As we saw last week, Titan’s surface is a tapestry of abundant carbon-rich chemistry, a delicious target for curious Earthlings to explore. The challenges are immense, including temperatures that make Minnesotan winters look positively tropical, a 90-minute-long communication gap with Earth, sand-like dunes ready to bog down wheeled vehicles and surface sunlight one thousandth the strength of what we receive here on Earth.
In the early stages of designing a suitable vehicle to explore Titan’s surface, engineers considered deploying a Montgolfière Balloon, that is, a hot-air balloon designed to descend from an orbiter and float 6 miles above the surface for several months. That was before the rapid development of drone technology, which led to the design of the Dragonfly mission, NASA’s most exciting attempt to date to explore the far reaches of our solar system.
My recreation drone and Dragonfly have rotors at each of their four corners, but there the resemblance ends. Dragonfly is an octocopter sporting eight 52-inch-long aluminum propellers with titanium leading edges, two at each corner rotating in opposite directions. With 1/7 Earth’s gravity and a thick atmosphere (characterized by the Huygens lander), Titan is a perfect environment for a drone. On Titan, a drone flies with 40 times the efficiency of one on Earth, which also makes landing on Titan a breeze compared to, say, Mars. Six years after launch, Dragonfly will hit Titan’s thick atmosphere at 16,000 mph, then rapidly decelerate, first using its aeroshell, followed by two parachutes before flying under its own power to autonomously scan the surface for a safe landing site. The whole procedure will take about two hours.
Although it’s easy to think of Dragonfly as a drone, its actual flying time is minimal. Rather, it’s a mobile lander, able to hop from one site of interest to another, each flight taking 20-30 minutes with a 16 Earth-day hiatus between flights. (That’s the length of a day on Titan.) One the ground, two drills, one on each landing skid, will send samples of surface material to a mass spectrometer via a “Dyson vacuum” type suction system. Particularly interesting samples — hopefully, those relevant to biological processes — will then be vaporized for fine (atomic scale) analysis. A Japanese-built seismometer will measure any Titanquakes, giving information on Titan’s subsurface ocean, while other instruments will measure the wind and composition of the atmosphere.
Solar panels are useless far from the sun under a hazy atmosphere, so Dragonfly will rely on a radioisotope thermoelectric generator, using the natural decay of plutonium 238 (half-life 84 years) to produce heat which will generate about 100 watts of electricity. Lithium ion batteries, recharged during the 16-day gap between flights, will power Dragonfly’s eight rotors.
A priority target for Dragonfly will be the inside of the Selk crater, an environment in which carbon-rich material and liquid water may have mixed for an extended period following the impact that created the crater. If (big if) hydrocarbon-based life once arose there, Dragonfly’s exquisitely sensitive on-board “chemistry lab” should be able to detect that. I can’t wait!
Barry Evans (he/him, barryevans9@yahoo.com) has a new book out, Amazon to Zodiac: 101 Scientific Curiosities across Time and Space. Available in your favorite bookstore or direct from the author.
This article appears in Humbuggery in Humboldt, Part 1.