Lori Sherea Glaze

Distributed‐style volcanism is an end member of terrestrial volcanism that produces clusters of small volcanoes when isolated magma bodies ascend from broad magma source regions. Volcano clusters can develop over millions of years, one volcano at a time, and can be used to infer unobserved geologic phenomena, including subsurface stresses and cracks during eruption periods. The Tharsis Volcanic Province covers approximately one‐quarter of the martian surface and hosts a large concentration of small volcanoes that formed from distributed volcanism. We present a catalog of 1,106 small volcanic vents identified within Tharsis Volcanic Province. This catalog includes morphologic measurements for each cataloged vent. Vent lengths range from 71 m to 51 km, widths range from 40 m to 3.1 km, and 90% of vents have lengths at least 1.5 times their widths. Additionally, 90% of edifices associated with vents have topographic prominences 1 Ga are found at the Tharsis periphery in the Tempe‐Mareotis region and Syria Planum. Vents in the Tharsis interior have reported ages <500 Ma. Regional trends in vent orientation and intervent alignment are dependent on nearby central volcanoes and fossae. We use these findings to hypothesize that within the most recent 500 Ma, magma was present under and to the east of the Tharsis Montes and that some of this magma erupted and built hundreds of small volcanoes in this region.

Distributed-style volcanism is an end member of terrestrial volcanism that produces clusters of small volcanoes when isolated magma bodies ascend from broad magma source regions. Volcano clusters can develop over millions of years, one volcano at a time, and can be used to infer unobserved geologic phenomena, including subsurface stresses and cracks during eruption periods. The Tharsis Volcanic Province covers approximately one-quarter of the martian surface and hosts a large concentration of small volcanoes that formed from distributed volcanism. We present a catalog of 1106 small volcanic vents identified within Tharsis Volcanic Province. This catalog includes morphologic measurements for each cataloged vent. Vent lengths range from 71 m to 51 km, widths range from 40 m to 3.1 km, and 90% of vents have lengths at least 1.5 times their widths. Additionally, 90% of edifices associated with vents have topographic prominences 1 Ga are found at the Tharsis periphery in the Tempe-Mareotis region and Syria Planum. Vents in the Tharsis interior have reported ages <500 Ma. Regional trends in vent orientation and intervent alignment are dependent on nearby central volcanoes and fossae. We use these findings to hypothesize that within the most recent 500 Ma, magma was present under and to the east of the Tharsis Montes and that some of this magma erupted and built hundreds of small volcanoes in this region.

Distributed-style volcanism is an end member of terrestrial volcanism that produces clusters of small volcanoes when isolated magma bodies ascend from broad magma source regions. Volcano clusters can develop over millions of years, one volcano at a time, and can be used to infer unobserved geologic phenomena, including subsurface stresses and cracks during eruption periods. The Tharsis Volcanic Province covers approximately one-quarter of the martian surface and hosts a large concentration of small volcanoes that formed from distributed volcanism. We present a catalog of 1106 small volcanic vents identified within Tharsis Volcanic Province. This catalog includes morphologic measurements for each cataloged vent including length, width, orientation, and topographic prominence. Vent lengths range from 71~m to 51~km, widths range from 40 m to 3.1 km, and 90% of vents have lengths at least 1.5 times their widths. Additionally, 90% of edifices associated with volcanic vents have topographic prominences 1 Ga are found at the Tharsis periphery in the Tempe-Mareotis region and Syria Planum. Vents in the Tharsis interior have reported ages <500 Ma. Vent orientations and alignments between vents are dependent on nearby central volcanoes and fossae. We interpret that a broad magma source region, centered to the east of the Tharsis Montes emplaced hundreds of the cataloged vents and the Tharsis Montes rift apron deposits over the last 500 Ma.

NASA’s Planetary Science Division (PSD) and space agencies around the world are collaborating on an extensive array of missions exploring our Solar System. Planetary science missions are conducted by some of the most sophisticated robots ever built and international collaboration is an essential part of what we do. NASA has always encouraged international participation on our missions both strategic (i.e., Mars 2020) and competitive (i.e., Discovery and New Frontiers) and other Space Agencies have reciprocated and invited us to participate in their missions.More specifically, NASA has had a long and fruitful collaboration with ESA on their planetary missions. Currently, NASA is involved in the BepiColombo mission (1 instrument in the Italian Space Agency’s instrument suite), and the Jupiter Icy Moon Explorer mission (one instrument and parts of two others). In concert with ESA’s Mars missions we have an instrument on the Mars Express mission, the orbit-ground communications package on the Trace Gas Orbiter (launched in 2016) and part of the DLR/Mars Organic Molecule Analyzer instruments going onboard the ExoMars Rover. Likewise, NASA’s Mars 2020 rover includes several international payload elements: Spain’s Mars Environmental Dynamics Analyzer (MEDA); Norway’s Radar Imager for Mars' Subsurface Experiment (RIMFAX); and the US SuperCam has a significant contribution from France.In 2016, ESA released a call for proposals in their 5th Medium-sized mission class (referred to as M5) as part of their Cosmic Vision program. ESA once again has been tremendous in welcoming possible cooperative proposals with NASA as in the EnVision orbital mission to Venus. EnVision would perform high-resolution radar mapping and atmospheric studies of Venus.International partnerships are an excellent, proven way of amplifying the scope and sharing the science results of a mission otherwise implemented by an individual space agency. Looking forward, NASA’s Planetary Science Division is initiating the next Decadal Survey, led by the National Academies of Science, Engineering and Mathematics, that will identify priorities for strategic missions in the decade 2023-3032.  There are many exciting destinations within the solar system and these missions will provide new opportunities for international partnership.The exploration of the Solar System is uniquely poised to bring planetary scientists, worldwide, together under the common theme of understanding the origin, evolution, and bodies of our solar neighborhood. NASA’s Planetary Science Division provides the planetary science community with opportunities to include international participation on NASA missions. NASA's Discovery and New Frontiers Programs provide U.S. scientists the opportunity to assemble international teams and design exciting, focused planetary science investigations that would deepen the knowledge of our Solar System. The most recent call for Discovery ideas will soon announce selections as part of Step 1 of the competitive process.  NASA continues to encourage the international science community to take full advantage of the many opportunities provided.

The current goals of the astrobiology community are focused on developing a framework for the detection of biosignatures, or evidence thereof, on objects inside and outside of our solar system. A fundamental aspect of understanding the limits of habitable environments (surface liquid water) and detectable signatures thereof is the study of where the boundaries of such environments can occur. Such studies provide the basis for understanding how a once inhabitable planet might come to be uninhabitable. The archetype of such a planet is arguably Earth's sibling planet, Venus. Given the need to define the conditions that can rule out bio‐related signatures of exoplanets, Venus provides a unique opportunity to explore the processes that led to a completely uninhabitable environment by our current definition of the term. Here we review the current state of knowledge regarding Venus, particularly in the context of remote‐sensing techniques that are being or will be employed in the search for and characterization of exoplanets. We discuss candidate Venus analogs identified by the Kepler and TESS exoplanet missions and provide an update to exoplanet demographics that can be placed in the potential runaway greenhouse regime where Venus analogs are thought to reside. We list several major outstanding questions regarding the Venus environment and the relevance of those questions to understanding the atmospheres and interior structure of exoplanets. Finally, we outline the path toward a deeper analysis of our sibling planet and the synergy to exoplanetary science.

New Horizons flies past MU ₆₉: After flying past Pluto in 2015, the New Horizons spacecraft shifted course to encounter (486958) 2014 MU ₆₉ , a much smaller body about 30 kilometers in diameter. MU ₆₉ is part of the Kuiper Belt, a collection of small icy bodies orbiting in the outer Solar System. Stern et al. present the initial results from the New Horizons flyby of MU ₆₉ on 1 January 2019. MU ₆₉ consists of two lobes that appear to have merged at low speed, producing a contact binary. This type of Kuiper Belt object is mostly undisturbed since the formation of the Solar System and so will preserve clues about that process. Science , this issue p. eaaw9771

Radar bright deposits on Venus that have diffuse margins suggest eruptions that distribute debris over large areas due to ground‐hugging flows from plume collapse. We examine deposits in eastern Eistla, western Eistla, Phoebe, and Dione Regiones using Magellan data and Earth‐based radar maps. The radar bright units have no marginal lobes or other features consistent with viscous flow. Their morphology, radar echo strength, polarization properties, and microwave emissivity are consistent with mantling deposits composed of few centimeters or larger clasts. This debris traveled downhill up to ~100 km on modest slopes and blanketed lava flows and tectonic features to depths of tens of centimeters to a few meters over areas up to 40 × 10³ km². There is evidence for ongoing removal and exhumation of previously buried terrain. A newly identified occurrence is associated with a ridge belt south of Ushas Mons. We also note radar bright streaks of coarse material west of Rona Chasma that reflect the last traces of a deposit mobilized by winds from the formation of Mirabeau crater. If the radar bright units originate by the collapse of eruption columns, with coarse fragmental material entrained and fluidized by hot gases, then their extent suggests large erupted volatile (CO₂ or H₂O) amounts. We propose that these deposits reflect the early stage of renewed magmatic activity, with volatile‐rich, disrupted magma escaping through vents in fractured regions of the upper crust. Rapidly eroding under Venus surface conditions or buried by subsequent eruptions, these markers of recently renewed activity have disappeared from older regions.