Is the Orange Material on Europa Surface a Life Form?
We’ve been systematically looking for life outside Earth for centuries now that we may have actually overlooked, without realizing that we had it already on sight for about 35 years.
This is what it appears looking at the Galileo mission pictures of the Jupiter’s moon Europa and at its resemblance with another Earth phenomena: ice Algae.
Not long time ago, 25 years or so, the solar system was a boring place. Not completely boring of course. There was the beauty of Saturn’s rings, the storm spot on Jupiter and so on, but at the end of the day we either had a desert geologically dead rocky planet, or a gas giant.
Then it came the water.*
Based on today’s data and analysis we now know that at least the Jupiter’s moons Europa, Callisto and Ganymede, and the Saturn’s moons Titan, and Enceladus posses a subsurface, global or partial, water ocean. This is a remarkable discovery that changes our whole picture of the solar system, and it’s never emphasized in textbooks of any level nor seems to be completely common knowledge. It also makes sense from a scientific standpoint. Since all the planets are formed from the same ingredients it’s reasonable to assume that, if Earth has liquid water, other bodies as well should probably contain it. The most interesting planet among these watery worlds is Europa. While the other oceans are most likely under a thick layer of perhaps 30 or more kilometers under the surface, the Europan ice layer could be as thin as a few kilometers or less, making the ocean directly connected to the exterior and the surface. The ocean is predicted to be about 150 Km (93 Miles) deep and extending globally around the planet which is about the size of our Moon.
The small eccentricity of Europa’s orbit around Jupiter makes so that the moon experiences tides that deforms the whole planet, generating heat, which in turn keeps the water liquid, cracks the ice and exposes the ocean to the surface, that afterwards freezes again in contact with the extremely low temperature of the aboveground.
Surface of Europa
Before the encounters with spacecrafts Voyager1 in 1979 and Galileo in 1997 with didn’t have much information about Europa.
The images, and the data we received show that the surface presents two main features that are predominant globally: ridges: long linear cracks on the ice which extend for several kilometers generated by the tides that deform and break the ice crust, and areas where the ice crust seems to be broken into pieces that went adrift upon temporary melting, like the ones in Earth’s polar region, and then quickly refrozen.
These areas present complex geometry of shapes and topography which are indeed called Chaotic Terrain(although there isn’t any terrain of sort, just ice).
Chaotic Terrain seems to be originated in areas of the ice crust which have experienced some level of melting from below, due to temperatures variation on the ocean generated, perhaps, by plumes of hot water coming from the bottom seabed, produced by volcanic activity.
A good environment for Life?
Despite the cold temperatures on the surface (-170 °C,-274 °F), the daily tides together with the contact of the ocean (where the temperature is 0°C) with the surface make it for an extremely interesting environment for the harboring of life.
Similar areas on Earth, like coastlines, where tides pool bring the water on and off carrying life forms, and making them interact with each other are rich environments where different species meet, evolve, and grow.
On Europa, similarly, organic material or life forms present on the ocean will benefit from the contact with the surface because of physical and chemical interaction due to exposure to radiations, and the presence of different elements on the surface, which can modify organic components and mix them together before they go back into the ice and on the ocean.
All of it sustained by fairly stable tides that open and close the cracks to the ocean daily.
Current data from the Galileo mission shows a thin atmosphere of molecular Oxygen, water ice for the ice crust, and traces** of organic material, Sulfur compounds, Hydrates, Carbon Dioxide, and other salts. These elements plus water are all basic blocks for life as we know it. Life itself needs more than just ingredients. It also needs some stability, a gradient of temperature from an energy source, and some interchange of elements.
All these, again, seem to be present on Europa.
Ice Snow, Red Snow, and Lichens: The Orange Stuff
The firsts images of Europa from Voyager showed the intricate lines and spots of an orangy color (known as the orange brownish material), alternated with whitish areas of the ice. Subsequent pictures and the follow up Galileo mission in 1997 showed more details and close up images of the ridges and the Chaotic Terrain. Both of these spacecrafts didn’t take direct color images. All the colors are inferred based on data, and the images are then reprocessed to obtain a closer approximation of what the human eye would see. Despite all measurements of both missions, and the Hubble Telescope, we unfortunately don’t have any more information about the molecular composition of the orange material. We can easily observe that its distribution varies with a higher concentration in areas where the ocean surfaced to the exterior, on ridges and on chaotic terrain. Therefore we can assume that its composition is from endogenous material coming from the ocean.
As today, there is no data, nor convincing theory of what the “orange stuff” may be and how it got to be displaced the way it is. On Europa’s surface there are no rocky elements, just ice. The closest real “terrain” that you can find is under 150 Km of water on the seabed.
Looking at different close up images from Galileo it strikes the resemblance of the orange material with another phenomena present on icy regions of Earth: Ice Algae.
The amazing close up image above of Europa’s surface taken by the Galileo spacecraft shows a material that actually resemble more the Earth’s Lichens. Lichens are a symbiotic organism, usually composed of a photosynthetic Algae and a fungal organism. They grow on rocky surfaces, without contact with terrain, they mostly assume dark coloration, and can survive harsh climates. Being the surface of Europa as hard as rock due to temperature, makes the resemblance with Lichens even more interesting. Another species that survives in very harsh icy climates, similar to Lichens, is photosynthetic, does not need contact with terrain, and assume dark pigmentation is the Ice Algae.
Ice Algae, are a group of somewhat distinct microorganisms that prosper in different icy environment. They are found on snow and permafrost in the Arctic region, Antarctica, and mountains. They have adapted to live in such harsh environment, with constant below zero temperature, scarce illumination, and nutrients. These Algae are found in ice surfaces which have also no direct contact with rocky material.
They come from genetically different ancestors although they all share some characteristic, like a dark, orange, brown and pink pigmentation, and more***.
This type of pigmentation allows for a filtering mechanism of the sunlight. The darker color absorbs more sunlight than the adjacent ice which reflects pretty much all of it, but it also filters some components of lights that are more useful for the biology of the organism. Some frequencies are converted through photosynthesis into chemical energy and some, more dangerous, like UV, are reflected. Some of the energy can be used to keep some water molecules in liquid state.
Facts
If we consider these organisms in light of what we see on the Europa surface we can highlight the following facts:
1 The Europa surface is a water ice crust with no contact with rocky elements but in contact with a deep water ocean.
2 The areas that have been in contact with the ocean present an orange-brown-dark material that extends from it of unknown composition, and displacement mechanism.
3 On Earth we observe that microorganisms, generically named, Ice Algae grow on ice surfaces, without necessary contact with rocky materials.
4 The Algae on Earth possess a dark brown, orange, pink, pigmentation that allows the organism to filter sunlight and transform it into usable energy through photosynthesis.
5 The Algae prospers and grows on the ice crust, interior and surface, and can extend for several kilometers.
Life at the extremes: The Extremophiles
Based on the data that we had after the Voyager and Galileo missions the sole idea of a possible life form living in such a tremendously harsh surface environment was completely non sense. Life on the oceans perhaps yes, but it was categorically excluded for aboveground.
The main reasons are the following:****
1 Temperature: The surface temperature is about -170 °C (-274 °F)
2 The enormous magnetic field from Jupiter produces a magnetosphere which accelerates charged particles that constantly bombard Europa’s surface.
3 Solar radiation irradiates the surface almost unshielded due to the presence of a thin atmosphere.
On the other hand, the same idea of what life was, in 1979, was very different from today’s.
At that time, for example, we didn’t know that some life forms could survive without Oxygen. Genetic mapping was very young, and an entire different biological Domain, Archaea, was just been proposed in 1977. In the past 35 years, the concept of what life is and how it evolves, changed and became fairly more rich and exotic. We discovered forms of life that can survive extremely harsh environment. We called them Extremophiles. Such environments for instance include, extreme cold and hot temperatures, nuclear radiation filled, acids pools, hydrothermal vents at the bottom of the ocean, deep caverns without any organic compounds, permafrost, and so on. The resistance of Extremophiles is also being tested on experiments on the International Space Station, and on simulated Mars environment. Both experiments show that the organisms survive and adapt surprisingly well to the conditions.
We discovered forms of life that need neither sunlight nor Oxygen to survive. They can use Methane, Sulfur compounds, and other materials to extract the energy they need.
Some of them like D.Radiodurans, a bacteria, can resist high level of nuclear radiation, bombardment of high charge particles, and hot and cold temperatures.
The mechanisms are not completely understood yet, but for example, a rapid repair of damaged DNA strands happen in D.Radiodurans and cells can pass the repaired DNA to injured ones.
Geology Vs. Ecology and Biology
The first thing that Geologists do when studying the images from a planet is to compare the features that they see with similar phenomena on Earth, and then try to construct a model based on the parameters of the planet under scrutiny.
For instance if we want to understand the Methane lakes of Titan, the first thing we do is to compare some of their characteristic with Earth lakes, so we can infer other features. Other examples include the study of dunes and waves on Titan, mountains and canyons on Mars, the ice cracks and adrift ice on Europa, and so on.
We can try to assume the same approach, not for Geology, but for Biology and Ecology.
We don’t usually do this in planetary exploration only because we never had a chance to do it. We were never, so far, in the position to directly observe a planet which could potentially harbor life. I’m not even sure biologists or ecologist are involved in first observations of spacecraft images of the solar system.
In the case of Europa however there are no reasons not to evaluate such approach.
We are observing a planet with an ice crust and a water ocean bigger than the Earth’s oceans combined, with a constant source of energy from tidal heating, a thin Oxygen atmosphere, and possible measurement of organic materials and other building blocks of life.
The Case
This is mostly a provocative and speculative writing. It doesn’t pretend to have the accuracy of a scientific paper, and it was born just for fun. We have no data to confirm that the orange material is a life form.
Notwithstanding based on the previous arguments, and on the assumption that life on Europa is similar to Earth’s life e.g. dark organism living in cold environments surfaces without contact with terrain are photosynthetic, I’ll attempt to build a case for its plausibility and try to analyze its consequences for the Europan ecosystem.
You will see that the results beside being in agreement with the current data and observations, give a better understanding of Europa as a global ecosystem where biological entities play a central role in the formation of the planet surface as we see it.
Considering the aforementioned facts, and from the comparison with Earth ice-snow Algae phenomena and Lichens, and the images and data from Europa, we can then try to infer the following:
1 The Orange material seen on Europa surface is in fact a Life form, similar to the Earth’s ice Algae-Lichens plus genes of Extremophiles organisms.
2 The Algae extends on Europa’s surface and crust from points where there was contact with the liquid ocean, for several kilometers either along ridges or on more heterogeneous distributions on areas of Chaotic Terrain.
3 The Algae due to its color is using photosynthesis to transform sunlight into energy to survive, filtering other types of radiation, and defending itself against high charged particles from the Jovian magnetosphere.
4 The Oxygen layer present on the thin atmosphere is a byproduct(either in part on entirely) of the Algae photosynthesis*****
5 The Algae is responsible(or partially) for the formation of the Chaotic Terrain. Due to its photosynthesis, and the production of water molecules, high concentrations of the Algae increases the local temperature of the ice crust, producing areas of thinner and weaker ice, easier to crack upon tidal stress.
Conclusions: Thriving with life
From this point of view, the Algae is an active agent in the ecosystem of the planet. It survives using photosynthesis probably fixing Carbon Dioxide from the underlying ocean and surface, and releasing Oxygen to the atmosphere. It produces heat in the process, and probably, similarly to some ice algae on earth keeping some water molecules in a liquid state. Due to this fact, in areas with high concentration of the Algae, deep throughout the crust, the temperature decreases and makes the ice columns weaker and more susceptible to cracks upon tidal stress, suggesting a candidate mechanism to explain the formation of Chaotic Terrain. Moreover images of impact craters show a lower concentration of algae, hinting at an annihilation process of the algae around the impact area.
This is also in agreement with current theories about Algae evolution on Earth. The pigmentation of the first Algae, when the layer of Oxygen in the atmosphere was thin, was on the red-brown side. It then changed to the green colors for plants on terrain as the atmosphere got thicker since the first accumulation of Oxygen from Cyanobacteria because this coloration is more efficient with the current atmosphere composition and thickness.
It is indeed, from my point of view at least, not too far fetched, to infer that such richness and complexity in adaptation as the one we observe on Earth is present on Europa as well in an otherwise thought unfit environment, and that the Europa Algae has adapted to survive, grow, and evolve in the presence of cold temperatures, high level of radiation, and bombardment of charged particles.
There is not hard data confirming that the orange material is indeed a life form. Nonetheless the point of the article is to highlight a connection between phenomena on Earth and the data and images from space, and to infer in a new fashion about Europa, using the tools of ecology and biology on top of the geological-chemical-physical, in light of our new understanding of the diversity of life forms.
The Europan Alga seems to be covering large areas of the planet, in a similar way as jungles and prairie cover Earth. Its adaption to this environment will also confirm that not only there is life outside Earth but that’s also similar to ours, and it’s using similar mechanisms to survive. Moreover it will suggest that the Europa’s ice crust, and ocean ecosystem is at the present, as rich in life forms as can be the Earth’s.
In the course of human speculation about observations of any kind, throughout history, a special place is taken by the simplest solution, also incarnated by the famous Occam’s Razor which states that everything considered among the proposed solutions, the one with less assumptions is the most likely to be true. Looking at Europa, with its icy permafrost crust, its ocean, its tides, and ridges, and looking at our planet, its ice surfaces, and the abundance of life, I can only think that these two worlds are not that different after all. Not even in their color preferences.
Notes
*It was actually known for a long time that the outer solar system is rich on water and that how Earth got to have water is still enigmatic. However these facts are rarely emphasized in textbooks nor are common knowledge.
**We have less certainty about these measurement coming from the NIMS of the Galileo spacecraft from which is harder to infer molecular composition.
***Although they don’t seem to have a common ancestor all Algae(and chloroplast in plants) are originated by the evolution of a prokaryotic bacteria called Cyanobacteria, capable of photosynthesis, considered responsible for the first large accumulation of Oxygen on our atmosphere. This bacteria is also extremely resistant to all Earth climates.
****We should note that just few inches of ice below the surface will shield most of the radiation and charged particles. Moreover the temperature increases as we more inward on the crust and it is 0°C on the liquid water ocean.
*****The current theories claim that the O2 in the atmosphere, and the whole atmosphere itself, it’s formed by the bombardment of highly charged particles, and sun radiation, and the consequent dissociation of O2 and other molecules from the H2O surface based on a reaction called Radiolysis.
References
Europa — The Ocean Moon: Search For An Alien Biosphere (Springer Praxis Books / Geophysical Sciences)
Shorter version of the above
Unmasking Europa: The Search for Life on Jupiter’s Ocean Moon
Observations of Europa’s Tenuous Atmosphere M. A. McGrath NASA Marshall Space Flight Center C. J. Hansen and A. R. Hendrix Jet Propulsion Laboratory
Composition and Detection of Europa’s Sputter-induced Atmosphere R. E. Johnson University of Virginia M. H. Burger University of Maryland/NASA Goddard Space Flight Center
Clathrate Hydrates of Oxidants in the Ice Shell of Europa KEVIN P. HAND,1,2 CHRISTOPHER F. CHYBA,3 ROBERT W. CARLSON,4 and JOHN F. COOPER5
Trace constituents of Europa’s atmosphere T.A. Cassidy∗, R.E. Johnson, O.J. Tucker
Sulfuric acid on Europa and the radiolytic sulfur cycle.Carlson RW1, Johnson RE, Anderson MS.
http://www.ncbi.nlm.nih.gov/pubmed/10506568
Titan (Cambridge Planetary Science, 14)
Titan Unveiled: Saturn’s Mysterious Moon Explored
Nasa Galileo Mission
http://web.archive.org/web/20070218123609/http://galileo.jpl.nasa.gov/
Europa on Wikipedia
http://en.wikipedia.org/wiki/Europa_(moon)
The sulphur dilemma: are there biosignatures on Europa’s icy and patchy surface? (J. Chela-Flores)
Extremophiles
http://en.wikipedia.org/wiki/Extremophile
http://en.wikipedia.org/wiki/Deinococcus_radiodurans
http://arxiv.org/abs/1109.6590
http://arxiv.org/pdf/1207.2098.pdf
http://arxiv.org/pdf/1310.7121v2.pdf
http://www.phycologia.org/doi/abs/10.2216/08-13.1
http://serc.carleton.edu/microbelife/extreme/extremophiles.html
http://science.nasa.gov/science-news/science-at-nasa/2004/10sep_radmicrobe/
Algae and Cyanobacteria
http://en.wikipedia.org/wiki/Algae
http://en.wikipedia.org/wiki/Watermelon_snow
http://en.wikipedia.org/wiki/Ice_algae
http://en.wikipedia.org/wiki/Cyanobacteria
http://www.ucmp.berkeley.edu/bacteria/cyanointro.html
http://www.ncbi.nlm.nih.gov/pubmed/17407410
http://www.ncbi.nlm.nih.gov/pubmed/23258841
http://www.ncbi.nlm.nih.gov/pubmed/19778274
Archaea
http://en.wikipedia.org/wiki/Archaea
Images Credits
http://solarsystem.nasa.gov/galileo/gallery/europa.cfm
http://planetimages.blogspot.com/
https://solarsystem.nasa.gov/multimedia/display.cfm?Category=Planets&IM_ID=11688
http://www.PlexusEco.com/EPOW/EPOW-Archive/archive_2011/EPOW-110411.htm
http://www.daviddarling.info/encyclopedia/C/cryobiology.html
