TAE: Titan Aerial Explorer

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TAE: Titan Aerial Explorer


Dr. Jonathan Lunine intends to submit a proposal in response to the Call for a Medium-size mission opportunity for a launch in 2022, as issued by ESA under its Cosmic Vision 2015-2025 Plan (http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=47371).

The title of the proposal is ?TAE: Titan Aerial Explorer?.

Signatures of support for this proposal can be found at the end of this page


The mission to be proposed includes a balloon with the capability for ground-penetrating radar, radio science and multi-spectral imaging and spectroscopy, aerosol analyses, and possibly other instruments. The goal is to explore the processes that are at work on the surface on and near-surface of Titan with sufficient resolution and wavelength capability to quantify Titan?s methane hydrologic cycle. Questions to be answered include the extent of fluvial erosion on Titan?s surface, the formation of rainclouds and the role of nucleating aerosols, the possible presence of small or transient low latitude liquid lakes, the composition of the surface and its modification by fluvial and aeolian erosion, and the detailed structure of the dunes.

These goals require combined in situ measurements, high-resolution surface studies, subsurface sounding, and regional- to global-scale coverage. The combination of requirements calls for a long-range balloon system which can be launched and delivered on a Soyuz-Fregat. This will be a challenging mission. Selected proposals go into a pre-phase-A type study period, so in essence we are proposing not a mission, but the study of a mission.

Your support for this mission will be crucial if ESA is to consider it among the many M-class proposals being submitted. We deeply appreciate your help.



On to Titan!

We propose the Titan Aerial Explorer (TAE) mission, that will deploy and operate a super-pressure helium balloon in the lower atmosphere of Saturn?s giant moon, Titan. The Cassini-Huygens mission revealed Titan to be a body with an active hydrological cycle involving methane, ethane and a variety of other organic molecules. It found methane oozing from the surface at the Huygens landing site, and liquid organics residing in vast near-polar deposits whose extent rivals or exceeds the great lakes and seas on Earth. Cassini observed methane clouds forming as convective storms in the summertime south, as ghostly echoes superimposed on methane seas sheathed in late winter darkness, and as unexpectedly vast outbursts in the mid-latitudes as the Sun crossed the equator of Titan at equinox. The geologic history of the surface remains a mystery after six years of Cassini data and will continue to be a mystery through the end of the Cassini mission. The variety of surface features and atmospheric phenomena seen only at moderate and low resolution by the orbiter tease us, because we know from nature of the one site visited in situ by the Huygens probe that hidden among the dunes and channels, the mountains and lake shores, is a complex history of climate change and chemical evolution tied to methane and its prodigious variety of organic products. We seek to understand this history by deploying at Titan the one type of vehicle that combines the mobility and coverage of the orbiter with the capability for high resolution and in situ observations demonstrated by the Huygens lander, and does so in an aerodynamically stable and low-risk fashion?an aerostat (balloon plus gondola).

The aerostat will carry a camera to observe the surface of Titan, collecting images over a variety of different terrains to look for clues to the geologic history of Titan, to ongoing fluvial erosion in which methane is the working material, and for evidence that Titan has experienced dry episodes in which the atmosphere thinned, and wetter epochs when methane seas extended further equatorward than they do today. Spectra of the surface will map out the locations and extent of deposits of major organic products of the methane chemistry. A radar sounder will probe the subsurface to look for evidence of layering associated with sedimentary deposition, cryovolcanism, tectonics, and other processes that might dominate the particular regional context elucidated by the imager. The balloon borne aerostat, floating just at or below the methane cloud base, will carry an instrument to sample the atmosphere looking for aerosols that nucleate methane-nitrogen cloud formation. It will measure ambient electric and magnetic fields to seek additional evidence for a subsurface water-ammonia ocean and determine the thickness of the ice crust above the ocean.


The mission begins with a launch sometime in the 2020-2023 timeframe on a 9-year trajectory of a carrier spacecraft containing the aerostat encased in a Huygens-like entry system. When the carrier nears Titan, it points and releases the Descent Module onto the pre-determined entry, descent and inflation trajectory. The probe enters Titan?s atmosphere at mid-latitude, deploys a parachute, releases the aeroshell heat shield and backshell, initiates balloon inflation, releases the helium tanks and establishes neutral buoyancy at ~8km altitude. The threshold science mission is to fly over one Titan hemisphere and the goal is a complete circumnavigation of Titan(assumed to require 6 months at 1 m/s net zonal movement). Science data are sent back to earth via a direct-to-earth communication system located on the aerostat. The instrument suite consists of three remote sensors?a camera, spectrometer and radar sounder?and three in situexperiments?an aerosol collector, magnetometer and device for measuring electric fields and conductivity.


TAE utilizes a helium-filled super-pressure (or ?pressurized?) balloon, rather than a hot air (montgolfi?re) design, as in many previous studies. Strict limitations on technology readiness level, relative robustness of the inflation scenario and mission lifetime were factors that weighed in our decision. The great advantage of the pressurized balloon is the maturity of its inflation and deployment scheme. Its disadvantage is relative sensitivity to the presence of small holes that can reduce dramatically the mission lifetime. To mitigate this, a key part of the proposed study is devoted to thoroughly assess options available to ensure integrity of the envelope.


In summary, TAE will provide dramatic high priority Cosmic Vision science using mature flight elements that assure mission success within ESA resources.


List of supporting scientists


If you?re interested in participating and co-signing this proposal, please fill the form below. The ideas we get via these e-mails and your names will be assembled and incorporated in the proposal.

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