Integrated system for filtering, enriching, and detecting trace gases paves the way for high-precision isotopic measurements and resource extraction from the planet's corrosive atmosphere
Venus, often regarded as Earth’s sister planet due to its comparable size and bulk composition, presents an extreme environment and distinctive atmospheric chemistry that not only make it a valuable natural laboratory for planetary science, but also pose unprecedented challenges and opportunities for in situ resource utilization. In a pioneering study published in Planet (Volume, 2 Issue 1), a team led by Researcher Nailiang Cao from the Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, together with Professors Xiaoping Zhang and Yi Xu from the State Key Laboratory of Lunar and Planetary Sciences at Macau University of Science and Technology, proposed an integrated detection strategy combining gas filtration, enrichment, and spectroscopic analysis, thereby offering a promising technical framework for high-precision atmospheric characterization and future resource utilization in Venus exploration missions
At present, our understanding of the Venusian atmosphere relies primarily on decades of remote-sensing observations and a limited number of in situ measurements. Although it is well established that the atmosphere is dominated by carbon dioxide and contains trace amounts of water vapor and sulfur dioxide, while the presence of phosphine and ammonia remains highly debated, decisive evidence is still lacking to resolve key scientific questions concerning Venusian geological activity, the planet’s history of water loss, and even the possible existence of biosignature. At the same time, the near-surface environment of Venus, characterized by pressures of about 90 bar, temperatures exceeding 460°C, and planet-encircling sulfuric acid clouds, poses an extraordinary challenge to any exploratory instrument. Even in currently planned missions such as NASA’s DAVINCI, the onboard tunable laser spectrometer and associated atmospheric instruments are designed to measure key gases and trace compounds during descent, yet high-sensitivity detection of multiple critical trace species and their isotopic signatures remain intrinsically constrained by measurement sensitivity and observational coverage. Although conventional remote-sensing techniques offer the advantage of large-scale global atmospheric coverage, their spectral resolution is often insufficient for high-precision retrieval of isotopic ratios involving C, H, O, N, and S.
To address these challenges, the research team proposed an integrated detection system that combines gas filtration, enrichment, and spectroscopic analysis. The first requirement is to mitigate the effects of the highly corrosive constituents in the Venusian atmosphere, whose cloud layer is dominated by sulfuric-acid aerosols and haze particles. To this end, the team designed a three-stage gradient filtration module incorporating two porous ceramic layers followed by a microporous polytetrafluoroethylene membrane. Working in concert, these multistage filters are intended to remove sulfuric-acid aerosols and solid particulates with diameters as small as 0.1 μm at efficiencies exceeding 99.99%. The module also integrates a thermal self-cleaning unit capable of continuously evaporating residual droplets and periodically removing sulfide deposits through high-temperature bakeout, thereby helping to ensure stable instrument performance during long-duration missions.
The filtered gas is then delivered to an enrichment module, a key component for the high-sensitivity detection of trace gases. Because species such as PH₃, NH₃, and H₂S are present at extremely low concentrations in the Venusian atmosphere, direct detection is often constrained by poor signal-to-noise ratio. The module therefore adopts a two-stage molecular-sieve adsorption scheme: first, a CO₂-selective sieve removes the dominant background gas to achieve preliminary enrichment of the target species; next, a high-selectivity sorbent captures and further concentrates the trace gases. This process effectively increases both target-gas abundance and spectroscopic signal strength, thereby facilitating subsequent high-precision analysis.
Finally, the spectroscopic detection module functions as the “intelligent eye” of the system. By integrating two laser spectroscopic techniques, it provides coordinated coverage from orbital remote sensing to in situ exploration. In remote-sensing mode, the system uses laser heterodyne spectroscopy, in which the target signal is mixed with solar radiation to produce a radio-frequency beat signal; subsequent narrowband filtering and Fourier transformation enable ultra-high-resolution spectral detection. The received signal is then demodulated through lock-in amplification to retrieve the absorption features of trace gases in the Venusian atmosphere, while also supporting target-region selection for lander or probe entry. or in situ exploration at 40–70 km altitude, the system employs OA-ICOS. The pretreated gas sample enters a high-reflectivity optical cavity, where multiple reflections produce a kilometer-scale effective path length and markedly strengthen the absorption signal. By scanning the characteristic absorption lines of isotopes such as H, N, and S, the system can retrieve gas abundances and isotopic ratios, including D/H, ¹⁵N/¹⁴N, and ³⁴S/³²S. Spectral simulations indicate that an operating pressure of about 20 mbar effectively suppresses pressure-broadening interference, achieving an optimal balance between detection sensitivity and fitting accuracy.
The importance of this work resides not only in its highly integrated technological framework, but also in its effective coupling of scientific exploration with in situ resource utilization. Because the Venusian atmosphere is dominated by CO₂ and also contains sulfur-bearing species and trace water, it represents a potentially valuable resource system. Extracted water could be electrolyzed to yield oxygen and hydrogen for life support and fuel production; CO₂ could be converted electrochemically into CO and O₂ for power generation or propellant synthesis; and sulfur species such as SO₂ and H₂S could serve as chemically energetic components of a redox system. In this sense, the key gases targeted by the proposed system are simultaneously scientific tracers and potential resources for future long-duration Venus exploration. The proposed modular design, featuring active and passive thermal control using phase-change materials to withstand the planet’s extreme temperatures, ensures compatibility with various mission architectures, including orbiters, descent probes, and potentially long-duration aerial platforms. This integrated framework promises to deliver multi-scale observations and cross-validated datasets, significantly improving the reliability of our atmospheric models. As the authors note, the rigorous laboratory validation of this system, focusing on heat-resistant materials, ultra-stable laser sources, and enhanced cavity technologies, will not only pave the way for a return to Venus but also establish a robust blueprint for resource-based exploration of other challenging worlds like Mars, Europa, and Titan, fundamentally changing how we approach the sustainable exploration of the solar system.
DOI：10.15302/planet.2026.26007