Explorer of Enceladus and Titan (E2T): Investigating ocean worlds' evolution and habitability in the solar system

Abstract

46Titan, with its organically rich and dynamic atmosphere and geology, and Enceladus, with its 47 active plume, both harbouring global subsurface oceans, are prime environments in which to 48 investigate the habitability of ocean worlds and the conditions for the emergence of life. We 49 present a space mission concept, the Explorer of Enceladus and Titan (E 2 T), which is 50 dedicated to investigating the evolution and habitability of these Saturnian satellites. E 2 T is 51 proposed as a medium-class mission led by ESA in collaboration with NASA in response to 52 ESA's M5 Cosmic Vision Call. E 2 T proposes a focused payload that would provide in-situ 53 composition investigations and high-resolution imaging during multiple flybys of Enceladus 54 and Titan using a solar-electric powered spacecraft in orbit around Saturn. The E 2 T mission 55 would provide high-resolution mass spectrometry of the plume currently emanating from 56 Enceladus' south polar terrain and of Titan's changing upper atmosphere. In addition, high-57 resolution infrared (IR) imaging would detail Titan's geomorphology at 50-100 m resolution 58 and the temperature of the fractures on Enceladus' south polar terrain at meter resolution. 59 These combined measurements of both Titan and Enceladus would enable the E 2 T mission 60 scenario to achieve two major scientific goals: 1) Study the origin and evolution of volatile-61 rich ocean worlds; and 2) Explore the habitability and potential for life in ocean worlds. E 2 T's 62 two high-resolution time-of-flight mass spectrometers would enable resolution of the 63 ambiguities in chemical analysis left by the NASA/ESA/ASI Cassini-Huygens mission 64 regarding the identification of low-mass organic species, detect high-mass organic species for 65 the first time, further constrain trace species such as the noble gases, and clarify the evolution 66 of solid and volatile species. The high-resolution IR camera would reveal the geology of 67 Titan's surface and the energy dissipated by Enceladus' fractured south polar terrain and 68 plume in detail unattainable by the Cassini mission.69

Analogue spectra for impact ionization mass spectra of water ice grains obtained at different impact speeds in space

“…Building on the work of Postberg et al, here we adapt laser desorption analogue experiments to mimic a wide range of feasible impact speeds, establishing an experimental methodology to predict and reproduce mass spectra generated by ice grains in the future. This will improve quantitative compositional analysis of mass spectra produced by impact ionization mass spectrometers on board not only Cassini, but also on future spacecraft intended to investigate icy moons, such as the Europa Clipper and Enceladus missions …”

Experimental and Simulation Efforts in the Astrobiological Exploration of Exooceans

“…They could characterise the plume material in detail and not only gave the first solid evidence for the existence of a subsurface ocean (Postberg et al 2009b), but further constrained properties like temperature, salinity and pH, and also the organic material emerging from the subsurface ocean (Postberg et al 2008(Postberg et al , 2009b(Postberg et al , 2011bGlein et al 2015;Postberg et al 2018b). Currently several mission concepts with an advanced in situ payload that builds upon the successful Cassini instruments have been developed (Lunine et al 2015;Reh et al 2016;Mitri et al 2018).…”

“…The instrument configuration is shown in the schematic on the bottom right (adapted from Postberg et al 2018b) et al 2012; Paganini et al 2019). The experiment is currently optimised for impact ionisation detectors like the CDA, the SUrface Dust Analyser (SUDA) (Kempf et al 2012) or the ENceladus Ice Analyzer (ENIA) (Lunine et al 2015;Reh et al 2016;Mitri et al 2018) but in the near future will be capable to simulate spectra of ice grains as they will appear in neutral gas mass spectrometers like INMS (Waite et al 2004), MASPEX (Brockwell et al 2016), or PEP-NIM (Barabash et al 2013).…”

“…The resulting atomic, molecular, and macroscopic fragments are then analysed using mass spectrometers. The inclusion of such spectrometers on board of future space missions (Kempf et al 2012;Lunine et al 2015;Reh et al 2016;Mitri et al 2018;Brockwell et al 2016;Barabash et al 2013) could help to detect potential characteristic patterns of biosignatures like amino acids, fatty acids, and peptides (Davila and McKay 2014;Creamer et al 2017;Klenner et al 2020a;Georgiou and Deamer 2014). At present, these in situ measurements are cost effective alternatives to sample return mission concepts.…”

Reduction of Saturn Orbit Insertion Impulse Using Deep-Space Low Thrust

“…Then, E 2 T is a medium-class mission to Enceladus and Titan led by ESA in collaboration with NASA and designed in response to ESA's M5 Cosmic Vision Call. E 2 T, which will use solar-electric power, aims at a launch opportunity in 2030 [52]. Finally, TSSM, originally proposed to launch in 2020 and then superseded by the Europa Jupiter System Mission, may be revived and continues to be studied for a later launch date.…”