The Planetary Science Journal
EISSN : 2632-3338
Published by: American Astronomical Society (10.3847)
Total articles ≅ 294
Latest articles in this journal
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac24aa
As the number of detected rocky extrasolar planets increases, the question of whether their surfaces could be habitable is becoming more pertinent. On Earth, the long-term carbonate-silicate cycle is able to regulate surface temperatures over timescales larger than one million years. Elevated temperatures enhance weathering, removing CO2 from the atmosphere, which is subducted into the mantle. At mid-ocean ridges, CO2 is supplied to the atmosphere from the interior. The carbon degassing flux is controlled by the melting depth beneath mid-ocean ridges and the spreading rate, influenced by the pressure- and temperature-dependent mantle viscosity. The influences of temperature and pressure on mantle degassing become increasingly important for more massive planets. Here, we couple a thermal evolution model of Earth-like planets of different masses with a model of the long-term carbon cycle and assess their surface temperature evolution. We find that the spreading rate at 4.5 Gyr increases with planetary mass up to 3 Earth masses, since the temperature dependence of viscosity dominates over its pressure dependency. For higher-mass planets, pressure dependence dominates and the plates slow down. In addition, the effective melting depth at 4.5 Gyr as a function of planetary mass has its maximum at 3 M⊕. Altogether, at 4.5 Gyr, the degassing rate and therefore surface temperature have their maximum at 3 M⊕. This work emphasizes that both age and mass should be considered when predicting the habitability of exoplanets. Despite these effects, the long-term carbon cycle remains an effective mechanism that regulates the surface temperature of massive Earth-like planets.
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac214c
Central stages in the evolution of rocky, potentially habitable planets may play out under atmospheric conditions with a large inventory of nondilute condensable components. Variations in condensate retention and accompanying changes in local lapse rate may substantially affect planetary climate and surface conditions, but there is currently no general theory to effectively describe such atmospheres. In this article, expanding on the work by Li et al., we generalize the single-component moist pseudoadiabat derivation in Pierrehumbert to allow for multiple condensing components of arbitrary diluteness and retained condensate fraction. The introduction of a freely tunable retained condensate fraction allows for a flexible, self-consistent treatment of atmospheres with nondilute condensable components. To test the pseudoadiabat's capabilities for simulating a diverse range of climates, we apply the formula to planetary atmospheres with compositions, surface pressures, and temperatures representing important stages with condensable-rich atmospheres in the evolution of terrestrial planets: a magma ocean planet in a runaway greenhouse state; a post-impact, late-veneer-analog planet with a complex atmospheric composition; and an Archean Earth-like planet near the outer edge of the classical circumstellar habitable zone. We find that variations in the retention of multiple nondilute condensable species can significantly affect the lapse rate and in turn outgoing radiation and the spectral signatures of planetary atmospheres. The presented formulation allows for a more comprehensive treatment of the climate evolution of rocky exoplanets and early Earth analogs.
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac260d
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac19a5
Mars Polar Science is a subfield of Mars science that encompasses all studies of the cryosphere of Mars and its interaction with the Martian environment. Every 4 yr, the community of scientists dedicated to this subfield meets to discuss new findings and debate open issues in the International Conference on Mars Polar Science and Exploration (ICMPSE). This paper summarizes the proceedings of the seventh ICMPSE and the progress made since the sixth edition. We highlight the most important advances and present the most salient open questions in the field today, as discussed and agreed upon by the participants of the conference. We also feature agreed-upon suggestions for future methods, measurements, instruments, and missions that would be essential to answering the main open questions presented. This work is thus an overview of the current status of Mars Polar Science and is intended to serve as a road map for the direction of the field during the next 4 yr and beyond, helping to shape its contribution within the larger context of planetary science and exploration.
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac1c6b
We present the discovery of 2013 VZ70, the first known horseshoe coorbital companion of Saturn. Observed by the Outer Solar System Origins Survey for 4.5 yr, the orbit of 2013 VZ70 is determined to high precision, revealing that it currently is in "horseshoe" libration with the planet. This coorbital motion will last at least thousands of years but ends ∼10 kyr from now; 2013 VZ70 is thus another example of the already-known "transient coorbital" populations of the giant planets, with this being the first known prograde example for Saturn (temporary retrograde coorbitals are known for Jupiter and Saturn). We present a theoretical steady-state model of the scattering population of trans-Neptunian origin in the giant planet region (2–34 au), including the temporary coorbital populations of the four giant planets. We expose this model to observational biases using survey simulations in order to compare the model to the real detections made by a set of well-characterized outer solar system surveys. While the observed number of coorbitals relative to the scattering population is higher than predicted, we show that the number of observed transient coorbitals of each giant planet relative to each other is consistent with a trans-Neptunian source.
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac24ff
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac235f
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac0538
The Martian climate system has been revealed to rival the complexity of Earth's. Over the last 20 yr, a fragmented and incomplete picture has emerged of its structure and variability; we remain largely ignorant of many of the physical processes driving matter and energy flow between and within Mars' diverse climate domains. Mars Orbiters for Surface, Atmosphere, and Ionosphere Connections (MOSAIC) is a constellation of ten platforms focused on understanding these climate connections, with orbits and instruments tailored to observe the Martian climate system from three complementary perspectives. First, low-circular near-polar Sun-synchronous orbits (a large mothership and three smallsats spaced in local time) enable vertical profiling of wind, aerosols, water, and temperature, as well as mapping of surface and subsurface ice. Second, elliptical orbits sampling all of Mars' plasma regions enable multipoint measurements necessary to understand mass/energy transport and ion-driven escape, also enabling, with the polar orbiters, dense radio occultation coverage. Last, longitudinally spaced areostationary orbits enable synoptic views of the lower atmosphere necessary to understand global and mesoscale dynamics, global views of the hydrogen and oxygen exospheres, and upstream measurements of space weather conditions. MOSAIC will characterize climate system variability diurnally and seasonally, on meso-, regional, and global scales, targeting the shallow subsurface all the way out to the solar wind, making many first-of-their-kind measurements. Importantly, these measurements will also prepare for human exploration and habitation of Mars by providing water resource prospecting, operational forecasting of dust and radiation hazards, and ionospheric communication/positioning disruptions.
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac25ed
The Planetary Science Journal, Volume 2; https://doi.org/10.3847/psj/ac1f22
The current data formatting and labeling standards for the Planetary Data System (PDS) are known as the PDS4 Standards. They supersede the PDS3 Standards, but they represent a complete redesign of the requirements and implementation, rather than even a major incremental revision, from the previous standard. At the heart of the PDS4 Standards lies a fundamental, philosophical change from the PDS3 paradigm: the PDS4 Standards clearly and specifically constrain the way that the bytes comprising observational data may be stored in their data files—that is, the data structures—to a much greater degree than the PDS3 Standards ever did, even in their most mature realization. In PDS4, the PDS has defined data structures optimized for the long-term preservation of observational data. We explore the history of the PDS and its standards through the examination of a single, simple data structure (the 2D image), to understand the evolutionary pressures on the data and on the PDS that led to the development of the archival data structure requirements for observational data at the core of the PDS4 standards.