Description: The New Frontiers Dragonfly mission to Titan, funded by the Science Mission Directorate (SMD) and led by the Applied Physics Laboratory (APL), includes an Engineering Science Investigation (ESI) called DrEAM, or Dragonfly Entry Aerosciences Measurements. DrEAM will provide key aerodynamic and aerothermodynamic data and assess the thermal protection system (TPS) performance on both the Dragonfly forebody and backshell. NASA's Ames Research Center (ARC) leads the DrEAM development effort and are partnering with the German Aerospace Center (DLR) to propose a comprehensive instrumentation suite, including a DLR-provided Data Acquisition System (DAS). The Dragonfly spacecraft is being designed to accommodate this ESI and the team is benefiting from the experience gathered from the Mars Entry, Descent, and Landing Instrumentation 2 (MEDLI2). APL has subcontracted Lockheed Martin Space (LMS) to build the Entry System's aeroshell and to integrate and install the DrEAM instrumentation. The DrEAM instrumentation will utilize the same techniques and processes as developed by MEDLI and MEDLI2 for vehicle integration. This commonality also enables Dragonfly to leverage the extensive ground test qualifications performed for MEDLI and MEDLI2 and claim substantial heritage for this system. Aerothermal environments and TPS response will be measured using sensors similar to the MEDLI2 Integrated Sensor Plug (MISP) and the COMbined Aerothermal and Radiometer Sensor (COMARS) suite, with the latter supplied by DLR. For MEDLI2, MISP used embedded thermocouples (TCs) to directly measure in-depth temperature of the TPS at several locations, which can also be used to infer surface environments via inverse analysis. For DrEAM, the MISP style plugs are known as Dragonfly Sensors for Aero-Thermal Reconstruction (DragSTR) plugs. On Schiaparelli, the COMARS suite included three total surface-mounted heat flux sensors, three pressure sensors, and one radiometer. For DrEAM, the COMARS package is known as the COmbined Sensor System for Titan Atmosphere (COSSTA), and will again measure backshell pressure and radiative and total heat flux. Atmospheric density measurements and capsule aerodynamic data will be obtained through pressure transducers similar to those used by the MEDLI Mars Entry Atmospheric Data System (MEADS). The DrEAM pressure sensors are known as Dragonfly Atmospheric Flight Transducers (DrAFT). Both DragSTR and DrAFT have flight heritage from MISP and MEADS on the MSL and Mars 2020 missions. The COMARS suite successfully flew on the ESA Schiaparelli EDM lander, and the lessons learned from this mission integration will also be used for DrEAM.

Benefits: Titan’s atmosphere predominantly consists of nitrogen (~98% by mole fraction) with small amounts of methane (~2% by mole) and other trace gases. CN is a strong radiator and is found in nonequilibrium concentrations for Titan entry. The accurate modeling of nonequilibrium CN radiation has proven to be a difficult task. Prompted by the Huygens mission, many experimental campaigns and analyses were performed to better understand the aerothermal environments experienced by the probe during Titan entry. However, the Huygens probe carried no heatshield instrumentation. Therefore, the DrEAM instrumentation suite will significantly advance the state-of-the-art not only by documenting the environment and performance of Dragonfly’s entry system but also by making key measurements in Titan’s atmosphere for the first time, thus providing new benchmark data applicable to entry science more generally. DrEAM will collect temperature, pressure and heat flux environments during entry, as well as inferring the methane abundance in the upper atmosphere.