When NASA’s new drone Dragonfly arrives on Titan, Saturn’s largest moon, it won’t roll across the surface like Curiosity, Spirit, and Opportunity have on Mars. Instead, Dragonfly is a dual-rotor quadcopter that will fly from point to point, using a vertical takeoff and landing (VTOL) system. It leverages existing drone technology we have on Earth to make the system work.
Titan is, in many ways, an ideal spot to try this kind of deployment. That moon’s combination of low gravity and a thick nitrogen-dominated atmosphere make it easy to fly in — or, at least, easy as things go when you’re flying a remote drone from nearly 800 million miles away and can’t make any mistakes.
XKCD addressed this concept in a substantial “What if” that evaluated all of the planets and moons in the solar system according to how well they’d support the flight of a Cessna 172 Skyhawk. In most cases, the plane would crash; sustained flight on Mars, for example, requires a ground speed of over Mach 1 just to take off. For Venus, XKCD author Randall Munroe notes, “Your plane would fly pretty well, except it would be on fire the whole time, and then it would stop flying, and then stop being a plane.”
But Titan? Titan is a different story. Munroe writes:
When it comes to flying, Titan might be better than Earth. Its atmosphere is thick but its gravity is light, giving it a surface pressure only 50 percent higher than Earth’s with air four times as dense. Its gravity—lower than that of the Moon—means that flying is easy. Our Cessna could get into the air under pedal power.
In fact, humans on Titan could fly by muscle power. A human in a hang glider could comfortably take off and cruise around powered by oversized swim-flipper boots—or even take off by flapping artificial wings. The power requirements are minimal—it would probably take no more effort than walking.
Designing a drone to fly remotely on a world where humans could take off under their own muscle power isn’t as difficult as engineering the same feat on Earth. Dragonfly will be an octocopter capable of surviving the loss of at least one rotor or motor. The aircraft should have a speed of ~36km/h (21mph) and can fly at up to 4km in altitude, in temperatures as low as 94K (-180C). It uses a combination of batteries and a radioisotope thermal generator to provide power. At night, the generator will recharge the batteries, which can then be used for another day of flying.
Solar power wasn’t an option for this mission; Titan only receives about 1 percent as much sunlight on its surface as Earth does, once the combined impact of distance and its thick nitrogen atmosphere are taken into account.
“Almost everyone who gets exposed to Dragonfly has a similar thought process. The first time you see it, you think: ‘You gotta be kidding, that’s crazy,’ ” Doug Adams, the mission’s spacecraft systems engineer, told NPR Tuesday. But, he says, “eventually, you come to realize that this is a highly executable mission.”
You can see a video of how Dragonfly will land below.
Dragonfly will have to fly autonomously; the delay between Earth and Titan is too large to allow for direct remote control. The aircraft won’t fly during Titan’s night (night on Titan is ~8 Earth days long).
During these periods of time, Dragonfly will collect and analyze samples, study seismology, monitor Titan’s weather, and perform local microscopic analysis with LED lights. It will carry a mass spectrometer, a gamma-ray and neutron spectrometer, meteorological sensors and equipment, and both microscopic and panoramic cameras for imaging. The mission is intended to allow Dragonfly to sample the materials at many different sites, scattered over far more terrain than the Martian rovers have been able to cover even after years of work.
Each NASA probe has expanded our understanding of the universe and given us a bigger, better window into the worlds that make up our solar system. Each new generation of probe has improved and expanded on the scientific capability of the one that came before. The Cassini-Huygens probe already vastly expanded our understanding of Saturn and its moon, Titan. Now, Dragonfly may tell us whether the chemical soup on Titan — which resembles Earth in its earliest days, albeit at a much lower temperature — is capable of producing any analogs to life, or chemical processes we can identify as part of the expected series of events for how life arose on Earth.
Even if we don’t find anything biological, however, Titan is still the only other world with sustained liquid on its surface. There are hydrological systems on Earth that may only be mirrored on Titan (albeit via liquid methane, not water). In some ways, it’s the closest thing to a mirror of our own planet that we know of, and the only one we can reach with current rocket technology.
Dragonfly is set for a 2026 launch and will arrive at Titan in 2034.