intospace 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.

Building the four VLTs, which have been named Antu (Sun), Kueyen (Moon), Melipal (Southern Cross) and Yepun (Venus) in the language of Mapuche people of Chile, was a formidable challenge, needless to say. Each has a giant mirror that is 8.2 metres in diameter but only 17cm thick: any thicker, and the mirror would be too heavy to move and point. Such thinness leaves the mirrors liable to deform as temperatures and air pressure fluctuate, however, and so each has 150 actuators fitted to its unpolished side. These push the mirrors to keep them within a few billionths of a centimetre of their proper shape. In addition, ESO astronomers use a laser-based system known as adaptive optics to measure turbulence in the upper atmosphere and to change each telescope’s internal mirror configuration to compensate for any disturbance they can measure.

The result is a cluster of astronomical devices of incredible power and flexibility, one that has been involved in an astonishing number of critically important discoveries and observations over the past decade, as ESO astronomer Olivier Hainaut explains. “Perhaps the VLT’s most spectacular achievement was its tracking of stars at the centre of the Milky Way. Astronomers followed them as they revolved around… nothing. Eventually they were able to show that something incredibly small and dark and massive lay at the centre of this interstellar waltz. This was the first time, we now know, that scientists had directly observed the effect of the supermassive black hole that lies at the heart of our galaxy.”

The Milky Way seen from the  Paranal Observatory in Chile.The Milky Way seen from the Paranal Observatory in Chile. Photograph: National Geographic Image Collec/Alamy

The VLTs also played a key role in providing observations which showed, from the behaviour of distant supernovae, that the expansion of the universe was actually accelerating thanks to the action of a force now known as dark energy. This discovery later won Saul Perlmutter, Brian Schmidt and Adam Riess the 2011 Nobel prize for physics. And in 2004 the telescopes were used to make a direct observation of an exoplanet – a planet that orbits around a star other than our Sun. It was another astronomical first. Until then scientists had only been able to infer the existence of exoplanets from the way they affected the movement of their parent star or its light output. “This was history-book material, a discovery of the same quality as Galileo’s drawings of the mountains on the moon or the satellites of Jupiter,” says Hainaut.

These discoveries have only whetted astronomers’ appetites for more, however. Hence the decision to build the £800m E-ELT – whose British funding will come through a £88m investment from the UK Science & Technology Facilities Council. Engineers have now completed a road to the mountain from Paranal and on 16 June are set to begin blasting to remove the top from Cerro Armazones. Then they will start to build the E-ELT using 798 hexagonal pieces of mirror to create a mammoth device that will be able to collect a hundred million times more light than the human eye. When completed in around 2025, the 2,700-tonne telescope will be housed in a 74 metre high dome and operated by astronomers working 20kms away in Paranal. It will be the world’s biggest eye on the sky.

An indication of the E-ELT’s potential is provided by ESO astronomer Linda Schmidtobreick. “There are fundamental issues that only a telescope the size of the E-ELT can resolve,” she says. “Its mirror will have a surface area 10 times bigger than any other telescope, which means it will take a 10th of the time to collect the same amount of light – ie the same number of photons – from an object compared with these other instruments.”

RobinThe astronomers’ residence: ‘As accommodation goes, it’s as exotic as you can get.’

For Schmidtobreick, this ability to collect light quickly is crucial to her research. She studies stars known as cataclysmic variables: pairs of stars in which one is pulling vast amounts of gas, mainly hydrogen, from its companion, a process that can trigger gigantic thermonuclear eruptions, sometimes within 30 seconds or so. “With current instruments, it can take minutes or hours to collect light from these objects, which is too long to resolve what is happening,” says Schmidtobreick. “But with the E-ELT, we will be able to study many, many more cataclysmic variables because we will be able to collect significant amounts of light from them in seconds rather than minutes or hours and so will be to resolve their behaviour.”

Simone Zaggia, of the Inaf Observatory of Padua, is another frequent visitor to Paranal and has a very different reason for backing the E-ELT. He believes it will play a vital role in the hunt for exoplanets – in particular, exoplanets that are Earth-like and which could support life. “At present, our biggest telescopes can only spot really big exoplanets, giants that are as big as Jupiter and Saturn,” he says.

“But we really want to know about the smaller worlds that make up the solar systems in our galaxy. In other words, we want to find out if there are many Earth-like planets in our part of the universe. More importantly we want to find out if their atmospheres contain levels of oxygen or carbon dioxide or methane or other substances that suggest there is life there. To do that, we need a giant telescope like the E-ELT.”

This point is backed by Gilmore. “We can see exoplanets but we cannot study them in detail because – from our distant perspective – they appear so close to their parent stars. However, the magnification which the E-ELT will provide will mean we will be able to look at them directly and clearly. In 15 years, we should have a picture of a planet around another star and that picture could show its surface changing colour just as Earth does as the seasons change – indicating that vegetation exists on that world. We will then have found alien life.”

Astronomers’ amazing home

A walk down the alleyway that leads from Paranal observatory’s entrance gate into its astronomers’ residence produces one of the most striking changes in surroundings you can experience in a few footsteps. Outside the air is parched and the ground bleached by sunlight from a sky that is hardly ever troubled by clouds. Push through the double swing doors and you enter a rainforest – and a path that leads down through towering ferns and tropical plants until you reach a swimming pool in the residence’s lowest level. As accommodation goes, it’s as exotic as you can get – though hedonism was far from the minds of the architects when they designed it.

To battle the arid conditions of the air at 8,600ft-high Paranal, they wanted a way to keep it moist and fresh for the scientists staying there. The answer was a swimming pool and an indoor tropical garden that is constantly watered with supplies imported by trucks from the coast every day. Moist air from the pool and garden then circulates around the rest of the residence. The result is a building that is remarkably airy and light – until 7pm when, every night, all openings and windows, including the vast glass dome over the pool, are closed and shuttered automatically to prevent any chink of light from affecting observations made on the mountain top.

The scale and style of Paranal and its residence is extraordinary and movie producers have fallen over themselves in their attempts to film it. Most have been turned down – with the exception of the 2008 Bond film,Quantum of Solace, whose final scenes were filmed here. (In contrast the last X-Men film was turned down flat because its producers wanted to fly helicopters near the observatory’s precious telescope complex.) Given the vast cost of building and running Paranal, filming was not allowed to disturb its tight observing schedule. “I was woken up by the sound of someone repeatedly jumping on to the balcony in the room next to mine,” one astronomer recalls. “It turned out to be the actress Olga Kurylenko – who plays the film’s heroine Camille. It was quite a shock. I mean you don’t get that sort thing happening at other observatories.”

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