Pluto has been a mystery for scientists from last few decades. The spacecraft that passed by the Pluto last year, exposed many wonders about it. Early studies about the observations that have collected by this aircraft, suggested of its difficult chemistry and even some form of pre-biological practices below Pluto’s surface. Complex layers of organic mist, water ice mountains from some strange geologic method and possible organics on the surface and a liquid water ocean underneath. All these specifications hints towards a world, of much more vitality than the scientists have supposed.
Michael Summers, a planetary scientist in the New Horizons team who specializes in the structure and evolution of planetary atmospheres, says: “The connection with astrobiology is immediate — it’s right there in front of your face. You see organic materials, water and energy”.
It was more than a surprise for scientists, when they found haze on Pluto. At first, looking at the images of Pluto, Summers was reminded of a world he has studied for decades while working at George Mason University.
Summers has also co-authored two research papers on the topics, “The Photochemistry of Pluto’s Atmosphere as Illuminated by New Horizons,” and “Constraints on the Microphysics of Pluto’s Photochemical Haze from New Horizons Observations” published in the journal Icarus in September.
Pluto’s atmosphere is much more different than Saturn’s largest moon the titans, with haze reaching out at least 200 kilometers above the surface, about ten times higher than scientists had supposed. But above 30 km Pluto shows a similar irony to Titan with condensation happening in a region that’s too warm in temperature for haze particles to occur.
There is same oddity in the highest reaches of Titan’s atmosphere at about 500 to 600 kilometers above the surface observed by NASA’s Cassini spacecraft. Through further observations, scientists resolute that the condensation is partially the result of Titan’s photochemistry.
Another surprise from the New Horizons mission was finding haze on Pluto at far higher altitudes than scientists expected. (NASA/JHUAPL/SWRI
Summers said: “This haze formation is initiated in the ionosphere, where there are electrically charged particles (electrons and ions). The electrons attach to the hydrocarbons and make them stick together. They become very stable, and as they fall through the atmosphere they grow by other particles sticking to them. The bigger they are, the faster they fall. On Titan, as you go down in the atmosphere the haze particles get more numerous and much larger than on Pluto”
In retrospect, Summers said the main difference is Pluto’s atmosphere is just 10 millibars at the surface, compared to Titan’s 1.5 bar. (A bar is a metric unit of pressure, with 1 bar equal to 10,000 pascal units, or slightly less than the average atmospheric pressure on Earth at sea level). The shape of the haze particles of the bodies affects the atmospheric pressure differently, as Titan’s particles taking much longer to fall to the surface and eventually become spherical, while Pluto’s haze particles fall more rapidly and grow into fractals.
Summers said: “With the possible production of hydrocarbons and nitriles (another organic molecule) on Pluto, even more interesting pre- chemistry for life could take place. You can start building complex pre-biotic molecules”.
These hazes specify the existence of tholins, a type of complex organic compound that may be a pioneer to the chemistry of life.
What’s also lavish on Titan are tholins, complex organic compounds created when the Sun’s ultraviolet light strikes the haze particles. It’s rare on Earth, but common on Titan and may have contributed to its orange color. There is also a reddish sort of on parts of Pluto’s surface, which could from a layer of tholins.
His quick calculation suggest that these tholins could be 10 to 30 meters thick, providing more organic material per square meter than a forest on Earth. This material may also change its chemical composition as cosmic rays strike the surface.
Summers said: “These are the things you need for life: organics, raw material and energy. While it’s a stretch right now to say Pluto is hospitable for life. I’ve been studying Pluto all my life, and never expected to talk about these things being there.”
Interestingly, reddish material was also mottled near Pluto’s ice volcanoes, or calderas. It’s likely that the dwarf planet could have a subsurface ocean similar to that suspected on Titan, Saturn’s Enceladus and Jupiter’s Europa.
Via NASA Astrobiology