SEARCHING THE SKIES

If you want to cover a lot of ground, the best way is to take to the sky

On 19 April 2021, the Ingenuity Mars Helicopter Scout became the first spacecraft to make a controlled powered flight on the surface of another planet. The drone-like rotorcraft hitched a ride aboard Perseverance, NASA’s most-advanced rover that’s armed with heavy robot arms, instruments and power-hungry ovens that can bake and analyse soil samples. Conversely, Ingenuity, which only has a mass of 1.8kg, carries just two cameras.

For what it lacked in instrumentation, Ingenuity made up for in range. While Perseverance had to spend weeks skirting around the outside of a boulder-strewn field, Ingenuity flew over it in minutes and was able to scout the path ahead. With such proof of potential, there’s no doubt that while Ingenuity might have been the first such flight, it won’t be the last.

Even before Ingenuity launched, NASA was already planning on sending its successor, Dragonfly, to Saturn’s moon, Titan, in 2027. This moon is simultaneously incredibly familiar and totally alien. Like our planet, it has a nitrogen-rich atmosphere at an Earth-like pressure, while the terrain is shaped by mountains and liquid lakes. Only it’s -180ºC. Instead of rock, the mountains are ice, and the lakes are filled not with water, but liquid methane and ethane. Hydrocarbons such as these are thought to have formed the building blocks of life here on Earth. Could they have done so on Titan as well?

To have a chance of answering these questions, Dragonfly will have significantly more scientific power than its Martian predecessor. The increased lift of its eight rotors, combined with Titan’s thick atmosphere and low gravity of 1.4m/s2, means that Dragonfly can have a mass of 4›0kg – enough to carry a heavy radio thermal generator and still have a significant science payload. Dragonfly will have spectrometers to analyse both the atmosphere and soil, as well as meteorological sensors and the all-important cameras. These will help the craft to navigate as it flies for more than 17›km across Titan’s surface – double the distance of all the Martian rovers combined – in just 2.7 years. The images they send back will be the best ever taken of the moon’s surface, and will finally reveal what’s hiding among the hills and lakes of Titan.