NASA will send a dual-quadcopter drone to hop across the surface of Titan, Saturn’s largest moon, the agency announced on 27 June. Named Dragonfly, the mission will launch in 2026 and arrive at Titan in 2034.
“Dragonfly is really a Mars-rover-sized drone that we’ll be able to fly from place to place on Titan,” says Elizabeth Turtle, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, who leads the mission.
The nuclear-powered Dragonfly can fly tens of kilometres in less than an hour, allowing it to cover ground much faster than a wheeled rover could. Over the course of a two-year mission, the drone could traverse hundreds of kilometres.
Hydrocarbon-rich clouds in Titan’s atmosphere rain methane and ethane onto the moon’s surface. The liquid collects in lakes and seas, which NASA’s Cassini spacecraft saw glimmering in sunlight in at various points from 2009 to 2017. Some of the lakes grow and shrink as seasons change on Titan.
Dragonfly will study the atmosphere as it flies around, and touch down for extended stays on the moon's surface. The drone will explore areas where methane- and ethane-rich lakes recently dried up — and in the process, might have left behind residue rich with organic compounds like those that may have existed on early Earth before life arose. "Titan has all of the key ingredients needed for life," says Lori Glaze, head of NASA's planetary sciences division.
Hop, skip and a jump
In 2005, the European Space Agency’s Huygens probe became the first spacecraft to land on Titan. It measured the temperature, pressure, and density of Titan’s atmosphere during its descent, and sent back pictures of the rugged, rocky landscape for 72 minutes after it touched down.
Dragonfly beat out a proposed mission to return a sample from Comet 67P/Churyumov-Gerasimenko, which the European Space Agency’s Rosetta spacecraft explored between 2014 and 2016. The Comet Astrobiology Exploration SAmple Return (CAESAR) project is led by Steve Squyres, a planetary scientist at Cornell University in Ithaca, New York. It would bring back at least 80 grams of material from 67P’s nucleus, by far the largest sample ever taken from a comet. NASA’s Stardust mission gathered about a microgram of dust from Comet Wild 2 in 2004.
Dragonfly is part of NASA's New Frontiers programme, which selects its planetary-science missions from proposals submitted by researchers that are subject to price limits. Dragonfly’s cost is capped at US$850 million in 2015 dollars — not including the mission's launch vehicle.
The three prior New Frontiers missions are New Horizons, which flew past Pluto in 2015 and a smaller rock in the outer Solar System earlier this year; Juno, which has been orbiting Jupiter since 2016; and OSIRIS-REx, which is circling the asteroid Bennu and will collect a sample of it next year to fly back to Earth.