Search Publications
Photochemistry of Methane and Ethane in the Martian Atmosphere
Taysum, Benjamin M.; Palmer, Paul I.
We develop an existing 1-D photochemistry model to include a comprehensive description of organic chemistry on Mars that includes the oxidation products of methane (CH4) and ethane (C2H6),a longer-chain hydrocarbon that can be used to differentiate between abiotic and biotic surface releases of CH4. We f…
Nondetection of Radio Emissions From Titan Lightning by Cassini RPWS
Gurnett, D. A.; Kurth, W. S.; Fischer, G. +1 more
The Saturn-orbiting Cassini spacecraft completed 126 close Titan flybys from 2004 until 2017. During almost all of them the Cassini Radio and Plasma Wave Science (RPWS) instrument was turned on to search for radio emissions attributed to Titan lightning. Here we report about their nondetection after close inspection of all Titan flybys throughout …
Postimpact Evolution of the Southern Hale Crater Ejecta, Mars
Balme, M. R.; Brough, S.; Ross, N. +4 more
As one of the youngest large (>100 km wide) impacts on Mars, Hale crater offers a unique opportunity to observe well-preserved deposits of Mars' former interior. We utilize visible imagery (Context Camera [CTX] and High Resolution Imaging Science Experiment [HiRISE]) and elevation data (Mars Orbiter Laser Altimeter [MOLA], High Resolution Stere…
Distribution of Eruptive Centers on Top of Large Shield Volcanoes in the Inner Solar System: General Classification and Glimpses of Their Subvolcanic Structure
Jacobo-Bojórquez, Rocío.; Cañón-Tapia, Edgardo
Processes that occur beneath a planetary surface control the spatial distribution of volcanic features in a volcanic zone. Volcanic vents frequently form clusters and alignments controlled by the lithospheric structure and the stress field. Previous works have determined the influence of stress at different scales in a volcanic area. In this work,…
Prolonged Lifetime of the Transient Ionized Layer in the Martian Atmosphere Caused by Comet Siding Spring
Gurnett, D. A.; Halekas, J. S.; Morgan, D. D. +4 more
In October 2014, the close encounter between Mars and comet Siding Spring produced a transient ionized layer in the upper atmosphere composed primarily of Mg+ and Fe+ ions. The layer was detected by instruments on three spacecraft, including the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on Mars Expre…
Water Vapor Vertical Profiles on Mars in Dust Storms Observed by TGO/NOMAD
Aoki, S.; Vandaele, A. C.; Daerden, F. +16 more
It has been suggested that dust storms efficiently transport water vapor from the near-surface to the middle atmosphere on Mars. Knowledge of the water vapor vertical profile during dust storms is important to understand water escape. During Martian Year 34, two dust storms occurred on Mars: a global dust storm (June to mid-September 2018) and a r…
Geological Evidence of Planet-Wide Groundwater System on Mars
Ori, Gian Gabriele; Salese, Francesco; Pondrelli, Monica +2 more
The scale of groundwater upwelling on Mars, as well as its relation to sedimentary systems, remains an ongoing debate. Several deep craters (basins) in the northern equatorial regions show compelling signs that large amounts of water once existed on Mars at a planet-wide scale. The presence of water-formed features, including fluvial Gilbert and s…
Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H2 Exosphere
Farrell, W. M.; Killen, R. M.; Tucker, O. J. +1 more
The solar wind implants protons into the top 20-30 nm of lunar regolith grains, and the implanted hydrogen will diffuse out of the regolith but also interact with oxygen in the regolith oxides. We apply a statistical approach to estimate the diffusion of hydrogen in the regolith hindered by forming temporary bonds with regolith oxygen atoms. A Mon…
A Diverse Array of Fluvial Depositional Systems in Arabia Terra: Evidence for mid-Noachian to Early Hesperian Rivers on Mars
Williams, Rebecca M. E.; Fawdon, Peter; Grindrod, Peter M. +4 more
Branching to sinuous ridges systems, hundreds of kilometers in length and comprising layered strata, are present across much of Arabia Terra, Mars. These ridges are interpreted as depositional fluvial channels, now preserved as inverted topography. Here we use high-resolution image and topographic data sets to investigate the morphology of these d…
Subsurface Sediment Mobilization in the Southern Chryse Planitia on Mars
Hauber, E.; Michael, G.; Brož, P. +2 more
The southern part of the smooth plain of Chryse Planitia on Mars hosts a large population of kilometer-sized (from 0.2 to 20 km) landforms spread over a wide area. Based on the investigation of a small part of this area, Komatsu et al. (2016, https://doi.org/10.1016/j.icarus.2015.12.032) p…