Jahnavi Shah

PhD Student, Planetary Science

2 truths and a lie: Science Edition

Which one of the three paper summaries below do you think is the lie?

  1. Europan impact craters display a large diversity and intermixed morphologies (e.g. central pits and domes). Studying the crater morphologies can provide insight into structure and thickness of the ice shell on Europa. This study performed impact formation numerical simulations using different shell scenarios and a variety of impact conditions (e.g. impactor composition, velocity, and angle) and compared the results to observed crater morphologies in order to determine most probable shell structure. The results suggest that the following two scenarios agree with observed crater morphologies and depth-diameter rations: 1) a fully conductive (thin) ice shell and 2) a conductive lid over a warm convective (thick) ice shell. Assuming that features such as domes and pits form post-impact, the conductive-convective model is preferred.
  2. Irregular satellites around giant planets form vast debris disks as result of their collisional histories. Such a debris disk is expected to be seen around Saturn, however this is inconsistent with the thin disk observed by the Spitzer Space Telescope, mainly concentrated around Phoebe (Saturn’s largest irregular satellite). This study used N-body simulations to create a 3D model of the debris disk in order to assess the particle distribution. The results suggest that larger moons contribute more dust compared to smaller satellites. Phoebe is likely the dominant source of material of the disk and the contribution from the smaller moons is one fourth of contribution from Phoebe.
  3. The Lunar Prospector Neutron Spectrometer mapped polar hydrogen on the Moon. The observed spatial distribution is inconsistent with the expected distribution derived from present-day lunar temperatures. This could be potentially explained by the reorientation of the lunar poles. A lunar true polar wander (TPW) has been suggested based on topographic, gravity, and remnant magnetism studies. This study used a 3D thermochemical convection model to investigate the thermal evolution of the Procellarum region and its influence on reorientation. The results suggest that the thermal anomaly in the region could have been enough to alter the density structure of the Moon, resulting in changing moments on inertia, and thus, a true polar wander.

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