Abstract EANA2025-13

Fiber optic sensors [1] are resilient to electromagnetic noise and require low power, whilst having low weight and high structural flexibility. The European Space Agency (ESA) made use of those properties when it implemented optical sensors in the GAIA and JUICE missions [2]. Herein, we call attention to the potentialities of fiber optical chemical sensors (FOCS) [3,4] for space applications and showcase ongoing efforts to build space mission-dedicated prototypes. We suggest these should be considered for the new generation of in-situ chemical characterization techniques [5].

We are currently developing extrinsic fluorescent FOCS. Extrinsic FOCS use an optical fiber only to transport light to and from a responsive material, in opposition to the fiber being the sensor itself, thus allowing for higher analyte specificity. Also, we focused on fluorescent responsive materials to maximize the analyte sensitivity. We developed a membrane sensitive to alkene molecules on hydrocarbon environments, being simultaneously specific to 1,3-butadiene (C4H6). The developed chemodosimeter [6] can detect alkene molecules in Titan’s methane-ethane lakes, where alkene moieties are likely reactants towards more complex organic products. Our special interest in 1,3-butadiene arises from the fact that it is the simplest conjugated hydrocarbon that can exist in the lakes of Titan, making it a likely component of Titan’s “organic rocks” [7]. Despite being predicted to form in the atmosphere [8], 1,3-butadiene was not yet detected on Titan. A future FOCS based on this membrane would address the limitations of both mass spectrometry and infrared spectroscopy in differentiating, in-situ, between hydrocarbon isomers.

We are also currently expanding the sensing capacities of FOCS to characterize the water oceans of icy moons. Inspired by previous applications to marine environments [9], we are developing pH FOCS to benchmark this technology against alternative pH meters appropriate for extraterrestrial environments such as Enceladus’ alkaline subsurface ocean [10]. So far, the immobilization of known pH indicators in polymeric membranes demonstrated negligible leaching in aqueous solutions and fast responses to ammonia-induced pH variations. Our results and experience so far suggest that FOCS should be considered a robust and space-ready chemical characterization technique.

Acknowledgements

The authors acknowledge funding by Fundação para a Ciência e Tecnologia (FCT) (UIDB/00100/2020, UIDP/00100/2020, LA/P/0056/ 2020, UIDB/04565/2020, UIDP/04565/2020, LA/P/ 0140/2020, 2021.04932.BD, and 2024.01442.BD). This work has the financial support of FCT for project ORIGINS (2022.05284.PTDC).

References

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