This video is a kind of combination of a news story from a few days ago and a happy addendum
to my recent video "Ten Ways We May Have Already Detected Alien Life".
As it turns out there is an eleventh possibility, and I was totally unaware of it until a viewer
brought it to my attention.
It's a detection of potential evidence of microbial life on Europa.
Very exciting indeed and more on that in a minute!
While Venus and Mars are both potential abodes for microbial life in our solar system, they
don't really allow for much more.
They are in general hostile environments that may have areas of refuge that might harbor
life.
But even those areas probably aren't particularly clement, so if life is there, it's likely
going to be simple with little room for developing complexity.
But several other places in the solar system hold the promise of potentially more complex
forms of life.
And while studies of these places are still in their infancy, each year it becomes increasingly
likely that both Enceladus and Europa -- and possibly quite a few more bodies in the solar
system -- have liquid water oceans located under shells of ice that could be right for
microbial and possibly even more complex life.
Several days ago, studying Enceladus' subsurface ocean may have gotten significantly easier.
Microwave observations have revealed that Enceladus' southern pole is quite a bit warmer
than was expected.
Temperatures start rising only a few meters below the surface.
This would suggest that liquid water at Enceladus may lay only a few kilometers below the surface
rather than locked up deep down and hard to access.
This bolsters research done in 2016 that suggested that at the south pole, Enceladus' ice could
be less than 5 kilometers thick.
These findings are interesting because they suggest that the ice could be thin enough
for ground penetrating radar to directly observe the ocean on a future mission to the Saturn
system.
This area of shallow heat is in the same general area of plumes of water ice that Cassini observed
to be spraying into space out of four huge cracks in Enceladus' ice.
These plumes have subsequently been shown to be salty, much like Earth's ocean.
That would suggest that the water beneath is indeed liquid and is interacting with the
solid rocky surface below it.
That idea is further bolstered by the new heat signatures.
But oddly the heat does not seem to be directly associated with the four fractures, called
the tiger stripes, but instead seem to lie under inactive dormant fractures.
And, what's even more odd about the heat is that it seems to be greater than what you
would get from solar heating or globally even gravitational flexing from Saturn.
Where is this additional heat coming from?
The answer seems to be the mechanics of just how Enceladus flexes as it orbits Saturn,
and that the southern pole is subject to greater tidal deformation than the rest of the moon
which generates extra local heat.
Only a future mission to this little moon-world will confirm the existence of the liquid water
ocean, though evidence for it mounts.
And, any future mission will also hopefully answer the question of whether the conditions
in that ocean are indeed right for life, how complex that life could be and ultimately
if it's there or not.
But it may be a while before we know.
There is a proposed mission to Saturn that could launch as early as 2020, and while it
would certainly study Enceladus, its main target would be the equally strange and interesting
moon Titan which also may harbor some sort of life and a subsurface liquid water ocean
of its own.
But more, despite being very cold it has surface fluids and a water cycle of sorts -- this
place has lakes and rain -- but instead of liquid water the fluids are hydrocarbons.
This opens the way for hypothetical exotic forms of life very different from that of
earth.
Titan is unique in the solar system because it could allow for life as we know it in its
subsurface ocean, but could also harbor surface exotic life that might use liquid hydrocarbons
in place of water as a solvent.
Instead of breathing oxygen, the microbes would breathe hydrogen and instead of using
glucose it would react the hydrogen with acetylene.
Such life would produce methane instead of carbon dioxide as life on earth does, leading
to the term methanogenic life.
And there are some forms of earth life that are methanogenic hydrogen breathers so at
least part of that alternative biochemistry does happen on earth.
Now, I did not include Titan on my list of possible detections of life, but it came close.
Titan is a very cold and extreme environment and we have never seen this extreme type of
methanogenic life in nature.
It is only hypothetical so until we do see it, skepticism and caution should be applied
to any claims and I'm not yet comfortable with classing this story as a potential detection
of life.
However, in 2005 astrobiologists Chris McKay and Heather Smith made an interesting prediction
that gave a way to potentially detect Titan's life if its there.
That led to some interesting findings indeed.
They advanced that if hydrogen consuming microbes are present in high enough numbers, they would
affect the ratios of certain gases in areas of Titan's atmosphere and would also yield
lower levels of hydrogen and acetylene than you would expect on Titan given the environment.
This is because the life would be consuming them.
In 2010, things got interesting.
Darrell Strobel of Johns Hopkins university studied the hydrogen levels at different altitudes
in Titan's atmosphere.
As it turns out, in the upper atmosphere you find much hydrogen.
The atmosphere is also such that this hydrogen flows downward into the lower atmosphere.
But, just above the surface the hydrogen abruptly disappears.
That satisfies part one of the prediction.
Coincidentally, that same month another paper by Roger Clark and his team at the USGS was
released that reported counter intuitively low levels of acetylene at the surface.
This is especially odd, since UV radiation should be creating lots of acetylene in Titan's
atmosphere.
That satisfies the second part of the prediction.
Taken together, the missing hydrogen and acetylene could be a sign of exotic life.
But one should not jump the gun with this potential detection, there are lots of natural
phenomena on the table to explain the oddness of Titan's atmosphere.
And we don't yet have a complete picture of either this moon's atmospheric chemistry or
its meteorology.
More research is needed with this one.
Unfortunately, the Saturn mission may or may not fly because precedence was given to the
Jupiter system for study by NASA.
This is for good reason, its moon Europa may hold even more promise for life than Enceladus,
though the gap there is narrowing.
But that's where an obscure paper comes in that proposes that we may have already detected
evidence of life on Europa.
Like Enceladus, Europa's surface is riddled with cracks that seem to allow materials from
the underlying ocean to make their way to the surface, even in the form of plumes spewing
into space such as those at Enceladus.
Around these cracks we see reddish staining that highlights the fractures and seems clearly
associated with them.
It has been speculated that frozen microorganisms from deep below could be the cause of this
strange coloration.
In 2002, planetary geologist Brad Dalton looked at the infrared signature of the staining
and compared it to the signature from photosynthetic algae that live around hot water springs here
on earth.
The signatures were eerily similar, but that alone wasn't conclusive proof of anything.
So Dalton looked at other microorganisms which he subjected to conditions similar to those
of the surface of Europa.
The results were beyond interesting.
For the experiment, he chose a variety of organisms to get a good sampling.
One was common E. Coli bacteria, another type was an extremophile capable of withstanding
high acidity in its environment and could be similar to what you might find living in
Europa's oceans, and the third was a truly amazing bacteria called Deinococcus Radiodurans.
D. Radiodurans probably deserves a video of its own on this channel.
This organism has been given the title of the world's toughest bacterium by the Guinness
Book of Records, and it well deserves it.
Scientists normally refer to organisms like this as extremophiles, but in the case of
this particular bacterium it is termed a polyextremophile.
This tenacious species can survive large amounts of radiation, extreme cold, vacuum, acidity
and even complete dehydration.
The bacterium is so resistant to radiation that it was suggested in a 2006 paper by a
Russian and American team of scientists that it did not evolve here at all and is of possible
Martian origin seeded here by a meteorite.
While an alien bacterium living among us is a somewhat disturbing idea, it is possible
-- though in fairness D. Radiodurans does not seem to cause disease.
But D. Radiodurans also bears genetics and biochemistry consistent with earth life, so
it's origins are more likely to be earthly.
But why it's so resistant to radiation remains a complete mystery to this day.
It's a case of biological overkill, and there's just no clear reason for it to have evolved
that way in Earth's environment.
But back to Europa.
All three of Dalton's microorganisms are different from each other, preferring different temperatures
and environments.
Subjected to conditions similar to Europa, Dalton found that once again aspects of the
infrared signatures of the organisms were similar to the Europan staining, but not exactly.
The original infra-red spectra of Europa were obtained by the Galileo spacecraft.
It found regular water ice in areas without the staining.
But in areas where the staining was present, it found distorted signatures consistent with
water ice bound to some other material.
This material could be biological, but other scientists point out that they could be something
else like salts such as natron or epsom salts, both of which incidentally can only form when
liquid water is present.
While those salts probably are present, there's a problem, they are white in color not reddish-brown.
And, when you look at Enceladus, it too has cracks and salt but no corresponding staining
like that at Europa.
And, another issue is that no mix of salts have been found that exactly match the spectra
at Europa.
So, the presence of other sulfur compounds on the surface have been advanced as being
responsible for the coloration.
One suggestion is that the compounds might be the chemical product of radiation striking
Europa's surface.
And there is an elephant in the room regarding Jupiter and sulfur.
It's the wildly volcanic moon Io and it spews sulfur into space like no other body in the
solar system and that material does seem to be collecting on Europa's surface.
But the Io sulfur collects on Europa in a very specific and odd way.
It deposits on the trailing side of Europa as it passes through Io's cast offs.
Like our moon, Europa is tidally locked and always presents the same hemisphere towards
Jupiter.
Jupiter rotates very rapidly, significantly faster than Europa orbits.
That leads to the effect of the Io sulfur depositing mainly on the trailing side of
Europa.
But a problem with both of these sulfur theories being responsible for the coloration is that
while you do see sulfur deposited on the trailing side of Europa, the cracks in the surface
are clearly associated with the staining.
You wouldn't expect a correlation like that with either radiation created sulfur compounds
or material from Io.
This would suggest that whatever the material is, it comes not from the surface but from
the ocean beneath.
If there is life in that ocean, then the coloration could be the remnants of it suspended in the
ice.
But biology as we know it doesn't match the spectra of the staining perfectly either,
but there may be an explanation as to why.
One interesting difference Dalton found in the Europa data is the conspicuous weakness
of two bands in the spectra of the bacteria that correspond with amide bonds in the protein
coatings of their cells.
Amide or peptide bonds are the glue that hold proteins together, without them you just have
amino acids which occur in nature without life.
Better data is needed to study this further, but Dalton notes that the amide bonds could
be broken in the high radiation environment of Europa's surface.
If you put those bands back in the Europa data in a stronger form, then the signatures
at Europa look much more like frozen bacteria.
But the paper also notes that amide bonds are strong, similar to those of water molecules
and are not easily broken.
But it's worth noting that amides absorb short ultraviolet light at 205 nanometer wavelengths.
That could also excite the bonds enough to break.
So you have radiation from Jupiter that could break down the amides but also UV from the
sun.
This opens up the possibility that if you study younger cracks actively emitting plumes,
the amide absorbance in the spectra should be higher than in older, sealed cracks.
Only more research will tell.
So add this as another potential detection of alien life.
Like Endeladus, the best way to solve this mystery is to land on Europa and directly
analyze the staining.
But, something close to that seems to now be the on NASA's agenda, but budget concerns
are currently threatening it.
Earlier I mentioned that further exploration of the Jupiter system had been given precedence
over a mission to Saturn.
This new Jupiter mission is called Europa Clipper and has received the green light for
funding from the U.S. Congress.
NASA intends a launch date around 2022 and the main focus of the mission is to study
the geology and subsurface ocean of Europa in conjunction with an ESA mission known as
the Jupiter Icy Moons Explorer, or JUICE.
That probe will study all of the Galilean moons other than volcanic Io and may shed
light on other potential subsurface oceans at Callisto and Ganymede as well as gather
more information on Europa.
In addition to the probes, the NASA mission was expected to feature a lander to directly
sample material from Europa, however funding for this is cut in the blueprint for the 2018
federal budget released several days ago.
Very disheartening indeed.
But the multiple flyby Europa Clipper mission itself remains funded, so one possibility
would be to include microsatellites that can pass through the plumes coming from cracks
in Europa's surface to directly sample and analyze material and look for biosignatures.
This mission is still early in its development, but in whatever form it takes, it is sure
to yield a treasure trove of information about Europa and its habitability and may just detect
evidence of life yet.
We shall see.
But there is one final thing worth noting regarding the Dalton research.
While none of the salts advanced as possible candidates are the right color for the staining,
the two extremophile bacteria in Dalton's study just happen to be colored pink and brown.
Thanks for listening!
I am futurist and science fiction author John Michael Godier and I went extra deep in researching
this one, so for those interested I have included links to all the relevant papers to this video
that are online plus citations for the ones that are not are in the description below.
And be sure to check out my books at your favorite online book retailer and subscribe
to my channel for regular, in-depth explorations into the interesting, weird and unknown aspects
of this amazing universe in which we live.
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