By trading wheels for helicopter blades, NASA is upping its game for the Dragonfly mission, a flying machine intended to explore Titan, an icy moon of Saturn. 

The team has started assembling the honeycomb panels for the aircraft's main body, completed a series of drop tests on the parachute system, and demonstrated that its compact chemistry lab can pick out tiny amounts of target molecules in test samples.

This NASA robot, expected to launch as early as 2028, is no space orbiter. Dragonfly will be an SUV-size, eight-rotor aircraft, designed specifically to navigate the hazy orange skies of Titan, a world larger than the planet Mercury. It will explore the alien landscape much like NASA's fleet of rovers, except Dragonfly will have a much faster way of getting from Point A to B. In the words of Back to the Future's Doc Brown: "Roads? Where we're going, we don't need roads." 

Titan, about 886 million miles from Earth, is the only moon in the solar system with a substantial atmosphere. But Titan's air is thick — about 1.5 times the pressure at Earth's sea level and roughly three times as dense, said Charles Malespin, who leads the team that built the hardware for analyzing Titan's samples. Because it is so cold in this alien world, gases like methane become liquids, and the atmosphere turns into a heavy blanket. Meanwhile, the moon has just one-seventh Earth's gravity.  

"That's why an octocopter is primed for that, because you could fly very easily through it," Malespin said. "We could cover a huge amount of terrain and explore a much larger area."

Scientists see Titan as a kind of time machine for understanding how life begins. Its methane‑rich atmosphere constantly produces complex organic molecules that dust the icy surface, creating dunes and deposits of carbon‑based material. On early Earth, similar chemistry may have helped make the building blocks of life, but our planet's surface has since changed dramatically because of life and geology. 

Titan, by contrast, stays frozen and preserves that chemistry. By flying from dune fields to an ancient crater where water and organics could have mixed, researchers hope Dragonfly will allow them to study how simple ingredients evolve into more complex molecules. 

"There was a melt pool that may have lasted up to about 1,000 years. That is a lot of time for chemistry to happen between the organics that are depositing in it and the water," said Melissa Trainer, a planetary scientist and the lead for Dragonfly's DraMS instrument, a quasi-acronym for its mass spectrometer. "Who knows what we could make in a 1,000-year chemistry experiment?"

For a handful of reporters at Goddard Space Flight Center in April, NASA walked through how the $3.35 billion mission will drill into Titan's rock-hard ice, analyze samples with its built‑in chemistry lab, and then lift off again to explore a new spot. The device will use a carousel of 40 sample cups, tiny ovens, and a laser to study the Saturn moon's plentiful organic material.

It's the opposite of what the tiny drone Ingenuity, which went kaput two years ago, faced on Mars. There, the air is about 100 times thinner than Earth's. To lift itself, Ingenuity needed very long blades and a featherweight body, leaving hardly any wiggle room to carry instruments.

But for Dragonfly, engineers can exploit its larger body to stuff it full of tools. 

"If you had cardboard wings, you could fly just by pushing because the atmosphere is pretty much so thick there," Malespin said. 

Mobility is the other key reason NASA built Dragonfly as an aircraft. Rovers like Curiosity and Perseverance on Mars move slowly, perhaps half a football field in a day. Dragonfly, on the other hand, could traverse miles.

Researchers will use the mission's measurements collected over three years to study prebiotic chemistry, the steps that occur on the way to making life. They are looking for familiar building blocks, such as amino acids, nucleobases, and fatty acids.

But one limitation for the mission is that Dragonfly can't explore Titan's lakes or seas of liquid methane and ethane at the north pole. Instead, the robot is built to explore an equatorial region of dunes. That's fine with the team, said deputy project scientist Shannon MacKenzie, because some of the materials scientists are looking for on Titan don't dissolve well in liquids anyway. 

"We want to go to the sand," MacKenzie said. "Those organic sand particles are probably the end result of a lot more of that chemistry than what we would be able to slurp up out of the lakes."

Awaiting those detections will take a great deal of patience for the team. The journey alone to get to Titan in the outer solar system will take nearly seven years.