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Professor sets sights on Saturn’s largest moon

Professor sets sights on Saturn’s largest moon

Proposed AVIATR mission would explore Titan

By Holly Bowen
Reprinted with permission from the Moscow-Pullman Daily News

Orbiting the solar system's sixth planet is a moon that may have more in common with Earth than its own home world, and Jason Barnes and a team of scientists and engineers are determined to explore it.

The assistant professor of physics at the University of Idaho has spent the past two years leading an international 31-person team that developed a mission concept to send an unmanned reconnaissance airplane to Titan, Saturn's largest moon.

The team's proposal, named Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR), was published in Experimental Astronomy in December.

Although it was recently passed up by the National Research Council's Decadal Survey, which recommends NASA's priorities for the next 10 years, Barnes said the team plans to keep improving the proposal so that it might be accepted by the survey in 2020.

Out of dozens of moons orbiting Saturn, why focus on Titan?

"Titan is really scientifically one of the most interesting places in the solar system," Barnes said. "There are only a couple of places in the whole solar system where there's an atmosphere and a solid surface like the Earth - Venus, Mars and Titan."

He said Titan experiences many of the same ecological processes that shape the Earth's surface.

Like Earth, Titan receives rainfall that causes erosion and the formation of streams and lakes. But unlike Earth, that rain is liquid methane, not water.

Studying geological processes on Titan, where the temperature, gravity and liquid composition is different, can help scientists better understand how those processes work on Earth.

"A lot of geological processes on Earth are characterized just based on empirical studies," Barnes said. "People do experiments and see, 'Oh, it works like this.' By going to Titan ... we can start to constrain what the actual physical characteristics are, the physics that govern rainfall and erosion on Earth without just being able to observe it."

Barnes said Titan is also of high astrobiological interest because it may be home to precursors to life - or some form of life itself.

"Although it's super-cold there, just above the temperature of liquid nitrogen," he said, "a lot of the ingredients for life as we know it seem to be there - liquid water, carbon and carbon compounds and an energy source."

He said ultraviolet radiation breaks down methane, a carbon compound, into more complex organic molecules that fall down to Titan's surface, which is made of frozen water.

"If you can somehow melt that ice, you can get the water and organics to mix," he said. "That's what we think may have happened in early Earth, although it was warmer here. There could have been more methane in the atmosphere then."

Barnes said Titan could also provide a window into Earth's distant future.

The sun has gotten brighter with age, and at its current luminosity, the heat causes some of Titan's methane to leak out of its atmosphere into space.

"As the sun gets brighter over the course of its lifetime, it will start to bake Earth to the point where it will boil off our oceans ... that process is going on in Titan today, but very slowly," he said.

He said that process won't begin on Earth until billions of years from now.

To explore Titan's atmosphere and surface, Barnes' team proposed AVIATR, which includes a space vehicle to reach Titan, an entry vehicle to descend into the moon's atmosphere and an air vehicle to fly through Titan's skies.

The airplane would be powered by heat from the radioactive decay of plutonium-238 but could also glide on Titan's thick atmosphere to store energy when transmitting data to Earth.

The total AVIATR project has an estimated price tag of $715 million, although it could have been more if the 31-member team was larger, Barnes said.

"The hardest part (assembling a team) was deciding who not to ask," he said. "In order to actually propose a mission to NASA, every person you put on there costs more money to pay them. We try to keep the team as small as possible and still be able to accomplish the scientific objectives."

He said many scientists believe a hot air balloon would be the logical choice to explore Titan, but the idea to send an airplane was originally proposed by Larry Lemke of NASA's Ames Research Center.

"He had trouble finding people to take him up on his idea. I was young and naive enough to start working on it," Barnes joked.

He said he's not discouraged by the fact that human space exploration is a long-term effort. For example, it would take about five years to build AVIATR and then seven-and-a-half years for it to reach Titan.

"Right now, I'm taking the benefit of people that did this 20 years ago," he said, citing the Cassini mission to Saturn and its moons as an example.

Cassini was proposed in the 1980s, launched in 1997, finally reached Saturn in 2004 and is expected to transmit data back to Earth through 2017.

"I'm benefiting from this groundwork that other people did 30 years ago," Barnes said. "I'm trying to return the favor by doing the groundwork for a future mission."

He said the fundamental research that comes out of space exploration leads to a better understanding of Earth and its place in the galaxy.

"Presumably we're not constrained to this planet forever," he said. "Eventually we're going to need to expand out into the solar system and into the galaxy tens of thousands of years into the future."

He said if the AVIATR project eventually receives funding, it would have a positive affect on the local economy because much of the funding would pass through the UI.

Although Barnes plans to continue working on AVIATR and other research, he has another project in the wings - teaching. He said he is teaching a graduate-level astrophysics course at the UI this semester, which begins Wednesday.