Did a Distant Solar System Send Life to Earth?

A new theory of how space debris travels increases the likelihood that star systems swap biology

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The inner solar system with a visiting comet

(Correction appended Sept. 26, 2012.)

Time was, the solar system was raining rocks. You only need to look at the cratered face of airless bodies like Mercury and the moon to get a sense of the cosmic crossfire that took place back when the local worlds were just forming and much of the debris that helped make them up was still flying free. Even now, planets and moons occasionally swap rubble, with odd bits of, say Mars, blasted into space by a long-ago meteor spiraling slowly in to get snagged by Earth.

This kind of planetary tissue exchange long ago gave rise to the  concept of panspermia — the idea that life on Earth may not have originated here at all, but rather was imported in the form of organic building blocks or even microorganisms from far away. Earth, in turn, may have similarly seeded other worlds. The catch is that the solar system is a limited place, with Earth the only place we know of that’s currently capable of supporting  wandering biology.

(PHOTOS: Snapshots of the Heavens: Amazing Astronomy Images)

Things get a lot more interesting if you expand the pool of candidate worlds to include those in other solar systems. This idea, called lithopanspermia, has always seemed like a nifty possibility, but not one worth much thought. The physics of interstellar transfer are so  complex that it would, for practical purposes, be impossible for any debris to make such a journey.  Or that was the belief. But a new paper published in the journal Astrobiology gives new energy to the lithospermia idea — concluding that  interstellar transfer of life might be a whole lot more possible than anyone expected.

(MORE: Alien Life Discovered in a Meteorite! Or Maybe Not.)

For astrophysicists, the easiest part of both panspermia and lithopanspermia has paradoxically been the biology itself. The universe is fairly awash in water, hydrocarbons and even amino acids — and all of them can be carried aboard free-flying space rubble. In 2011, geologists announced that a meteorite that landed on Earth in 2000 not only contained amino acids and other prebiotic materials, but that all of them existed in different stages of complexity — meaning that the meteor had actually been cooking them up en route, probably with the help of traces of on-board water and heat released by radioactive material.

But if organic cargo can survive — and even thrive — on such a long journey, there’s still the matter of how you ship it from sender to receiver, and here’s where lithopanspermia ran into trouble. Old models of interstellar transfer relied on the idea of rubble being flung out of a solar system by gravitational encounters with large bodies like Jupiter, meaning that they’d be traveling at speeds of about 8 km per second — or nearly 18,000 mph. That’s way too fast for the rocks ever to be captured by the gravity of another star system, even if they did reach one. “It is very unlikely that even a single meteorite originating on a terrestrial planet in our solar system has fallen onto a terrestrial planet in another solar system, over the entire period of our solar system’s existence,” wrote astrophysicist H. Jay Melosh of the University of Arizona in a 2003 paper that attempted to put the lithopanspermia idea to rest once and for all. If our rocks can’t get out, other rocks have no greater chance of getting in.

(MORE: Why Are Tomatoes Red? Blame the Meteor)

That, however, is only if you stick with the old model for how the debris was set free in the first place. A team of researchers from Princeton University, the University of Arizona and Centro de Astrobiologia in Spain took a different approach, developing computer models of a slow-boat transit method known as weak transfer. Under this process, rubble  spirals slowly outward through a solar system until it reaches a spot so far from its parent sun that it requires only a slight perturbation to nudge it into interstellar space. “At this point,” says Princeton astrophysicist Edward Belbruno, one of the authors of the paper, “you’re escaping so slowly that randomness and chaos theory is involved in getting you out.”

The problem is that low speed can also mean slow transit time to the next solar system, with a trip lasting  1.5 billion years or more, longer than even the toughest organic material could survive. About 4.5 billion years ago, however, when the sun was just being born, it was part of a tight grouping of nascent stars known as the local cluster that was comparatively densely packed — and that could have cut transit times dramatically.

“After about 100 to 200 million years, the stars scattered, and the transfer likelihood went dramatically down,” says Belbruno. “But you do have a window.” Encouragingly, analyses of terrestrial rocks reveal that Earthly organics may indeed have formed in the solar system’s comparative babyhood, directly within the departure window.

On its face, the number of rocks that would reach another solar system seems small — 5 to 12 out of every 10,000. But since trillions of rocks per year make the low-speed escape, that means a whopping one billion in that same year might be captured by neighboring worlds — and we could be on the receiving end of similar numbers from elsewhere. It may still be unlikely that anyone alive today will ever meet an alien— but the odds just went up a little that we all could be the aliens.

MORE: Explosion on Jupiter. Did the Planet Take a Hit For Earth?

PHOTOS: Window on Infinity: Pictures From Space

(An earlier version of this story mentioned the 5 to 12 per 10,000 number, but did not mention that such a low figure could still add up to one billion per year.)

95 comments
online earth
online earth

hi.

       I Am Talking About Earth.

online earth
online earth

hi.

       I Am Talking About Earth.

lokiii
lokiii

I remember this crackpot theory coming out when NASA was desperately trying to say they found like on Mars.  They claimed an impact hit mars and sent debris to earth.  Let's put a little logic into this shall we.  Any impact big enough to drive debris out into orbit and out of the gravitational field of mars would have sent the debris up in a semi-molten state,  the rocks would have spend millenia in space before getting to earth being bombarded by intense heat, cold, and radiation.  The debris would then fry hitting the atmosphere.  And to top it off the rock, has been sitting for years, perhaps millions, and them some dumb science shmuck says there is earthlike creatures in the rock....  Of course it does, it wasn't picked up the instant it landed!!!!

Plumbline
Plumbline

What did the first man who landed on the moon quote........awe inspiring........

Genesis 1:1..........   In the beginning God created the heavens and the earth.

fishhook
fishhook

The million images sent to earth by various telescopes show that the various solar systems and galaxies are spinning like cyclones. Under the centripetal force dispersals millions of meteors are escaping at very slow tangential velocities into inter stellar space. The speeds range from supersonic to very sluggish. At such slow speeds neither organic vapor nor heat is severely lost from the travelling object especially at very low temperatures. ThatThat at least explains Why icy comets can remain frozen and supportive of molecular life preservation by the time they arrive other solar systems or galaxies. Life in such scenario is formed at random on those planets whose atmospheres are conducive to metabolic synthesis of organicf life.

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53underscore3
53underscore3

I think that the idea of panspermia is pretty pointless, for two reasons:

1. It's bad science, because beyond transport, it's untestable

2. It doesn't really solve the issue of how life began, it just moves it elsewhere.

Arieldarkstar
Arieldarkstar

This Science is so bought and ridiculous, get a grip people

ArchieDeBunker
ArchieDeBunker

I believe in the God who said "Let There Be Light" - and in so doing created the "Big Bang" that you love to believe in - and from that act came everything else that has ever been created.  When you demonstrate, conclusively that the Universe stemmed from some other cause I will listen to you.  Until then, I'll believe in the Truth as presented in the World's most important book - The Holy Bible.

svarduhl
svarduhl

Life on earth was actually already on its way because the solar system had the necessary elements of life that were inherited to the sun being a second generation star from an exploding supernova. These heavy elements were elaborated at the core of the massive star that spread through space in the resulting debris that were

driven away in the cloud that eventually formed our solar system with the sun

and our earth. These elements exist today in our own bodies: carbon, oxygen,

magnesium, iron, etc.

Kasbohmc2
Kasbohmc2

God created the Heavens and the Earth, and also created Man and Woman. 

Hotstuf
Hotstuf

And your current God came from?  What did this God do for the eternity that preceeded "his" creation of the heavens and earth?

Raimo Kangasniemi
Raimo Kangasniemi

Don't you know it's hell as a destination for people who trouble religious believers with awkward questions like that? Saint Augustine of Hippo himself said so, so it must be true... right? ;)

Kasbohmc2
Kasbohmc2

First, thanks for your reply.

Second, to address your reply point-by-point:

1) God (in Christianity and Judaism) is not a "current God."  He has existed for all eternity, and will exist for all eternity to come.  He did not "come" from anywhere; he has always "been," and always will "be."

2) Regarding what God did before creating the Heavens and the Earth, I cannot say, nor can anyone else.  Such an answer can never be known by us until we leave this world.

Bobby_77
Bobby_77

This article doesn't make a lot of sense if we take into consideration outside earth's or any other liveable planet's conditions. No biological object will escape radiation and extremes of tempreratures.. In other words, you get off the pond, you die..

Raimo Kangasniemi
Raimo Kangasniemi

Nope. Many Earth bacteria for example need just a little coating of dust to survive in vacuum in Earth's distance from the Sun based on laboratory tests.

owl905
owl905

Since the research indicates active processes during travel through the Void, your dismissive based on sure-death seems a tad misplaced. 

"all of them existed in different stages of complexity"

owl905
owl905

Inventing absurd definitions of atheists, and concocting critiques of the Origin with nonsense about what caused it ... it's a sad reflection of the need to find a religious angle; the article is about new research on the physical drivers in the Universe.

But if it is going to get hijacked by the same old anti-reality groups, then listen up - it lays out very simply, and put very eloquently, by the conclusion of Stephen Hawking - God didn't create the Universe because there was no time to create God before it.

ArchieDeBunker
ArchieDeBunker

And what, pray tell, is your explanation for the cause of the "Big Bang?"  There isn't one "atheist" alive who hasn't thought about where the Universe came from - or in these days, "what caused the Big Bang."  That's the reason they claim to be Atheists - because it's so plainly obvious that the God of the Bible created it all when He said "Let There Be Light," the people who call themselves "Atheists" only do so because they desparately want not to believe that they have souls which will live on beyond their bodies - and may be answerable for their refusal to accept the tenets of Christianity.  As you said, a lot of people don't spend any time thinking about these thing.  In most cases, that's because when they start to ponder them, they get frightened so they use every mental trick they can find (including the belief that "it all just happened") to convince themselves that they don't have to worry about it. 

rkel
rkel

 I  find the idea of a creator and everlasting life, to be a comforting notion, the problem is that I look at the world and it just doesn't make any sense to have one true Christian God. What could be more comforting than an absolution of one of the most frightening parts of life, death itself?

First, the world has been around for billions of years, humans for hundreds of thousands of years. Biblical history only dates back 6,000 years. So what was the role of God, before he gave proof of his existence.

You and I were never there to see or speak with Jesus, yet we are supposed to believe the word of man. Why is it that as time goes on, we stop seeing all this religious activity we did over such a short period of time.

What gives Christianity more credence than Judaism, Islam, the Gods of the Native Americans, Greeks, Romans, and the whole of Eastern Religions?

The things that the bible states that are untrue in terms of time, feasibility, and actual science are numerous (Genesis, Adam and Eve, Noah, Earth as center of the Universe, etc).

Why would God not tell you of his existence, why not help infants and children the world over, who have never known nor will know of Christianity, why not provide them help? He works in mysterious ways is a convenient explanation for what doesn't seem to be the message of Christ in helping your fellow man.