The hazy skies of Saturn’s moon Titan are the next destination for the growing use of flying drones to explore the solar system. This time, scientists are preparing not to just hop but soar up to 13,000 feet and cover hundreds of miles in search of evidence of ancient microbial life.
It’s a major step beyond the success of NASA’s Ingenuity drone on Mars, and it signifies that flying robots from Earth will play an increasingly important part in the exploration of our solar system.
“Ingenuity was a technology demonstration,” said Alex Hayes, an associate professor and the director of Cornell University’s Center for Astrophysics and Planetary Science in Ithaca, New York. “You can now expect follow-ons to expand that technology to actual science missions that use flight.”
In July, Hayes and his colleagues detailed the scientific goals of the Titan probe, called Dragonfly, which is scheduled to launch in 2027 and arrive around Saturn by 2034. Its main purposes will be to look for chemical traces of microbial life on the moon and to study the “methane cycle” — a much colder analog of the water cycle here on Earth — that shapes its landscape.
Dragonfly has been in planning for more than a decade, roughly since the Cassini mission to the Saturn system deployed the Huygens lander to the surface of Titan in 2005.
Titan’s surface is obscured by the heavy haze of its dense atmosphere, but the brief Huygens mission revealed tantalizing glimpses of its landscape, with dunes, dry riverbeds and lakes of liquid hydrocarbons.
Unlike Mars, where the very thin atmosphere and relatively high gravity make flying difficult, the atmosphere on Titan is roughly four times denser than ours, although unbreathable, and its gravity is a bit less than on our moon.
“Titan is the easiest place to fly in the solar system,” said professor and planetary scientist Jason Barnes of the University of Idaho in Moscow, Idaho, and one of the principal investigators for the Dragonfly mission.
The half-ton Dragonfly lander will spend several days in one spot, carrying out science experiments while its batteries recharge from a radioisotope thermoelectric generator, and then it will fly for up to an hour or more to a new location.
Dragonfly will do most of its science on the surface, but its eight rotors will let it fly much higher and farther during its initial 32-month mission than Ingenuity.
“We really think of ourselves as a lander,” Barnes said. “We spend 99 percent of our time on the ground.”
Key to the scientific goals of the Dragonfly mission is to sample the floor of Selk crater, which was created by a meteorite impact on Titan maybe millions of years ago.
Titan’s surface is so cold — minus 290 degrees Fahrenheit — that any water there is frozen as hard as rock, although there are extensive lakes of methane and ethane.
Like some other moons of Saturn and Jupiter, however, Titan is thought to have liquid water beneath its crust, and the Selk impact may have forced some of that liquid to the surface for a time.
The subsurface waters may be the best place on Titan for microbial life to have evolved, so Dragonfly will take samples from the crater floor to look for its frozen chemical traces, Barnes said.
The flying lander will also be able to study the composition of the dunes on Titan’s surface — the type of terrain where a rover would get stuck — and the weather in Titan’s atmosphere, including its methane rain.
Barnes explained that the chemicals that now exist on Titan are similar to the chemicals that existed on Earth in its very early days, and the Dragonfly mission will help scientists better understand them.
The new details of the Dragonfly mission come just a few weeks after the extraordinary success of NASA’s Ingenuity drone on Mars.
“Ingenuity and the whole Perseverance project have exceeded expectations,” said Athena Coustenis, who directs research on planetary rovers for the French government and whose team worked on the cameras for the mission.
Ingenuity was only due to make five test flights. But it’s now made 12 flights, and it’s scouting new terrain for the Perseverance rover it piggybacked on.
The success of the tiny drone, which weighs only 4 pounds, has renewed attention on plans for even larger flying probes — such as the 60-pound Mars Science Helicopter, a six-rotor design that could explore the red planet without backup from a rover.
Coustenis, who was not involved in the recent Dragonfly study, noted that only Earth, Mars, Titan and Venus have dense-enough atmospheres for flying vehicles and that two Soviet missions, Vega 1 and Vega 2, had successfully explored the clouds of Venus with balloons in 1985.
While planetary rovers can only travel at relatively slow speeds for limited distances, flying probes could cover large distances on remote planets and moons while avoiding treacherous terrain.
Titan was the “obvious next destination for flying machines” like Dragonfly, she said, but there were also proposals to explore both Titan and Mars with fixed-wing drones and even balloons — although balloons in the thin Martian atmosphere would need to be very big and could carry only small experimental payloads.