NASA Plans on Sending a Rotorcraft to Explore Titan, a Moon of Saturn
NASA recently announced that it had selected Dragonfly, a helicopter that will be designed and built at Johns Hopkins University, to be onboard the next New Frontiers Program spaceship landing on Titan, a moon of Saturn. The craft will be launched in 2026 and is expected to land on Titan in 2034. The Dragonfly will let NASA plan exploratory missions to dozens of locations across Titan, sampling and measuring the composition of its surface materials, characterizing the habitability of Titan’s environment, and investigating the progression of prebiotic chemistry.
Scientists consider the icy Titan to be the most Earth-like world in the solar system planet. During its 2.7-year mission, Dragonfly will explore environments from organic dunes to the floor of an impact crater, where liquid water and complex organic materials key to life once existed together. Its scientific instruments will be built by institutions across the nation.
“Titan is such an amazing, complex destination,” said Elizabeth “Zibi” Turtle, Dragonfly principal investigator from the Applied Physics Lab at Johns Hopkins. “We don’t know the steps that were taken on Earth to get from chemistry to biology, but we do know that a lot of that prebiotic chemistry is actually happening on Titan today. We are beyond excited for the chance to explore and see what awaits us on this exotic world.”
Titan is larger than the planet Mercury and is the second largest moon in our solar system. As it orbits Saturn, it is about 886 million miles away from the Sun, about 10 times farther than Earth. Because it is so far from the Sun, its surface temperature is around −290°F. Its “air” pressure is also 50% higher than Earth’s.
Dragonfly will be taking advantage of 13 years’ worth of data from NASA’s Cassini Mission to choose its targets. It will first land at the equatorial “Shangri-La” dune fields, which are eerily similar to the linear dunes in Namibia in southern Africa, before moving on to other areas in a series of “leapfrog” flights of around five miles, stopping along the way to take samples from compelling areas with diverse geography. It will finally reach the Selk impact crater, where there is evidence of past liquid water, organics—the complex molecules that contain carbon, combined with hydrogen, oxygen and nitrogen—and energy, which together make up the recipe for life.
Dragonfly will also leverage decades of autonomous drone experience and well-understood flight dynamics on Earth and apply them in a whole new environment. Dragonfly marks the first time NASA will fly a multi-rotor vehicle for science on another planet.
Dragonfly will be a rotorcraft lander, much like a large quadcopter with double rotors (an octocopter). The craft should be able to fly despite the loss of a rotor or motor. Each rotor will be able to tolerate the loss of at least one rotor or motor. Each of the eight rotors will be about 3.3-ft in diameter. The aircraft will travel at about 22 mph and be able to climb to 10 m/s or 36 km/h and climb to an altitude of 13,000 ft.
The craft weighs about 990 lb, measuring 10 ft long and 10 ft from rotor tip to rotor tip. It will be designed to fly in temperatures down to 94 K (−290.5°F).
Aerial flight on Titan should be relatively benign as the atmosphere is four times as thick as Earth’s, it’s gravity only 14% of Earth’s, and there are low winds. This means Dragonfly’s flight power need only be one-fortieth of what it would need on Earth, but it will have more drag on it than it would on Earth. The motors are electric, powered by batteries that will be recharged at night (192-hr long) by a Radioisotope Thermoelectric Generator (RTG). The RTG power source has been proven in several spacecraft.
The craft will remain on the ground during the Titan nights, which last about eight Earth days or 192 hours. Activities during the night may include sample collection and analysis, seismological studies, meteorological monitoring, and local microscopic imaging using LED illuminators as flown on the Phoenix lander and Curiosity rover. Dragonfly will take samples suing acquisition drills and hoses, one on each landing skid, for delivery to an onboard mass spectrometer. The craft will communicate directly to Earth with a high-gain antenna.
During daylight hours, the craft will be able to stay aloft a few hours on each charge. NASA scientists estimate it will fly a total of about 108 miles over Titan, nearly double the distance traveled to date by all the Mars rovers combined.
“With the Dragonfly mission, NASA will once again do what no one else can do,” said NASA Administrator Jim Bridenstine. “Visiting this mysterious ocean world could revolutionize what we know about how life formed in the universe. This cutting-edge mission would have been unthinkable even just a few years ago, but we're now ready for Dragonfly’s amazing flight.”
The program is estimated to cost $1 billion.
Michael Buckley is senior public affairs officer at the Applied Physics Laboratory at Johns Hopkins University.
