TIME space

Maybe We Really Are Alone In the Universe

Jeffrey Kluger is Editor at Large for TIME.

As a new TIME book explains, a cosmos with trillions of planets does not guarantee more than one with life

You may as well get a lot friendlier with life on Earth—every microbe and mammal, every bird and bug, and especially every human being. Because when it comes to biology, our planet may be the whole show.

Forget the overwhelming math—those trillions upon trillions of planets that are likely out there, at least some of which should be inhabited. Snuff out the one match head that is life on Earth, and the whole universe goes biologically black. We can search for biology all we want, send up all the here-we-are signal flares we can invent, but the fact is, no one will answer—ever—because no one is there.

That, like it or not, may be the truth, and it’s not just the picnic skunks who say so. Some very credible researchers have crunched the numbers and run the odds and taken a good hard look at them without the little frisson of hope even many of the most serious scientists bring to their work—and they come up empty. That’s not easy to accept because for a long time other, equally credible scientists have made a strong case for alien life.

Perhaps the most influential of the life-is-out-there advocates, astronomer and SETI Institute founder Frank Drake, made his bones in the extraterrestrial game with his eponymous equation, a satisfying—if coldly arithmetical—case for the likelihood not only of life in space but of intelligent life. According to Drake, the n in his equation—the number of civilizations in the Milky Way alone capable of producing detectable radio signals—equals the rate of the formation of sunlike stars in our galaxy, times the proportion of stars that are orbited by planets, times the proportion of those planets that would offer life-supporting conditions, times the fraction of those on which life does exist, times the fraction of life-forms that are intelligent, times the fraction of intelligent life-forms capable of transmitting signals, times the length of time such a civilization actually sends those signals before either perishing or going silent for any other reason.

Simple, right? Honestly, it kind of is. Filling in all of the x’s in the Drake equation—which, admittedly, is itself an act of conjecture, albeit highly informed conjecture—typically yields an estimate of thousands of civilizations. Drake himself put it at 10,000. The late cosmological popularizer Carl Sagan estimated the figure at an astounding 1 million. Even if they were off by a factor of 10 or 100 or 1,000, it is clear we are not remotely alone.

Unless we are.

Paul Davies, a cosmologist at Arizona State University and the author of the book Eerie Silence—which takes exactly the dim view of our ever encountering an alien intelligence that its title suggests—finds almost no part of the intelligent-life argument persuasive. The biggest hole he finds in the Drake equation is the one involving the subset of planets that could support life that actually do. The fact is, we have absolutely no empirical data that allows us to put a value on that variable in a responsible way. We know of precisely one world on which life has existed, and the rest is largely guesswork. Fill in that one Drake blank with a zero, and the entire equation collapses to zero too.

Davies, though, goes well beyond the flaws of the equation, arguing that there is a perfectly credible case to be made for the presence of life on Earth as a result of a succession of flukes, each more improbable than the one before it, which, together, could occur only a single time in a trillion trillion tries. A chimp randomly pounding a typewriter might indeed come up with Hamlet. Once. It wouldn’t matter if there were 40 billion other chimps hammering away, just as, as Davies has written, it doesn’t matter if there are 40 billion planets in the Milky Way capable of sustaining life. Only a single one will.

Furthermore, he believes that in the improbable event an intelligent civilization exists, it is surpassingly unlikely it would send any messages our way. The popular notion is that because we’ve been transmitting radio and TV signals for more than a century—and because those signals are spreading into space at the speed of light—surely a sophisticated species would have gotten wind of us. Problem is, in a universe that stretches for 13.8 billion light-years in all directions, the 100 light-years our signals have traveled so far make them a decidedly local broadcast.

Most discouraging is that in all the years we’ve been looking for an extraterrestrial sign (and no, crop circles don’t count), there has been, well, only an eerie silence. SETI’s antennas have been pointed skyward for half a century, listening for a repeating signal that would suggest an intelligent sender; so far, nothing. There was one thrilling moment—on Aug. 15, 1977—when SETI scientist Jerry Ehman, working with Ohio State University’s radio telescope, picked up a signal a full 30 times as strong as the background noise of deep space. It was tracked for 72 seconds and had a frequency similar to that of the spectral line for hydrogen. (That’s relevant because SETI scientists have long believed that since hydrogen is the most common element in the universe, it might be chosen as a sort of universal sending frequency.)

On the printout that the radio telescope produced of the signal, Ehman wrote one word: “Wow!” Forevermore, what he heard that night has been known as the Wow! signal. It was never heard again, though, and today it is assumed to have been an atmospheric anomaly, a reflection from space debris or of earthly origin. What it almost certainly was not was an alien semaphore.

Of course, it’s much too early to consider any of this proof of a negative. The universe is huge and ancient, and a 50-year exploration isn’t even a single pixel in the sweeping mural of time. Science does make hard, sudden turns: one day there was no Copernicus saying the Earth isn’t the center of the universe, and then there was—and nothing was ever the same again. Ditto Einstein and his relativistic universe; ditto Leeuwenhoek and the previously unseen biosphere revealed by his microscope. And so it could still be with the discovery of alien life.

Until then, there may be something to be gained from thinking of the Earth as the universe’s only wilderness preserve. If life is indeed a cosmic one-off, it makes it all the more important that we act as this planet’s responsible caretakers. Snuff this biological light, and the descending darkness won’t just be our fault. It will be our crime.

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TIME space

Mars Probably Had More Water Than the Arctic Ocean, Study Says

ISRO/AFP/Getty Images Mars is seen in an image taken by the ISRO Mars Orbiter Mission (MOM) spacecraft released on Sept. 30, 2014.

The size of the Martian ocean is significantly larger than previously thought

Mars likely had a body of water larger than the Arctic Ocean, according to a new study by NASA scientists.

The size of the Martian ocean is significantly larger than previously thought and provides further evidence that the planet may have once had the ability to support life. The body of water would have been large enough to cover the planet’s entire surface in 450-feet deep water, according to the study published in the journal Science, though it was likely concentrated in smaller areas.

“Our study provides a solid estimate of how much water Mars once had, by determining how much water was lost to space,” said Geronimo Villanueva, a NASA scientist and study author. “With this work, we can better understand the history of water on Mars.”

The scientists analyzed water on Mars today and compared it to water from a 4.5-billion-year-old Mars meteorite to determine how much water was likely lost in the past four billion years.

Still, questions remain about what happened to the large body of water. “With Mars losing that much water, the planet was very likely wet for a longer period of time than was previously thought, suggesting it might have been habitable for longer,” said Michael Mumma, a NASA scientist and study co-author.

TIME life in space

Bill Clinton Is Right: There Are Aliens in Space

The former president weighs in on the existence of ET—and he's probably right

One of the good things about being an ex-President is that you get to say the kinds of things you could never say when you were still the most powerful person in the world. Take aliens—the space kind. Last night, during an appearance on Jimmy Kimmel’s show, the 42nd prez admitted not only that when he was in the White House he ordered a review of all of the documents related to the long running rumors over aliens landing in Roswell, N.M. in 1947, but that he would not be surprised if we did eventually get a cosmic caller.

“If we were visited someday I wouldn’t be surprised,” he said, “I just hope it’s not like Independence Day,” a reference to the 1996 movie in which aliens do land—and behave very, very badly.

Has Clinton gone ’round the bend? Not a bit–depending on whether you subscribe to the life-is-easy or life-is-hard school of thought. Physicist, broadcaster and author Paul Davies of Arizona State University is one of the leading proponents of the we’re-all-alone camp, arguing in his aptly titled book The Eerie Silence that biology emerging from dead chemicals was such a cosmic longshot that it’s entirely possible it happened only once, here. But that position is becoming increasingly untenable.

First, there are about 300 billion stars in the Milky Way and our galaxy is one of at least 100 billion in the universe. So, as the overworked idiom goes, do the math. What’s more, ever since the Kepler Space Telescope was launched in 2009, close to 4,000 candidate planets have been discovered in the Milky Way and close to 1,000 have been confirmed.

Planets aren’t the same as biology—witness Earth’s lifeless brothers and sisters in our solar system—but the increasingly evident presence of water and organic chemicals in asteroids, comets and throughout the interstellar medium suggests that the ingredients for life are everywhere. If that’s so, it may take little more than that chemistry plus some energy source (light or heat) plus time to cook up something living. Clinton may have had his political critics in his eight years in the White House, but science, in this case, appears to be on his side.

TIME life in space

A Geyser Moon With a Hidden Ocean

Saturn's moon Enceladus, photographed by the Cassini spacecraft.
Stocktrek Images; Getty Images Saturn's moon Enceladus, photographed by the Cassini spacecraft.

Enceladus, one of the gems of the solar system, is home to a great, salty reservoir of water—just the place to find life

When the Cassini spacecraft got its first closeup look at Saturn’s moon Enceladus after the probe’s arrival in 2004, it was rewarded with a jaw-dropping sight: gigantic geysers of ice particles and water vapor spewing hundreds of miles into space from the icy world’s southern hemisphere. These plumes are so prolific that they continuously resurface Enceladus’ sparkling white surface with a fresh coating of ice crystals—and still have enough left over to be the main source of ice particles that make up Saturn’s E-ring.

It hasn’t been entirely clear where the geysers come from, however. Circumstantial evidence points to a subsurface ocean—the ice, as Cassini found by flying through the plumes, is laced with salts, suggesting a body of water in constant contact with a rocky bottom. It’s not crazy to imagine such an ocean, either: the constant flexing Enceladus feels from tidal forces caused by Saturn’s gravity would keep the moon’s core warm, melting what would otherwise be a solid coating of ice from below. That’s just what scientists see on Jupiter’s moon Europa—which appears to have its own, albeit less prominent, plumes of water vapor.

But a new paper in Science has turned “not crazy” to “almost certainly true.” By measuring subtle distortions in Enceladus’ gravitational pull as Cassini whips past different regions of the moon, planetary scientists have found a slight excess of gravity in the moon’s southern hemisphere—and a large underground body of water is exactly what would produce that kind of measurement. “It wasn’t a surprise to find a water reservoir,” said lead author Luciano Iess, of the Sapienza Universita di Roma, in Italy, at a press conference. But its size and extent, he said, were unknown.

Not any more: Cassini’s readings show that Enceladus’ buried sea, which lies some 30 miles (48 km) beneath the surface of the 500-mile-diamater (804 km) moon, is at least several miles deep. “It’s deepest near the south pole,” said co-author David Stevenson, a planetary scientists at Caltech, “and it appears to extend at least halfway to the equator in all directions.” It might even span the entire moon, said Iess. “Our data neither exclude nor confirm a global ocean, or whether there are other water pockets.” But at the very least, said Stevenson, “It contains as much or more water than Lake Superior.”

That’s a big deal, and not just because the idea of liquid water so far from the Sun’s warming rays would have been considered absurd a few decades ago. Scientists who speculate about life beyond Earth have long been convinced that water is a basic requirement for biology—and along with Jupiter’s moons Callisto, Europa and Ganymede, and Saturn’s Titan, this makes five places in the Solar System’s frigid regions where life could plausibly exist.

Water alone isn’t enough, of course: life as we know it is built out of complex carbon-based molecules, and without those you’re out of luck. But the same flybys that detected salts in Enceladus’ plumes also found traces of methane and carbon dioxide. These molecules are too simple to qualify as evidence for life by themselves, but, said Cornell’s Jonathan Lunine, who wasn’t involved with the research, “taken all together, the water, salts and organic molecules make the interior of Enceladus a very attractive potential place for life.”

In fact, says planetary scientist Kevin Hand, of NASA’s Jet Propulsion Laboratory, the discovery of life here, should it ever happen, might be an even bigger deal than finding life on Mars. The reason: Mars and Earth are close enough together that asteroid impacts have blasted rocks from one planet to the other many times in the history of the Solar System. If life arose on Earth, it could have hitched a ride over to Mars inside a meteorite and infected our sister world—and it could have happened in the opposite direction as well.

That being the case, if we should find DNA-based life on Mars, it wouldn’t necessarily be clear that life arose independently. “For me,” says Hand, “finding a second origin of life is absolutely crucial. When we find a second origin in our solar system, then we can then think about exoplanets and say, ‘Okay, we know that if the conditions are right, life is likely to get started, and then it’s off to the races.’”

In order to find out for sure, we need to take a harder, closer look at these icy moons than any NASA probe has done to date. For his part, Hand has been involved in a potential mission called the Europa Clipper, while the European Space Agency is planning the Jupiter Icy Moons Explorer, currently slated for a 2022 launch.

Nobody’s planning a return to the Saturn system yet, but given the new, firm evidence of an ocean on Enceladus, it might be time to think about doing so. “Enceladus is a gem of the Saturnian system,” says Hand, “with many untold secrets that can only be answered by a new mission.”

The real trick, of course, will be getting Congress to pay for it.

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