Helicopters on Titan

Jason Barnes hesitates to call the upcoming Dragonfly mission to Saturn’s moon Titan a helicopter.

“Dragonfly is a nuclear quadcopter lander,” said Barnes while admitting that it sounds at least a little bit crazy. Barnes, a professor of physics at the University of Idaho and deputy principal investigator for Dragonfly, made a presentation at an online astrobiology colloquium at the University of Washington this week. Dragonfly will search for signs of life, biosignatures, on the distant moon.

Why Titan?

Barnes noted there are several good reasons for a mission to Titan. It’s one of just four places in our solar system with both a solid surface and a significant atmosphere—the others being Earth, Venus, and Mars. Titan has important similarities to Earth, especially the pressure and composition of its atmosphere.

Online seminar
The online colloquium was attended by more
than 100 people. This slide compared places
with an atmosphere and solid surfaces.

“The combination of a thick atmosphere and low gravity make Titan the easiest place to fly in the entire solar system,” Barnes said. He noted that we’ve focused on finding water in the search for life, and there’s lots of water on several of the icy moons of the outer solar system.

“The real reason that Titan among these is the most compelling target, I think, is not the water, it’s the carbon,” Barnes said.

He explained that Titan’s atmosphere is made up of mostly nitrogen, but that it contains about 5 percent methane. Ultraviolet light from the Sun breaks methane molecules down into smaller ones that then recombine into larger complex carbon chains that eventually rain down to the surface of Titan.

“They provide the carbon from which you can potentially build up prebiotic and possibly biotic molecules to start the process of how we think life may have formed on Earth four billion years ago,” Barnes said.

Where to look

Observations from the Cassini mission and its Huygens probe have given us several places to look. There are large dunes of organic material on Titan separated by open areas of the moon’s water-ice crust. The impact crater Selk may have once contained a huge water sea that remained liquid for tens of thousands of years—a great place for life to form. Hopscotching to these various places is how the concept of the mission came about.

“We came upon this solution because we needed mobility to be able to get to both the water ice and organic sediments,” Barnes said. “We call it a rotorcraft relocatable lander because we spend almost all of our time on the ground.”

Indeed, Dragonfly will fly to a new spot only about once every Earth month, using time on the surface of Titan to conduct a battery of experiments. One of the mission’s main goals is finding chemical biosignatures. Barnes figures it will be the first mission with such a specific goal since the Viking landings on Mars. He added that there won’t be a rush to judgement on the question of life.

“There’s no silver bullet when it comes to looking for biology,” Barnes said, adding that no single indicator will make them declare they found it. “This is going to be a long, scientific process by which we put in multiple lines of evidence to try to see if we can figure out what’s going on.”

A big spacecraft

Dragonfly. Image: Johns Hopkins APL

Dragonfly will be about two or three meters tall, about three and a half meters long, and weigh about half a ton. It will carry four instruments: a camera suite with eight cameras in all, a mass spectrometer, a gamma ray/neutron spectrometer, and environmental monitoring systems including a seismometer.

The launch of Dragonfly is set for 2026, and it will take about eight and a half years for the craft to get to Titan.

“Exploration of the outer solar system is a process for the patient,” Barnes said.


Watch Barnes’s entire presentation:

Please support Seattle Astronomy with a subscription through Patreon.