Are Aliens Out to Get Us?

Jonathan Cooke

For a species that is so often looking up to the stars thinking ‘are we alone?’, we tend to populate our fictional universes with less than benevolent compatriot species. Look at some of the more popular science fiction movies and stories to be released in the last century. War of the Worlds, Alien and even the recently released Life all approach the question of extraterrestrial life the same way: it’s out there, and it’s out to get us.

Since it is such a speculative field, there is virtually no consensus on how we might react upon first contact, simply because we don’t know what sort of aliens will turn up. The developing view is that, if there is other life in the universe it’s likely to be microbial in nature. If there is anything that the much-lauded tardigrades have taught us, it is that microbial life will find a way to survive. Therefore, most space-based programs are focused on the detection of this so called primitive life (Is it fair to call it primitive when they can do some pretty amazing things?).

Most missions have focussed on our closest sister, Mars, and its dry riverbeds that provide some tantalising bits of evidence that all might not be dead on the red planet. Methane is unusually high in the Martian atmosphere. As a gas that is highly reactive and therefore tends to disappear without regular top ups, this is indicative that something is replenishing it. Methane in our own atmosphere is typically produced from biotic sources; meaning that, from our experience, traces of methane might be indicative of life.

Of course, alternative theories exist for the presence of methane, including geological sources of the gas. But what if our rovers were to discover bacteria living on the surface of the red planet? What would we do with it? Well it wouldn’t be coming to our planet anytime soon –  none of the rovers currently on the planet are equipped for that sort of mission. Even then, the samples would have to be tested and tested again to ensure that they aren’t just contaminants from Earth. They’re unlikely to alive by the time they reach Earth under strict contamination procedures. So, don’t worry, no Martian plague will be giving you the sniffles.

Alien View From The Moon Earth

Image Credit: Max Pixel

Anywhere else we are currently scouting for life would face similar contamination issues. Europa for instance, one of Jupiter’s larger moons, is being targeted as our next life-seeking venture to the stars. With an ocean thought to be buried underneath its permanent ice-sheet casing, many scientists believe that ocean temperatures may just be warm enough to support the development of life, if again, simple in nature.

So that basically covers what’s known; in our solar system –  at least there won’t be any tripods bursting out the ground anytime soon to exterminate us and Tom Cruise! But what about farther afield? Well, many radio telescopes are turned to the farthest reaches of our galaxies; and news publishers love a good story of astronomers finding ‘habitable’ exoplanets. If you pay attention to the Drake equation, there should be 1,000 to 100,000 intelligent civilizations in our galaxy. So why haven’t we heard from our cosmic neighbours.

There are many reasons that we might not have heard from them, and many reasons we should be thankful for that. If we’ve learnt anything from our own behaviour on Earth, the less technologically advanced society rarely survives first contact with a more advanced society. The most glaring example of this is the fate of the Native Americans in the wake of Europeans discovering the New World.

This is the cautionary tale that Stephen Hawking told in 2010 when questioned about our first meeting with E.T. On the other hand, many scientists question the validity of Hawking’s reasoning. As mentioned above, many are more worried about what the aliens bring with them accidentally rather than deliberately. As illustrated in H. G. Wells’ famous novel The War of the Worlds, contact with a previously unencountered pathogen can be devastating to any organism. Whether it was the Mayans and typhoid and influenza, to African swine fever in the American pork industry, foreign pathogens tend to wipe out whole communities before any resistance can develop. Just ask the abandoned Mayan cities of the Amazon.

Of course, other questions arise which are a bit harder to answer. What if the alien civilization is warlike? What if their ethics system is not comparable to ours? What if, and this has been considered, we are the ‘life, but not as we know it’ variety in the universe? Many astrobiologists have postulated that silicon based lifeforms may exist (we are carbon based), so what if we’re just too alien for them to visit?

An even sadder alternative is that we are truly alone, that alien life is non-existent, (considered highly unlikely) or that we are one of the first intelligent civilizations to evolve in the galaxy. Perhaps intelligent life is the exception rather than the rule. The Fermi paradox points to how extremely unlikely our own path to survival was. Maybe many creatures on that road seemly get snuffed out by Natural Selection before that point.

In any case, what keeps many scientists up at night is not thoughts of alien invasions, but thoughts of alien illnesses. Perhaps what we should be preparing for, and indeed looking for, is what makes little green men feel ill.

TRAPPIST-1: Could This Newfound Star System Hold Alien Life?

Josh Bason

On February 20th 2017, NASA announced a press conference to discuss a “discovery beyond our solar system”. Two days later they revealed the TRAPPIST-1 system; a series of seven earth-size planets orbiting a star 39 light years from Earth. The announcement of this discovery and the discussion that followed has circled one tantalising question – could the TRAPPIST-1 star system harbour extraterrestrial life?

The scientists at NASA certainly seem excited about the concept. Their search for exoplanets – that is, planets orbiting stars other than our own sun – had until this point yielded only a handful of potentially habitable worlds. Among TRAPPIST-1’s seven planets, however, no less than three have shown this potential, setting a record for the most known earth-like planets orbiting one star.

These worlds were highlighted by the scientists primarily for their location in the so-called ‘habitable zone’. This describes the range of orbit sizes where, dependent on the size of the planets and the star, it is neither too hot nor too cold for life to sustain life.

pplanet

Artists impression of the surface of TRAPPIST-1f, the fifth planet in the TRAPPIST-1 system Credit: NASA/JPL-Caltech/R. Hurt, T. Pyle

Further investigations by NASA scientists have also yielded promising results. Using precise measurements of the size and mass of the planets, the researchers were able to calculate estimates for the density of each of TRAPPIST-1’s worlds. These density measurements are key to understanding exoplanets as they give us our first insight into their composition.

Of the seven planets in the newly-discovered system, six have been described as ‘rocky’ – that is, more comparable solid planets like Earth and Mars than gas giants like Jupiter and Saturn. The seventh planet, which has the widest orbit and an undetermined mass, has been provisionally described as ‘snowball-like’.

Despite these hopeful indications, there is also a body of evidence which is significantly less inspiring. Firstly, while it’s tempting to imagine TRAPPIST-1 as a distant copy of our own solar system, the absence of two planets is not where the dissimilarities end. The most striking difference between this newly-discovered system and our own is the star which lies at the centre.

The star is classified as an “ultra-cool dwarf”, meaning it is both ten times smaller than our sun and less than half its temperature. While this doesn’t sound like a recipe for warm earth-like planets, the small size of the star is counteracted by the proximity of the planets which orbit it.

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NASA’s illustration of the size of TRAPPIST-1. (Credit: NASA/JPL-Caltech/R. Hurt, T. Pyle)

The seven worlds of the TRAPPIST-1 system all orbit between one and five million miles from their star. This means that all seven planets could fit comfortably in the space between the sun and Mercury, with its 58-million-mile orbital distance. While the size of the TRAPPIST-1 system isn’t necessarily a barrier to the formation of life, it certainly represents a significant divergence from the only solar system where we’ve ever observed it.

It’s also important to bear in mind how little is known about the planets of the TRAPPIST-1 system. Despite the array of concept images released by NASA in the wake of the announcement we don’t, in fact, have any idea what the planets look like. The planets were found, or more accurately their existence was inferred, by observing the light emitted by the star they orbit.

This process, known as transit photometry, involved watching the star’s brightness over time and finding dips in luminescence when planets passed in front of it. From this information, NASA scientists extrapolated a range of information, such as their size, mass and orbital distance. What this technique doesn’t reveal, however, are other key factors that determine the habitability of a planet.

Because of this, we still do not know whether any of the TRAPPIST-1 planets contain atmospheres, which are vital for life, or magnetic fields, which can protect life from deadly solar wind. NASA are also not discounting the possibility that some or all the planets may be ‘tidally locked’, meaning that one side may permanently face the sun with the other half perpetually facing away. Conventional wisdom suggests life would be impossible on such a planet, as one half would be too hot for life and the other too cold. More recent evidence, however, has suggested otherwise.

planet2.png

NASA’s idyllic concept art is based almost entirely on speculation. (Credit: NASA/JPL-Caltech/R. Hurt, T. Pyle)

Furthermore, since the announcement of the NASA’s discovery, two pieces of research have poured cold water on hopes of life in the TRAPPIST-1 system. The first, published on March 30th, detected frequent flares emitted from the system’s star. Considering the small orbital distances of the nearby planets the authors feared that these huge releases of energy may disrupt the atmospheres of the planets and that without the protection of strong magnetic fields, life in the system may be impossible.

If that wasn’t disheartening enough, research published on April 6th revealed a new climate model to assess the habitability of exoplanets. The study concluded that only one of the planets, TRAPPIST-1e, was likely to support liquid water. If this planet does not possess a substantial enough magnetic field to weather the flares from its nearby star (something scientists feel is unlikely), all hope for life in TRAPPIST-1 may be lost.

Despite this disappointing news, research into TRAPPIST-1 continues. NASA has announced plans to use its new James Webb Space Telescope, launching in 2018, to search for key atmospheric components such as oxygen and water in the system.

The increased sensitivity of the Webb telescope will also allow the surface temperature and pressure of the planets to be measured, answering yet more questions about the habitability of the system. Until then, however, the hospitability of the TRAPPIST-1 system remains very much in question.