Is There Life in Space?

By Peter Cawdron

IT MAY SURPRISE YOU TO LEARN we already have an answer to this question, and the answer is, “Yes.”

Congratulations, you’ve just finished the shortest article ever published in “Perihelion.”

“Wait,” I hear you say. “There’s no life in outer space! We’ve never found life on Mars or anywhere else.”

Ah, now the discussion is getting interesting.

Okay, let’s examine this debate in more detail.

First, whether we’ve found life on Mars or elsewhere in our universe is immaterial as the absence of evidence isn’t evidence for absence. Just because we haven’t found something doesn’t mean it doesn’t exist. If anything, it is a leap of logic to assume something doesn’t exist just because we don’t have firm evidence yet. Now, that’s not to justify a belief in leprechauns or Bigfoot, but there are numerous examples in history where we were surprised to learn just how shortsighted we have been.

In the early 1900s, everyone assumed there was just one galaxy, ours. There was no evidence for any other galaxies out there in space, and yet within a century we were able to raise that estimate to two hundred billion galaxies in the visible universe (and there's probably considerably more beyond them).

It’s only been in the last few centuries that we’ve come to understand that microbes rule the planet.

Life is astonishingly resilient. Regardless of where we go on Earth, we find life. Dig down under several kilometers of desolate ice in Antarctica and what do you think you’ll find? Life. How about six miles beneath the sea in the Mariana Trench? Life.

Life has thrived despite pressures a thousand times greater than we experience at sea-level, pressures equating to eight tons per square inch. That’s the equivalent of an African bush elephant putting all its weight on your thumb.

You’ve probably heard of “clean rooms,” meaning rooms where there’s no contamination, but here on Earth we’ve all but given up on the idea. Even in the cleanest rooms where spacecraft are built, bacteria thrive on various surfaces. What’s more, all our efforts to eradicate them only make them grow more resilient. Microbes are particularly hardy, and it’s no wonder, they’ve survived on Earth for 3.8 billion years.

Chernobyl may have been a disaster for us, but it wasn’t for fungus, which prosper on the astonishingly high levels of gamma rays.

Deinococcus radiodurans is another example, a species of bacterium that can withstand half a million rads; a mere ten thousand rads will kill a human.

Life on Earth is astonishingly diverse and resilient, so why wouldn’t life be prolific elsewhere?

But there’s no proof

Ah, but someone might protest, “You have no proof there’s life in outer space.”

Yes. I do.

There’s an astonishing amount of proof for life existing in outer space. In a word, it’s Earth. You see, Earth does not exist in isolation from the universe at large. Earth is a very tiny part of an enormous expanse we call the cosmos. That there is life on Earth is proof there is life in outer space because we are in outer space.

As Carl Sagan put it when the Voyager space probe took a photo of Earth from a distance of almost four billion miles, we are living on a pale blue dot.

At first, this answer might seem a little disingenuous, but it’s not. Historically, we’ve assumed Earth was all important, special, and unique. According to some religions, Earth is the center of creation. Everything revolves around Earth. Certainly, in every day life it seems that way. And it’s easy to take for granted the scientific knowledge we have accumulated that tells us the Earth turns on its axis each day.

Watch the way the shadows fall in your backyard over the course of a day. Try as you may, it’s next to impossible to convince yourself Earth is turning as you’re sitting still and nothing appears to be moving. Have you ever watched the Earth turn? Nope. But you’ve seen plenty of sunrises and sunsets. And yet the Sun never rose or fell. We moved.

We humans have had a tough time letting go of the idea that we’re the center of the universe. We’re not. Earth holds no special place of privilege in the cosmos. Sure, it’s unique in that it’s home for us, but there are a number of surprisingly unique characteristics to Saturn as well, and moons like Europa and Io have amazed us with their natural wonders. As some of these moons have subsurface oceans, they may yet harbor life.

What about elsewhere?

The real question is not, “Is there life in outer space?” but “Is there any other life in outer space?” And the answer to that question is, we don’t know.

Yet.

We haven’t gathered enough evidence to make a call one way or another, but there’s certainly no reason to think there isn’t.

In 1984, the last of the wild aborigines were discovered in the remote outback of Australia. They had never had any contact with the outside world, having no idea just how vast the world actually was. On those handful of occasions they saw planes in the sky, they would hide in trees from what they thought of as “demons.” Like so many others before them, they thought the world consisted of little more than what they could see around them. They assumed there was nothing else out there in much the same way people assume there’s no other life in outer space, and yet how wrong they were.

Life on Earth is unique

“But,” some might ask, “How could there be any other life in outer space? Life on Earth is unique.”

Is it?

With a handful of exceptions, the ratio of elements in our bodies is a rough match to the ratio of elements found scattered elsewhere throughout the universe. Hydrogen, for example, is the most abundant element in the universe and it’s also the most abundant element in our bodies, being a principle part of the water molecule (H20). Helium is the next most abundant element in the universe, but being chemically inert, there’s no role for it in organic chemistry. Oxygen, though, is number three in the universe and is the next most common element in our bodies. Following that is carbon, and so on it goes, right down the list.

I can hear the objections already, “But our body is built from unique combinations of these elements, irreducibly complex stuff like DNA.”

Not so fast.

DNA is an astonishing molecule. When we think of molecules, we normally think of simple molecules, like H20 for water and NaCl for salt, where two atoms join to form a novel combination that has distinct chemical properties.

DNA is also technically a single molecule like a molecule of water or a salt molecule, only it’s composed of up to 200 billion individual atoms arranged in patterns of smaller segments made from other molecules linked together. It's kind of like Lego on a grand scale. By coincidence, that’s roughly the same number of stars in the Milky Way.

DNA is remarkable. We haven’t found anything like it outside of living organisms, but we have found the building blocks of DNA in deep space.

NASA’s Stardust mission found several of the amino acids that carry information, forming genes within the DNA molecule. These molecules occurred naturally on the comet Wild 2.

The Goddard Astrobiology Analytical Laboratory extracted two of the nucleobases that form DNA from meteorites (adenine and guanine, which are two of the four chemical bases that make up both DNA and RNA). According to NASA, asteroids are “behaving like chemical factories.”

In addition to this, we have found over a hundred different types of organic molecules floating in vast clouds in space.

Astronomers at the Kitt Peak radio telescope in Arizona observed organic molecules in the Sagittarius B molecular cloud some 26,000 light years from Earth. They were able to isolate the sugar molecule glycolaldehyde, which on Earth forms several complex sugars, ribose, the spine of DNA and RNA as well as glucose when it reacts with other sugars and carbon molecules. Oh, and alcohol. They found lots and lots of alcohol. Somewhere in the region of a billion, billion, billion liters of alcohol. It seems ET has a sweet tooth and is a bit boozy, so perhaps we have more in common with aliens than we thought.

Seriously, to put this in perspective, this particular molecular cloud contains three million times the mass of the Sun. That is to say, as this molecular cloud slowly collapses over hundreds of millions of years, it will give rise to hundreds of thousands, perhaps millions of stars that will develop their own planetary systems already rich in organic chemicals. Roughly 4.8 billion years ago, our Sun formed from a similar cloud, and here we are. There really is no reason to think life is rare in the universe.

What are the odds of finding life in outer space?

The existence of lottery tickets demonstrates how utterly appalling we are at understanding odds.

What are the odds of winning the popular Mega Millions jackpot? They’re one in 135 million. It’s a big number, and that’s the problem. We have no idea what that means in practice. What is a million? Try picturing a million of anything. How about apples. What does a million apples look like?

There is a technique that can help us to understand these kinds of numbers. It’s called picturing orders of magnitude. Can you imagine ten apples? Sure. Picture a fruit bowl with ten apples in it. Easy. Okay, now picture ten bowls of apples. Congratulations. You just pictured a hundred apples.

Ten bowls of apples would fit on the average Persian rug, so to get to a thousand apples, picture ten Persian rugs in your backyard, each with ten bowls, each with ten apples.

To get to ten thousand, picture ten back yards on your street, each with ten Persian rugs with ten bowls with ten apples. A hundred thousand? Easy, ten streets.

For convenience sake, we’re going to assume ten streets equates to a block. Jump in an airplane, cruise to about five thousand feet and look down on ten city blocks and you’ve got a million apples laid out before you. Do that a hundred and thirty five times and you’re getting to the kind of numbers that equate to winning the lottery.

If that puts it in perspective, assuming you were born in the U.S., you have better odds of becoming President than you do of winning the lottery, as those odds are only one in ten million.

The chances of becoming a professional athlete, something that is exceedingly difficult to accomplish, are considerably better at one in 22,000. And you’re probably not going to want to hear this, but you have far greater chance of being audited by the IRS—that comes in at one in 175.

So what are the odds of there being any other life in outer space? It’s difficult to determine conclusively, as we only have one example, Earth. But we can make a fairly good estimate based on our knowledge of astronomy and the prevalence of the various elements essential for life.

One interesting point to consider, though, is that even absurdly unlikely events do happen, like winning the Mega Millions lottery. Even events with lousy odds can become quite frequent if you’re dealing with large enough numbers.

You’ll be pleased to know that your chance of being struck by lightning is low, at one in 700,000. When you consider that there are seven billion people on Earth you realize that a lot of people are being struck and killed by lightning each year. Care to hazard a guess at how many die this way? Would it surprise you to learn that 24,000 people are killed by lightning each year, and almost ten times that are injured? Yet being struck by lightning is a very rare event. Dating a supermodel is far more likely, at one in 88,000. Knowing that 24,000 people are killed by lightning each year, then, will probably make you a little more cautious the next time a big electrical storm rumbles in the sky.

Our ability to intuitively understand probabilities involving numbers in the hundreds of thousands, millions, billions or trillions is poor. We just don’t deal with these numbers in every day life so we have no comprehension of what they mean in practice.

When you consider statistical probabilities, the chance that no one will be killed in the next year by lightning is a stunning 1010133—that’s ten with over ten thousand zeros following it!

So seemingly impossible, unlikely events can still be quite common if you’re dealing with large enough numbers. And that’s important to understand when we consider life elsewhere in the universe, because if there’s one thing the universe has is size. There’s a lot of “stuff” in the universe. Far more galaxies and stars and planets than we could ever imagine.

There have been a number of attempts at quantifying the probability of life arising elsewhere in the universe, most notably, the Drake Equation. But recently an alternative has been proposed, called the Seager Equation, that seeks to narrow the focus from the generalized question “What’s the chance of life arising anywhere?” to a very pointed and specific “Based on what we know, what are the chances we will be able to find life elsewhere in the next decade by detecting biosignature gases?” The Seager Equation is expressed as:

Where:
N is the number of planets with detectable biosignature gases.
N* is the number of stars within the sample.
FQ is the fraction of quiet stars.
FHZ is the fraction with rocky planets in the habitable zone.
FO is the fraction of observable systems.
FL is the fraction with life.
FS is the fraction with detectable spectroscopic signatures.

If we inject realistic figures based on our current scientific understanding and the ability of a new generation of satellite telescopes like the James Webb to search for exoplanets, this is what we get ...

N*=30,000
FQ=(0.2)
FHZ= 0.15
FO=0.001
FL=1
FS=0.5

N=2. Two.

That’s two planets with signs of life!

Now, some might question the assumptions in this equation, pointing out that FL (Fraction With Life) is high, being arbitrarily set at one, and they’d be right. But there are other factors that are deliberately understated. The sample size is 30,000 stars. The James Webb Space Telescope is capable of scanning 500,000 stars in the immediate neighborhood, each with potentially dozens of planets, and not just a paltry 30,000. And until it is launched in 2018, we really don’t know just how many stars it will be able to scan. Half a million may very well be on the low side.

What probability do you want to assign for finding other forms of life in space? At this point, we really have no way of knowing what some of these values are, but we do know that there are at least 70 billion trillion (7×1022) stars in the known universe. Other estimates are several orders of magnitude higher again, at an octillion or 1029, that’s 1,000,000,000,000,000,000,000,000,000,000 stars.

Remember our lightning example? Even highly improbable events can be commonplace given big enough numbers. If the chances of life arising around a given star are stupendously small, at one in a trillion or 1011, there would still be trillions upon trillions of planets with life in our universe.

Interestingly, though, if the odds were that low, then the chances of life arising in our galaxy are less than one, as there’s less than a trillion stars in the Milky Way, which could explain why we haven’t found any other forms of life. But for the odds to be that low, there would have to be something wrong with the majority of galaxies (as the majority of galaxies are like ours, having less than a trillion stars). Point being, even if we take a worst case scenario, it seems highly unlikely we are entirely alone. The odds are against it.

Personally, I think the search is only just beginning. We’ve looked at so little of the universe, it’s no surprise we haven’t found life elsewhere. In the words of Neil deGrasse Tyson, “Life doesn’t exist anywhere but Earth? That’s like filling a cup with ocean water and saying there aren’t any whales.”

Where is everyone?

“So why haven’t we found any other life in outer space?”

Good question.

The answer is, we’ve only just begun to look.

Space is big.

Space is really, really big.

Space is unimaginably big. Just when you think you've begun to imagine how big it is, you realize it's even bigger.

Imagine if the Sun was the size of a Swiss Fitness Ball, the kind you see people rolling around on in the gym. On that scale, Earth would be a chickpea almost a hundred yards away. Assuming you’re reading this somewhere in the U.S., the closest star would be near India and roughly the size of another Swiss Fitness Ball. In between is a whole lot of nothing, with only the occasional chickpea for Mars or baseball for a planet like Jupiter.

Our galaxy is roughly a hundred thousand light years across, but with our existing technology we’ve only been able to image planets within 2000 light years of Earth, with most of the planets being found within 300 light years. In practical terms, we’re wading in the ocean unsure how deep the water really is.

The James Webb Space Telescope (JWST), launching in 2018, is over a hundred times more sensitive than the Hubble Space Telescope, but even then, there are vast swaths of our galaxy that we cannot explore because they’re obscured by the dense core at the heart of the Milky Way.

With tools like the JWST, NASA’s chief scientist Ellen Stofan is convinced we’ll have “definitive evidence” for life beyond Earth in the next couple of decades. JWST will do this by examining the atmosphere of distant planets to look for the distinct signatures of life, at least life as we understand it here on Earth. Such detection is indirect, as NASA will consider every known possible non-organic mechanism to explain the chemistry of these distant planets. Those planets that can’t be explained by natural chemical processes will become candidates for harboring life. And in this way, our search will slowly narrow down the possibilities for where life can exist elsewhere in our galaxy.

Given we already know life thrives on Earth regardless of how hostile space can be, and given the close association of life on Earth with the chemicals and molecules we can observe in space, finding life elsewhere in the universe seems more a matter of when, not if. 

Further Reading

Discovering other galaxies.
NASA clean rooms develop entirely new species of bacteria.
Extremophiles.
Life in lakes under Antartica.
Life in the Mariana Trench.
Pressure in the Mariana Trench.
Two hundred billion galaxies in the universe.
Pintupi Nine are found in the Australian Outback.
Comparison between elements in the universe and our bodies.
200 billion atoms in a single DNA molecule.
Amino acids in meteorites and comets.
Kitt Peak observations.
Alcohol found in space.
Odds of winning the lottery.
What are the odds of finding life in outer space?
Drake’s Equation.
Seager’s Equation.
Picturing the size of solar system.
James Webb Space Telescope.
NASA confident of finding life beyond Earth.

Peter Cawdron is an Australian writer specializing in hard science fiction. He is the author of “Anomaly, “What We Left Behind,” and other best-selling books. His acclaimed short story, “Trixie and Me,” is a free ebook on Amazon.com.