NASA is going back to the moon—just not the one you’re thinking of.
The space agency announced today that it will launch a robotic mission to Titan, the largest moon of Saturn, in 2026. The mission, named Dragonfly, will deliver a dronelike spacecraft to the surface. The space copter, which indeed resembles its eponymous insect, will hop from one spot to another, making measurements of the ground and the atmosphere as it goes.
For a moon, Titan has quite a few things in common with Earth. It has an atmosphere and weather. Liquid rains down from thick clouds, filling basins and canyons, then evaporates back into the sky, where the process starts over. On Earth, this loop involves water. On Titan, it involves methane. Temperatures on the moon are so extreme that the gas flows as a liquid there, producing bodies of liquid as big as the Great Lakes of North America.
There are some crucial differences between Earth and the Saturnian moon, of course; for example, the surface temperature on Titan is always a chilly 292 degrees below zero Fahrenheit (180 degrees below zero Celsius), give or take a degree or two. The atmosphere is so thick that very little sunlight touches the ground.
And yet Titan is among one of the best candidates for extraterrestrial life in the solar system—just not the kind we’re used to. “Titan has all of the key ingredients needed for life,” says Lori Glaze, the director of NASA’s planetary-science division.
NASA’s first observations of Titan date back to the Voyager missions that toured the outer planets and moons in the 1970s and ’80s. The spacecraft’s cameras couldn’t penetrate Titan’s atmosphere, the thickest in the solar system. The moon looked like a marble the color of mustard, so smooth and featureless that it felt almost defiant, guarded against these flying objects from another land.
A European spacecraft arrived on Titan in 2005. From beneath the haze, the Huygens probe captured photographs and beamed them back to Earth. The views felt at once alien and familiar. “Suddenly we get a picture of gullies, which we didn’t know existed,” Jonathan Lunine, who has studied Titan since the early 1980s, once told me about the moment the images arrived. “I screamed when I saw those.” On Earth, flowing water carves gullies into rocky landscapes. On Titan, methane is responsible.
The tour didn’t last. Huygens exhausted its batteries in less than three hours. But astronomers still had eyes on Titan. Huygens was dropped off by Cassini, a NASA spacecraft that remained in orbit around Saturn until 2017, occasionally swinging by the moon to collect data and pictures.
Cassini provided evidence for the methane lakes there. Scientists had long predicted their existence, but they were full of surprises. Titanian lakes are calm and textureless, with only a few ripples here and there. The kind of waves rolling across Lake Michigan are nowhere to be found, and scientists are still trying to figure out why.
When Cassini ran out of fuel, NASA faced an uncomfortable scenario. A dead spacecraft is impossible to control, and scientists worried that Cassini would tumble into Titan and scatter itself across the surface, possibly contaminating life—if any existed. To protect the hazy moon, engineers deliberately shoved Cassini into Saturn, a gaseous planet incapable of hosting life.
Dragonfly will search for signs of life, ancient and present. In Titan’s atmosphere, spacecraft have detected carbon, hydrogen, nitrogen, ethane, and other elements on which life on Earth depends. They’ve even found a compound that could interact with the methane and ethane to create cell-like membranes. Scientists suspect that Titan might even have water—real, actual H2O—lurking beneath its surface.
“These ingredients that we know are necessary for the development of life as we know it are sitting on the surface of Titan,” says Zibi Turtle, the principal investigator for the mission and a planetary scientist at Johns Hopkins University’s Applied Physics Laboratory. “They’ve been doing chemistry experiments, basically, for hundreds of millions of years, and Dragonfly is designed to go pick up the results of those experiments and study them.”
After decades of orbiters, rovers, and landers, the thought of a little drone buzzing around an alien world is refreshing, almost unimaginable. According to the Dragonfly team, the spacecraft could cover tens of miles in an hour. Thanks to Titan’s fleecy atmosphere and low gravity, bouncing around is quite easy. (If astronauts joined Dragonfly, they could don winged suits and flap around the terrain, coasting alongside the robot.)
“In just a few flights, Dragonfly will be able to go farther than the Opportunity rover on Mars has in the last 12 years,” Peter Bedini, the program manager for Dragonfly, once said. (RIP, Opportunity.)
The journey from Earth to Titan, however, will be quite the trek. Dragonfly won’t arrive on Titan until 2034. Two thousand thirty-four! “That’s the curse of exploring the outer solar system,” says Curt Niebur, the NASA scientist who led the effort to select the mission. “It takes a long time to get there.” Cassini took seven years to reach Saturn.
The Dragonfly mission is part of a NASA program that funds medium-size space missions designed to cost about $1 billion. The same program has churned out some of the agency’s most successful ventures deep into the solar system. There’s OSIRIS-REx, which recently sidled up to a nearby asteroid and discovered that it was mysteriously spewing bits of itself into space. There’s Juno, which circles Jupiter and regularly delivers stunning photographs of the giant planet’s shape-shifting clouds. And there’s New Horizons, the spacecraft that captured close-ups of Pluto and, more recently, an icy object at the edge of the solar system whose named sparked a controversy involving Nazis. The Dragonfly mission beat out another project, an effort to visit a comet orbiting between Mars and Jupiter and to return a piece of it to Earth.
It is thrilling to consider that a little bug-shaped drone might be the one to answer one of the most pressing questions in human history: Are we alone? If life exists on Titan, it’s unlikely to be the kind we see in Hollywood movies. Tiny microorganisms, feeding off an alien environment tailored to their needs, are far more plausible. But even those certainly count.
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