| 03.18.2018

An atmosphere for life–Graduate Student Shannon Mackenzie studies life beyond Earth and the effect of atmospheres on distant moons


Imagine a moon like the Earth’s moon, but with an atmosphere. A moon that has an ocean not like the Earth’s ocean, but an ocean that flows underneath a bed of ice, unbelievably thick, covering the surface of the entire moon. A moon with volcanoes that spew not molten magma, but ice particles.

These moons are a reality and they are currently in orbit. Their names are Titan, Enceladus and Europa. Faculty and graduate students of the University of Idaho study these cosmic wonders, hoping their observations will lead to the discovery of microorganisms in some of the furthest depths of the solar system.

“On Titan the game is the same, but the players are different,” said Shannon Mackenzie, a UI graduate student studying physics.

Nicholas Eastman-Pratt | Argonaut

Nicholas Eastman-Pratt | Argonaut

Mackenzie didn’t always want to be a physicist. She said she watched a lot of “Star Trek” when she was a child and that inspired her to explore the depths of the solar system, but what really landed her in the world of science was someone telling her she couldn’t do it. She took that as a challenge and has found herself a nice chunk of success in the field.

Although she enjoyed fantasizing about space and the final frontier, Mackenzie has found the real science stuff is so much cooler than some of the stuff anyone can think up.

“It is a very exciting time,” Mackenzie said. “We think there are a couple different targets in the solar system to find life.”

Mackenzie is one of the researchers investigating these wonders of the solar system. Mackenzie’s academic focus is on Saturn’s moon Titan. She believes between Enceladus, Europa and Titan, Titan exhibits the most promise to shelter microorganisms.

In order for life to thrive, an environment must have liquid water, chemistry and energy, Mackenzie said. Titan has all three. Titan’s atmosphere contains carbon and hydrogen. The only component missing is energy.

“Water isn’t that uncommon, there is a ton of water ice in the solar system,” Mackenzie said. “What’s uncommon is liquid water. Titan has a liquid ocean under its crust.”

Titan is 10 times farther from the sun than Earth, therefore it only receives a small fraction of the sun’s rays, which provide just enough energy to possibly support extremely basic plant life, Mackenzie said. However, the sun is not the only potential source of energy that can provide life. On Titan the gravitational friction between Saturn and its unique moon produce enough energy to generate life, Mackenzie said.

“If you can get these to work together you have all the things you need to make life: water, chemistry and energy,” Mackenzie said.

Mackenzie said Enceladus and Europa also contain liquid water. What sets Titan apart from Enceladus and Europa is its atmosphere.

“Titan is the only one with an atmosphere,” Mackenzie said. “It is the only one with methane and ethane.”

Because Titan has an atmosphere, precipitation is enabled by way of liquid methane.

Liquid methane rains down from the atmosphere creating methane lakes and rivers. It then evaporates and returns to the atmosphere where the cycle continues, Mackenzie said.

“My thesis is about Titan and how its surface interacts with its own atmosphere,” Mackenzie said. “What’s cool is that it’s really not that complex because it’s a lot like Earth.”

Titan’s atmosphere is only a little thicker than the Earths. The Earth’s atmospheric pressure is measured at 1 bar and Titan’s measures in at 1.5, Mackenzie said.

“If we find out how much chemistry to carbon there is, if the right temperatures are there, if the pressure is okay, then you know whether or not an environment is inhabitable by Earth life,” Mackenzie said.

The evidence Mackenzie and her colleagues have found has been based on careful observations and well formulated, highly educated, theories, about the genesis of life.

“We do not fully understand the genesis of life, how things come to be,” Mackenzie said. “But we are finding life in seemingly uninhabitable environments on Earth, so we think maybe its possible elsewhere.”

By studying the possibilities of life on other planets Mackenzie and her peers hope to discover more about Earth. If they can understand if life can or cannot exist outside Earth, they can then reach a deeper understanding of life on Earth.

Kevin Neighbors 

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