IcarusPub Date : 2025-07-05DOI: 10.1016/j.icarus.2025.116734
Mikkel Bregnhøj , Svend J. Knak Jensen , Jan Thøgersen , Kai Finster
{"title":"Exploring the impact of wind-driven saltation on methane in the atmosphere of Mars","authors":"Mikkel Bregnhøj , Svend J. Knak Jensen , Jan Thøgersen , Kai Finster","doi":"10.1016/j.icarus.2025.116734","DOIUrl":"10.1016/j.icarus.2025.116734","url":null,"abstract":"<div><div>The presence or absence of methane in the atmosphere of Mars has been a matter of intense investigations and debate for decades. Current theories and observations require some as-yet unidentified mechanism that can remove methane from the lower martian atmosphere on a timescale of a few weeks or less.</div><div>In this work, we experimentally tested if methane sequestration by wind-driven saltation of martian surface minerals can explain the observations. Triboelectric charging of sand particles during the frequent martian dust storms could potentially provide the energy needed to chemically sequester methane and thereby act as a sink for methane on Mars. We performed laboratory experiments with basaltic martian mineral analog sand from Gufunes, Iceland, which was abraded by tumbling end-over-end in a container made from a monolithic block of the same mineral. In this way, wind-driven saltation was simulated in an all-basalt environment with minimal interference from wall-effects.</div><div>The results show that methane is not affected during more than 100 terrestrial days of simulated saltation in the all-basalt environment. This stands in contrast to similar experiments using quartz or glass simulation containers. Furthermore, methane remains unaffected by saltation in the presence of excess amounts of Mars-relevant oxidants, such as oxygen and perchlorate salt, which again contrasts to experiments performed in glass containers. However, methane is oxidized to carbon dioxide in the presence of reactive hypochlorite salt. Our results are discussed in the context of recent reports on the chemistry of oxychlorine species on Mars, and they highlight the need to account for wall-effects in experimental simulations of wind-driven saltation in planetary environments.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116734"},"PeriodicalIF":2.5,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IcarusPub Date : 2025-07-04DOI: 10.1016/j.icarus.2025.116732
Wendy M. Calvin , Samuel F.A. Cartwright , Ava E. Covington
{"title":"Physical characteristics of Martian south polar ices determined by spatial- and intimate-mixture modeling","authors":"Wendy M. Calvin , Samuel F.A. Cartwright , Ava E. Covington","doi":"10.1016/j.icarus.2025.116732","DOIUrl":"10.1016/j.icarus.2025.116732","url":null,"abstract":"<div><div>Twenty-one spectral types for the perennial Martian south polar ices were determined from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data using k-means clustering. These data are higher spatial resolution than any previous measurement of these ices. We present both linear and radiative transfer models of those CRISM spectral types to determine the relative abundance and effective grain size of the three components that make up these surfaces: carbon dioxide ice, water ice and non-ice material. Most cluster means are well represented by a linear combination of five spectra, two types of CO<sub>2</sub> ice, two types of water ice and a non-ice surface. To first order, each CRISM pixel is comprised of sub-pixel spatial mixtures of these five. We then use radiative transfer models to determine the best fit effective grain size and relative abundance of the five components. We use a relatively featureless area of the polar layered deposits for the non-ice component. Our models are consistent with prior modeling work and show very large grain sizes (mm to cm) in the residual CO<sub>2</sub> with very small amounts of water (<0.04 wt%). Water dominated terrains have a wide range of grain sizes but are uniformly ∼80 % water ice. We identify a unique spectral type (C1) that does not have an equivalent in prior studies and may represent CO<sub>2</sub> ice deposited when the atmosphere contained less water vapor following the dust storm of MY28.</div></div><div><h3>Plain language summary</h3><div>Ices at the south pole of Mars show absorption features associated with water ice, carbon dioxide ice and non-ice material. Prior work identified twenty-one spectral types that range in appearance from only carbon dioxide ice (CO<sub>2</sub>) to only water ice (H<sub>2</sub>O) with many mixtures in between these two. For the first time we model these mixed spectra using both linear least squares statistical approaches and more sophisticated models that account for the interaction of light with individual material grains where different grains are closely packed together. Most mixed spectra are well matched by the simple linear least squares fit of five different components. We then model those five components using the close-packing model. We find for the CO<sub>2</sub> only ices the grains are very large and have minute amounts of water. For water ice dominated spectra they consistently are ∼80 % water 20 % non-ice material. One spectral type is unique and may reflect special conditions that occurred during one year when Mars experienced a large global dust storm.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116732"},"PeriodicalIF":2.5,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IcarusPub Date : 2025-07-03DOI: 10.1016/j.icarus.2025.116730
Denggao Qiu , Jianguo Yan , Jun Huang
{"title":"Explosive volcanic eruption at Lassell Massif: Implications for lunar silicic volcanism","authors":"Denggao Qiu , Jianguo Yan , Jun Huang","doi":"10.1016/j.icarus.2025.116730","DOIUrl":"10.1016/j.icarus.2025.116730","url":null,"abstract":"<div><div>Volcanism manifests as either calm effusive or violent explosive eruptions depending on the gas content of the atmosphere and water interactions. Explosive volcanic eruptions on the Moon are limited by the lack of atmosphere and water; however, recent remote sensing and numerical modeling results suggest that the Moon may have been wet in the past, and thus influenced the form of volcanic eruptions. Lunar morphology, spectral and gravity data are used in this work. Investigations of the topography, chemical composition, and subsurface structure of the Lassell Massif using an oxide content inversion model and a three-dimensional density inversion model reveal that explosive volcanic eruptions did in fact occur on the Moon. A negative ellipsoidal density anomaly with a value of ∼ − 230.5 kg/m<sup>3</sup> was identified beneath the northern portion of the Lassell Massif, suggesting that it is a silicic magma chamber. Furthermore, an investigation of the topography and chemical composition of the area shows that magma was ejected to the south. This research provides suggestive insights into the possible presence of endogenic water or other volatile species are present on the Moon. In the future, locations associated with silicic volcanism will be the preferred targets for further lunar investigations of endogenous water.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116730"},"PeriodicalIF":2.5,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144564035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IcarusPub Date : 2025-07-03DOI: 10.1016/j.icarus.2025.116725
Anna-Irene Landi , Michael Gaft , Cristian Carli , Fabrizio Capaccioni , Giovanni Pratesi
{"title":"Insights into the mineralogy of the Rantila aubrite: A luminescence and VNIR reflectance spectroscopy study","authors":"Anna-Irene Landi , Michael Gaft , Cristian Carli , Fabrizio Capaccioni , Giovanni Pratesi","doi":"10.1016/j.icarus.2025.116725","DOIUrl":"10.1016/j.icarus.2025.116725","url":null,"abstract":"<div><div>Rantila aubrite fell in Rantila, Gujarat, India, in August 2022. This study aims to investigate the mineralogy and mineral-chemistry of three fragments of this meteorite and correlate them with reflectance spectroscopy in the visible and near-infrared spectral range (VNIR) and Laser-Induced Time-Resolved Luminescence (LITRL). Aubrites very low Fe<sup>2+</sup> content prevents luminescence quenching under UV light exposure, allowing these meteorites to exhibit well-defined luminescence. The investigated samples have different appearances. One consists of a light-coloured portion primarily composed of FeO-free enstatite, along with forsterite, diopside, plagioclase, minor sulphides (troilite, alabandite, daubréelite, and (Fe,Ca,Mn,Mg)S), and kamacite. The second sample is composed mainly of the same light-coloured portion and hosts a dark forsterite clast. The third sample is mainly made of dark glass. Minor terrestrial weathering is observed, with the detection of sporadic iron oxides/hydroxides. The chemical composition of the detected phases indicates highly reducing conditions during the formation, as expected for an aubrite. The mineral chemistry is similar among the different fragments in terms of major elements concentrations; some differences are observed for minor elements. Luminescence spectra indicate Cr<sup>3+</sup> and Mn<sup>2+</sup> as activators in diopside and forsterite, respectively, for two of the three samples. Ce<sup>3+</sup> is the activator in the third sample, which lacks forsterite and has lower Cr<sub>2</sub>O<sub>3</sub> contents in diopside compared to the other two samples. Therefore, the differences in mineral chemistry observed through electron microprobe analysis (EPMA) are further emphasized by luminescence data. Investigating the luminescence behaviour could provide a valuable contribution to the mineralogical-petrological study of these materials. VNIR reflectance spectra are consistent with low Fe<img>Ca pyroxene and forsterite. The main absorption typical of mafic minerals (∼0.9 μm) is deeper than what has previously been observed in aubrites: this can be related to the slightly higher FeO concentrations, which, despite being very low (<0.4 wt%), still contribute to the absorption. Absorption features at ∼1.4 μm and ∼1.9 μm are consistent with low terrestrial weathering presence. Increasing the knowledge of the correlation between spectral properties and mineralogy/mineral chemistry on highly reduced meteorites will be useful for future investigation of Mercury with the ESA's BepiColombo mission, specifically for the interpretation of the data expected from the Spectrometer and Imagers for MPO BepiColombo Integrated Observatory SYStem (SIMBIO-SYS)/Visible and near Infrared Hyperspectral Imager (VIHI) and Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) instruments</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116725"},"PeriodicalIF":2.5,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IcarusPub Date : 2025-07-02DOI: 10.1016/j.icarus.2025.116729
Tetsushi Sakurai , Takuya Ishizaki , Akiko M. Nakamura
{"title":"Experimental study on thermal and mechanical properties of sintered glass materials: Implication for physical properties of primordial porous materials in the solar system","authors":"Tetsushi Sakurai , Takuya Ishizaki , Akiko M. Nakamura","doi":"10.1016/j.icarus.2025.116729","DOIUrl":"10.1016/j.icarus.2025.116729","url":null,"abstract":"<div><div>Planetesimals underwent consolidation processes in the early solar system, which altered their thermal and mechanical properties. Sintering—a process that forms solid necks between particles—is considered one such process in planetesimals, influencing their filling factor, or porosity, as well as their thermal and mechanical properties.</div><div>In this study, to better constrain and understand the thermal and mechanical properties of planetesimals that evolved from initially powdery or granular bodies, as well as those of boulders on small bodies, which are considered remnant planetesimals, we prepared porous sintered samples consisting of glass particles with filling factors ranging from 0.35 to 0.75, corresponding to porosities of 65 % to 25 %. We then measured their thermal diffusivity, elastic wave velocity, and flexural strength, and derived empirical relationships for the normalized values—scaled by those at a filling factor of 1—as functions of filling factor or porosity. The normalized thermal diffusivities and elastic wave velocities of the sintered glass materials in this study showed similar dependencies on the filling factor. Moreover, the upper limits of the normalized elastic wave velocities were consistent with those of snow at corresponding filling factors, suggesting that these upper limits may be independent of the matrix material.</div><div>The derived empirical relationships apply to materials with porosities higher than those of meteorites. We estimated the porosity of a low-thermal-inertia boulder on the surface of asteroid Ryugu based on its thermal inertia, assuming no influence from internal cracks. The result suggests that the boulder's porosity may be higher than values previously reported, and should be regarded as one of the possible porosity estimates.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116729"},"PeriodicalIF":2.5,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IcarusPub Date : 2025-07-01DOI: 10.1016/j.icarus.2025.116726
Emily L. Mason , Scott D. Guzewich , Christopher Edwards , Álvaro Vicente-Retortillo , Daniel Viúdez-Moreiras
{"title":"Comparing Navcam dust devil detections to transient daytime convective vortex signatures in REMS pressure and ultraviolet data","authors":"Emily L. Mason , Scott D. Guzewich , Christopher Edwards , Álvaro Vicente-Retortillo , Daniel Viúdez-Moreiras","doi":"10.1016/j.icarus.2025.116726","DOIUrl":"10.1016/j.icarus.2025.116726","url":null,"abstract":"<div><div>The Mars Science Laboratory (MSL) Curiosity rover has collected over seven Mars Years (MY) of meteorological data. We compare visible dust devil detections in Navigational Camera (Navcam) observations to signatures detected using the Rover Environmental Monitoring Station (REMS) pressure and Ultraviolet (UV) Sensors. Using methodology from previous work, we search for pressure drops and corresponding transient decreases in the UV signal to detect dust-laden vortex signatures that can be compared to dust devil detections from Navcam. Results from these detections show a strong seasonality and topographical influence in pressure drops, but coincident UV drops, which are indicative of dust-laden vortices, tend to be more frequent in certain locations and do not strictly follow this seasonality. Diurnal patterns in dust devil detections by REMS compare well with Navcam detections, with a strong increase in these detections near 10:00 LTST, a peak near local noon, a gradual decrease in afternoon hours, and some interannual variability. UV detections fall off towards Marker Band Valley, an area with high surface thermal inertia and limited sand cover, as do Navcam detections, suggesting that sand availability plays an important role in where dust devils are forming.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116726"},"PeriodicalIF":2.5,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144571874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IcarusPub Date : 2025-06-29DOI: 10.1016/j.icarus.2025.116704
Catriona H. McDonald , Amy Bonsor , Auriol S.P. Rae , Paul B. Rimmer , Richard J. Anslow , Zoe R. Todd
{"title":"Constraining the survival of HCN during cometary impacts","authors":"Catriona H. McDonald , Amy Bonsor , Auriol S.P. Rae , Paul B. Rimmer , Richard J. Anslow , Zoe R. Todd","doi":"10.1016/j.icarus.2025.116704","DOIUrl":"10.1016/j.icarus.2025.116704","url":null,"abstract":"<div><div>Cometary impacts have been invoked as an atmosphere-independent method of stockpiling hydrogen cyanide (HCN), a key prebiotic feedstock molecule, into environments favourable for the onset of prebiotic chemistry on the early Earth. This work revisits the prospects for cometary delivery of HCN through new impact simulations of idealised cometary bodies using the shock physics code iSALE combined with simple chemical modelling. Using temperature and pressure profiles for material within spherical, non-porous comets with a high resolution of Lagrangian tracer particles, we assess the survival rate of HCN across a range of impact velocities, sizes, and angles, assuming both steady state and equilibrium chemistry. We find that HCN survival is extremely limited at impact velocities above the escape velocity of the Earth, unless the impact occurs at extreme obliquity (<span><math><mrow><mi>θ</mi><mo>∼</mo><mn>15</mn><mo>°</mo></mrow></math></span>). We present a parametrisation of the survival of HCN as a function of impact velocity, angle, and cometary diameter, which provides an upper limit to survival in more realistic scenarios to aid with future studies investigating the role of comets in the origins of life. Although successful HCN delivery may be possible in our idealised model, we neglect to consider the effect of atmospheric passage, and our results suggest that delivery alone is not likely to be sufficient for the onset of prebiotic chemistry.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116704"},"PeriodicalIF":2.5,"publicationDate":"2025-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IcarusPub Date : 2025-06-27DOI: 10.1016/j.icarus.2025.116721
Nandita Kumari , John Mustard , Timothy D. Glotch
{"title":"Particle size and albedo effects on emissivity spectra of lunar analog minerals and rocks in the intermediate infrared region","authors":"Nandita Kumari , John Mustard , Timothy D. Glotch","doi":"10.1016/j.icarus.2025.116721","DOIUrl":"10.1016/j.icarus.2025.116721","url":null,"abstract":"<div><div>Visible/near-infrared (VNIR) and thermal infrared (TIR) spectroscopy have been widely used to detect and characterize the abundances of silicates across the solar system. Recently, intermediate infrared (IMIR) reflectance spectroscopy (∼4 - 6 μm) has been proposed as a tool to quantify the Mg# in olivine and pyroxene with varying iron, magnesium and calcium content. The lunar surface is composed of rocks with mixed particle sizes and thus quantifying the effects of particle size is extremely important to increase the robustness of IMIR spectroscopy as a tool for lunar surface exploration. Similarly, space weathering has been known to cause optical darkening and affect the spectra of the lunar surface materials across a broad wavelength range. In this study, we have identified the emission features of lunar analog minerals/rocks and their variations with changes in particle sizes and albedo at IMIR wavelengths in simulated lunar environment (SLE). We find that the lunar analog minerals display an increase in emissivity and striking decrease in feature contrast with an increase in particle sizes or decrease in albedo. This study shows that while this wavelength range works well in reflectance space for sample characterization, using it for emissivity measurements via orbital remote sensing or in-situ rovers requires extensive study.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116721"},"PeriodicalIF":2.5,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144564034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IcarusPub Date : 2025-06-27DOI: 10.1016/j.icarus.2025.116702
John P. Ortiz , Kevin W. Lewis , Roger C. Wiens , Philip H. Stauffer , Dylan R. Harp , Harihar Rajaram
{"title":"Modeling barometric pumping of martian methane: Implications for Perseverance sample timing and gas loss from drilled cores","authors":"John P. Ortiz , Kevin W. Lewis , Roger C. Wiens , Philip H. Stauffer , Dylan R. Harp , Harihar Rajaram","doi":"10.1016/j.icarus.2025.116702","DOIUrl":"10.1016/j.icarus.2025.116702","url":null,"abstract":"<div><div>There are many challenges surrounding the interpretation of martian methane signatures. Atmospheric methane variations detected by the Sample Analysis at Mars (SAM) instrument on board the <em>Curiosity</em> rover remain difficult to explain given the lack of a confirmed methane transport mechanism from subsurface sources. Furthermore, the biogenic or abiogenic origin of martian methane cannot be determined outside of isotopic analysis in an Earth-based laboratory. Building on our previous work modeling barometrically driven seepage of methane through fractured rock coupled to a simplified atmospheric mixing scheme, we now use the same model framework to estimate the methane concentration in the shallow subsurface. Our results indicate that subsurface methane levels also exhibit strong seasonal and diurnal variability, with peak concentrations occurring during specific windows of time that depend on both solar and atmospheric forcing.</div><div>This insight has implications beyond Gale crater. At Jezero crater, where the <em>Perseverance</em> rover is collecting samples for potential return to Earth, strategic selection of sampling times could enhance the chances of recovering methane-bearing rock. Our results suggest that the timing of sample collection – both time of day and time of year – can significantly affect the likelihood of capturing methane within the collected cores if barometric pumping is a significant driving factor. Sample timing optimization could increase the potential for detecting organics or signatures of habitability in Mars Sample Return, augmenting the overall scientific return of the Mars 2020 mission and possibly bringing us closer to understanding the origin of methane on Mars. However, a preliminary analysis of methane loss rates from collected samples indicate that unless sample tubes can be sealed within a few hours of collection, the majority mass fraction of methane is likely to escape.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116702"},"PeriodicalIF":2.5,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IcarusPub Date : 2025-06-26DOI: 10.1016/j.icarus.2025.116708
Bhavesh Jaiswal , Nirupam Roy
{"title":"Observability of radio reflections from exoplanet ionospheres with next generation radio telescopes","authors":"Bhavesh Jaiswal , Nirupam Roy","doi":"10.1016/j.icarus.2025.116708","DOIUrl":"10.1016/j.icarus.2025.116708","url":null,"abstract":"<div><div>Much has been learned about exoplanets and their atmospheres in the last three decades with the help of highly sensitive optical telescopes. Limited observations using X-ray telescopes have revealed the presence of ionospheres with very high density plasma around the hot Jupiter HD189733b. Owing to high density, the cutoff frequency of this plasma would lie in the range of few GHz. As the planet goes around the star, we suggest it might be possible to capture the stellar radio emission reflected from the ionosphere of the planet. We find that the reflected spectrum has a slope which is representative of the plasma density profile of the ionosphere and has a cutoff frequency. After investigating the reflection and free-free absorption process in the ionosphere, we find that this reflected signal, though feeble, can be captured by very sensitive radio telescopes operating in the low frequency range. We estimate the reflected signal from the ionosphere of a hot Jupiter and find that the flux ratio of the planet to the star are about <span><math><mrow><mo>∼</mo><mn>0</mn><mo>.</mo><mn>01</mn><mtext>%</mtext></mrow></math></span>. In the view of development of facilities like Square Kilometer Array, it might be possible to capture the reflected radio signal from the ionosphere and constrain the thermal state of the ionosphere.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"441 ","pages":"Article 116708"},"PeriodicalIF":2.5,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144564033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}