Stability analysis of the Martian obliquity during the Noachian era

Mars in the aftermath of a colossal impact

The abundance of highly siderophile elements (HSEs) inferred for Mars' mantle from martian meteorites implies a Late Veneer (LV) mass addition of ~0.8 wt% with broadly chondritic composition. Late accretion to Mars by a differentiated Ceres-sized (~1000 km diameter) object can account for part of the requisite LV mass, and geochronological constraints suggests that this must have occurred no later than ca. 4480 Ma. Here, we analyze the outcome of the hypothetical LV giant impact to Mars with smoothed particle hydrodynamics simulations together with analytical theory. Results show that, in gene…

火星中混凝土尺寸的预测：来自两个独立约束输入的预测：大气尘粒大小和倾角驱动的湿润持续时间

Martian concretion sizes predicted from two independently constrained inputs: atmospheric dust grain size and obliquity-forced wetting duration

研究通过大气尘粒大小和倾角驱动湿润持续时间两个独立约束输入，揭示火星混凝土尺寸一致性源于全球统一的细尘颗粒限制生长，形成机制与液态水接触尘土有关，且每个混凝土记录单一湿润事件。

Obliquity dependence of the formation of the martian polar layered deposits

Mars' polar layered deposits (PLD) are comprised of layers of varying dust-to-water ice volume mixing ratios (VMR) that may record astronomically-forced climatic variation over Mars' recent orbital history. Retracing the formation of these layers by quantifying the sensitivity of deposition rates of polar material to astronomical forcing is critical for the interpretation of this record. Using a Mars global climate model (GCM), we investigate the sensitivity of annual polar water ice and dust surface deposition to various obliquities and surface water ice distributions at zero eccentricity, pr…

Evidence of Low-latitude Fluvial and Glacial Activity during the Martian Amazonian Era

The Martian obliquity cycle is predominately influenced by Solar and Jovian tidal forces. The present-day axial tilt of Mars (25 degrees) is predicted to cycle between 0 degrees and 60 degrees (Mischna & Richardson 2005) with excursions up to 80 degrees(Laskar et al. 2004). We focused on Arabia Terra, a region especially well-suited for studying glacial migration due to its location in the northern mid-latitude (20-40 degrees North, 0-30 degrees East) zone, and its heavily cratered terrain. We created glacial and fluvial morphology distribution maps with the ESRI Aeronautical Reconnaissance Co…

Outgassing History and Escape of the Martian Atmosphere and Water Inventory

The evolution and escape of the martian atmosphere and the planet's water inventory can be separated into an early and late evolutionary epoch. The first epoch started from the planet's origin and lasted $\sim$500 Myr. Because of the high EUV flux of the young Sun and Mars' low gravity it was accompanied by hydrodynamic blow-off of hydrogen and strong thermal escape rates of dragged heavier species such as O and C atoms. After the main part of the protoatmosphere was lost, impact-related volatiles and mantle outgassing may have resulted in accumulation of a secondary CO$_2$ atmosphere of a few…

早期火星中低气压大气下的季节性融化

Seasonal thaws under mid-to-low pressure atmospheres on Early Mars

针对早期火星黯淡年轻太阳悖论，本研究利用ESTM模型和EOS辐射传输代码，发现1.3-2.0巴CO₂主导的大气在合适轨道参数下可产生季节性融化，中等含量CH₄可拓宽其参数空间。