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Evidence for Support of Microbial Life on Io

By , San Francisco, CA


For there to be life on a planet or moon, there must be sufficient heat from an energy source and a livable chemical composition for any form of life. On Io, energy sources present on Io include volcanic activity, tidal heating from friction, and thermal energy. We have found evidence of silicate rock, iron forsterite, silicon L, chondrite, and LL chondrite from meteorites which make up Io. Another piece of evidence for possible life to survive is the protection from radiation in the lava tubes. The average temperature is -130 °C and the volcanic temperature is 1649 °C providing evidence that they live in the tubes. Due to the composition and energy, we have found Io can support microbial life.  This research can inform changes in how scientists gather samples from other planets when looking for life.

Keywords: Io, Volcanoes, Silicate rock, Tidal heating

Hubble Space Telescope (Water on Ganymede
Keck Telescope
Pioneer II
Voyager 1 & 2

With its juxtaposition of snowfields and below zero temperatures to intensely heated volcanoes, Io is a land of ice and fire [1]. With an average density of 3.5275 g/cm3, it has the highest density of any moon in our solar system [5].  It is generally overlooked as a location that could support life due to the radiation from Jupiter because it is so close to Jupiter. However, even if Jupiter’s radiation strips water from Io’s surface, there is a possibility of microbial life underground [2]. This possibility is evident in the amount of water ice on Europa and Ganymede (Jupiter’s other moons). There are many places microbes can thrive on Io, such as in the lava tubes. Some missions that have collected important data on Io include Pioneer II, which studied its composition, Voyager I, which discovered its landscape and volcanic deposit, and Galileo that observed its volcanoes and major eruptions. Examination of this data from these missions lead to evidence of microbial life on Io.

In our research paper, we examined photos from the Keck Telescope of the Surt volcano on Io and from the Hubble Space Telescope that gave us information of the moon’s surfaces and gases. Pioneer II, Voyager I, and Galileo missions collected data on the climate and landscape of Io. We analyzed these data sets and missions in order for evidence that Io can support microbial life within its lava tubes. We used their results of volcanic activity and thermal energy from the friction of Jupiter pulling inward to piece together why Io has microbial life.
Results and Discussion

We believe that Io can support microbial life. Io has an average surface temperature of -130°C but near the volcanoes can reach 1649°C [1]. In 1999, the Galileo mission observed the volcano Prometheus and found not only high thermal emissions, but a deposit of bright yellow and white material that is rich in sulfur dioxide frost [3]. Io itself has a 90% sulfur dioxide atmosphere.
The mission examined the Pillan Patera region of Io using a solid-state imager to examine how sulfur dioxide plays a role similar to water and carbon dioxide on Earth [4]. This similarity could mean that the sulfur compounds could provide sufficient energy for the microbes to survive. The best environment for the microbes to thrive in are the lava tubes because the tubes can protect organisms from radiation and provide nutrients such as sulfide and H?S that can be oxidized to sulfur dioxide or sulfate [2]. The lava tubes on Earth provide shelter and an energy source regardless of the location and climate. They also act as an insulator keeping temperatures consistently high and trapping all moisture sufficient for the microbes.
Io is mainly silicate rock which also constitutes the majority of the Earth’s crust, and iron, the most common element on Earth. Voyager 1 in 1979 found details of the gradients that are on Io's surface. Besides volcanoes, Io has mountains, dissolved sulfur lakes, hundreds of kilometers of calderas, and hundreds of kilometers of low viscosity liquid flow.

Based on our examination of missions and studies, due to the livable climate provided by the lava tubes found there is a potential of microbial life on Io. Within the tubes, there is enough thermal energy from heat and sulfuric compounds to provide shelter for microbial life. We need to send a “radiation-resistant probe that is capable of detecting the chemistry and physical state of subsurface and surface liquids on Io” [1] to Io gain knowledge. It is important to explore because we can never truly dismiss Io’s habitable niche without deeper exploration of its surfaces and underground.

[1] Choi, CQ. 2010. The Chance for Life on Io, Astrobiology.
[2] Schulze-Makuch, D. 2010. Io: Is Life Possible Between Fire and Ice? Journal of Cosmology, v. 5, p. 912-919.
[3] Russell C.T. and Kivelson, M.G., 1998. Detection of SO in Io's Exosphere, Science, v. 287
[4] Lopes, R.M.C. and Spencer, J.R., 2007. Io After Galileo: A New View of Jupiter's Volcanic Moon, Springer Science & Business Media, 374.
[5] Schubert, J. 2004. Interior composition, structure, and dynamics of the Galilean satellites, Jupiter: The Planet, Satellites, and Magnetosphere, Cambridge University Press, p. 281-306.

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