Alien Life Could Easily Planet Hop in This Tantalizing Solar System

By Carl Engelking | June 13, 2017 2:19 pm

An artist’s conception of TRAPPIST-1. (Credit: ESO)

If we detect alien life on a planet in the TRAPPIST solar system, there’s a chance they’ve already spread to one or more of the other six planets orbiting this ultra-cool, ultra-tiny star some 40 light-years away.

In May 2016, scientists made headlines when they discovered three, Earth-size, rocky planets (in February scientists announced they found four more) orbiting a red dwarf star that’s roughly the size of Jupiter. Planets in this system huddle around their home star in tightly packed orbits—TRAPPIST-1b circles its star once per day. And since red dwarfs are cooler than our sun, it’s thought that several of these planets could be habitable, despite close proximity to their star.

This tightly packed solar system begs a tantalizing question: Are these planets exchanging life via space rocks? There are theories that life on Earth may have come from Martian rocks. And if that’s the case, Harvard University researchers Mansavi Ligam and Abraham Loeb argue that the odds of the same thing occurring in the TRAPPIST-1 system are magnitudes higher.

Sowing Seeds

The panspermia hypothesis, credited to Big Bang skeptic Fred Hoyle, underlies all of this life-exchanging talk. Basically, it states that asteroids, comets and meteorites laden with microbes crash into virgin planets, and the surviving microbes sow new life. A few years ago, scientist Steven Benner threw out a provocative idea during a geochemistry conference: Perhaps life on Earth began with organisms clinging to rocks from Mars.

Billions of years ago, conditions on Earth were far too hellish for life to take root. But perhaps a major impact sent Martian rocks flying into space on a course toward Earth. The rest, as they say, is history. It’s still a theory, but there are organisms that can survive the ravages of space—ahem, tardigrades.

In a study published Tuesday in Proceedings of the National Academy of Sciences, Ligam and Loeb built a mathematical model, borrowing from theoretical ecology, to see how the panspermia hypothesis might play out in the TRAPPIST-1 system. Based on their analysis, if Mars could send life to Earth, it’s far more likely that the same thing would happen at TRAPPIST-1.

If you boil down the math, their results are intuitive: The distance between two planets in the TRAPPIST-1 system is tens of times less than the distance between Earth and Mars, which increases the efficiency of material exchanges. Thus, there’s a higher chance TRAPPIST planets are throwing life-seeds back and forth.

An Exciting Theory, But a Theory Nonetheless

Of course, there’s no telling what kind of organisms, if any, would be hitching a ride on TRAPPIST-1 rocks, so it isn’t possible to know if TRAPPIST organisms would survive the trip. Their model is also very simplified, because we just don’t know much about TRAPPIST-1. When did the planets settle into their orbits? Are there a sufficient number of meteorites slamming into planets to launch life-seeding rocks through space (a.k.a. cause spallation)? These are just a few Ligam and Loeb raise in their work.

Looking forward, we first need to determine if life indeed exists in TRAPPIST-1. Telescopes that will be launched in the coming years will be able to probe planets’ atmospheres in the system to detect biosignatures associated with life as we know it on Earth. Scientists could also search for “red edge” spectral signals that hint at the presence of vegetation.

If life exists, researchers could then theoretically verify the panspermia hypothesis, as well. If “red edge” signals are the same on various TRAPPIST-1 planets, that would indicate life sprung forth from a singular source.

Life as we know it relies on “left-handed” amino acids and right-handed sugars, for example. If organisms on TRAPPIST-1 planets all adhere to the same chirality rules, that’s a good sign that life hopped from planet to planet. But if the rules were different on each planet, it would be an indication that life evolved in isolation.

Extraterrestrial life will always capture even the most casual stargazer’s imagination, and these theories about TRAPPIST-1 are certainly titillating. Unfortunately, patience will be the mantra for years to come, as we’ll need to wait for new, technologically advanced telescopes to come online before putting hypotheses to the test.

CATEGORIZED UNDER: Space & Physics, top posts
  • Uncle Al

    I planted Cherokee Purple tomato seeds given 20,000 rads of Cs-137 gamma irradiation two weeks prior. Some malformed but still fertile flowers. Nearly 6-feet tall and growing. Fruiting is better than two control plants’.

    NASA measures 90 rads/year free space irradiation. Optimistically (30,000 rads)/(90 rads/year) = 333 years travel radius to Bob, the tomato planet. Major gravitational slingshot accelerations, delayed canister rupture. 300 seeds/gram. One tonne payload is 300 million voyagers. Proxima b, 4.22 ly, 1% lightspeed will do it. Braking is an engineering exercise (hydrogen atom resistance during the trip?).

    • Erik Bosma

      Cherokee Purple…. so proud you lived, so sad you died!! Eric Burdon, right?
      Geez, I didn’t know he was into tomatoes.

      • Uncle Al

        Heirloom tomato – huge, gooless, bursting with flavor. We toured a nuclear facility. Two pounds of assorted seeds got genetic ticklers. Parent fruit ripens in about a month. The first filial generation grows next year.

        Another hospitable planet would also be nice.

        • Erik Bosma

          The smell always gives away a great tomato from the odorless red things that get sold in our supermarkets. They obviously grow on a steady diet of 10-10-10 and not much more.

  • Mike Richardson

    Facinating. Although it’s too early to tell if there is actually life in this system, the apparent density of such Red dwarf systems indicates that they may frequently have more planets in their habitable zones than we would expect based on our own example of the solar system. There are many other variables to consider, such as the radiation flux from red dwarves (typically greater than larger stars like Sol, which don’t have mega flares), the likelihood of the planets being tidally locked to the star, and of course the ease at which life develops in the first place. The universe is truly a marvelous place, constantly showing us that the more we learn, the more our preconceptions are shaken.

    • Tom Hunter

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    • Kate K

      Extra terrestrial space voyaging life is going to be inorganic AI. The only thing up to question is whether it killed its organic inventors first or not.

      Planetary habitability is meaningful in rise of live, but in my opinion much less relevant in any intelligent life’s exploration outside their system.

      • Tom Whitley

        “Planetary habitability is meaningful in rise of live” – What?

  • Erik Bosma

    This discovery suddenly lends a little credence to that ‘Firefly’ sci-fi series that was on a few years back. Although a little hokey it was not bad entertainment until I realized they were planet-hopping on a weekly basis. “Wait”, my superior mind said to my grown-up kids who didn’t give a care (and never had for that matter), “if they’re flying from planet to planet like that within a week then they’re breaking all kinds of space rules not to mention many kinds of time ones.”
    But wait, Dad!” they all chorused together, “those planets are all going around the same sun and they’re only a few million miles apart!”
    After my derision and mocking subsided I sat down and gave them a very informative 2 hour lecture on mechanics of solar systems which they, no doubt, found stunningly interesting. I then picked up the remote and crushed it under my Star Trek boot.
    “Well kids, looks like Dad f**ked one up, eh?”, I said as I plodded off through the deep snow and the 100 km/h winds to the local Radio Shack. Good thing it wasn’t winter…

  • OWilson

    I’m always amused by the popularity of the logic that life on this Goldilocks blue verdant planet must have got here from that dead global desert called Mars. Even after 50 years of detailed exploration of Mars, the theory won’t die!

    Aside from it not making a great deal of sense, other than to Bible Bashers, it throws absolutely no light whatsoever on life’s actual origins :)

  • Don Crawford

    This is not an “exciting” theory; it is absurd. One has to understand the way the eternal LIFE-WAVE rotates from plane to planet. There was life on Mars eons ago; now Mars is a “dead” planet undergoing decomposition. The Moon is also a dead planet and undergoing decomposition as well. The Moon, however, is the Progenitor of earth. The Moon was earth’s parent, and much older than earth, contrary to what science believes. One day the LIFE-WAVE will move on and earth will, like the two above, be dead and undergo decomposition, like all dead bodies. One must study the Ancient Wisdom concepts of Globes, Chains, and Schemes to understand this Law of Cycles.

  • Don Crawford

    Our entire Universe and all things within it are ALIVE. Each planet is a living entity, the planet being his body of manifestation. LIke, the solar Logos is the creator of our solar system and all within it and his body is our solar system. Ditto all the planets. Science will never find the Truth of Life and Existence by applying a Materialistic paradigm in its research. Truth is by way of a Spiritual paradigm, which transcends our senses and even our lower minds.

  • KieSeyHow

    And, what “truth” is that? I see a photo of a rock…


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