NASA has chosen its next planetary mission, which will send a flying rover called Dragonfly to Saturn's largest moon, Titan. The size of the Curiosity Mars rover, the unmanned, nuclear-powered explorer will not have wheels, but will fly through the Titanian atmosphere using eight rotors as it looks for organic molecules, including the building blocks for past or present life.

Sending a robotic rotorcraft 842 million miles (1.4 billion km) from Earth and expecting it to whiz about on a moon with a methane atmosphere – where the -290° F (-179° C) temperature turns water into ice as hard as granite – may seem a trifle ambitious, but it does make engineering sense.

Unlike the Moon and Mars, where previous rovers were sent, Titan has 0.133 Earth gravity combined with an atmosphere that is four times as dense as our planet's. This means that flight on Titan is actually easier than on Earth – which is fortunate because the surface is a mixture of lakes, sea, and streams made of liquid hydrocarbons, and sand dunes made of organic "snow." That makes wheeled or tracked rovers impractical for the foreseeable future, but a rotorcraft that can hop from place to place is another matter.

Since Dragonfly isn't scheduled to launch until 2026 and arrive at Titan in 2034, it's still in the design phase, but the basic blueprint is for a Curiosity-sized rover set on a pair of landing skids and equipped with eight one-meter (3.3-ft) rotors powered by batteries charged by a radio-thermal generator (RTG) nuclear power plant. It will be able to fly at 22 mph (36 km/h) at an altitude of up to 13,000 ft (4,000 m), in a series of flights that will be as long as five miles (eight km).

Drawing on data from the Cassini mission, the plan is that Dragonfly will launch on a still-undecided rocket, then travel to Saturn on an eight-year voyage aided by a series of slingshot trajectories. It will be delivered to the surface of Titan at the equatorial Shangri-La dune fields by a protective aeroshell equipped with parachutes. Once down, it will spend its initial 2.7-year mission recharging during the Titanian night and flying during the day, covering up to 108 miles (175 km).

As it travels, it will study the surface using an imaging mast as well as a mass spectrometer, gamma ray and neutron spectrometer, and geophysics and meteorology package. Its primary mission will be to study the floor of the Selk impact crater that may have once had conditions where liquid water and complex organic molecules could have existed for tens of thousands of years. The hope is to not only learn more about Titan itself, but also to seek signs of present and past life.

"Titan is unlike any other place in the solar system, and Dragonfly is like no other mission," says Thomas Zurbuchen, NASA's associate administrator for Science. "It's remarkable to think of this rotorcraft flying miles and miles across the organic sand dunes of Saturn's largest moon, exploring the processes that shape this extraordinary environment. Dragonfly will visit a world filled with a wide variety of organic compounds, which are the building blocks of life and could teach us about the origin of life itself."

Source: NASA

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