Titan’s Surface Much Like That of Earth

Saturn’s moon Titan may be light-years away from Earth, but the two bodies have many characteristics in common: Wind, rain, volcanoes, tectonics and other Earth-like conditions all sculpt features on Titan, but act in an environment many times colder than Antarctica.

“It is really surprising how closely Titan’s surface resembles Earth’s,” said Rosaly Lopes, a planetary geologist at NASA’s Jet Propulsion Laboratory (JPL)in Pasadena, Calif. “In fact, Titan looks more like the Earth than any other body in the solar system, despite the huge differences in temperature and other environmental conditions.”

To help solve these mysteries about Titan’s atmosphere, scientists developed a 3D climate model of how it might respond to solar heat over time.

“The most important implication of these findings is that Titan appears closer to an Earth-like world than once believed,” Charnay told SPACE.com.

Their simulations revealed the lower atmosphere of Titan appears separated into two layers that are both distinct from the upper atmosphere in terms of temperature. The lowermost boundary layer is shallow, only about 2,600 feet (800 meters) deep and, like Earth’s, changes on a daily basis. The layer above, which is 1.2 miles (2 kilometers) deep, changes seasonally.

The existence of two lower atmospheric layers that both respond to changes in temperature help reconcile the formerly disparate findings regarding Titan’s boundary layer, “so there are no more conflicting observations,” Charnay said.

Although conditions on Titan’s surface are a frosty -179 degrees Celsius, it is the only body in the solar system other than Earth that has a nitrogen-rich atmosphere. The second largest moon in the solar system–behind only Jupiter’s Ganymede–Titan also resembles Earth in having a complex weather cycle, landscapes carved by liquid flow, and volcanic activity, albeit of a freezing cold variety. It may in fact resemble our planet in the earliest stages of its existence.

Titan has long fascinated astronomers as the only moon known to possess a thick atmosphere, and as the only celestial body other than Earth to have stable pools of liquid on its surface. The many lakes that pepper the northern polar latitudes, with a scattering appearing in the south as well, are thought to be filled with liquid hydrocarbons, such as methane and ethane.

“With an average surface temperature hovering around -180 °C, water cannot exist on Titan except as deep-frozen ice as strong as rock,” Lopes says. On Titan, methane takes water’s place in the hydrological cycle of evaporation and precipitation (rain or snow) and can appear as a gas, a liquid and a solid. Methane rain cuts channels and forms lakes on the surface and causes erosion, helping to erase the meteorite impact craters that pockmark most other rocky worlds, such as our own Moon and the planet Mercury.

It’s really cold, but there are some interesting characteristics for humans. For example, gravity on Titan is just 14% of the Earth’s, so humans could fly just by flapping some strap-on wings. With ∼1.5 bar surface pressure, humans wouldn’t have to wear pressure suits, though they would need oxygen masks … though wrapping-up warm might be advisable.

However, the real problem is distance, with Titan being roughly a billion miles from Earth. That would mean a journey of at least seven years. Compared to Mars, Titan is a long-haul destination, but it could yet prove the most alluring both for humans to visit, and for the search for extraterrestrial life.