Arsenic-based life and Astrobiology

3 07 2012

File:Arsenate.png

It’s been some time since the controvertial announcement that “arsenic-based life” had been discovered on planet Earth.  With time, however, the less-sensational reality of the discovery has been made more clear, and I think it is sensible to review the current state of the research as it relates to the biochemistry of life and the idea of “alternative” biochemistries.

An Imminent Announcement

NASA "meatball" insignia 1959–82 and 1992–presentThe recap: Making some serious waves back in November of 2010, NASA released a media advisory stating that a news conference would be held days later that would reveal “an astrobiology finding” that would “impact the search for extraterrestrial life.”

The journal Science strictly embargoed details until the news conference was held.

Of course, the internet went bezerk.  NASA’s announcement, the first of its kind since the announcement of potential bacterial fossils in Mars meteoriete ALS-84001, seemed to hint to many that a rover had finally hit paydirt.  Signs of extraterrestrial biology had finally been found!

However, the rampant speculation that followed only fueled an initial spike of disappointment with the actual announcement: that young biogeochemist and astrobiologist Felisa Wolfe-Simon led a research team that discovered, as was popularly-reported, “arsenic-based” life here on Earth.

Wolfe-Simon’s discovery was  published in the journal Science and was actually met with a fair degree of sensationalism right out of the gate, followed by sharp criticism that survives to this day.

File:GFAJ-1 (grown on arsenic).jpg

Magnified cells of bacterium GFAJ-1 grown in a medium containing arsenate. (Credit: NASA)

GFAJ-1: The Arsenic Experiment

A critical question of astrobiology is whether or not life is required to take advange of the same chemistry we do, i.e., that our biochemistry is the only biochemistry that works.  If other types of chemistry were available to life, (such as silicon-based life hypothesized on Saturn’s moon Titan,) then this implies that opportunities for life elsewhere in the universe are great in number.

If not, then life may be more rare; waiting for the perfect “goldilocks” conditions before it can arise.

Testing this hypothesis, astrobiology researchers have been pressing for evidence of so-called “shadow biospheres,” or examples of life taking advantage of different or exotic chemistries right under our own noses.  In other words, seeking out environments where life might have evolved out of necessity to take advantage of different, ordinarily toxic chemical elements is one strategy to investigate the question here at home.

With this objective in mind, Wolfe-Simon (and colleagues) proposed that instead of phosphate (PO4), life might find a way to substitute arsenate (AsO4, depicted in the header)  into its DNA.  Specifically, by isolating an extremophile (an exotic bacterium) from the bizarre ecosystem at work in the alakaline, salt-ridden, and arsenic-laden Mono Lake, Wolfe-Simon’s research team claimed success: the identification of an organism that was capable of substituting arsenic for a small percentage of its phosphorus!

Clarifying “Arsenic-based” 

Wolfe-Simon’s findings, which were obtained when the GFAJ-1 bacteria were grown in a culture doped with arsenate, are more accurately described as identifying a potential “arsenic-utilizing” as opposed to “arsenic-based” form of life.  Even so, the results were considered a boon for those proposing widening the technical search for extraterrestrial life.  In this view, should life be utilizing very different biochemistry than what we’re accustomed to, it is possible that the instruments on our rovers, etc., might not even detect it (or recognize what it was that was being detected).

However, the results have been hotly-debated since, and more recently, have been outright cast into doubt when researchers just this year used a separate analytical method and failed to detect arsenic in the GFAJ-1 bacteria.

The Take-Home

The jury is still out considering whether or not we’ve actually detected so-called “alien” biochemistry or hard evidence of a shadow biosphere.  That having been said, the justification and approach is still in my opinion a solid one.

It remains within the realm of possibility that extraterrestrial life (or terrestrial life under extreme conditions) might, due to opportunity or necessity, be chemically different from our own.

Food for thought.





Antimatter Hazard Symbol pops up!

18 04 2012

Antimatter containment pod as rendered in Second Life. Note the triangular Antimatter Hazard Symbol at left. (Image credit: Benjamin Swem; Symbol credit: Ben McGee)

A red-letter day!  The Antimatter Hazard Symbol I proposed nearly two years ago has found its first physical application!

…Well, pseudo-physical, anyway.

While the symbol, (which is based on internationally-accepted color coding in combination with Title 10 of the U.S. Code of Federal Regulations, Part 835, Subpart G posting guidelines,) has found its way into online articles here-and-there, it hadn’t found it’s way onto something more substantial until now.

Second view of the antimatter containment pod as rendered in Second Life. Note the triangular Antimatter Hazard Symbol at left. (Image credit: Benjamin Swem; Symbol credit: Ben McGee)

Benjamin Swem, a Second Life user also known as Krahazik Zaytsev, recently asked my permission to use the symbol.  His application?  In true, classical science-fiction fashion, it was to be affixed to an antimatter containment pod powering a fictitious spacecraft he was in the process of creating to sell in-world.

I’m must say I’m quite pleased with the result.

The symbol, for those who hadn’t seen my original proposal, is a modification of the familiar radiation “trefoil,” replacing the “caution” yellow-and-black coloring with the more threatening “danger” red-and-black.  Each of the radiation “foils” has been bisected to impart the concept of additional energy, the foils themselves have been inverted to further distinguish it from a “ordinary” radiation trefoil, and the center of the symbol is two inverted circles overlapping (instead of one circle) to represent the interaction of matter with antimatter. 

Instantly familiar, intuitive, yet more ominous is what I was after.  (A symbol doesn’t do anyone any good if no one recognizes it, so why not leverage existing symbology as an advantage?)

  • *For the scientifically-inclined, the radiation symbol is also very technically-accurate one.  Considering the actual threats posed by antimatter, a primary danger of proximity to annihilating antimatter (even in storage systems!) is from gamma-rays emitted as particles and anti-particles collide.  For electrons and positrons, this energy is a gamma-ray with peak energy observed at 511 keV, which can penetrate even very thick shielding.  (We actually use the annihilation of naturally-occuring positrons to help calibrate our instruments, so make no mistake, antimatter exists! – Just naturally in small enough quantities that it doesn’t really cause any negative effects.)

Admittedly, it’s a bit early to be terribly concerned with protecting the public from incidental encounters with antimatter – but thinking about it ahead-of-time can’t hurt.

And in fact, with the relatively-recent discovery of natural sources of antimatter, we may develop the ability to amass stores of the material sooner than we imagined.

So, feel free to use the hazard symbol as you wish; All I ask is that you just let me know how you intend to use it and send me a link or image of the result!

Proposed Antimatter Hazard Symbol, modeled after 10 CFR 835 requirements for Radiation labeling and posting. (Credit: Ben McGee)





Titan eclipses Mars

22 08 2010

Cassini spacecraft view of Saturn's 3200-mile-wide moon, Titan, with the smaller, 698-mile-wide moon Dione actually 600,000 miles behind it. Credit: NASA/JPL/Space Science Institute

Titan has eclipsed Mars.  Not literally, mind you, but conceptually.  With active surficial geology the likes of which are known only to Earth, and considering the recent discovery of possible biochemical signatures of alien life, to me Titan has become the most interesting exploration destination in the solar system.

Take the above image, for starters.  Whereas most other rocky worlds in our solar system offer an unbridled view of craters, mountains, and ancient plains, Titan’s dynamic, hazy atmosphere betrays little.  Truly, the giant moon, which is larger than the planet Mercury itself, is a world shrouded in mystery.

-And, the more we learn about Titan, the more we have reason to believe it is the most Earth-like world this side of a few trillion miles.

(As an aside: My hat is off to the CICLOPS Cassini spacecraft imaging team for giving us real-life pictures like this.  Thanks to them, images from our science today trump the science fiction special effects of a decade ago.)

Unlike Mars, Titan offers us lakes, rivers, clouds, and rain – A full, living hydrologic cycle that is active not billions of years ago, but today.  (Yes, “hydrologic cycle” is perhaps a slight misnomer, because on Titan the active fluid is methane/ethane, not H2O, but the process appears to be the same.)  -And, perhaps most excitingly, scientists have recently discovered evidence that may indicate methane-based alien biochemistry at work.

Specifically, a flux of hydrogen molecules toward Titan’s surface, (rather than away as would be expected,) may indicate the consumption of the gas on Titan (as aerobic life on Earth consumes oxygen); A distinct lack of the hydrocarbon acetylene, one of the most potent chemical energy sources on Titan, may betray that hydrogen-breathing, methane-based life is consuming acetylene as food.

And at least hypothetically, all of the potential chemistry checks out.

If all of this together doesn’t spell impetus for further investigation, I can’t imagine what does.  To boot, because it is so cold out at Saturn’s distance from the Sun and despite Titan’s weaker gravity, the condensed atmospheric pressure on Titan is practically identical to what we experience on Earth, making human exploration all the more feasible.

Have spacesuit, will travel.  Titan or bust.





Space Race Ads, Society, and a Book Alert

17 07 2010

Illustration of a manned nuclear exploration spacecraft and landing capsule in Mars orbit. Credit: Douglas/TIme Magazine, 1963

This one hits close to home for me.  I’ve been collecting space advertisements from the 1950s and 1960s for some time now, and I even have a few gems under glass hanging on my office walls.  Why?  Because they’re meant to inspire.  Truly inspire.  And not just through the now-dated imagery of flashy ships and alien worlds – just the text is intended to fire up the mind and spirit.  Let me give you an example, (sans-illustration for effect):

TOUCHDOWN ON THE MOON (1953)

  • “When the first space ship touches down on the moon, who will be its passengers?  Not the grownups of today, but our grandchildren or great-grandchildren.  In their imaginations may lie the final answer to man’s dream of conquering outer space.  Books for the young that stimulate the imagination are a specialty of Rand McNally …  textbooks and books of nature, science and adventure.  Who knows but that some youngster may find in a Rand McNally book the inspiration that will lead another step closer to travel in space?  And perhaps when that first space ship touches down on the moon, the pilot will check his bearings by Rand McNally maps.”

That’s it.  No pushing of products, no sales pitch for a new line of books or maps.  This is an entire ad funded by Rand McNally that is simply intended to inspire a reader about the amazing possibilities that await, and to let them know that Rand McNally is planning to be a part of it.

The effect is greatly magnified by the dominating illustration of a lunar lander that, for being a concept sketch, looks remarkably like what the real lunar lander would wind up looking like sixteen years later.

Apparently, the entire world was like this for a couple of decades.  Full of vision.  Sprinkler companies took out ads declaring with pride their involvement in nuclear rocket tests by providing fire suppressions systems.  O-ring companies for cars took out ads entitled, “WHEN WE MAN THE IRON MINES OF MARS,” proposing that when off-world resourcing takes off, they’ll work to be a part of it.  We were going to own the future and make it ours.

I don’t think we really realize today just how much of an effect our social marketing has on our outlook on life as a society.  At least, I can say that I didn’t realize it until I started finding and reading these advertisements.  Almost immediately, I found myself suddenly more optimistic about my own dreams of spaceflight.  And then it hit me – these things really do affect what we think about and how we view the world.

Take another example, again (I know, some may groan,) just the text:

HE OPENED THE DOOR TO SPACE…

“It was small compared with the giants men send up today.  And for all the racket it didn’t go much higher than the barn roof.

This didn’t matter to Robert Goddard.  The big thing was that it flew.

They’re all over the front pages now.  Rockets with names like Atlas and Explorer and Vanguard probe the heavens and stretch for the moon, chipping away at space… because a young physics professor from Worcester, Mass., taught them how.

But in those days only boys were supposed to take rockets seriously.  They discovered them in the books of Jules Verne and H.G. Wells.  Bob Goddard did.  And he carefully noted in the margins whenever these friends violated scientific fact.

At college his first experiements filled the labs with smoke.  Later, with savings from his modest salary, he shopped hardware stores for “rocket parts.”  And in his workshop a dream began to have shape.

On a cold March morning in 1926, out on his Aunt Effie’s farm in Auburn, the dream took flight.  With the first successful launching of a liquid-fueled rocket, Bob Goddard turned science fiction into fact.

And he made us remember something, this stubborn Yankee professor … that America is a land where free men have made a habit of doing the impossible.  In such a climate no boy’s dreams are ever really out of reach.

John Hancock Mutual Life Insurance Company.”

That’s it!  See?  No pitch!  No promotion!  Just an ad, (a big ad, beautifully illustrated with a painting of Goddard shielding his eyes from the light of that first test on the farm,) making us all remember that we as Americans stare danger in the face and eat impossibility for breakfast.  Incredible!

In the web of day-to-day exposures, especially in the 21st century with digital media coming at us from all directions, our outlook is heavily influenced by what we unintentionally see or read.  Are we an instant gratification culture, or do we think about the future?  Or do we think at all, or just react?  Much may be told about our society at any given time through the eyes of our advertisements.

Not that it would ever happen, but I think modern corporations should take a nod from their fathers’ ad men.  They should take the time, (and, yes, money,) to help us see the world as it might be.  -Help us to remember our strengths and see how we might all participate in creating a better, more exciting future.  We did it before, and then we went to the moon.  I don’t think that’s coincidence.

So, if you’re interested, but you don’t want to go through the time and trouble of finding some of these ads for yourself, don’t worry.  This brings me to my second point – a new book has just been released from historian Megan Prelinger, entitled “Another Science Fiction: Advertising the Space Race 1957-1962.”  In it, she visually documents through page after page of reproduced ads how the companies that would be the first to take us to space recruited the men and women who would be the ones to figure out how to actually do it.

A must-have for any serious, aspiring astronaut as well as the more casual space enthusiast.

-Or maybe for advertising executives that want to change the world for the better.  Again.





Plant living on the Moon?

13 06 2010

Lunar Oasis project logo. Credit: ParagonSDC, Odyssey Moon LLC

If plans unfold as originally intended, one unexpected result of Google’s Lunar X Prize (which, like the original Ansari X Prize, is intended to spur private industry involvement in space development,) may be the transport and growth of the Moon’s first living plant.

Odyssey Moon Ventures LLC and Paragon Space Development Corporation announced a partnership in spring 2009 to create and deliver a lunar greenhouse.

Industry titan Paragon, a forerunner in space life support systems, is leading the charge with Odyssey, which was formed to compete for the Lunar X Prize, to create a “Lunar Oasis.”  This isn’t the first time Paragon has been involved with a project of this sort, as they’d previously designed a potential Mars sealed plant growth chamber for NASA’s Jet Propulsion Laboratory.

Lunar Oasis module prototype. Credit: Odyssey Moon LLC

The Moon is a particularly harsh environment, even when compared to Mars, and the the Lunar Oasis will need to protect its floral inhabitant(s) from solar and cosmic radiation while providing a temperate environment able to supply and manage nutrients, water, carbon dioxide, and oxygen.

According to their press release more than a year ago, the ideal astro-plant is from the Brassica family (of mustard fame), which needs only 14 days to complete a growth-seed cycle.

As fate would have it, this is also the length of a lunar day.

Now, we haven’t heard from the Lunar Oasis guys in a while, (more than a year,) and this may indicate that the project has fallen away, which would be a pity.  Projects like these, which capture the spirit and imagination – something familiar taking hold on an alien world – are exactly what we need these days to kindle the public mind to engage with private space.

Anyone else heard anything?








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