A Blog by

What Hillary Clinton Says About Aliens Is Totally Misguided

A flying saucer hovers over downtown Ithaca*. Have we been visited by aliens? Hillary Clinton is going to find out. (N. Drake)
A flying saucer hovers over downtown Ithaca*. Have we been visited by aliens? Hillary Clinton is going to find out.
Photograph by Nadia Drake

In the spring of 1999, a UFO flew over downtown Ithaca, New York. I was standing on the roof of a house near the Cornell University campus and managed to snap a few characteristically crappy pictures of the alien object, which vaguely resembled a flying saucer wearing a top hat.

It hovered above the Ithaca Commons for a minute before turning east and soaring over the Cornell University clock tower. As it flew, the craft made a sound that resembled bacon sizzling in a frying pan. Then, just as quickly as it had appeared on that sunny Saturday afternoon, the UFO vanished. The whole encounter lasted maybe a few minutes.

I would later learn that it wasn’t the first time Ithaca had been visited by a UFO. In fact, sightings were pretty common in the area during the latter half of the 20th century—just as they are in some UFO hotspots around the world, like Area 51 in Nevada, the Welsh Triangle, and Wycliffe Well, Australia. Witnesses tend to use similar language when describing spacecraft shapes, sounds, and the aliens themselves, which ostensibly lends credibility to their testimony. After all, how could so many people be wrong?

Even Hillary Clinton appears reluctant to doubt the sightings.

“There’s enough stories out there that I don’t think everybody is just sitting in their kitchen making them up,” Clinton said during a recent interview.

Clinton, it seems, has at least one foot inside the UFO spacewagon, and in recent weeks has promised to get to the bottom of what’s really going on at Area 51. She says that if she’s elected in November, she’ll open up as many of those documents as she can (some are already available) and reveal the truth about possible extraterrestrial visits to Earth. Meanwhile, John Podesta, her campaign chair, appears to be piloting that spacewagon. A rabid X-Files fan (as am I, no shame), Podesta tweeted, “Finally, my biggest failure of 2014: Once again not securing the #disclosure of the U.F.O. files. #thetruthisstilloutthere,” when he left the Obama White House last year.

It’s disappointing that influential people are helping fan the flames of conspiracy theories that refuse to wilt beneath the weight of truth. One hopes it’s just a campaign stunt, meant to increase Clinton’s popularity among a group of people who might be inclined to vote somewhat more conservatively. Yet given Podesta’s and Clinton’s track records on the topic, it seems more likely the pair really believes there might be something to expose.

Perhaps those documents are tucked into a cardboard box stashed in an old railway car, waiting for Clinton and Podesta to arrive with their flashlights. But I’d wager much more than my house that there’s exactly zero credible evidence supporting alien encounters with this planet—and I’d love for warp drives and battlestars to exist as much as anyone would.

After a few minutes, the spacecraft turned east and flew over the Cornell campus*. (N. Drake)
After a few minutes, the spacecraft turned east and flew over the Cornell campus*.
Photograph by Nadia Drake

Wait. Didn’t I see a UFO over Ithaca?

Yes, I did see a UFO over Ithaca. I can even tell you exactly what it was made of: an upside-down frying pan with a saucepan lid on top, some fishing line, and a big stick. A classmate and I had manufactured the photos for a course we were taking on the search for life in the universe. Our goal was to win a classroom debate about whether aliens had visited Earth, and step one was proving just how easy it is to fabricate evidence.

Sorry to disappoint. (Not really.)

Step two involved addressing the volumes of eyewitness claims, and explaining why such testimony can be unreliable. If you’re skeptical, check out the decades of research that have been done on the reliability of witnesses testifying in court. In these situations, our brains often fill in or edit details based on preconceived biases or post-encounter information—and then we subconsciously convince ourselves that our memories are accurate when in fact, they’re not.

This is where Clinton’s reasoning about people sitting in their kitchens making stuff up falls apart. Beliefs are potent. The brain is a powerful tool, and it can lead us to some incredibly wrong recollections and conclusions. And in these situations, assuming there’s safety in numbers is foolish (for more on that topic, start with the Salem witch trials).

During high school, I spent a few summers working alongside my father at the SETI Institute. One of my jobs was to answer letters. This was back in the day when people stuffed paper into envelopes, so I’d start by sorting the letters into two piles. One pile was for correspondence that requested scientific information; the other was for claims of UFO sightings. I’d read these with interest, wondering what it was people thought they saw. Many were convinced that my family had aliens buried in our basement (I’m not saying we do, I’m not saying we don’t**). Often, the reports were incredibly detailed, with one particularly colorful account unfolding over 10 handwritten pages describing how beeping robotic space balls followed a family around.

There’s a familiar saying that extraordinary claims require extraordinary evidence, and that evidence—or any proof, really—was never there.

It never is.

So I’d respond with a standard letter explaining what SETI actually does, and include a brochure about the scientific search for extraterrestrial life, which I think is as interesting as the fantasy.

That search began in 1960, when my dad pointed a telescope in Green Bank, West Virginia at a pair of sunlike stars. He was listening for telltale signs of technology broadcasting itself across the cosmos. All he heard was silence. And all we’ve heard since then is silence. But in the intervening half-century, the search for life beyond Earth has moved beyond straining to hear distant cosmic murmurs to looking for evidence of microbial life much closer to home, in our own solar system. Eventually, we’ll take a close look at the atmospheres of faraway planets and keep an eye out for the signatures of living, breathing, biological ecosystems.

And that’s science, which is step three in evaluating alien encounters. It’s true that we don’t know everything there is to know about propulsive technologies, or how the universe works. But we do know that the distances between the stars are so vast, and the energetic requirements for space travel so monumental, that visiting an alien world is far from trivial. It’s not nearly enough to say that alien civilizations might be using technologies we’re completely unaware of. Science demands verifiable proof.

And “proof” of flying saucers and crashed alien spacecrafts amounts to little more than unverified anecdotes.

This is why it’s unhelpful and irresponsible for Clinton and Podesta to be teasing the public as they are. Go ahead and open up the Area 51 files (or at least the ones that don’t compromise national security), but do it in the name of true government transparency rather than uncovering aliens.

* Not really. Please don’t reuse this image without that important caveat.

** We don’t have aliens buried in our basement.

A Blog by

Need to Punch Some Holes In Mars Rocks? Practice Here.

When NASA launches its next Mars rover in 2020, the robot will search for signs of ancient life on the red planet -- and stash rock samples for a future rover to retrieve. (NASA/JPL-Caltech)
When NASA launches its next Mars rover in 2020, the robot will search for signs of ancient life on the red planet — and stash rock samples for a future rover to retrieve. (NASA/JPL-Caltech)

Not all rocks are created equal. It’s a mundane but inescapable fact that turns out to be particularly problematic if you’re designing a drill for a robot that will be poking holes in Mars.

But who really worries about such things? A team at NASA’s Jet Propulsion Laboratory, where the newest Mars rover is being readied for a 2020 launch to the red planet.

That’s who.

When it’s millions of miles away from Earth, the new rover will not only need to search for signs of ancient life, it will need to be prepared for all the alien rocks it meets. Especially because, unlike its cousin Curiosity, this next-gen robot won’t just be drilling holes in those rocks: It will also be collecting rock cores and stashing them in various spots on the planet’s surface. If all goes well, the rock samples will be picked up and returned to Earth by a future rover, kind of like an interplanetary golden retriever. It’s a complicated strategy that forms the next step in NASA’s long-term plan to explore our small reddish neighbor, a plan that could eventually add human footprints to the rover tracks already pressed into the dusty, formerly wet Martian surface.

But first things first. The Mars 2020 rover needs to be able to drill, extract, store, and deposit all those cores.

“We don’t quite know what we’ll encounter when we get to Mars,” says JPL’s Matt Robinson, deputy product delivery manager for the rover’s sampling and caching subsystem. “We need to have a range of rocks we’re going to test.”

Guinea rocks are piled high along the walls of the rock room. (NDrake)
Guinea rocks are piled high along the walls of the rock room. (NDrake)

Robinson and I are standing in a cavernous lab on the JPL campus, in a place appropriately called the Rock Room. Somewhat ominously, there’s a sign on the door warning against the dangers of inhaling pure nitrogen gas. “Two breaths of 100% nitrogen can cause immediate unconsciousness with no warning,” it says in all-caps, which seems a bit out of place, considering that Mars wears a thin, gassy veneer of carbon dioxide. But no matter.

As its name suggests, the rock room is filled with baskets and baskets of rocks, mostly collected from sites in southern California. There are hard rocks and soft rocks and in-between rocks, and they’re all the geological equivalent of guinea pigs for the drill prototypes Robinson and his colleagues are developing. Like these rocks, some of the Martian targets will be hard and less likely to yield to the machinations of a nosy robot, while others will easily crumble under pressure. As evidence of the team’s ongoing experiments, there are piles of rocks bearing numerous cylindrical gouges.

“It’s somewhat of a design-by-test,” Robinson says. “You do the mechanical design, you build a prototype, then you come into the test bed and you test it.”

Opposite the rock piles are illuminated racks of clear plastic tubes, each holding a 4-inch-long cylindrical rock core. These dozens of tubes are the handiwork of the 2020 drill prototypes, and are almost exactly the type of thing the rover will be stashing on the Martian surface. The various cores are different colors and consistencies, and there’s more material in some tubes than others.

Drill prototypes have collected dozens of cores from test rocks. (NDrake)
Drill prototypes have collected dozens of cores from test rocks. (NDrake)

It occurs to me that it would be bad for the rover to accidentally cache an empty tube for future retrieval.

“Will the tubes on the rover be clear? Could you see into them?” I ask.

“It’s going to be a metal tube so you can’t really see into it, but there’s a camera that will look in and see how much sample there is,” Robinson assures me. He pauses, thinking. “But it would be nice to – like in Star Trek IV — have transparent aluminum…that would be really cool.”

Whales on Mars would also be nice.

Alien humpbacks aside, the plan right now is for the 2020 rover to retrieve as many as 42 rock cores and distribute them in strategic sites that are still TBD. That way, a future rover will only need to visit several locations to retrieve the cached samples instead of inefficiently retracing 2020’s path.

“This is our ambient robotic coring station,” Robinson continues, showing me one of the three drill prototypes the team is currently working with. As imagined, the 2020 drill would have a variety of bits available for tackling rocky obstacles; when the rover encounters an enticing rock, all it needs to do is shove its arm into a tool carousel and select the bit that’s best for the task. When it’s done with one tool, the rover can easily swap it out for another.

Right now, the retinue of options being tested includes a brush that will help smooth rock surfaces pre-drilling, as well as a dozen different bit prototypes. The team is also experimenting with stabilizing legs so the rover can achieve maximum rock-punch, as well as having the rover collect loose material from the surface, called regolith.

“The great thing about this test bed is it’s got a drill press that’s easy to set up and operate,” Robinson says, before the clamor of an ongoing test drowns out the rest of his sentence.

Test rocks await their fate on a platform that can be transformed into a Mars-like environment. (NDrake)
Test rocks await their fate on a platform that can be transformed into a Mars-like environment. (NDrake)

We move into the space where the third prototype lives, and it looks like I’ve stepped into a concert hall. On a small stage, the proto-arm is surrounded by multiple rocks, each with multiple lights and cameras aimed at it. The stage, it turns out, is hydraulic powered – and when the team wants to test the drill under Mars-like conditions, the whole platform can be launched upward until it docks with a pressure chamber hovering overhead.

“We actually raise it up and there are clamps up there which it clamps onto,” Robinson says. “You can pump down to Martian pressure and Martian temperature.”

On Mars, the surface pressure is about 60 0.6 percent that of Earth’s, and temperatures range from a wintry day in Ithaca, NY to somewhere you absolutely wouldn’t want to be. Robinson says the team runs roughly half its tests in the Mars-chamber, under the watchful eye of all those cameras.

But there are more differences between Mars and Earth than simply temperature and pressure.

“Does the different Martian gravity have any effect on the drill?” I ask.

“Gravity actually does affect the robotic arm quite a bit,” Robinson says. He explains that the team has to factor in weaker Martian gravity when teaching the rover where to retrieve bits and stash tubes. “If you were to go to those same joint angles on Mars, it would not work,” he says. “So we have to compensate for that in software. On the flipside, we’re now more capable because we carry less weight. So it’s both tricky and it’s good.”

All of this means that when NASA’s next rover arrives on Mars, expect the red planet to be poked, prodded, zapped and drilled into with all the precision that a wheeled, nuclear-powered robotic surgeon can offer – courtesy of these piles of geologic guinea pigs collected from spots on Earth.

In other words, as Albert Markovski astutely notes in the movie I Heart Huckabees: “You rock, rock.”

A Blog by

Oxygen Discovery Could Complicate Search for Alien Life

Scientists did not expect to find molecular oxygen at Comet 67P/Churyumov-Gerasimenko.
Scientists did not expect to find molecular oxygen at Comet 67P/Churyumov-Gerasimenko.

The strange, duck-shaped comet that ESA’s Rosetta spacecraft has been orbiting for more than a year just got a bit stranger: Like plants on Earth, the comet is blowing molecular oxygen, O2, into the space around it. Molecular oxygen is thought to be rare in the cosmos – or at least exceptionally tricky to detect.

“It is the most surprising discovery we have made so far,” says Rosetta team member Kathrin Altwegg of the University of Bern. The team first spotted the oxygen about a year ago and took its time ruling out sources other than the comet itself. “The first time we saw it,” Altwegg says, “I think we all went a little bit into denial because it is not expected to be found in a comet.”

Of course, molecular oxygen is common on Earth, having first been pumped out in enormous quantities by photosynthetic blue-green algae about 2.5 billion years ago. Until now, though, astronomers have only spotted gaseous O2 in a handful of other places, including two distant molecular clouds. The new observations, reported today in Nature, not only force a reconsideration of the very early solar system, they also throw a bit of a curveball at scientists hoping to identify the signatures of life on other worlds.

“The finding is definitely a wake up call for exoplanets and the search for life,” says Sara Seager of MIT. “O2 is the most prominent gas on our biosignature gas list.”

Back to the Beginning

Comets are icy, space-traveling time capsules. Unlike planets, where internal ovens have more or less cooked and rearranged the planet’s ingredients, a comet’s original building blocks are preserved. So, scientists can use the icy dirtballs to peer back in time, all the way to the beginning of the solar system when small bits of frozen debris were colliding and forming comets. As the thinking goes, the molecules trapped in a comet reflect the composition of the dusty primordial nebula that swirled around the very young sun.

Out there, far beyond the orbit of Neptune, temperatures were obviously quite cold. But until now, no one thought it was cold enough or placid enough for two oxygen atoms to meet, link up, and stay together.

“All the models say it shouldn’t be there,” says study author Andre Bieler of the University of Michigan in Ann Arbor.

And while molecular oxygen only accounts for a small percentage of the total amount of stuff escaping from the comet – about 3.8 percent, relative to water – finding it at 67P is still enough to make scientists reconsider the composition and temperature of that primordial dust cloud. “This ice hasn’t been heated up enough to be reprocessed,” Bieler says.

Gassy molecular oxygen has only been observed around two other stars, suggesting that it’s a rare component of the interstellar medium. Perhaps, scientists now say, that result reflects the difficulty of detecting O2 remotely.

“When we find new molecules in comets, they’ve nearly always been found in the interstellar medium,”says Mike A’hearn of the University of Maryland, College Park. But, he adds, “the abundance [in 67P] is low enough that it’s unlikely we would have ever seen it in remote sensing.”

O2 and the Search for Little Green Microbes

Here’s what the problem could be for scientists hunting for the signatures of life on exoplanets: No one thinks there are exhaling microbes on 67P. Yet molecular oxygen, as Seager says, is at the top of the list of gases that could indicate the presence of extraterrestrial life. And if it is naturally common in the cosmos, then O2 might need to be reconsidered as a potential biosignature.

On the other hand, high levels of O2 in a planet’s atmosphere could still reflect the presence of life.

“The O2 lifetime is so short in atmospheres it won’t be present for long unless it is continually produced,” Seager says, noting that there are many ways to produce molecular oxygen that don’t necessarily involve life. “The comet shows us there are situations we hadn’t considered, and this will happen over and over again.”

A Blog by

The New $100 Million Search For Life in the Cosmos

Can you hear me?

More than a half-century after the first modern search for communicating extraterrestrial life, humanity’s quest to find intelligent beings in the cosmos is getting a much-needed boost. Today, Silicon Valley billionaire Yuri Milner announced a $100 million project that will scan the sky for radio signals from other worlds. Called Breakthrough Listen, it will be the most powerful search for extraterrestrial intelligence ever undertaken on Earth.

“In one day, Breakthrough Listen will collect more data than a year of any previous search,” said Milner, who’s also behind the lucrative Breakthrough Prizes in physics, mathematics and the life sciences. “The scope of our search will be unprecedented.”

Milner announced the 10-year initiative at a ceremony in London that included remarks from theoretical physicist Stephen Hawking, who discussed the ubiquity of life’s building blocks in the cosmos, as well as the possibility that Earth’s lights might already be gleaming in alien eyes.

“It’s time to commit to finding the answer to the search for life beyond Earth,” Hawking said. “We are life, we are intelligent, we must know.”

Snooping on the Cosmos

Beginning in early 2016, Breakthrough Listen will eavesdrop on stars in 100 neighboring galaxies, the galactic plane and disk, and the 1 million stars closest to Earth. So far, the Green Bank Telescope, at the National Radio Astronomy Observatory in West Virginia, and the Parkes Observatory in New South Wales, Australia will be helping look for celestial signals of otherworldly origin.

The Green Bank Telescope, located in Green Bank, West Virginia, is home to the largest fully steerable telescope in the world.

“Approximately 20 percent of the annual observing time on the GBT will be dedicated to searching a staggering number of stars and galaxies for signs of intelligent life via radio signals,” said Tony Beasley, director of the National Radio Astronomy Observatory, in a statement.

These telescopes will peer at the sky in a multitude of frequencies, searching for the answer to that timeless question of whether the cosmos is filled with chatter, or if Earth is just a lonely beacon, murmuring messages into a sea of silent, sterile worlds. There is also an optical SETI component that will search for laser signals from other worlds, as well as a competition for interstellar message design (details TBD). Data from the project will be publicly available, ready for digging into by anyone with the tools and motivation. In fact, Milner said, it’s totally possible that any signal in those data might not be found by one of the professional astronomers involved in the project.

“We have the greatest opportunity ever to detect intelligent folks in the Universe,” says astronomer Geoffrey Marcy of UC-Berkeley, who is one of the co-investigators leading the project at Green Bank. Joining Marcy as a co-investigator on the Green Bank portion of the work is astronomer Frank Drake, of the SETI Institute.

“The plausibility of extraterrestrial intelligence has grown, the promise of success in searches has grown,” says Drake, who’s better known to me as Dad. “We will finally have stable funding so that we can plan from one year to the next, we can hire very talented people to carry out the work…it may take a long time, but it’s our best chance to get all of those treasures of knowledge that will accrue if we do indeed detect another intelligent civilization.”

From $2,000 to $100 million

In 1960, Dad performed the first modern search for extraterrestrial intelligence. Called Project Ozma, it looked for signals from alien worlds orbiting the nearby sun-like stars Epsilon Eridani and Tau Ceti. From April through July, astronomers monitored a handful of radio frequencies for artificial signals.

“The entire budget for the project was exactly $2,000,” Dad says. (Project Ozma inspired the name of this blog.)

The next year, Dad crafted his eponymous equation. It predicts – based on seven factors – the number of detectable, communicating civilizations in our Milky Way galaxy. Some of those factors, such as the prevalence of planets orbiting other sun-like stars, were total question marks in 1961. No one had ever really tackled these unknowns, so strange was the idea that such a thing could be scientifically respectable.

Even though the skies have stayed eerily quiet, in the half-century since Project Ozma, SETI has grown from an infant field on the fringe of science to a well-known endeavor. Now, some of the factors in the Drake Equation are very well known – including the prevalence of planets around other stars (others, alas, are just as vexing as in 1961). In fact, we now know that most stars have planets, and that a good percentage of those planets happen to be Earth-like.

“We learned only last year from the NASA Kepler mission that one in five sun-like stars harbors an Earth-size planet at lukewarm temperatures, suitable for life,” Marcy says.

A Sky Filled With Life

Based on that estimate, there could be tens of billions of habitable worlds in our galaxy. If you want to see a star that might incubate a habitable planet, all you need to do is go outside on a clear night and gaze into a small patch of sky. What’s more, Marcy says, astronomers are finding that the cosmos has been liberally sprinkled with the building blocks of life as we know it – organic molecules that can be used to form proteins and nucleic acids.

“Among all of those billions of planetary petri dishes, who could doubt that some of them sparked biochemical reactions that spawned replicating molecules, something like DNA,” Marcy says. “The only remaining question is how often Darwinian evolution leads to brainy creatures.”

We don’t know the answer to that question, and we won’t know until we look.

“We may not answer it,” says Martin Rees, astronomer royal and chair of the project’s advisory board. “But this gives a bigger chance that it will be answered in our lifetime.”

A Blog by

A Vanishing Island, an Alien Mudball, and the Search for Life on Enceladus

Last week, the Lunar and Planetary Science Conference brought more than 1,700 scientists to The Woodlands, Texas. Through presentations and poster sessions, many of the solar system’s worlds briefly had a chance to shine — even the little ones, like comet 67P/Churyumov-Gerasimenko, dwarf planet Ceres, and all those icy moons in the outer solar system. We’ve already reported the latest results from Mercury, speculation about icy plumes on Ceres, mysterious happenings in the Martian atmosphere, and a newly discovered, concealed crater on the moon’s nearside. There are a few more stories on the way. For now, here’s a small selection of the many interesting things I happened across while vicariously traveling through the solar system. — Nadia

Searching for Life on Enceladus

The plumes erupting from the south pole of Saturn's moon Enceladus can be searched for signs of extraterrestrial life. (NASA/JPL/Space Science Institute)
Geysers erupting from the south pole of Saturn’s moon Enceladus can be searched for signs of extraterrestrial life. (NASA/JPL/Space Science Institute)

Small and lively, Saturn’s moon Enceladus is one of the prime targets in the search for extraterrestrial life. Its icy crust hides a subsurface ocean that erupts into space via fractures in the moon’s south pole that continually spit salty water into space. Ever since NASA’s Cassini spacecraft spotted the geysers in 2005, scientists have discussed the possibility of flying a spacecraft through them and searching for signs of life. Now, one of the space missions entered in NASA’s Discovery Program competition aims to do just that. As described by Cornell University’s Jonathan Lunine during a poster session on March 17, the Enceladus Life Finder (ELF) would fly through the Enceladian plume and collect some of the water coming out (“If Enceladus has life, we will find it,” the poster said). Instruments aboard the solar-powered spacecraft would look for life’s signatures in the alien water by studying the ratios of amino acids, searching for bias in the number of carbon atoms in fatty acids, and determining whether chemical isotopes line up with known biological processes.

“Flying through the plume and collecting material is exactly what Cassini has done multiple times to get data on the composition,” Lunine says. “That makes ELF a very low risk and high reliability science mission.”

ELF is one of 28 proposals entered in the Discovery program competition, open to missions costing $450 million or less. NASA will select between three and five candidates for more serious consideration this fall, and eventually choose one winner.


Alien Landforms on an Alien Moon

Yardangs in China, used by scientists as a comparison for possible yardangs on Saturn's moon Titan. (Jani Radebaugh
Yardangs in China were used by scientists as a comparison for possible yardangs on Saturn’s moon Titan. (Jani Radebaugh)

Titan, Saturn’s largest moon, has a surface that’s surprisingly Earth-like in many respects (except that where water falls and flows on Earth, liquid hydrocarbons fall and flow on Titan). There are rivers and seas, deserts, dunes, and yardangs. Wait – yardangs? On Earth, yardangs are exotic-looking features sculpted by wind-driven erosion. The deserts of Africa, the Middle East, Asia and South America are all home to alien-looking yardangs, fields of which can stretch for 100 kilometers. Now, Jani Radebaugh of Brigham Young University and her colleagues think they’ve spotted yardangs on Titan’s northern hemisphere in images taken by NASA’s Cassini spacecraft. The features are crisscrossed by river channels and are near an area that looks as though it may have been an ancient lakebed, perhaps suggesting a wetter past on the moon. Intriguingly, they’re also near a patch of domes that could be erupting cryolavas onto Titan’s surface. If the features are yardangs, Radebaugh says, they point to strong, persistent winds on Titan’s surface, as well as the presence of volcanic ash or soft, liquid-deposited clays. “They’re ephemeral,” says Radebaugh, who presented the data March 19. “Yardangs might tell us a little bit more about climate and about changing conditions – what is allowing them to persist?”


When Worlds Collide, Sometimes You Get a Mudball

Egg-shaped dwarf planet Haumea could have formed after two smaller bodies collided and congealed. (NASA)
Egg-shaped dwarf planet Haumea could have formed after two smaller bodies collided and congealed. (NASA)

Spinning like a furious egg-shaped top, dwarf planet Haumea is one of the solar system’s most rapidly rotating large bodies. It’s parked out in the Kuiper Belt, beyond Pluto, and orbits an average distance of 6.4 billion kilometers from the sun. It has two little moons, which scientists have used to determine that 1,400-kilometer wide Haumea is mostly rock, despite having a surface covered in pure, crystalline water ice.

Scientists think the solar system’s egg may have been cooked during a slow-motion collision between two 1,300-kilometer wide bodies. But rather than being completely obliterated, the cores of the two colliders congealed, Arizona State University’s Steve Desch described on March 17. As those cores merged, their outer layers were flung into space, leaving just a thin rind of ice on newborn Haumea’s surface. Inside, though, something different was happening. Warm temperatures helped water seep deep into the interior, driving what’s known as “mudball convection” and turning Haumea into something like a massive, sludge-filled Cadbury egg.


Volcanism in Valles Marineris?

Small, pitted volcanic cones cover the floor of Valles Marineris in an area called Coprates Chasma. (NASA/JPL-Caltech/MSSS)
Small, pitted volcanic cones cover the floor of Valles Marineris in an area called Coprates Chasma. (NASA/JPL-Caltech/MSSS)

Raked across the Martian equatorial plains is a giant canyon network known as Valles Marineris. It’s more than 4,000 kilometers long and can be more than 7 kilometers deep – in other words, it dwarfs the Grand Canyon. Now, after studying images shot from Mars orbit, scientists think they’ve spotted a population of relatively young, pitted volcanic cones at the bottom of the canyon, in a section known as Coprates Chasma.

Valles Marineris is just south of the Martian equator and is one of the larger canyon networks in the solar system. (NASA)
Valles Marineris is just south of the Martian equator and is one of the larger canyon networks in the solar system. (NASA)

There are more than 100 of these cones, many of which have summit craters from which lava could have flowed. And, the area surrounding the cones is covered in textures resembling lava flows, says Ernst Hauber, of Germany’s Institute for Planetary Research, who described the newly identified volcanic cones on March 19. Hauber and his colleagues compared the cones on Mars to similar cones on Earth, and ruled out steam vents, erosion, and other non-volcanic origins. Hauber says the find is not necessarily surprising, as volcanism is thought to be one of the processes that helped build Valles Marineris, but that the observations provide some of the strongest evidence so far for the idea. Confirming the cones’ volcanic nature could be done using orbiting spacecraft to make better maps of Coprates Chasma and observe the minerals in the area, but “the best way would be to send a rover,” Hauber says.


Now You See It, Now You Don’t

The Magic Island in Titan's Ligeia Mare, as seen by NASA's Cassini spacecraft. (NASA/JPL-Caltech/ASI/Cornell)
The Magic Island in Titan’s Ligeia Mare, as seen by NASA’s Cassini spacecraft. (NASA/JPL-Caltech/ASI/Cornell)

Titan’s Magic Island has vanished. The strange feature first appeared in Cassini spacecraft target=” blank” images of Ligeia Mare, the second-largest sea on the Saturnian moon, in summer 2013. An unexpected apparition, the “island” appeared to be floating just offshore, near a convoluted patch of shoreline. But in images taken in October, the island was gone. It reappeared in August 2014, in the same spot and looking vaguely similar. By then, scientists had also seen another “magic island” in Kraken Mare, Titan’s largest sea. Yet in January of this year, Ligeia’s Magic Island had disappeared again. Scientists aren’t sure what the island really is, but they don’t think it’s a submerged landmass exposed by fluctuating sea levels. Instead, the team’s best guesses are that the Magic Island is either waves on the sea surface, a collection of floating, solid materials, or radar-reflective bubbles. What is clear is that Titan’s surface is full of action.

“These really are transient, dynamic phenomena that are occurring in the seas,” says Cornell University’s Jason Hofgartner, who provided a Magic Island update on March 20.

A Blog by

Auroras Reveal Buried Ocean on Jupiter’s Moon Ganymede

Auroras wrapped around Jupiter’s moon Ganymede, the solar system’s largest moon, have confirmed that a salty ocean hides beneath the world’s surface.

Ganymede, as seen by NASA's Galileo spacecraft in 1996. (NASA/JPL)
Ganymede, as seen by NASA’s Galileo spacecraft in 1996. (NASA/JPL)

The observations, made with the Hubble Space Telescope, add Ganymede to a long list of places in the solar system where water is abundant. They also suggest a way for scientists to remotely look for water on distant exoplanets. Described today in the Journal of Geophysical Research, the results are a slick observational feat, and the first time auroras have been used to remotely peer inside a world.

“We aren’t at Jupiter. Hubble is at the Earth, and yet it can probe the internal structure of this moon, remotely,” said Heidi Hammel of the Association of Universities for Research in Astronomy. “That’s a really powerful tool.”

Alien Auroras

Auroras circling Ganymede (shown in blue) can be used to probe the moon's interior. (NASA/ESA/J/Saur)
Auroras circling Ganymede (shown in blue) can be used to probe the moon’s interior. (NASA/ESA/J/Saur)
At 5,200 kilometers across, Ganymede is bigger than the planet Mercury. It’s the only moon in the solar system that generates its own magnetic field, propelled by a rotating liquid iron core.

Finding evidence for a buried sea on Ganymede isn’t exactly surprising – scientists have suspected the moon hosted a subsurface ocean for decades. Data collected by NASA’s Galileo spacecraft, which orbited Jupiter between 1995 and 2003, strongly suggested that an ocean lived beneath the moon’s surface. But it wasn’t a done deal.

“It still was 50-50,” said study author Joachim Saur, a geophysicist at Germany’s University of Cologne.

Then, in 2010 and 2011, Hubble took a close look at the moon. More specifically, it looked at the auroral bands ringing Ganymede’s poles. Hubble studied the auroras in the ultraviolet, but Saur said the shimmering lights would be visible to human eyes.

“If somebody could be standing on Ganymede looking up into the night sky, it would appear as red aurora, to you,” he described.

The locations of Ganymede’s auroras depend on the moon’s magnetic field. But as Jupiter rotates, its immense magnetic field tugs on Ganymede’s auroras; physics predicts the auroras should wobble around the poles by about 6 degrees as Jupiter spins. Yet multiple hours of Hubble observations suggested the auroras weren’t rocking as much as they should – an effect that could only be explained by a counterbalancing, electrically conductive (i.e., salty), buried ocean.

“The aurora in all these cases moved by approximately 2 degrees, only,” Saur said. “Our new HST observations provide the best evidence to date for the existence of an ocean on Ganymede.”

(NASA/ESA/A Feild)
Jupiter’s magnetic field tugs on Ganymede’s auroras, causing them to rock around the moon’s poles. But the amount of rocking depends on whether an electrically conductive ocean is buried beneath the moon’s surface (blue lines). (NASA/ESA/A Feild)

The Hubble observations don’t offer much detail about the ocean itself, but scientists say it has to be within 330 kilometers of the surface. The ocean’s depth remains a mystery, but it could contain more water than Earth’s oceans. What’s more, observations of Ganymede’s surface terrain suggest that at some point long ago, the ocean spilled onto the moon’s surface. “We believe that there have been times when that ocean may have communicated with the surface of Ganymede in the distant past,” said Jim Green, NASA’s director of planetary sciences.

Ocean Worlds and Exo-Worlds

The new Hubble observations suggest that in the future, similar strategies and powerful space telescopes could be used to infer the presence of water on distant exoplanets. The data also officially add Ganymede to the A-list of places in the solar system in which water is abundant. It’s an esteemed list, headlined by the planet Mars, Jupiter’s moon Europa and the Saturnian satellites Titan and Enceladus. Indeed, it seems the more we look, the more water we find – particularly in the outer solar system.

“The solar system is now looking like a pretty soggy place,” Green said. “Water is really of an enormous abundance.”

Ganymede's ocean is likely sandwiched between two layers of ice, limiting the amount of chemical nutrients it might host. (NASA/ESA/A Feild)
Ganymede’s ocean is likely sandwiched between two layers of ice, limiting the amount of chemical nutrients it might host. (NASA/ESA/A Feild)

But Ganymede’s ocean isn’t quite like the better-studied seas lying beneath the surfaces of Europa and Enceladus, both of which are tantalizing targets in the search for life beyond Earth.

Unlike those oceans, Ganymede’s sea is probably sandwiched between two layers of ice, says Robert Pappalardo, of NASA’s Jet Propulsion Laboratory. That makes it a less intriguing astrobiological target because it’s harder for rock-derived chemical energy to leach into the sea. Ganymede is also less geologically active than either Europa or Enceladus, which makes it harder for chemical nutrients from the surface to work their way into the ocean.

“Ganymede’s ocean is lesser on the probability scale of where we would expect life to exist or where we could search for it,” Pappalardo says.  “Nevertheless, understanding Ganymede is very important in comprehension of the range of icy satellite ocean environments that are possible, and to our understanding of how icy satellites and their oceans form and evolve.”

A Blog by

Instead of Waiting for E.T. to Phone, Let’s Call E.T.

Finding an intelligent alien civilization would easily rank among the most profound discoveries in human history.

So far, though, there are no signs of communicating extraterrestrial life, no messages from the stars suggesting that humans are not alone in the universe. Maybe, some scientists argue, it’s time for us to take a more active role in the interstellar conversation. Instead of simply eavesdropping on the cosmos as we’ve done for the past half-century, perhaps Earth should begin transmitting messages to the stars – big, blazing telegrams meant to prompt an extraterrestrial reply.

But actively sending signals into the cosmos is more than a slightly controversial idea. Recently, a statement posted online asserted that messaging extraterrestrial intelligence (METI) carries “unknown and potentially enormous implications and consequences.” Signed by a number of well-known scientists – and people such as Elon Musk – the missive asks that a vigorous international debate take place before any new messages are sent.

That debate erupted at the American Association for the Advancement of Science’s annual meeting, where several contentious exchanges broke out as scientists gathered to discuss the pros and cons of interstellar messaging.

“We should launch active SETI as an ongoing complement to our traditional passive SETI projects,” said Doug Vakoch, director of interstellar message composition at the SETI Institute. “It’s a matter of diversifying our search strategies.”

But undertaking a targeted interstellar messaging campaign without considering the potential consequences is foolish, argued astrophysicist and science fiction author David Brin. The seeming lone voice of dissent among the convened panelists, Brin noted that attracting the attention of an unknown advanced civilization could bring potentially disastrous results. And, he said, it’s impossible to predict whether aliens are going to play nice or be real jerks.

“This is the only really important scientific field without any subject matter,” Brin said. “It’s an area in which opinion rules, and everyone has a very fierce opinion.”

Right now, there are no official messages waiting in Earth’s interstellar outbox. But Vakoch and others are floating the suggestion of using the Arecibo Observatory’s mega-powerful transmitter to send a series of messages in the down time between the observatory’s other studies. It wouldn’t cost much at all, and it would join the ongoing campaigns to listen for alien transmissions. While the question of what to include in those messages is obviously important, it’s taking a backseat to the issue of whether those messages should be sent at all.

“Active SETI, I gotta admit, is a controversial topic,” Vakoch remarked.

Despite the ongoing controversy, it wouldn’t be the first time interstellar messages have been beamed into space. A handful of transmissions have already left Earth’s shores and set sail across the cosmos. Perhaps the best known of these messages was sent from Arecibo in 1974, as part of a ceremony marking the completion of an upgrade to the giant radio telescope. Composed by astronomer Frank Drake, the message has been hurtling through space at the speed of light, destined to intersect in 25,000 years with a globular star cluster in the constellation Hercules.

And then there’s all the stuff that’s wafting into space without any such effort from Earthlings. These murmurs from Earth include the high frequency chirping of military radars, TV and radio transmissions, and the interplanetary radar used to study numerous asteroids in the solar system. Recently, technologies like cell phones and cable TV have turned Earth into a slightly quieter pale blue dot, but for many decades, our intra-planetary communications were easily leaking into space.

True, those signals are much harder to detect than a blast of directed radio waves from Arecibo, but SETI Institute senior astronomer Seth Shostak argued that any civilization advanced enough to show up and annihilate the planet is also advanced enough to detect those murmurs. In fact, he notes, our technology isn’t too far from being able to do the same. “We are within one or two centuries of being able to find the equivalent of ourselves,” he said.

In other words, it’s too late to shut up and hide.

But Brin isn’t buying it. And he bristles at the suggestion that he and his colleagues are simply worried about “slathering Cardassian invaders.” Instead, he implores, wouldn’t it make more sense to have a conversation about the potential ramifications of METI before we begin shouting into the void?

It does seem like a conversation is beginning to take place.

At the meeting, several panelists attempted to cut through the supposition and opinion by drawing analogies between METI and other controversies. Astrobiologist David Grinspoon noted the obvious link between METI and NASA’s Planetary Protection Office, created to prevent biological contaminants from being passed between Earth and other solar system bodies. “That’s a discussion that’s been had internationally, and I think that’s quite relevant here,” Grinspoon said. He also noted that fears of extraterrestrial intelligences with nefarious intent are not dissimilar to concerns about the motivations of artificial intelligence.

“That certainly presents an existential threat. It may be tiny — people have different opinions on it – but how are we dealing with that?” Grinspoon asked, noting that no one has shut down artificial intelligence research.

Later, federal judge David Tatel offered the rather salient observation that this debate is not unlike the controversy swirling around dual-use research on harmful pathogens, where learning more about nasty viruses could be used to engineer an especially potent bioweapon. And noted similarities with the current debate over geoengineering and how to combat climate change.

“Both of these have similarities with active SETI,” he said. “Both could produce great benefits or have catastrophic consequences.”

A Blog by

40 Years Ago, Earth Beamed Its First Postcard to the Stars

Forty years ago, on Nov. 16, 1974, Earth beamed its first postcard to the stars.

The message left our home planet on a warm and sticky day in Puerto Rico and has been flying through the galaxy at the speed of light ever since. In about 25,000 years, it will collide with a cluster of more than 300,000 stars.

Unlike the radio signals that had been leaking from Earth since the late 1930s, this postcard was the first deliberate transmission to an alien civilization. Meant to be decipherable by extraterrestrial beings, the message contained some key information about the species that had sent it.

“It was a message that would actually inform anyone who did receive it that we existed, and tell them a little bit about what we were like,” says my dad Frank, who had the responsibility of constructing and sending what’s now known as the Arecibo Message. “And it was also a message to ourselves in that it showed what an intelligent civilization can do to contact other civilizations.”

Dad had been given just one month to write Earth’s first radio greeting to the stars.

It was 1974, and the Arecibo Observatory’s giant radio telescope had just gotten a major upgrade. Beamed into space by the Observatory’s powerful, one million-watt transmitter, the message would cap a ceremony marking the completion of the improvements (you can listen to it being sent, below). But it was a secret – only the ceremony’s organizers knew ahead of time what would happen, and they envisioned a transmission lasting about 3 minutes.

So, it needed to be relatively simple.

Texting Aliens

Fortunately, Dad had been thinking about how to write postcards to aliens for a while. Sending a message to other worlds, while simple in principle, becomes almost impossibly complex when it’s time to actually write the letter. Aside from the question of what to say, there’s the issue of how to say it.

For starters, not just any language will work – think about how difficult it is to understand the many languages spoken on Planet Earth. The chances of an alien civilization understanding, “Hi, we live on Earth and are friendly,” are vanishingly small, just like your chances of understanding “Vie minut johtajanne luo” are practically zero unless you speak Finnish. Numbers and equations, while more concrete, are still written using arbitrary symbols. And things like distance measurements are just as arbitrary as words.

So how does one compose a missive with the best chance of being universally understood?

“From day one, I’ve always thought pictures work,” Dad says. “Sending pictures is easy. We do that all the time, with great results.”

Black and White

Dad set up a grid and drew crude shapes and symbols by shading in squares. A 3-minute transmission at 10 bits of information per second meant he had at most 1,800 squares to play with.

The Arecibo Message, with colors added to identify the various components. (norro)
The Arecibo Message, with colors added to identify the various components. (norro)
His pencil traced the shapes of the numbers one through 10, in binary code. It encoded a representation of five chemical elements essential for life on Earth (hydrogen, oxygen, nitrogen, phosphorus and carbon), which he then used to draw the sugars, bases, and backbone that form life’s genetic instructions.

Then, he drew a depiction of double helical DNA, wrapped around “3 billion” written in binary code. This is the approximate number of characters (“base-pairs”) in a human genetic sequence. Below that, he shaded a human into the message, with “14” on one side, and “4 billion” on the other. The first number represented the height of an average human, in units of 12.6 centimeters – the length of the radio waves used to send the message.

The second number? In the 1970s, that was the human population of Earth.

Next came a map of the solar system (which included Pluto, since it was still one of the nine classical planets), with the Earth offset from the others, toward the human, to signal that this was our home planet. And lastly, he sketched a representation of the Arecibo telescope itself, with its size noted in units of radio wavelengths, to indicate the level of technology used to post the letter.

Sending the message would mean translating the grid into binary code, where zeros and ones denoted which squares were shaded and which were open (black squares = 1, white = 0). To decode the message, recipients would need to figure out how to organize that string of numbers into a grid with the correct dimensions, recognize that the grid contained symbols, and then decipher the meaning of those symbols. The finished message had 1,679 bits; 1679 is the product of prime numbers 23 and 73, which offers a hint about how to lay out the grid.

Test Transmission

Dad tested his message by sending it to his friend and colleague Carl Sagan, who hadn’t been involved in writing it and had no knowledge of its content. He wanted to see if Carl could figure out what was in there.

“And more importantly,” Dad adds, “Make sure he would not find things in it that were equally plausible decryptions but were wrong, which would be misleading and give inaccurate depictions of our civilization.”

Perhaps not surprisingly, Carl got almost everything right, and quickly. But the chemistry eluded him, Dad recalls, adding that biochemists he sent it to later got that part almost immediately. “People recognize things that are in the area in which they have expertise,” he says.

To Hercules

And then it was time to choose a destination.

Sitting in a sinkhole, the Arecibo telescope is somewhat limited in its steering ability. So the postcard needed to be addressed to somewhere roughly over Arecibo at 1pm on November 16, 1974, the time of the ceremony.

The heart of M13, the Great Cluster in Hercules. (ESA/Hubble and NASA)
The heart of M13, the Great Cluster in Hercules. (ESA/Hubble and NASA)

Scouring the star charts, Dad identified a worthy target: M13, the Great Cluster in Hercules. With more than 300,000 stars – and probably at least that many planets! – M13 was perfect, and its heart would fit entirely in the telescope’s beam. An Arecibo-type receiver on any of those worlds should have no trouble detecting the message. (Some people, Dad notes, think the cluster will have moved in 20,000 years, and that the message will miss it. That’s not true, he says. “It will have moved a little bit, but only a fraction of the width of the beam of transmission,” he says.)


At 1pm, just as planned, the Arecibo transmitter came to life. For a few moments, a smooth tone filled the crags and valleys of the surrounding jungle terrain.

And then the transmitter began to sing a series of alternating tones. “It sounded like a bird warbling,” Dad recalls. Over nearly three minutes, the 1,679 bits of information hurtled into space, carrying this message from Earth – the first deliberate radio transmission from the humans on our little blue planet – to whatever beings might live in that great cluster in Hercules.

“When we sent the last character, and it stopped and we went back to that steady tone, everybody was crying,” Dad says. “We were hearing what it would be like to actually contact another world. That was what that sound was. It had the aura of human beings doing something marvelous that involved the whole cosmos.”

But there was another surprise to come. Unintentionally, Dad had coded another dimension into the message. As the transmitter began to send those alternating tones, one of the engineers in the control room recognized a bit of Morse code. Hiding in the first notes of the warble was the simplest greeting of all:


A Blog by

This Massive Stellar Flare Would Have Been Catastrophic for Nearby Planets

Not too far away, a small star recently unleashed an unexpectedly intense series of flares. The series kicked off with a behemoth eruption that was 10,000 times more powerful than anything ever recorded from the sun. For a few brief moments, the star blazed many times brighter than normal.

Another half-dozen flares and two weeks later, the episode ended. But the explosive cluster had been hotter, more powerful, and longer-lasting than scientists had expected to see. It would definitely not be good news for any planets orbiting close to the tempestuous star.

The star is a young red dwarf that is only about one-third the sun’s mass. It’s part of a binary dwarf system called DG Canum Venaticorum (or DG CVn for short), located about 60 light-years away. Red dwarfs are the most plentiful type of star in the galaxy, outnumbering everyone else by about three to one. Small, cool, and remarkably long-lived, these stars are considered by many scientists to be excellent hosts for life-friendly planets.

But on April 23, you would not have wanted to be anywhere near this little star. Spinning 30 times faster than the sun, the star’s rapid rotation amplified a burgeoning distortion in its magnetic field. When the tension finally snapped, it launched the mega-flare into space. As observed by NASA’s Swift satellite, that initial explosion reached a temperature of about 200 million Celsius (more than 12 times hotter than the center of the sun). It released enough high-energy X-rays to briefly outshine the star itself — and its nearby friend — in all wavelengths of light.

If a comparable flare had erupted from the sun and been followed by a cloud of charged particles, Earth would be in a bit of trouble, says astronomer Rachel Osten of the Space Telescope Science Institute. Those particle storms that often accompany flares are called coronal mass ejections, and when they’re energetic enough, they can disrupt both ground- and space-based communication systems.

“In terms of our own space weather, it is the mass ejections and energetic particles that can do the most damage,” she says. “The effects [of this mega-flare] would be worse than the biggest space weather event we’ve experienced so far.” (Here’s a description of the massive 1859 eruption known as the Carrington Event.)

But in addition to messing with power grids, knocking out short-wave radio communication systems and disrupting the global positioning system, such a mega-flare would have a notable bright side: Spectacular auroras, observable down to very low latitudes instead of just around the poles.

Of course, this little star’s super-spasm was no threat to our home planet. But any planets in its life-friendly zone would have been in for a rough time. “It must surely have been catastrophic,” says astrophysicist Stephen Drake of NASA’s Goddard Space Flight Center.

Red dwarfs are cooler than the sun, so planets warm enough to have liquid water on their surfaces orbit nearer the star, at perhaps one-tenth the Earth-sun distance. Because of that, these planets are tidally locked in orbit and always have the same face pointed toward their star. In other words, one half of the planet is bathed in perpetual day, the other half blanketed by endless night.

A mega-flare of this size, followed by a coronal mass ejection, would not be a welcome occurrence for a planet snuggled close to DG CVn — especially not for the part of the planet staring at the star.

“Any ozone layer on the star-facing hemisphere would surely be destroyed, the upper atmosphere would be hit by this large pulse of radiation, and then, maybe several hours later, if the geometry lined up, the associated coronal mass ejection would crash into the planet’s magnetosphere, and likely completely collapse it to the planet’s lower atmosphere on the star-facing hemisphere,” Drake says. “I would imagine that this, if the planet supported life, would produce the kind of major extinction event that we see a number of examples of in the Earth’s history.”


Many astronomers are excited about the possibilities of finding habitable planets around red dwarf stars. In addition to being close to the star and relatively easy to spot, these planets also have the luxury of maturing into old, old, old age. Red dwarf stars are exceptionally long-lived, with lifespans calculated to be on the order of trillions of years, so any nearby extraterrestrial lifeforms theoretically have lots of time to evolve.

But one of the chief concerns raised when discussing habitable planets around red dwarfs is the stars’ propensity for violent stellar outbursts, which could deal deadly blows to any organisms struggling to gain a toehold on their home worlds.

Yet flares the size recorded earlier this year around DG CVn are rare, Drake says, and tend to occur when the stars are very young — as this star is. Scientists estimate DG CVn is only about 30 million years old, which makes it less than one percent of the solar system’s age. So, planets forming around it are still very young, and far from habitable at this point.

“Any planets it may have in its habitable zone are still completely inhospitable to life,” Drake says. “Their surfaces are likely still molten. It took life perhaps a billion years to eventually develop on the Earth, as you know, so DG CVn still has lots of time to become the host star of a planet with life.”

A Blog by

Europa’s Crust Conceals a Most Earthlike Feature

For centuries, the icy moons of the outer solar system hovered beyond Earth’s grasp. These were cold, sterile worlds – small, frozen spheres with brittle surfaces that didn’t do much except reflect shards of distant sunlight.

Now, of course, we know those moons are anything but dead. One of them – Jupiter’s moon Europa – harbors a rather Earthlike feature, scientists reported this week in Nature Geoscience. Like Earth’s, Europa’s crust might be broken up into a patchwork of tectonic plates. On Earth, the shifting of tectonic plates is responsible for the movement of continents, violent earthquakes, and volcanic eruptions.

Europa is the only other body in the solar system that shows strong evidence for plate tectonic activity – and the implications for life beneath its surface are intriguing.

“It’s a bit like the Earth, which gets everyone excited,” says planetary scientist William McKinnon of Washington University in St. Louis. “But this is a very exotic realm. We’re not talking about rock, we’re talking about ice.”

Discovering Europa

Galileo described the first cluster of icy satellites, the four largest around Jupiter, in the early 1600s. Night after wintry night, he watched as three strange “stars” swirled around the giant planet. The stars weren’t behaving as he’d expected, and traced odd patterns in the sky. Gradually, Galileo realized that his stars swore allegiance to great old Jupiter rather than the glittering black backdrop. After several months, Galileo concluded that he was not, in fact, seeing stars. He was watching planetary bodies moving around giant Jupiter – and there weren’t just three of them, but four.

A translation of the key passages of Galileo Galilei's journal detailing his discovery of four moons orbiting Jupiter. (Image and caption, NASA)
A translation of the key passages of Galileo Galilei’s journal detailing his discovery of four moons orbiting Jupiter. (Image and caption, NASA)

“I should disclose and publish to the world the occasion of discovering and observing four Planets, never seen from the beginning of the world up to our own times,” Galileo wrote in his Sidereus Nuncius. “I summon all astronomers to apply themselves to examine and determine their periodic times, which it has not been permitted me to achieve up to this day.”

Just like that, the Galilean moons were described. They wouldn’t be known as Ganymede, Callisto, Io, and Europa for another 250 years. Those were not the names proposed by Galileo, who instead called them the “Medicean planets,” after the powerful Medici family, whose influence had spread throughout Europe. Rather, it was German astronomer Johannes Kepler who suggested naming the quartet after Jupiter’s collection of lovers.

Coming Into Focus

It wasn’t until the mid-1900s, when the first of Earth’s robotic explorers visited the realm of the giant planets, that these distant moons stepped into the spotlight. Far from Earth and far from familiar, the former stars were anything but ordinary.

Little Io, which makes its home around Jupiter, proved to be the most volcanic body in the solar system. Ganymede is the largest moon in the solar system. And Europa, the smallest of Galileo’s moons and the sixth-largest moon of any, wasn’t just another spherical ice cube.

Europa during Voyager 2's closest approach on July 9, 1979. (NASA/JPL)
Europa, seen during Voyager 2’s closest approach on July 9, 1979. (NASA/JPL)

The 3,100-kilometer wide moon had a perplexingly young surface that suggested some kind of active replenishing of the frozen crust. Crisscrossed with rusty red lines and patches, Europa’s shell was anything but polished. It contained patches of jumbled icy blocks, now known as “chaos terrain,” and long fractures suggestive of geologic fault lines.

What’s more, observations of the moon’s magnetic field by the Galileo spacecraft strongly suggested the frozen crust encapsulated an immense global ocean – a large body of water, containing as much as three times the amount of liquid in all of Earth’s oceans combined. Heated by the gravitational squeeze of Jupiter and shielded from the planet’s intense radiation belts, the ocean, scientists quickly realized, might be capable of incubating extraterrestrial life.

Before long, revisiting Europa was at the top of every astrobiological wish-list. But that hasn’t happened yet.


Now, recent observations suggest the little moon’s crust hides a very Earthlike characteristic – a global system of tectonic plates. Scientists suspect that just like on this planet, those plates slip past and dive beneath one another, producing areas with telltale signs of geologic activity.

Such a system helps solve a long-standing conundrum at Europa: Put simply, scientists needed to figure out how the moon stays the same size.

Europa’s surface is estimated to be between 40 and 90 million years old. That’s much, much younger than its 4-billion-year age. In other words, something must be resurfacing the moon and erasing the cratered evidence of bombardment that would ordinarily pile up, as it does on Europa’s pockmarked neighbors.

Finding that special something wasn’t too hard. When scientists looked at Galileo spacecraft images of Europa, they found areas where new ice had recently appeared. Called dilational bands, these were stretches where the crust looked as though it had cracked and been pushed apart by new ice welling up from beneath. And those bands weren’t small.

“This can be in excess of 20 or 30 kilometers,” says University of Idaho planetary scientist Simon Kattenhorn, an author of the paper describing plate tectonics on Europa. “These are very wide zones, where the two sides moved apart like rigid plates.”

The large, ruddy smear in the middle of this image from the Galileo spacecraft is an example of a dilational band, where new ice is being pushed through cracks in Europa's crust. (NASA/JPL-Caltech/SETI Institute)
The large, ruddy smear in the middle of this image from the Galileo spacecraft is an example of a dilational band, where new ice is being pushed through cracks in Europa’s crust. (NASA/JPL-Caltech/SETI Institute)

The trouble was, scientists studying the Europan surface couldn’t find the opposite: Places where old crust was destroyed. Without those areas, the moon would just keep growing and growing. Which it isn’t.

“If you’re going to open up the ice, and the moon isn’t expanding like a balloon, then what happens at the other end?” McKinnon says.

A simple explanation is that as new material emerges, portions of the moon crinkle or fold in response. There’s a little bit of evidence for that.

Another possibility, which has been investigated for years, is that subduction zones between tectonic plates in the moon’s crust are helping remove material from the surface. As one plate dives beneath the other, old bits of surface are being recycled.

This process is what Kattenhorn and Louise Prockter, of The Johns Hopkins University Applied Physics Laboratory, think they’ve found evidence for. The pair spotted subduction zones by studying old Galileo spacecraft images of a surface patch on Europa’s northern hemisphere. Based on the patterns of fractures, folds, and streaks, they rewound the geologic clock and tracked the movements of different areas through time (in a fashion analogous to that which identified South America and Africa as once being joined).

False-color image of Europa’s trailing northern hemisphere, where subduction zones are hypothesized to exist. (Caption and credit, NASA/JPL/University of Arizona)
False-color image of Europa’s trailing northern hemisphere, where subduction zones are hypothesized to exist. (Caption and credit, NASA/JPL/University of Arizona)

When Prockter and Kattenhorn reassembled the Europan puzzle, they found they were missing a piece. In the not-so-distant past, an area roughly the size of Massachusetts had disappeared. The pair attributed that disappearance to a subduction zone near the reddish band known as Minos Linea.

“We were really surprised and excited,” Kattenhorn says. “It’s not like, ‘Wow, we’ve discovered something new!’ It’s more like, ‘Now it all makes sense.’ If you take portions of the surface away, and you make new material, over geologic time periods, the surface will recycle.”

On Europa, these tectonic plates live in the icy crust itself. They’re in the uppermost, brittle portion of the shell, rather than floating just above the ocean surface or riding atop the moon’s core. Whether the plates gradually slide past one another, without any major build-up of tension – or move quickly, with dramatic, shattering releases of tension like on Earth – is unclear.

“If the stress is building up and building up like on Earth – if that really does happen on Europa – then maybe the plate does shift downward suddenly to create a seismic release of energy,” Kattenhorn says. “Even on Earth, there’s still so much we don’t understand about the earthquake process. We know even less about ice.”

One marked disappointment is that the terrain above the subduction zone isn’t more spectacular – it’s pretty ordinary, and wouldn’t be noticeable except through the kind of detailed reconstruction the pair did. That’s why no one has found it until now.

“It’s an even, low-lying band of terrain,” McKinnon says. “It doesn’t have any of the hallmarks from the Earth, it’s not particularly suggestive of anything.”

The team isn’t sure yet if plate tectonic activity is associated with the recently discovered massive plumes of water vapor venting from the moon. Kattenhorn and his colleagues are working on determining that, and on verifying these initial observations. He and others would really like to see evidence for the same process at different sites on the moon – and would especially like some new images to peruse.

“If this could be convincingly demonstrated in another area or two, then that would cinch the story. Kind of like the plumes,” says the Jet Propulsion Laboratory’s Robert Pappalardo, pointing to the recent failure to spot those plumes again. “You see it once, and it’s exciting. But the scientific method says it’s got to be repeatable. So let’s go look again, or look somewhere else.”

Revisiting a Small, Icy Incubator

The astrobiological implications of tectonic plates on Europa are profound. Previously, scientists had struggled to explain how nutrients and oxygen might seed the moon’s subsurface ocean, locked beneath that icy crust. The most obvious source of these molecules is the moon’s surface, where radiation from Jupiter cleaves oxygen from water ice and produces such compounds as hydrogen peroxide and formaldehyde. These compounds are vital chemical reactants and energy sources for lifeforms living beneath the surface.

Europa, as seen by the Galileo spacecraft in 1996. On the left, a true color image. On the right, a color-enhanced version. (NASA)
Europa, as seen by the Galileo spacecraft in 1996. On the left, a true color image. On the right, a color-enhanced version. (NASA)

Giant, icy conveyor belts regularly moving chunks of surface ice into the interior could be an efficient way to deliver such energy and oxygen to the ocean below.

“That’s a big deal for getting at the chemical energy part of habitability. It’s one of those key ingredients for life,” Pappalardo says.

All of these data, scientists say, are excellent arguments for why we need to revisit Europa. It’s the place in the solar system most likely to host alien life today, and it’s a curious geological world that we’re just beginning to understand.

But though the National Academy of Science’s 2011 Planetary Decadal Survey placed a mission to Europa among its highest priorities, that mission keeps running into budget trouble. Over the last few years, teams designing the mission have cut the original US $4.7 billion mission proposal into half – and then into half again.

“NASA is looking at whether there’s anything that can be done for a billion dollars,” Pappalardo says. Though it sounds like a lot, that price tag is a challenge. Europa is far away, and any spacecraft spending any time around the moon will need heavy radiation shields, which add to launch costs.

Pappalardo and others are working on designing what’s called the Europa Clipper mission, which could launch as early as 2022. Rather than orbiting the moon, the spacecraft would perform a series of fly-bys, gathering data that would reveal information about the moon’s gravity and its ocean. “We’ll see what happens in the spring with the next budget cycle,” he says.

Additionally, the European Space Agency is eyeing a 2022 launch for its Jupiter Icy Moons Explorer mission, which would investigate the giant planet as well as Europa, Callisto, and Ganymede.

So perhaps Europa and its enigmatic ocean are squarely on the horizon.

Imagine what it would be like to zoom in for a close look at this watery moon and make a full-throttle attempt to unlock its secrets. My guess is, those initial observations would provoke an astonished response similar to Galileo’s, when he looked through his telescope and saw distant Europa for the first time.

A Blog by

A New View of Europa

Europa is like a spherical ice cube that has partially melted. In fact, if you shook this small moon of Jupiter, you might hear a sloshing sound.

That’s because a deep, global ocean lies beneath the moon’s frozen, criss-crossed crust – an ocean that might be as much as 100 kilometers deep. In fact, Europa’s ocean is so vast that it contains between two and three times as much water as all the oceans on Earth, combined.

What swims in that alien sea? We don’t yet know. Maybe nothing. But astrobiologists have placed Europa at – or near – the top of their visitation wish-list for decades. That massive ocean, which is likely filled with minerals from the alien ocean floor, plus the possibility of hydrothermal sea vents, makes this small moon one of the best places to look for life beyond Earth in the solar system.

Piercing that icy crust and sinking a spacecraft into the ocean is no trivial matter, though. But not to worry: Scientists are working on solving that problem. And maybe in the next decade or so, Earth will send a spacecraft to this faraway moon, a probe tasked with sniffing around and possibly scouting out landing sites for future spacecraft.

It wouldn’t be the first time a robotic emissary had the moon in sight, though. In the 1990s, the Galileo spacecraft zipped through the Jovian system and studied the solar system’s most massive world. Part of that campaign included taking pictures of the many moons in Jupiter’s gravitational clutches.

If you thought you’d seen all the images Galileo had to offer, you’d be wrong. NASA released a new view of Europa today. It’s a reprocessed version of images taken on November 6, 1997, and spans an area that’s roughly 160 square kilometers. Those red streaks that look like highways are formed by sulfur-containing compounds oozing through the ice. And if the streaks are anything like what we see on Earth – up in the Canadian Arctic – then maybe they’re the mark of life beneath the surface.

A Blog by

An Alien Origin for Life on Earth

This is the second of three blog posts associated with this week’s episode of Cosmos: A Spacetime Odyssey, which addresses life in the universe. Read the first one here.

Whether the universe is filled with alien beings who wish upon stars, struggle to understand the subatomic realm and argue over who’s paying for dinner is not yet known. We’re looking for them.

But in the search for life, there’s another fundamental question that has gone unanswered for millennia. Step one in the development of any civilization is life itself. How, exactly, does life get going?

“The essential message of life has been copied and recopied for more than three billion years,” says Neil deGrasse Tyson, on this week’s episode of Cosmos: A Spacetime Odyssey. “But where did that message come from?”

Even on Earth, the origin of that on-switch is murky. We don’t know how a pile of organic molecules, their atoms arranged in intricate rings and bridges, gained the ability to survive and replicate, to wall themselves off from a young Earth’s iron-rich seas and oxygen-free air.

Some ideas suggest that life’s first gasp came from shallow ponds, warmed by a sun still in its childhood; others point to bubbling hot springs, clays, ice, or to warm, energy-rich vents erupting from the deep ocean floor.

For decades, scientists have tried to replicate the planet’s primordial recipe for life. They’ve mixed salty brews, spiced them with metals and smelly gases, and jolted the mixes with electricity, or sunlight, or heat, then reset the timer and started all over with a new handful of ingredients and instructions. These experiments have taught us a lot. Among other things, we’ve learned that amino acids are sort of easy to make from scratch, that complex metabolic pathways can emerge from a seemingly random mix of ingredients, and that single-stranded, ribonucleic enzymes can replicate themselves indefinitely.

But none of these experiments have produced the secret sauce that sparked the first single-celled organisms. Each time, when the oven timer chirped, there was no life.

Enter: Another theory that’s been simmering for years (millennia, even). What if, it asks, instead of being baked from scratch on Earth, life came from the stars?

“If life can withstand the hardships of space, and endure for millennia, then it could ride the natural interplanetary transit system from world to world,” Tyson says. “What this means is that life doesn’t have to start over again.”

Illustration of the 1833 Leonid Meteor shower. Could meteorites have carried life to Earth? (Edmund Weiss/Wikimedia)
Illustration of the 1833 Leonid Meteor shower. Could meteorites have carried life to Earth? (Edmund Weiss/Wikimedia)

Called panspermia, the theory suggests that organisms hitchhiking from one world to another can spread the organic seeds of life throughout the cosmos. Launched into space aboard blasted out bits of planetary debris, these space-faring life-forms could, upon arrival at an alien planet, survive and thrive – perhaps evolving into spiders, sharks (or spidersharks?), dandelions and elephants.

Obviously, no one knows whether panspermia actually happens. For years, the idea failed to gain strong scientific traction. But recent pieces of circumstantial evidence suggest that in some environments, such as the inner solar system, versions of panspermia aren’t so farfetched.

For starters, fragments of other planets have made their way to Earth. We have pieces of Mars and Mercury (maybe), and (probably) Venus on our planet. Pieces of Earth have undoubtedly made their way to our neighbors. This exchange of crusty planetary material, if it harbored the right kind of hardy organism, could conceivably transfer life from one world to the next, says astronomer Caleb Scharf of Columbia University.

“I’d say that a plausible, but entirely unproven, mechanism exists for the transfer of viable organisms,” Scharf says.

There are creatures on Earth that would probably consider an interplanetary trip a worthy challenge. Take tardigrades, for example, the tiny, tough invertebrates that have survived 10 days in space. Lichens have survived the same freezing vacuum for more than two weeks. Some microbes, like Deinococcus radiodurans, are especially tolerant of the levels of radiation they’d likely encounter during a trip to Mars. And organisms frozen for centuries beneath the ice in Antarctica have been revived in labs.

“We have no reason to believe that some microbes can’t survive interplanetary journeys inside of meteorites,” says astrobiologist David Grinspoon of the U.S. Library of Congress.

But, he says, spending two weeks in space and living to tell the tale is different from crash-landing after a decades-long interplanetary voyage and setting up shop in a new world. It isn’t enough to simply arrive – organisms have to thrive.

“We tend to separate the possibility of exchange of viable organisms between planetary bodies and the possibility that they can ‘seed’ a world,” Scharf says. “It’s just not clear that even the hardiest Earth microbes, dumped supersonically onto Mars (for example), are going to get a foothold. The Martian surface is nasty for terrestrial biology.”

Interplanetary panspermia as a dispersal mechanism seems fairly plausible, then, if unproven. Is it possible that young Earth, Venus, and Mars traded life-forms for a few hundred million years? (See Scharf’s treatment of a panspermic paradox here.)

Cosmos also introduced the idea of interstellar panspermia, which magnifies all the challenges associated with the inner solar system’s planets playing meteorite ping-pong. In other words, it’s a bit trickier to transport life from stellar system to stellar system. Distances are much greater, and the time it would take for a meteorite bearing life-forms to arrive on another world is substantially longer. To some scientists, it seems unlikely that such a thing is possible.

“Eventually, cosmic radiation would shred the genetic material beyond any ability to self-repair,” Grinspoon says.

On the other hand, he notes, stars are born in clusters. And at the age when young stars are busy assembling their planetary systems, the distances between them are much smaller. Our solar system would have exchanged material with these systems, Grinspoon says. Perhaps it’s during this period of stellar infancy that stars stud their sister systems with seedlings.

And there’s a third version of panspermia waiting in the wings, one proposed by Francis Crick and Leslie Orgel in 1973: Directed panspermia, or the idea that intelligent beings intentionally send life to other worlds.

“It now seems unlikely that extraterrestrial living organisms could have reached the earth either as spores driven by the radiation pressure from another star or as living organisms imbedded in a meteorite,” they wrote. “As an alternative to these nineteenth-century mechanisms, we have considered Directed Panspermia, the theory that organisms were deliberately transmitted to the earth by intelligent beings on another planet.”

But the pair concludes that there’s feeble evidence supporting the deliberate seeding of Earth with alien life, and similarly feeble evidence supporting the abiotic emergence of life on Earth. “Both theories should be followed up,” they wrote.

The idea that faraway, intelligent beings – or perhaps the bored teenagers of the species – might be intentionally hurling life at planets is truly science fiction. But it’s a universe of infinite possibilities, right?

“If you imagine that intelligent, technological life exists on other worlds – which I do imagine,” Grinspoon says, “Then what would lead you to conclude that nobody anywhere in the galaxy has ever tried such a stunt?”

Looking toward the stars for our origins seems, perhaps, like the kind of explanation one ought to turn to when all other attempts to flick life’s on-switch have failed. It’s more than plausible that the building blocks of life – amino acids, nucleobases, sugars – were delivered to Earth by asteroids or comets. We know that asteroids in the solar system are carrying complex organic molecules. And not only that, complex organic molecules have been spotted wafting through interstellar space.

Put more simply, the galaxy is littered with the building blocks of life. But it could also be littered with life itself. And maybe, from across the interstellar sea, some of those organisms came to Earth, crawled out of their space rocks and flourished on their new cosmic shores.

NASA researchers have found the building blocks of DNA in a meteorite. (NASA's Goddard Space Flight Center/Chris Smith)
NASA researchers have found the building blocks of DNA in a meteorite. (NASA’s Goddard Space Flight Center/Chris Smith)


A Blog by

The Best Way to Eavesdrop on Aliens

This is one of three blog posts associated with this week’s episode of Cosmos: A Spacetime Odyssey, which addresses life in the universe. Watch it Mondays on the National Geographic Channel.

Though humanity’s origins are humble, our dreams are grand.

It took millennia for our ancestors to leave their watery cradles. But from those primordial ponds, they eventually emerged and pressed their footprints into land. Those footprints would march through the eons, marking an inexorable progression toward the hairy, bipedal, big-brained beings we are today.

In just a fraction of the time it took those quivering creatures to evolve the lungs needed to breathe Earth’s freshly oxygenated air, our empires have risen and fallen, ideas have wrought the deaths of millions and humans have become an interstellar species.

It wasn’t until 1937 that the first powerful FM transmitter was built and began transmissions at a frequency that could fly into outer space. Those early signals, along with the crude chirps of World War II radars, the first moon bounce of 1946, and all of our TV broadcasts have been zooming into the cosmos for many decades, travelling at the speed of light.

“The leading edge of these signals has already washed over thousands of planets of other stars,” says Neil DeGrasse Tyson, in this week’s episode of Cosmos: A Spacetime Odyssey. “What if other worlds are sending their stories into space? Since 1960, we’ve been listening for extraterrestrial radio signals, without hearing so much as a tolling bell. But our search has been sporadic and limited to small parts of the sky. For all we know, we may have just missed an alien signal, looking in the wrong place at the wrong time.”

It’s a plausible and disheartening reality.

My first story for this blog was about the 1960 search Tyson references, called Project Ozma. Conducted at the Green Bank Observatory in West Virginia, by my father, Frank Drake, the search targeted just two stars. For three months, those stars refused to be anything but quiet. But scientists didn’t quit – in fact, Project Ozma launched an era of listening to the cosmos. Over the last half-century, more than a hundred such searches for extraterrestrial intelligence have been conducted – and all have been met with that same stubborn silence.

One obvious explanation is that humans are alone, that we are the only species in the galaxy to have slipped the surly bonds of single-celled solitude and begun broadcasting our stories into space.

But it’s much too early to conclude that.  A realistic explanation is that our searches haven’t been good enough. Tyson is right: They’ve been sporadic and limited in scope.

So if aiming the world’s largest single-dish radio telescope at the stars, or harnessing the computer power of a thousand idle PCs isn’t enough, then what is?

“You need to look at many stars, you need to look almost continuously, and you need to cover a large piece of the radio spectrum,” Dad said, when I asked what his ideal, Earth-based SETI search would be. “If you want to build just one system to do this, you have to put it very near the equator. It’s the only way you can look at the whole sky, every day.” (Better still, he says, would be to have two telescopes placed opposite one another along any line through the center of the Earth — you could monitor the entire sky continuously.)

Dad describes his ideal telescope as comprising a square kilometer radio telescope – kind of like the planned Square Kilometer Array – but with many dishes arranged in a single, dense cluster. Positioning the dishes close together is essential for observing the largest possible number of stars at the same time, which is important for SETI searches. “The game is to look at as many stars as possible since we don’t really have a clue as to which are the best candidates,” he says.

But if you’re looking at 1,000 stars at once, I ask, how will you know which star a signal might come from? “We would love to have that problem,” came the wry response. Turns out, by paying close attention to how the signal shifts in frequency as the Earth rotates, you can figure out which is your lucky star.

“The technology to do this actually exists,” Dad says. “It doesn’t require new inventions.”

A giant telescope, parked on Earth’s equator like a shiny badge, staring into the sky day and night? Sounds pretty good. But the challenges are enormous. The good news is, none are insurmountable. The computing power needed to synchronize incoming data and then process those data, plus the costs of electricity, construction, and management – none of that is negligible. Dad’s figured out how to make most of these things work. The bad news is, as always, cost – possibly as much as $20 billion.

In this age where the U.S. government is nickel-and-diming programs and struggling to scrape together even a tenth of that number for a single solar system mission, $20 billion is enormous. But this is also an age where a 10-year-old Internet company paid $19 billion for an instant-messaging app. For roughly the same price, we could instant-message the cosmos.

How long would it take for such a telescope to find a signal? That’s another question Dad gets a lot, apparently. “You have to make two guesses,” he says. “One is the answer to the Drake Equation [which estimates the number of detectable civilizations in our galaxy], and the other is, how often do they actually send a message our way? There’s no logic I know of that can answer that second thing.”

It could be days, it could be weeks, it could be never.

Whether Earth is the only fertile planet is a question I grew up thinking about, surrounded by replicas of the Pioneer plaque and instruments meant to bring the stars the closer to Earth.

Surely there’s another species out there that has clawed its way from oozing, primordial murk and evolved through eons of uncertainty and shifting skies and become aware of the questions posed by the stars. Perhaps these are the same beings that are now decoding the transmissions from Earth that are streaming across the light-years.

“I am sure they are out there,” dad says.

A Blog by

Saturn’s Largest Moon Would Host Really, Really Weird Life

Ah, Titan. Saturn’s largest, haziest moon had a brief starring role in last night’s Cosmos: A Spacetime Odyssey. Toward the end of the episode, Neil DeGrasse Tyson eases his spaceship into one of the moon’s dark, oily seas. He wanted to see what was down there—more specifically, what kind of life might be down there.

After spending most of an hour describing the evolution of life on Earth, it was time to turn toward alien terrains and chemistries—to a place that, while not so very far away, could host some very, very strange lifeforms.

There’s a world I want to take you to, a world far different from our own, but one that may harbor life. If it does, it promises to be unlike anything we’ve ever seen before,” Tyson says, in the episode.

Titan is deceptively Earth-like. It has a thick, nitrogen atmosphere. Seasonal rainstorms produce wet patches that are visible from orbit. It has lakes. In fact, Titan is the only place in the solar system, besides Earth, with stable liquids on its surface. Those liquids flow through rivers and streams, pool into lakes and seas, sculpt shorelines and surround islands, just like on Earth.

But Titan’s puddles aren’t filled with water—the moon is soaked in hydrocarbons. Methane and ethane, compounds that are gassy on Earth, are liquid on Titan’s frigid surface. Here, temperatures hover around -179 Celsius (or -290 Fahrenheit). It’s so cold that water ice is rock-hard—in fact, the rocks littering the moon’s surface are made from water. Water is everywhere on Titan, but it’s locked in a state that’s inaccessible for life-sustaining chemistries.

Ask an astrobiologist about the prospect of finding life on Titan, and they’ll say the shrouded, orange moon is the place to go if you’re looking for bizarre life. Life that’s not at all like what we know on Earth. Life that, instead of being water-based, uses those slick, liquid hydrocarbons as a solvent. Life that, if we find it, would demonstrate a second genesis—a second origin—and be suggestive of the ease with which life can populate the cosmos.

Life that’s worth taking a chance to find?

“We will never know if liquid water is the only special solvent in which life can form and propagate unless we go and sample these damn lakes and seas,” planetary scientist Jonathan Lunine of Cornell University said during a recent astrobiology conference. Lunine has spent years studying Titan; at one point, he and his colleagues designed a spacecraft that could land on the moon and float in one of its hydrocarbon seas [pdf].

Titan's surface, snapped by the Huygens lander.NASA/ESA/JPL/University of Arizona
Titan’s surface, snapped by the Huygens lander. NASA/ESA/JPL/University of Arizona
Titan's surface, snapped by the Huygens lander. NASA/ESA/JPL/University of Arizona

Thinking about life on Titan isn’t new. In the 1970s, Carl Sagan and chemist Bishun Khare, then at Cornell University, were already publishing papers describing the organic chemistry that might be taking place on the Saturnian moon. At that point, though, the large bodies of liquid on the moon’s surface hadn’t yet been spotted, so Sagan and Khare were thinking about the types of reactions that might be taking place in the moon’s atmosphere (in 1982, Sagan and Stanley Dermott proposed that such lakes might exist). Later, Sagan and Khare would show it was possible to make amino acids using the elements found in the moon’s haze.

In the 1990s, the Hubble space telescope offered hints of a wet world, but it wouldn’t be until NASA’s Cassini mission that scientists got a good look at the moon. In 2004, the spacecraft began peering beneath Titan’s cloudy shroud; in 2005, Cassini sent the Huygens probe parachuting through the haze to a spot on Titan’s equator. Data sent back to Earth revealed a world that looks very much like ours—just with a completely different chemistry.

What that different chemistry means for the possibility of life is still speculative.

“Think about life on Earth—we’re all either in water or we’re fancy bags of water,” says astrobiologist Kevin Hand of the Jet Propulsion Laboratory. “On Titan, life in the lakes would be ‘bags’ of liquid methane and/or ethane. That 90[Kelvin] liquid would be the solvent and then whatever is dissolved into the lakes would be the material that’s used to build the other components needed for life, and to power metabolism.”

Powering metabolism is tricky at those temperatures, though, which is one of the reasons why some scientists are hesitant to focus on sending a probe to Titan. Nonetheless, astrobiologists are studying the reactions and pathways that life might use to gain some traction on Titan—including things like breathing hydrogen and eating acetylene.

“Which elements are easy and which elements are hard to access if you’re a ‘weird’ microbe living in Titan’s lakes?” Hand says. “At this point we don’t really know—work is ongoing.”

I had a few questions after watching the Cosmos depiction of Titan’s alien seas. First, if I were a weird life form on Titan, would I be able to see Saturn through Titan’s hundreds of kilometers of haze? Or would the most spectacular planetscape in the solar system be hidden behind that smoggy curtain?

“Even with the human eye, Saturn would be visible as a faint, bright-ish blob in the nighttime haze,” Lunine says. “And if you have eyes that extend even a bit beyond human sight into the nearest part of the infrared, the ringed world would be clearly seen floating ethereally in the skies of Titan.”


Second, the scene with Tyson in the spacecraft shows a craggy, chaotic seafloor, with things that look like hydrothermal vents. How much do we really know about Titan’s seafloors?

Large bodies of liquid in Titan's northern hemisphere, mapped by Cassini in 2006. NASA/JPL-Caltech/USGS
Large bodies of liquid in Titan’s northern hemisphere, mapped by Cassini in 2006. NASA/JPL-Caltech/USGS
Large bodies of liquid in Titan's northern hemisphere, mapped by Cassini in 2006. NASA/JPL-Caltech/USGS

Turns out, we know quite a lot about Titan’s seashores, and slightly less about its seafloors. Until now, scientists had mostly used seashore shapes and surrounding topography to infer what the seafloors might be like. But in May 2013, the Cassini spacecraft aimed its radar at the depths of Ligeia Mare, the second largest sea on Titan (Kraken Mare, which Tyson took a swim in, is the largest). Using the radar data, the team created a map of the sea’s floor—its bathymetry—and saw that Ligeia Mare plunges to a depth of 160 meters (524 feet). The northern seabed is gentler and smoother than the southern, which is riven with flooded valleys and punctuated by steep peaks.

Getting the depth profile meant that scientists could estimate how much liquid hydrocarbon rests in Ligeia Mare: As much as 100 times more than the oil and gas reserves on Earth combined.

Next up? Peering into the depth of Kraken Mare, which covers an area of at least 400,000 square kilometers, or approximately equal to the size of Germany. “Kraken appears to consist of no fewer than three distinct basins, each about the size of Ligeia Mare,” Lunine says. “So there’s a lot of sea to see on Titan.”