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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

THE INFLUENCE OF A GRANULAR TARGET'S PACKING DENSITY ON CRATER MORPHOMETRY AND EJECTA KINEMATICS: EXPLORATORY EXPERIMENTATION

With current orbital cameras providing images of planetary surfaces at ever increasing fidelity, it is now possible to resolve meter-scale craters (e.g. [1]). As the morphology and morphometry of small craters have been demonstrated to be sensitive to the physical properties of the impactor and target in both laboratory-based [2,3] and modeling studies [4,5],these newly resolvable features offer an opportunity to probe the near-surface properties of impacted planetary surfaces. In order to robustly infer near-surface structure from craters formed on complex surfaces with poorly known physical properties, it is imperative to understand how small changes in target properties are manifested in the final morphometry of an impact crater. Here, we present early experimental results on the effects of changes in bulk density of granular tar-gets(inclusive of porosity) on crater morphology and the cratering process.

C J Cline↗
NASA NTRS2022

Eta Carinae: An Evolving View of the Central Binary, Its Interacting Winds and Its Foreground Ejecta

FUV spectra of η Car, recorded across two decades with HST/STIS, document multiple changes in resonant lines caused by dissipating extinction in our line of sight. The FUV flux has increased nearly tenfold, which has led to increased ionization of the multiple shells within the Homunculus and photodestruction of H 2 . Comparison of observed resonant line profiles with CMFGEN model profiles allows separation of wind–wind collision and shell absorptions from the primary wind P Cygni profiles. The dissipating occulter preferentially obscured the central binary and interacting winds relative to the very extended primary wind. We are now able to monitor changes in the colliding winds with orbital phase. High-velocity transient absorptions occurred across the most recent periastron passage, indicating acceleration of the primary wind by the secondary wind, which leads to a downstream, high-velocity bow shock that is newly generated every orbital period. There is no evidence of changes in the properties of the binary winds.

Massive stars↗
NASA NTRSDate not supplied

As Seen by Parker Solar Probe: In-Situ Signatures of Wave-Particle Interactions Driven by Solar Ejecta

Parker Solar Probe (PSP) is sampling regions of the inner heliosphere never seen before to address where and why energy flows between the Sun and earth. With the onset of solar maximum, recent encounters have witnessed the increase in solar activity. We present in-situ signatures of coronal mass ejections and other smaller transients of coronal origin. Using simultaneous measurements from the SWEAP and FIELDS instrument suite, both ion and electron-scale dynamics are investigated in coincidence with both lower frequency electromagnetic and higher frequency electrostatic waves. We present an overview of these wave-particle interaction observations and hypothesize on their role in plasma energization and subsequent solar wind heating.

J. L. Verniero↗