A Galactic Biosphere?

My Brother/Sister, the Alien

In Confessions of an Alien Hunter: A Scientist's Search for Extraterrestrial Intelligence (a full review is forthcoming), Dr. Shostak, in his brief mention of panspermia as one possible way life originated on Earth, brings up an interesting point about panspermia:

Panspermia's importance would change if life could survive in rocks that travel not just between adjacent planets but between the stars. If interstellar infection is possible, just a few points of genesis - or even one - might conceivably seed the entire galaxy. So life's beginnings could be highly improbable, but life's distribution could be widespread. In essence, the "biosphere" would extend over light-years. (88)

Thus, if life originating on its own is rare, we can see a scenario where that life eventually spreads throughout the galaxy. We would all be members of the same galactic biosphere - brother and sister creatures in one galactic family

Another way life can spread from one genesis is seeding by an early alien sentient race. This is a notion used by some Hollywood writers. In many science fiction shows we often see humanoid aliens. One reason is that especially for early Hollywood, humanoid aliens were easier on the special effects budget, thus sometimes writers and producers explained the similarity among humans and aliens by using the idea of early race spreading their DNA throughout the galaxy. For instance, in a Star Trek: The Next Generation episode (Season 6 episode "The Chase"), we discover there was an ancient race that seeded the galaxy (leaving clues in each "offspring's" DNA), thus explaining why so many alien races looked so similar. Why would sentient aliens purposefully seed the galaxy? It may be difficult to understand their motivations for sowing their seed amongst the stars, but some possibilities are:

1. as a means to continue their species / terraforming, 
2. by accident, 
3. as scientific experiments, 
4. as the result of a religious decree (one purpose for life is to spread life, to join in on creation, e.g.) or 
5. a combination of the above.

The Grand Diversity of Life

But even if the residents of the Milky Way are related,  life, as we have seen on Earth, comes in a stunning array of diversity. From the deep sea, to deep mines, to hot springs, to tropical forests, to arid deserts, to perpetual frozen ice caps we find life in a myriad of forms. If we look into Earth's past via the fossil record, we find even more strange life forms. Extend this into space, onto other planets, and even if there is a common biosphere bound, the variety of expressions life can take will be mind boggling.

Or, My Half-Brother/Half-Sister, the Alien 

In addition, even if life originating on its own is a rare occurrence, in a galaxy of hundreds of billions of stars (estimates run between 200 - 400 billion) and with even more planets (possibly a couple of trillion), there is the possibility that life has originated independently in at least a few places. There could be several galactic families. One wonders if primitive, slow metabolic germs from different origins land on the same planet, would there be a possibility that they could intermix, creating a hybrid life form.

Life in the (Extremely) Slow Lane

But back to the rare origin idea. Dr. Shostak is skeptical of this idea as this would involve million year rides on blasted (from a meteor impact), life-infected, rocks through the harsh vacuum of space. However, as I discussed in an earlier post, Panspermia, Long-Lived Bacteria, and Interstellar Distances, scientists have found microbes with very slow metabolisms that are over a hundred thousand years old living deep (as in miles deep - never seeing the light or fresh air of day) in rocks, and others that have survived lying dormant for a half a million years deep in permafrost. Some studies indicate some bacteria can live suspended in sediments, amber, and halite for millions of years.

So maybe there is a galactic biosphere. Aliens that come to realize this may develop philosophies and  theologies that accepts all life on all planets around all stars in the galaxy as extended family.

One way to answer this question is to find life on another planet - even "just" microbial life. If we find that life originated more than once in the same solar system, it is a strong indicator that life originating on its own is not all that rare. It does not mean that panspermia is not an ancillary method, but that the galactic biosphere has gotten more complex and is, in fact, a large collection of individual (though not necessarily isolated) biospheres.


References:

Shostak, Seth. Confessions of An Alien Hunter. Washington, D.C.: National Geographic, 2009.

Image credit: 1. "DNA" by Lynette Cook. 2. "Dark Matter" by Ryan Bliss, DigitalBlaphemy

The Visitors...

The Visitors arrive...


Yet another alien invasion show. Not that that's a bad thing (the show that is - alien invasion would be a bad thing). I am looking forward to the re-imagining of the 80's series. However, it got me to thinking again about the possible motivations for an alien species to invade the Earth, and the many difficulties involved with invading an already populated planet.

1. Atmosphere: a sentient species will be evolved to their specific environment. Slight changes can prove to be very toxic. An alien invading Earth would need to be able to breathe our particular blend of gasses. That would be a rare alien. Ah, but what about spacesuits or masks? True, those would help, but then why take over a planet that you can not breathe unassisted on? I would think it be easier to terraform a barren, or nearly so, planet than to "terraform" one with an already fully developed ecosystem. Though as mentioned in previous posts, postbiologic / robotic sentience creatures probably can withstand a very wide range of atmospheres.
   
   
2. Nutrition/Dietetics: a sentient species coming to Earth to use us as food would run the risk of finding us to be indigestible or even poisonous. Even if their genetics/physiology are somehow close to ours (that DNA is somehow a normal result of biochemical processes leading to life in the universe), there are many example on Earth where food that is nutritious to one creature, is not nutritious to another (and may even be poisonous). Of course, if the aliens find Earth life to be eatable, it stands to reason that Earth life would, in turn, find the aliens eatable as well, from mammalian predators to invertebrate parasites.
   
   But it is more likely that our physiological makeup will be too different to be of any use dietetic use. The To Serve Man recipe book would not be a top seller for aliens. Although if Earth animals were heavily processed, the aliens possibly could get some food value from them - but a lot of work for little return. Why not find a suitable barren planet, terraform it, and raise food more suitable to their physiology? If the aliens are postbiologic, which many think aliens would probably be (a next natural step in evolution for sentient species), they probably do not need biological food anymore anyway.
   
   
3. Disease/Immunity: I have read conflicting opinions on this matter. One opinion is that humans and disease have evolved side by side - it's a continual arms race as our immune systems evolve to better protect, and diseases evolve to defeat our systems. An alien system would be, well, alien. Diseases have evolved to attack other Earth creatures and are finely tuned to Earth creatures and thus would not be able to attack an alien creature. Others are of the opinion that an alien would be wide open to attack, since their defense systems have never seen Earth diseases and thus have no finely tuned defenses or mechanisms to block or fight them.
   
   In addition to diseases, there are all manner of venomous arachnids, insects, snakes, toads and poisonous plants that an alien would have to contend with. Many would not care if the creature they are in contact with is from the Earth or not. How many of us have put a straw or stick into an ant hill and see the ants swarm and viciously attack the stick? Would the alien bodies be able to tolerate foreign venom or poison?
   
   However, with advanced nanotechnology (or technology advanced beyond it), aliens may very well have postbiologic systems to help them deal with diseases, venomous creatures, and poisonous plants - such matters may be of no real threat or concern to them.
   
   
4. Other environmental factors: we have evolved in a particular gravity well, in a particular magnetic field, with certain ranges of light and other radiation hitting our planet's surface, and a certain range of temperatures. Any invading alien would need to have come from a planet similar to ours if they have any plans for long term domination. Unless, of course, they are postbiotic creatures.
   
   
5. Water: many alien invasion scenarios have aliens coming for our water. Yet we are discovering that water is rather common in the cosmos. There is water on the moon, Venus, Mars, many of the moons of our gas giants, in comets and meteors. Why mess with a populated planet when water is probably much closer to home?
   
   
6. Overpopulation: some alien scenarios have aliens invading because their home planet is overpopulated. I guess their entire solar system would have to be too, for them to move out into the stars to expand. If they were postbiologic and still felt the need to increase their population, they could easily colonize barren systems first or large space stations (Dyson spheres?).
   
   
7. Salvation I: several scenarios have dying aliens coming to Earth in order to do medical experiments to either create some vaccine or gene therapy that can restore the alien's health, or to create alien-human hybrids so that the aliens can continue to live on, albeit in a rather different form. Besides the difficulties of two species evolving on two planets being compatible enough to be of any use to the other medically, again it would seem logical that an interstellar space faring race would be able to evolve into postbiological forms and thus not need to invade another planet to save their species. Though Studying other biologies can help uncover any universal biology laws and principles and thus help a species understand itself better.
   
   But let us say, for the sake of argument, that they cannot or are unwilling to go the postbiologic route and need to leave their star system (going nova?) and colonize another system (ours) and thus need to create hybrids to survive in our very alien environment (this scenario also assumes they cannot or do not have time to terraform another unpopulated world). A hybrid would feel and be different than the aliens - it would be a new species, experiencing the universe differently, and thus evolving away from the invading alien's culture and identity. How is that helping anything? They might as well just impart their knowledge to another race and consider the torch passed and not bother with the whole hybrid thing.
   
   
8. Salvation II: ala The Day the Earth Stood Still, aliens may invade to save us from ourselves, baring any alien version of a Prime Directive, or to prevent us from being a danger to our space neighbors (not all of our space neighbors may be advanced enough to be safe from dangerous space faring races).
   
   
9. Salvation III: alien missionaries come to convert us.

I am sure there is more that I have not thought of.

Alien Missions

Overall, it seems that for the most part postbiologic creatures would have very little drive to invade another planet. At least for physical reasons. But they may have psychological or theological reasons. For instance they find the postbiologic evolutionary step incredibly repugnant or blasphemous. They may fear for their safety or for the safety of other less develop extraterrestrial species and decide to keep us restrained or contained until we, in their minds, have matured enough. Maybe they have long forgotten their own early sentience past and look upon our aggression with psychological or theological horror. They may look upon us as heathens and feel the need to forcibly spread their theology upon us. Now those are scary thoughts indeed.

Image credit: ABC

First confirmed images of exoplanets

© Credit: Gemini Observatory

Gemini and Keck observatory astronomers, using adaptive optics, have taken the first photos of confirmed exoplanets. Readers may recall the First Picture of an Extrasolar Planet! post Oct 3, also from Gemini Observatory - but that one is yet to be confirmed to be a planet. Three planets were confirmed. The planets in the photo to the right, taken by the Gemini Observatory, are two super Jupiters circling the star HR 8799 located 130 light-years away in the Pegasus constellation. The planets are circling 40 and 70 AUs from the central star. Astronomers at the Keck II Observatory discovered the third planet, circling 25 AUs away. HR 8799 is a very young star about 1.5x the mass of the Sun, and 5x brighter. The planets were probably formed 60 million years ago, far too young for life. But in the future...

© Credit: "Gemini Observatory Artwork by Lynette Cook"

Which raises an interesting thought. Far into the Earth's future, whatever sentient life form is the dominant species at the time, may have to abandon the Earth as the Sun expands and boils away the Earth's atmosphere and oceans. The planet may have to be abandoned - by then if there are any Earth-sized planets or Earth-sized moons circling the gas giants of HR 8799, they will be old enough to be hospitable for life. Future Earthlings may have to abandon this solar system for another. It would be probably easiest to colonize/terraform a planet that is ready for life, but on which life has yet to establish itself or has yet to firmly establish itself. That way the Earthlings can form the planet to their needs. This would, thus, have to begin some time before the Earth needs to be abandoned. 130 light-years is quite a distance away, but for a technologically advanced civilization that is desperate, very desperate, it could be done. Even if it was by robots including robotic ships that carried suspended genetic material to seed not only Earth life, but whoever the sentient life form is (we hope it will still be humans).

References:

"Gemini Releases Historic Discovery Image of Planetary 'First Family.'" Gemni Observatory. 13 Nov. 2008. Web. 20 Nov. 2008. <http://www.gemini.edu/threeplanetspr>.

"First Picture of Likely Planet around Sun-like Star." Gemini Observatory. 15 Sept. 2008. Web. 5 Oct. 2008. <http://www.gemini.edu/node/11126>.

"Planetary First Family Images." Gemini Observatory. 13 Nov. 2008. Web. 20 Nov. 2008. <http://www.gemini.edu/node/11150>.

Introduction to The Drake Equation

The Drake Equation

I really shouldn't go on without at least an introductory mention of the famous (and controversial) Drake Equation created by Dr. Frank Drake in 1960.

Dr. Drake's equation is a tool for estimating the number of intelligent advanced civilizations presently in the Milky Way galaxy that we would theoretically be able to communicate with.

The Drake Equation is

N=(R)(fp)(ne)(fl)(fi)(fc)(L)

where N is the number of civilizations we can communicate with at this time in the galaxy, and where:

• R = average star formation rate (10/yr)
  
• fp = percent of those with planetary systems (50%)
  
• ne = average number of planets that can potentially support life per star with planetary systems(2)
  
• fl = percent of the above planets where life actually begins - life started on Earth very quickly, water and the complex organic building blocks for life are common in the universe (100%)
  
• fi = percent of habited planets where intelligent life evolves (1%)
  
• fc = percent of intelligent life that develop communication technology capable of transmitting into space(1%)
  
• L = lifetime of all such civilizations on a particular planet - civilizations may collapse and rise again, or nearly wipe themselves out and the survivors rebuild (10,000 years)

The values in the parentheses are Dr. Drake's estimations. Using Dr. Drake's original values we arrive at N=10. As new data rolls with increasing frequency, these values tend to change. For more discussion see below. 

Assumptions

• Liquid water is required for life, 
• type M stars are too cool, 
• type O and B stars are too short lived, 
• life will develop if given a chance, 
• developing intelligence gives a survival edge, 
• and technologically advanced civilizations do not consistently prematurely destroy themselves because of their technological advances (global atomic war, for instance).

R, fi, and ne Discussion

As mentioned above, as new data rolls with increasing frequency, these values tend to change. Presently, the value for R is thought to be 6 per year. And, as mentioned a few times before in other postings in this blog, we are increasingly discovering certain intelligent traits first thought to be reserved just for humans cropping up in other animals: birds that make and keep tools, ferrets purposefully lying, and dogs mapping language to mention just a few. This indicate that the first estimation for fi (a mere 1%) may be too low.

If, however, sentient, intelligent life is so rare that we are the only one in the galaxy, or even the universe, then the vale for fi may be infinitesimally small. But, if we are the average result of habitable planetary system, and if life is found to have once existed on Mars, and to exist on Europa, then the value for fi becomes 33% (and ne becomes 3). That life formed quickly on Earth, a wet rock orbiting an average star in a nondescript part of the galaxy, then maybe, just maybe, it can form in extrasolar systems as well.

Calculate N for Yourself

See the Drake Equation Calculator on the right. Type in your own values for the variables in the Drake Equation to calculate N.

Habitable Zones and Habitable "Hot Spots"

Personally, I believe the habitable zone estimates are a bit conservative. For instance, Jupiter's moon Europa, despite being outside of our solar system's Habitable Zone, may have liquid water beneath its icy surface, and many scientists feel that Europa could support life. Thus, Habitable Zones could actually be larger, or a system could have Habitable "Hot Spots" (which includes not only planets, but large moons as well) in addition to its Habitable Zone . Maybe even an occasional type M stars could have habitable planet (see Color of Life for some discussion about life in a M class star system).

In addition, the equation does not take into account life that is spread to other planets by advanced civilizations (whether unintentionally from exploration or purposefully from terraforming). And finally, life is constantly surprising us with its great diversity here on Earth - our definition of what is life may need to be expanded.

Additional Drake Equation Posts.


Reference:

Schilling, Govert and Alan. M. MacRobert. "The Chance of Finding Aliens." SETI: Searching for Life. Sky and Telescope Magazine. 15 January 2008. <http://www.skyandtelescope.com/resources/seti/3304541.html>


Image credit: © Lynette Cook

Alien Safari!

© NASA, JPL

Alien Safari, from NASA's JPL can help you "Discover some of the most extreme organisms on our planet, and find out what they are telling astrobiologists about the search for life beyond Earth" (Alien Safari, par. 1).

The Safari includes the weird methane-ice worms found deep 80 miles off the coast of Louisiana. Life finds a way yet again! Though, to be fair, this doesn't necessarily mean that life can originate everywhere, just that life, once established, is tenacious and difficult to get rid of (you can, unfortunately, eliminate individual species easily, but getting rid of life entirely is extremely difficult). So it may bode well for terraformers more than for those searching for alien life. However, I still bet on life being rather common in solar systems.

Alien Safari destinations:

• Living Without Sunlight
• Highest Radiation Dose
• Most Acidic
• Farthest Underground
• Strangest Habitat
• Hottest

Reference:

"Alien Safari." Planet Quest. Jet Propulsion Laboratory. 16 December 2007. <http://planetquest.jpl.nasa.gov/AlienSafari_launch_page.html>

Terraforming Mars

Astrobiology Magazine has a neat (OK, neat for space geeks) online interactive program that allows you to "Build a Virtual World" by playing around with many different environmental factors, from reflected sunlight (albedo) to the amount of methane in the atmosphere - it then tells you how much of Mars would be habitable under the conditions you set.

The Genesis Project

Reference:

"The Genesis Project." Astrobiology Magazine. 7 December 2007. <http://www.astrobio.net/news/terraform.php>