Dragonfly, a nuclear-powered drone to explore Titan

Bigger of the 18 moons of Saturn, Titan fascinates the astronomers. This moon has a dense atmosphere, ocean and a complex organic chemistry that could house a form of life. To explore this system based not on carbon but methane, various solutions are under study. Johns Hopkins Johns Hopkins offers a bold solution: parachuting a drone On the surface of Titan.

A drone can easily fly in the dense atmosphere of Titan

Since the Voyager missions and especially Cassini / Huygens in 2005, scientists know a little more about the very specific characteristics of Titan and notably this amazing system based on methane. Nevertheless the surface itself retains its mysteries and it is not excluded to find there traces of life. As part of its New Frontiers initiative, NASA plans to explore this area and various laboratories offer very different technical solutions to explore this huge moon.The presence of an atmosphere four times denser than that of the Earth, of a gravity which represents only 1/7 of our own, makes it possible to envisage an aerial exploration, preferably a rover that can only cover one Very limited operating area. Various helicopter, airplane and balloon projects have already been proposed at NASA, the Johns Hopkins Applied Physics Laboratory consists of a quadcopter drone, the Dragonfly.

By embarking on a mass spectrometer, the drone will be capable of performing atmospheric and surface analysis, as well as being able to analyze the subsoil with a gamma ray spectrometer. It will obviously be equipped with camera and various sensors of pressure / temperature / anemometer / seismic to realize measurements throughout its titanic journey.

Some flights to cover the same surface as a rover in 12 years

The Dragonfly, an electric quadrupter powered by a nuclear battery.

The choice of the drone against the rover is justified by the researchers of the JHU by the fact that in some flights only, Dragonfly can cover more surface than Opportunity after 12 years on Mars. The drone has many advantages, especially to explore a moon whose surface is very diverse, but any drone pilot will tell you, the question of autonomy remains the Achilles heel of the drone. Not simple to reload a drone between two flights at a distance of more than 1,195 million km. Rather than creating a base powered by solar panels on which the drone would reconnect between each flight, which would mechanically limit its range of action and solar radiation is very low on Titan. The engineers preferred to equip the Dragonfly with a nuclear power source, a standard MMTGG from NASA (a multi-mission thermoelectric generator), a plutonium nuclear power source already used on various space probes, and Rover Curiosity. For a weight of 45 kg (on land), a MMRTG delivers 125 W at the beginning of the mission and 100 W after 14 years of use. This power, which is constant but relatively low, will necessitate the embedding of batteries in the drone, which risks limiting its lifetime. In addition, plutonium generates heat that will be particularly welcome to reheat the electronic components of Dragonfly. The average temperature on Titan is of the order of -180 ° C. Using the images provided by the cameras of the drone, the researchers will be able to choose the landing site, the flight being then automatically carried out by the drone. An unknown however, the very first landing site on Titan. The descent module will be equipped with lidar to scan the surface of Titan during the dive to the surface. The researchers do not exclude that the drones could then end up in a tree, but would already be there a major discovery in itself!

Tests of the Dragonfly have begun, Nasa has to choose

The first testbed of the Dragonfly, equipped with a fictitious MMRTG.

A first drone is tested on land to develop the software to control the future Dragonfly. The reliability of the guidance and piloting software is a key point of the project because all the drone’s abilities would be annihilated if the drone strikes a titanium dune at the beginning of the mission or crashes in the event of a methane storm.

Obviously, it does not have its plutonium generator. The construction of a prototype at scale 1 is planned to test the algorithms and to refine the automatic piloting of the drone if the NASA selects the concept proposed by the JHU.

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