What we know about the surface becomes the foundation for the fundamental questions that require a return visit. What processes have reshaped the surface, erasing, except in a few terrains, the many craters that should have accumulated? Why hasn't the rain of hydrocarbons buried the surface over the age of the solar system, and where does new methane come from to replace that lost to the formation of the hydrocarbons? Are there cryovolcanoes that bring liquid water to the surface? What types of pre-biotic chemistries occur on a world rich in hydrocarbons? And is there evidence of life, either that formed on the surface from the interaction of water and the hydrocarbons or carried up from the deep subsurface global ocean? Or is there life based on non-water chemistries?

These questions cannot be answered by landing at any single location on Titan. Fortunately, this moon's thick atmosphere and low gravity make this the easiest world in the solar system for flight. The team proposing the Dragonfly mission have designed a rotorcraft lander that can fly several tens of kilometers in a single flight to a new site. In an hour or so of flying, the craft might travel further than the Opportunity rover has crawled across the surface of Mars in fourteen years. Over the course of several years at Titan, the craft could explore a variety of terrains hundreds of kilometers apart.

The Dragonfly proposal is possible because of the recent advances in multirotor technology to enable steady flight (think of all the quadcopter hobby drones as inexpensive examples) and autonomous flight. Cassini's maps of the surface enable scientists to identify interesting locations to visit but are too low resolution (the smallest details are hundreds of meters across) to be useful to for inflight navigation. On each flight, Dragonfly would be given a target location to fly to. During the flight, a combination an inertial measurement unit, radar, and optical navigation would be used to track progress. Once at a landing area, a laser system (lidar for those familiar with the technology) would map the site to find a safe touch down site.

On arrival at Titan, the Dragonfly craft, safely enclosed in its entry capsule, would directly enter the atmosphere. Once the initial descent is completed, the Dragonfly rotorcraft would separate from the capsule and guide itself to its first landing. Much of Titan's equatorial regions are covered by dunes that crest at 50 to 200 meters separated by flat plains two to four kilometers wide. The craft would use its sensors to guide itself to one of these interdune areas to enable that crucial safe first landing.

The sands themselves are known to be composed of frozen organic particles that likely are material blown in from large areas of the moon's surface. With its first landings in the dune sea, the Dragonfly lander can explore how far organic chemistry has proceeded on this hydrocarbon rich world. The interdune plains may also contain exposed water ice that is the bedrock of Titan's surface. Sampling the primordial water ice crust is a high priority to explore the chemistry present when Titan formed and the surface and atmosphere may have been much different than they are today.

Because Titan's surface is likely rugged at small scales, the Dragonfly team won't send the craft to land at an unseen location (except for that first landing). Instead, on its first flight following the initial landing, the craft would be sent to scout for a next safe landing site and then would return to the initial (and known to be safe) landing site. On the second flight, the Dragonfly craft would fly past the second known safe landing site to scout a third, and then return to the second site. In this way, the mission would leapfrog from one known safe site to the next, using its sensors to make up for the lack of high resolution orbital imagery.

Beyond the dune seas, Titan has a rich variety of terrains to explore. Life on the Earth is based on organic chemistry enabled by liquid water. The surface of Titan is too cold for liquid water – the water ice is as hard as rock – but impacts would melt the ice, mixing the hydrocarbons with liquid H 2 O for as long as tens of thousands of years. Where liquid water and the organic material on the surface mixed, complex pre-biotic chemistry likely occurred, making Titan a natural laboratory to explore the possible origins of life. These sites would provide natural laboratories to explore the resulting pre-biotic chemistry and explore avenues for the origins of life.

Cassini's data hint at features that may be extensive cryovolcanic flows where water from the interior ocean reached the surface. If the liquid water originated in the deep interior ocean, sampling these areas may allow the Dragonfly instruments to determine the composition of that ocean, including searching for signs of any life that may exist there.

While liquid water on the surface has likely been a rare event, liquid methane plays the role on Titan that water does on Earth. The methane falls as rain, flows through river systems, and ends in lakes and seas. Close to the equator where the Dragonfly craft would roam, it appears that the seas have largely dried up. The evaporation of the seas could have concentrated chemical reactions, and the present dry-to-moist surface would preserve the resulting material for Dragonfly's instruments to sample. Several areas near the equator have been identified as possible dry sea beds. (The currently-filled methane seas in the north polar region would be in darkness and out of sight of Earth for telecommunication during the Dragonfly mission. Their exploration would need to wait for another mission a decade or so later).

The Dragonfly's explorations would be tempered by the need to carefully manage its power use. The craft would carry a radioisotope power source that at Titan would supply a constant ~70 Watts of electrical power. (And as importantly, it provides plentiful supply of waste heat to keep the craft warm on the -180-degree Celsius (-290-degree Fahrenheit) surface.) That supply is too low for the major power-hungry activities – flight and returning data to Earth – but is enough to recharge a large battery. Operations would proceed at the pace of each Titan day (around 16 Earth days). During the night, the battery recharges, followed by a daytime flight and a series of science activities and data downlinks. During the long night when Earth is out of sight, the craft would power down many systems to keep its meteorology and seismic instruments powered and permit battery charging. (The Curiosity rover on Mars is similarly power limited. Its radioisotope power source charges a battery that powers driving and many operations. The difference is that days on Mars have a similar length to our own.)

The public information on how far the Dragonfly craft might go in a single flight is somewhat vague – the design is not yet complete and there's a tradeoff between larger batteries and weight and volume. One article discusses an example battery that could allow up to 60 kilometers flight. It then states that flights would be kept substantially shorter to provide a safety margin. If the average distance between landing sites is 20 kilometers when the goal is to transit distances, then over a five Earth year mission, the craft might fly 1500 to 2000 kilometers. Not all Titan days, though, are likely to be spent with the goal of putting kilometers on the odometer. If the craft finds a cryovolcanic volcano or flow, for example, it may spend many months doing short flights to different locations within the flow. Some Titan days may be spent doing aerial reconnaissance to map the feature. Other Titan days might be spent doing bunny hops between features in a single landing area.