NASA’s Dragonfly mission will send a rotorcraft lander to the surface of Titan in the mid-2030s.
Dragonfly was officially selected for flight by NASA as the fourth New Frontiers mission on 2019 June 27. Launch is planned for 2027, with Titan arrival in the mid-2030s, during the local northern hemisphere winter. Image credit: NASA.
One of the most important discoveries from the last two decades of planetary exploration has been the astrobiological potential of icy moons.
Many of these moons harbor liquid-water reservoirs beneath their crusts, comprising a new class of solar system body: ocean worlds.
If biology requires carbon, water, and energy, then ocean worlds may offer the Solar System’s best chance for life beyond Earth.
Saturn’s hazy moon Titan is unique among ocean worlds in that carbon, water, and energy interact on the surface:
(i) complex, potentially tholin-like organic compounds cover most of the surface;
(ii) crustal ice can be melted by impacts, and liquid water from the subsurface ocean may erupt in cryovolcanic flows;
(iii) solar and chemical energy could power biochemistry.
Titan’s profusion of organic riches, especially when exposed to transient liquid water, has created potentially habitable environments, the remnants of which are available on the moon’s surface today.
“Titan represents an explorer’s utopia,” said Dragonfly co-investigator Dr. Alex Hayes, a researcher in the Department of Astronomy at Cornell University.
“The science questions we have for Titan are very broad because we don’t know much about what is actually going on at the surface yet.”
“For every question we answered during NASA’s Cassini mission’s exploration of Titan from Saturn orbit, we gained 10 new ones.”
Though Cassini has been orbiting Saturn for 13 years, the thick methane atmosphere on Titan made it impossible to reliably identify the materials on its surface.
While Cassini’s radar enabled scientists to penetrate the atmosphere and identify Earth-like morphologic structures, including dunes, lakes and mountains, the data could not reveal their composition.
“In fact, at the time Cassini was launched we didn’t even know if the surface of Titan was a global liquid ocean of methane and ethane, or a solid surface of water ice and solid organics,” Dr. Hayes said.
The Huygens probe, which landed on Titan in 2005, was designed to either float in a methane/ethane sea or land on a hard surface.
Its science experiments were predominantly atmospheric, because they weren’t sure it would survive the landing.
The science goals of the Dragonfly mission, which will be the first mission to explore the surface of Titan, include:
(i) investigation of Titan’s prebiotic chemistry;
(ii) exploration of the hazy moon’s habitability;
(iii) search for chemical biosignatures from both water-based ‘life as we know it’ (as might occur in the interior mantle ocean, potential cryovolcanic flows, and/or impact melt deposits) and potential ‘life, but not as we know it’ that might use liquid hydrocarbons as a solvent (within Titan’s lakes, seas, and/or aquifers); consideration of both of these solvents simultaneously led to the initial landing site in Titan’s equatorial dunes and interdunes to sample organic sediments and water ice, respectively.
“What’s so exciting to me is that we’ve made predictions about what’s going on at the local scale on the surface and how Titan works as a system, and Dragonfly’s images and measurements are going to tell us how right or wrong they are,” Dr. Hayes said.
Dragonfly will spend a full Titan day (equivalent to 16 Earth days) in one location conducting science experiments and observations, and then fly to a new location.
“The science team will need to make decisions about what the spacecraft will do next based on lessons from the previous location — which is exactly what the Mars rovers have been doing for decades,” Dr. Hayes said.
The science goals of the Dragonfly mission are outlined in a paper published in the Planetary Science Journal.
_____
Jason W. Barnes et al. 2021. Science Goals and Objectives for the Dragonfly Titan Rotorcraft Relocatable Lander. Planet. Sci. J 2, 130; doi: 10.3847/PSJ/abfdcf
