Professor Sara Seager of Massachusetts Institute of Technology says her team of scientists is looking for biosignatures from gases emitted by alien life forms on habitable extrasolar planets. Many of these gases could be detected remotely by telescopes, but could end up having quite different compositions from those in the atmosphere of our planet.
Prof. Seager and her colleagues explained,
“Thousands of exoplanets are known to orbit nearby stars. Plans for the next generation of space-based and ground-based telescopes are fueling the anticipation that a precious few habitable planets can be identified in the coming decade. Even more highly anticipated is the chance to find signs of life on these habitable planets by way of biosignature gases.”
Seager’s team proposes in their paper published online in the journal Astrobiology that all stable and potential volatile molecules should be considered as possible biosignature gases, laying the groundwork for identifying such gases by conducting a massive search for molecules with six or fewer non-hydrogen atoms in order to maximize their chances of recognizing biosignature gases. They say they promote the concept that “all stable and potentially volatile molecules should initially be considered as viable biosignature gases.”
The scientists created a list of about 14,000 molecules that contain up to 6 non-H atoms. About 2,500 of these are CNOPSH (C – carbon, N – nitrogen, O – oxygen, P – phosphorus, S – sulfur, and H – hydrogen) compounds.
This means that instead of the costly and controversial method of netting strange creatures from the bottom of the sea, these scientists have decided to search and find thousands of curious, potentially biogenic gas molecules.
Comparing the planet you live on to the size of other celestial bodies has got to be one the biggest mind-blowing experiences a human can go through. To put yourself into perspective and recognize that we are but a nano-blip on the radar of extraterrestrial life makes it all that much more apparent why we haven’t been visited yet… or have we…?
We’ve been conditioned by television and movies to accept the likelihood of intelligent life elsewhere in the universe. “Of course there’s intelligent life out there; I saw it last week on Star Trek.” We’ve seen it all, from the cute and cuddly ET to the fanged monstrosity of Alien.
But is it likely that we’re not alone in the universe? And if intelligent life is out there, why haven’t they contacted us yet?
The first person to address this question in a systematic way was Frank Drake, who invented the Drake equation to predict the number of extraterrestrial civilizations in the galaxy. His equation is rather complicated, but here’s a simple version of his argument.
First, let’s count how many stars are in the galaxy. To quote one of my predecessors, “Billions upon billions!” And how many of those stars have planets? Until recently, we really didn’t know. But over the past 20 years, astronomers have made remarkable progress in discovering planets around other stars. We now know that many stars have planets orbiting them.
Could creatures actually live on any of those planets? Many of them are just giant balls of gas, or else too hot or too cold to contain liquid water, which is the basis of all life on Earth. But a few of them do seem to be at the right temperature. These are the Goldilocks planets: not too hot and not too cold for liquid water. (And that’s without even considering the possibility that exotic forms of life could survive without water.)
Now we enter murkier territory. How likely is it that life will develop on a potentially habitable planet? We don’t know the answer, but life on Earth got going very shortly after the formation of our solar system, and it has wedged itself into every available niche, no matter how hostile.
Colonies of bizarre creatures flourish in perpetual darkness near deep ocean vents, where superheated sulfur-rich water spews from under the ground. Radiation-resistant bacteria bask happily in levels of radioactivity that would instantly kill a human being. And then there’s the tardigrade, which looks like a microscopic eight-legged teddy bear, that can thrive in liquid nitrogen or boiling alcohol. So the probability of life developing on habitable worlds seems very high.
And how likely is it that this life will develop intelligence? This remains an open question (which is scientist-speak for “we haven’t got a clue”). But many scientists consider intelligent life almost inevitable, in which case the galaxy should be teaming with alien civilizations.
If the galaxy is crawling with aliens, where are they? Interstellar travel is limited by the speed of light, so maybe it’s no surprise that no one has visited us. But we should at least be able to detect alien radio signals, either from attempts to contact us directly, or in the form of alien TV reruns. Why haven’t our alien friends contacted us? This question was famously asked by the Italian physicist Enrico Fermi, so it’s called the Fermi paradox: all of our arguments suggest that alien civilizations should be common, yet we’ve seen no sign of them.
One possibility is that intelligent life really is rare. My own personal opinion (and it’s just an opinion) is that life is common, but intelligent life is rare (something many of us suspect based on our own experience). While life developed in the relative blink of an eye after the birth of the solar system, it took billions of years before we smarties showed up on the scene. And remember that “survival of the fittest” doesn’t always mean “survival of the smartest.” While intelligence is certainly a useful survival trait, it seems far from inevitable. If not for an errant asteroid, the dinosaurs might still rule the world.
Another possibility is that intelligent life inevitably destroys itself. Until recently, our options for total self-destruction were limited to nuclear weapons. But we are on the edge of expanding our armada to include genetically engineered viruses (think: Ebola meets the common cold!).
And consider the dangers posed by nanomachines, tiny self-replicating robots programmed to convert matter into more robots. Imagine a tiny robot, no bigger than the width of a human hair, designed to provide some useful function, programmed to build a copy of itself, using materials from its environment. Now you have two machines, and both can create duplicates, giving us four machines. But what if this process got out of control? The nanomachines could rapidly consume the entire Earth, converting it, along with everyone on the planet, into “grey goo.” British astronomer Martin Rees discusses these and other catastrophic possibilities in his book, Our Final Hour. Have all our potential alien visitors succumbed to self-destruction?
Or is it possible that the galaxy really does contain other forms of intelligent life, but something prevents contact with us? Here we enter the realm of more speculative ideas. (Translation: when a scientist says “speculative,” it really means “a very interesting idea that’s only one step removed from complete nonsense.”)
Among the more speculative possibilities: maybe the galaxy is a dangerous place, full of robotic probes sent out by hostile aliens to wipe out any competition, so everyone else is in hiding. Perhaps we really shouldn’t have put a detailed description of the location of our solar system on our own space probes. It’s a bad idea to reach out and try to touch ET when we might get a call from the Alien instead.
An even more bizarre suggestion is that superior civilizations have decided to avoid contact with lesser beings such as ourselves, so that we live in a kind of cosmic zoo, complete with a “Do not talk to the animals” sign.
Panspermia is the (hilarious) name given to a theoretical discussion about terrestrial life originating from someplace extraterrestrial, beyond Earth. The panspermia argument began with Francis Crick, the co-discoverer of the structure of DNA molecules. If “panspermia” sounds like a science fiction idea from the 70’s you aren’t thinking too far off. While Crick is famous for the DNA thing, he actually had a more implausible idea about aliens and the origin of life. One that never stood up to scientific scrutiny but makes its way back into scientific debates from time to time.
Who knows? Maybe this guy started it all.
Over the years there have been several discoveries panspermia supporters point to excitedly, claiming they have found proof of alien life. The latest new piece of evidence comes from Milton Wainwright at The University of Buckingham. While the object was found embedded in a weather balloon designed to collect upper atmosphere debris, and it is undeniably a biosignature of some sort, it doesn’t definitively support the panspermia theory, despite recent, high-profile headlines.
Wainwright himself admits this: “Unless, of course, we can find details of the civilization that is supposed to have sent it in this respect, it is probably an unprovable theory.”
Um, yeah. So the guy quoted all over the new evidence is actually the first in line to warn against jumping to the conclusion that we are all aliens. Still, it’s a very exciting theory. Let’s take a look at other samples from various parts of Earth and beyond that have allowed dreamers to fabricate theories of life’s supposed extraterrestrial origin.
Biosignatures don’t have to be chemical. They can be magnetic, as suggested in this space.com article from 2011, or it could be described by the morphology, meaning the shape and size of fossilized evidence could indicate a living thing once left its mark. Biosignatures that support the idea of alien life or panspermic origins to terrestrial life are inconclusive but that doesn’t stop enthusiasts from pointing and claiming they have proven the theory correct. Here’s why the evidence supporting panspermia is still inconclusive:
Tiny, microscopic magnetite crystals were found in meteoriteALH84001. Not a lot can be proven from this undeniably interesting piece of space rock. The meteorite is likely Martian in origin. It’s famously debated because of a handful of potential biosignatures. Some scientists insisted only bacteria could have caused the crystal formations . They turned out to be wrong; similar formations can be found forming by complex physics, without life intervening.
Several other “possible biosignatures” have been investigated int he sample. There is a working hypothesis but not an empirical confirmation of life. Proof of an extraterrestrial form of life would mean these so-called biosignatures could have been formed by a living thing and only a living thing – which is clearly not the case. One such biosig was a small-pattern texture that resembled one from a known bacteria. A scientific majority ultimately decided these textures were small to be fossilized cells. Meteorite ALH84001 is a curiosity, a rare find and an amazing natural occurrence but it is not proof of the panspermia theory.
Then there is the Kerala red rain phenomenon happened in Kerala, India from 25 July to 23 September 2001. Heavy showers brought a peculiar, red-coloured liquid. The “blood rains” fell all along the southern Indian state of Kerala staining fabrics and causing alarm. Other colours were reported but the majority of reports and samples were red in color. It’s happened several times since, most recently in June 2012.
Kerala Red Rain
A photo-microscopy examination brought an initial rumor to the media: the source oft he red color was a meteor shower or explosion from asteroid particles heating up on entry to Earth’s atmosphere. Early misreports like that often cause rumors or conspiracy theories when the official story gets redacted. In this case, a detailed study commissioned by the Government of India announced the rains had been dyed by airborne spores originating from a prolific colony of terrestrial, forest algae.
It’s still a mysterious phenomenon but the genetic makeup of the cells found in red rain is far too common for the sample to be extraterrestrial.
Tardigrades are so durable they seem to be able to survive for a long time when they enter a strange, dehydrated state. Tardigrades are one of the only species who can suspend their metabolism and going into a state of cryptobiosis. Several varieties of tardigrade can stay hibernating for nearly 10 years. While in this state, tardigrade metabolism falls to 0.01% and their water content goes down to 1% of normal.
Tardigrades would make excellent space travellers because they can withstand extreme environments most other lifeforms would be destroyed in, including extremes of temperature, pressure, dehydration and radiation, environmental toxins, and outer space vacuum conditions.
Wikipedia points out: tardigrades are the first known animal to survive in space. On September 2007, dehydrated tardigrades were taken into low Earth orbit on the FOTON-M3 mission carrying the BIOPAN astrobiology payload. For 10 days, groups of tardigrades were exposed to the hard vacuum of outer space, or vacuum and solar UV radiation. After being rehydrated back on Earth, over 68% of the subjects protected from high-energy UV radiation revived within 30 minutes following rehydration, but subsequent mortality was high; many of these produced viable embryos. In contrast, dehydrated samples exposed to the combined effect of vacuum and full solar UV radiation had significantly reduced survival, with only three subjects of Milnesium tardigradum surviving. In May 2011, Italian scientists sent tardigrades on board the International Space Station along with other extremophiles on STS-134, the final flight of Space Shuttle Endeavour. Their conclusion was that microgravity and cosmic radiation “did not significantly affect survival of tardigrades in flight, confirming that tardigrades represent a useful animal for space research.” In November 2011, they were among the organisms to be sent by the US-based Planetary Society on the Russian Fobos-Grunt mission’s Living Interplanetary Flight Experiment to Phobos; however, the launch failed. It remains unclear whether tardigrade specimens survived the failed launch.
Tardigrades can survive in space but that doesn’t mean they came from space. They have strong genetic ties with several other animals in the Panarthropoda group. They appear to have evolved on Earth but will likely be studied for years to come because of the adaptable nature of Earth life they represent.
Like a lot of pseudo-science, there are elements of hope and truth to tons of the details. Labeling bad science or non-science for what it is enables us to dream bigger and keep a better-informed, watchful eye on the available data. If you are feeling the sting of yet another science news story letting you down, recharge your creative side with this 90’s CGI classic that illustrates the crucial principles of panspermism:
Jonathan Howard is a skeptic and freelance writer working for Cosmoso.net
You can reach him at this email address: firstname.lastname@example.org
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Look, I mean… I want aliens to exist. As of Summer of 2013, statistically half of the United States believes there are aliens. Roughly a third of Americans believe there are intelligent aliens. While it isn’t the largest sampling size, the veracity of this stat is pretty unchallenged. (The HuffPost/YouGov poll was conducted June 11-12 among 1,000 adults using a sample selected from YouGov’s opt-in online panel to match the demographics and other characteristics of the adult U.S. population. Factors considered include age, race, gender, education, employment, income, marital status, number of children, voter registration, time and location of Internet access, interest in politics, religion and church attendance.) I’d love to update this post with better data but I think a fifty-fifty split as to whether aliens exist or not makes it a particularly interesting debate.
While I believe it is better for humanity to be prepared and I understand the spirit of searching for alien life forms, I am having trouble squaring belief in alien life as scientifically accurate.
On the one hand, several prominent, respected, high-profile scientists claim to believe in aliens(or at least a high probability of aliens) yet there is currently no scientific data supporting the existence of extra terrestrial life. Skeptical attempts to try to answer this frame the question, from Fermi to Degrasse Tyson, have stood largely unchallenged and withstood criticism when finally challenged. Until science can truly answer all questions about the conditions needed to reproduce life as it is found on Earth it’s difficult to know the statistical probability of finding life as we know it on similar planets. Good science requires skepticism and a strict definition of truth; believing in aliens without empirical data is bad science.
It’s actually harder to get data on this subject than it should be but National Geographic did a pretty solid attempt about 2 years ago, though. The gist of the statistical info is this: maybe not the majority but possibly half and even by the low-end estimates a huge percentage of Americans believe in aliens. Those people might be really great dreamers and thinkers in their own way but they are coming to the conclusion that extraterrestrial life exists using bad science.
Back in the early 60’s, Dr. Frank Drake made the first noteworthy attempt to quantify the aspects needed for Earthlings to detect intelligent life on other planets with what became known as the Drake Equation. Most of the scientists who believe in aliens argue that extraterrestrials are a mathematical probability. For example, Stephen Hawking said, “To my mathematical brain, the numbers alone make thinking about aliens perfectly rational,” in his Discovery Channel series called Stephen Hawking’s Universe. The problem is, without knowing exactly how life on Earth began there is no way to know the mathematical probability of it happening anywhere else.
Dr. Frank Drake was responding to one of the most famous cases against extraterrestrials, though, an earlier, 1950’s argument usually called The Fermi Paradox. Last Thursday (Jan. 28th, 2015) Neil Degrasse Tyson explained his interpretation of the Enrico Fermi’s classic – and still indestructible- argument:
“[Enrico Fermi] said that the universe has been around a really long time, and technological evolution, when it happens, happens fast. If there are [advanced] aliens in the galaxy, they should have been here by now. Because if they live approximately as long as we do, they can send colonies out to other star systems, set up base camps, and then [those base camps] send out other colonies. So one grows to ten, grows to a hundred, grows to a thousand,” Tyson explained. “And you can grow the number of colonies exponentially in the world very quickly, so where are they?”
You can watch last weeks Degrass Tyson lecture in Denver, CO in its entirety, here:
So, until new data arrives or a deeper understanding of life on Earth can be had, belief in Aliens is unsupported by any credible data. Contemporary Americans are pretty great at disregarding science in the name of what simply sounds cool or interesting, though, so most people will continue to believe in aliens.