Welcome to a Special Edition of The Dark Extropian Report. It’s been a bumper few weeks, months and years even in the world of astrobiology, and in particular in the area related to the theory of Panspermia – the idea that life came riding in on an asteroid or comet to our planet. This is one of the very core ideas of Dark Extropianism; that we are inextricably bound to the cosmos, on a grand scale that at the very least is inter-planetary. That our fate lies there as much as our origins do. That we are more than just star dust, but part of a living system that spans billions of years, who’s distance is measured by the speed of light. That ecology is something that spans the galaxy. That we are not meant to stay here, that our destiny lies amongst the stars.
The clip above is from the recent Cosmos: A Spacetime Odyssey series and serves as a decent, if dated, overview. Since much of the science we’ll be covering was only conjecture at best when they were rendering those sweet, sweet animations.
We’ll start with a very basic definition of Panspermia and then go through the news and latest science to elaborate upon it, and then look at some of its implications.
Panspermia (from Greek πᾶν (pan), meaning “all”, and σπέρμα (sperma), meaning “seed”) is the hypothesis that life exists throughout the Universe, distributed by meteoroids, asteroids, comets, planetoids, and also by spacecraft, in the form of unintended contamination by microbes.
Panspermia is a hypothesis proposing that microscopic life forms that can survive the effects of space, such as extremophiles, become trapped in debris that is ejected into space after collisions between planets and small Solar System bodies that harbor life. Some organisms may travel dormant for an extended amount of time before colliding randomly with other planets or intermingling with protoplanetary disks. If met with ideal conditions on a new planet’s surfaces, the organisms become active and the process of evolution begins. Panspermia is not meant to address how life began, just the method that may cause its distribution in the Universe.
Panspermia can be said to be either interstellar (between star systems) or interplanetary (between planets in the same star system); its transport mechanisms may include comets,radiation pressure and lithopanspermia (microorganisms embedded in rocks). Interplanetary transfer of material is well documented, as evidenced by meteorites of Martian origin found on Earth. Space probes may also be a viable transport mechanism for interplanetary cross-pollination in our Solar System or even beyond.
The correct term for life arriving on one of these various celestial bodies then is: lithiopanspermia.
Lithiopanspermia – “the transfer of organisms in rocks from one planet to another” – has three stages to it, each of which need to be proven to validate the overall theory.
- Planetary Ejection
- Survival In Transit
- Atmospheric Entry
The evidence for each of these three stages effects, proves, other panspermic mechanisms too; in particular, the potential transport of the seeds of life via space probes and robot explorers. Something that should be factored into all future extra-planetary missions.
Everybody knows it was a giant asteroid smashing into the Earth that killed the dinosaurs. One of the previous five extinction events, the Cretaceous–Paleogene, a cosmic catastrophe. Just last year it was calculated that the power of this event was “strong enough to fire chunks of debris all the way to Europa”. From Mars to the moons of Jupiter, little chunks of frozen dino meat and a whole lot of Earth fragments could quite probably have come raining down. As Neil deGrasse Tyson explains in the clip at the top, from the beginning of the Solar System big rocks have been crashing into one planet sending a bunch more flying into others. There was likely a healthy exchange of material between Venus, Earth and Mars for billions of years. Life could have started and stopped on each multiple times, being preserved by an inter-planetary ark made of asteroids. We will only find out more as we look around the Solar System. Carefully.
CT scans have also revealed smaller iron-rich spherules resembling “blueberries,” the iron-oxide concretions discovered on Mars a decade ago by the Opportunity rover and thought to have precipitated out of water. The edges of these veins and spherules would all be good places to look for organic signals, says Andrew Steele, a biogeochemist at the Carnegie Institution for Science in Washington, D.C., who is probing the rock for organics.
So far, Steele has found no hint of martian biology—just trace amounts of organic molecules associated with volcanic processes. But he has found plenty of Earth bugs in the cracks—something that he takes as a good sign. “It’s a very habitable rock,” he says. “All it needs is a little warmth.”
That’s a rock they found in the North African desert that formed on Mars 4.4 billion years ago, got launched into space by another asteroid 5 million years ago and landed on Earth a mere thousand years or so ago.
As was stated earlier, Panspermia addresses the mechanism by which life arrives on a planetary body, not its origin. What it means is that the Solar System could be filled with branches of one or more Trees of Life spread by giant rocks coming down from the heavens. One place astrobiologists have long studied is the deep ocean; home of the hydrothermal vents and their resident form of extremophiles, thought to be quite similar in habitat to ice moons like Europa. A massive event like the Chicxulub impact could well have sent chunks of this deep ocean habitat on a course straight to Europa, directly seeding it with a perfect life form.
The detailed environments on the early Earth and the conditions, under which life could originate billions of years ago are largely unknown. In consequence, the possible processes which may have taken place can neither be proven nor excluded. Therefore, most of the models proposed so far are focused on singular elementary steps of prebiotic developments. In its long history, the corresponding discussion about the crucial location on early Earth shifted from the Earth’s surface to the deep sea, from volcanic outlets to shallow ponds. Lacking plausible alternatives, extraterrestrial regions like Mars or the interplanetary space have also been included.
On the other hand, the continental crust was, during a long time, neglected in the discussion. “This region, however, offers the ideal conditions for the origin of life“, Prof. Schreiber says. His focus is on deep-reaching tectonic fault zones which are in contact with the Earth’s mantle. As for example in the region of the “Eifel” in Germany, they are channeling water, carbon dioxide and other gases which constantly rise to the surface. This fluid mixture contains all necessary ingredients for prebiotic organic chemistry.
The implications being two fold. Firstly, wherever an asteroid crashed there were likely living passengers catching a cosmic ride as they were dispatched into the void. Secondly, this prebiotic process could have arguably occurred just as easily on Mars or Venus over time. Increasing the strength of the argument that independent strands of life have been exchanged across the Solar System for perhaps as long as it has existed.
That sufficiently addresses just how life could be ejected from one planetary body to another, and that it is has been occurring over billions of years, and is in fact an ongoing process. Comet Siding Spring, for instance, is thought to have delivered a payload of meteorites as it passed by Mars just recently, permanently altering the planet’s chemistry.
Now to show that life can survive the trip through the vacuum of space.
Survival In Transit
As we saw above, they’re looking pretty hard at Black Beauty to find confirmation that it, or meteorites like it, could have acted as an inter-planetary transport system for the local ecosystem.
What about comets? That’s the exact thing the ESA were asking when they dispatched the Rosetta probe. And despite the Philae Landers short and dramatic landing, it did indeed detect organic molecules before powering down:
It has not been disclosed which molecules have been found, or how complex they are.
But the results are likely to provide insights into the possible role of comets in contributing some of the chemical building blocks to the primordial mix from which life evolved on the early Earth.
Preliminary results from the Mupus instrument, which deployed a hammer to the comet after Philae’s landing, suggest there is a layer of dust 10-20cm thick on the surface with very hard water-ice underneath.
As anyone who watched Ambition – the excellent piece of space propaganda the ESA produced – knows, the water alone has been a key factor in making this planet what it is. Which by itself argues strongly enough that the origins of life on Earth are not terrestrial alone but lie in the heavens too.
More evidence than that is needed to make the case for an ecology that spans the Solar System. Like proof that more complex life forms, like bacteria, can survive such a voyage:
In 2002, a team led by astrobiologist Charles Cockell at the University of Edinburgh, UK, discovered a unique group of cyanobacteria in Haughton crater in northern Canada. The bacteria live in tiny pores and cracks of near-translucent rock, formed during the intense heat and pressure of the asteroid or comet impact that made the crater, about 23 million years ago.
Cockell’s team found that the altered crystal structure of the rocks absorbed and reflected UV rays. This suggests the rock could shield the bacteria while letting enough sunlight through to allow them to photosynthesise.
Complex life evolved long before the crater formed, but there have been countless space rock strikes in Earth’s history. “That raised a whole bunch of questions about whether the unique geology of impact craters could have been a good UV shield on the early Earth,” says Casey Bryce, a member of Cockell’s lab.
Bryce and her colleagues got an unusual chance to test the notion in 2008. As part of the European Space Agency’s EXPOSE mission, the team sent some of the crater rocks to the International Space Station (ISS). Before lift-off, they grew samples of the cyanobacteria either in plain glass discs or in discs of the impact-altered rock. Once in space, these discs were mounted on the outside of the ISS, where they were left exposed for nearly two years.
The bacteria received radiation doses far more intense than conditions on early Earth. When the samples were returned to the lab, the microbes in the glass discs were dead.
“However, when we cracked open the impact-shocked rocks we were able to detect chemical signals of life and rejuvenate the dormant cyanobacteria,” says Bryce. The team’s findings provide the first direct evidence that crystal cocoons formed by impacts might have been radiation-proof cradles for early life.
Asteroid and comet impacts are ubiquitous in the solar system, so Pontefract thinks impacts could have helped kick-start life on rocky planets and then shielded whatever emerged. Crater rocks could provide refuges even now for life on other planets, such as Mars, she says.
It sounds almost… no, exactly… like a natural mechanism for the seeding and reseeding of life on and between planetary bodies.
Which leaves just one more part of the overall theory of Panspermia to prove, and that’s the most recent and exciting news of all. Confirmation that life can survive reentry. Something that has profound and cosmic, and also disturbing, implications.
The biggest obstacle to the theory of Panspermia has always been reentry. Even if life could survive in the cold, empty void of space how could it remain intact after a fiery descent through the atmosphere? Thanks to some Swiss and German scientists, this last charge against the resilience of life has been dropped:
In a new study published today in PLOS ONE, a team of Swiss and German scientists report that they dotted the exterior grooves of a rocket with fragments of DNA to test the genetic material’s stability in space. Surprisingly, they discovered that some of those building blocks of life remained intact during the hostile conditions of the flight and could pass on genetic information even after exiting and reentering the atmosphere during a roughly 13-minute round trip into space.
The findings suggest that if DNA traveled through space on meteorites, it could have conceivably survived, says lead author Oliver Ullrich of the University of Zurich.
The rocket test may fall short of representing the faster speed and higher energy of a meteor hurtling into our atmosphere, but it does suggest that even if the outside of a meteor was scorched, genetic material in certain places on the meteor could survive higher temperatures than scientists had previously realized and make it to Earth. The findings are “a stop on the way to understanding what the limits are for DNA’s survival,” says research scientist Christopher Carr of the Massachusetts Institute of Technology, who was not involved with the work but called the results “provocative.” The next steps, he says, would be to further pin down what temperature and pressure would ultimately kill DNA.
And the implications are immediately very, very messy for astrobiologists and all the world’s space programs. Because as lead author, Oliver Ullrich, of the paper says:
“DNA attached to a spacecraft has the potential to contaminate other celestial bodies, making it difficult to determine whether a life form existed on another planet or was introduced there by spacecraft.”
Which means the Martian rovers could be acting as technological panspermic vehicles…
When space agencies send robot explorers to other planets, they give them a deep clean to remove all Earthly signs of life. The idea is to avoid contaminating another world, which would make it more difficult to detect genuine aliens. Thiel says her work suggests agencies should coat their robots with artificial DNA before cleaning, to confirm it has all been removed.
The case for future robot explorers being assembled in orbit by robot factories becomes incredibly strong.
It means, moving forward, being very careful about what we send out of Earth and where. It means thinking about the whole Solar System on an ecological scale. And taking any return missions equally seriously.
Because a plague is a hell of a way to confirm life existing beyond our planet. And the idea of a comet being integral to the Black Death is a scary enough history lesson to make us start watching for unexpected visitors with much greater attention. (Support the Sentinel Mission here!)
Categorising probable locations of life as natural reserves to preserved and protected, not infected. Ice moons like Europa and Enceladus in particular. Especially when there are non-invasive observation options, like just flying by and collecting a sample from the plumes of Enceladus.
As we learn more and more about the universe we occupy. And make intelligent choices about our future role in it. Using advances in synthetic biology to be self-aware vectors for the transmission of life and the resurrection of dead worlds.
And build a whole new spacefaring civilisation of our very own.
In conclusion: exciting and potentially very dramatic times!!! It makes one feel positively Cosmopomorphical.
Which is one of the aims of Dark Extropianism; to break the mind of out regular thinking. To embrace the void. To see beyond the normal and find new answers to old questions. To expand the scope of our dreams and the nature of our hopes. Which is why we’ve found Panspermia so fascinating a concept to begin with, and have tracked all developments closely to bring the good word to you now. To testify!
This has been The Dark Extropian Report. In this instance, a mind expanding journey that resituates our place in the Solar System and the Cosmos. Redefining ecology for a dying world, in the midst of the Sixth Extinction, in which we are the asteroid. Delivering that knowledge that while we may be killing the planet, the seeds of life for a new world could well be stowed away on the Voyager probes, now exiting our Solar System.