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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Disk-satellite interactions

The rate at which angular momentum and energy are transferred between a disk and a satellite which orbit a central mass is calculated. It is shown that the angular momentum and energy transfer at Lindblad resonances tends to increase the satellite's orbit to lowest order in eccentricity, whereas the transfer at corotation resonances tends to decrease it. The results are applied to the interaction between Jupiter and the protoplanetary disk. The angular momentum transfer is shown to be so rapid that substantial changes in both the structure of the disk and the orbit of Jupiter must have taken place on a time scale of a few thousand years.

Goldreich, P.↗
NASA NTRS1979

Dynamics of the accumulation process of the Earth group of planets: Formation of the reverse rotation of Venus

A numerical simulation of the process of formation of the terrestrial planets is carried within the framework of a new theory for the accumulation of planetary and satellite systems. The numerical simulation permitted determining the parameters of the protoplanetary disk from which Mercury, Venus and the Earth were formed as result of the evolution. The acquisition of a slow retrograde rotation for Venus was discovered during the course of the investigation, whereas Mercury and the Earth acquired direct rotation about their axes. Deviations of the semimajor axes of these three planets as well as the masses of the Earth and Venus from the true values are small as a rule (l 10%). It is shown that during the accumulation of the terrestrial planets, there existed a profound relationship between the process of formation of the orbits and masses of the planet and the process of formation of their rotation about their axes. Estimates are presented for the radii of the initial effective bodies and the time of evolution for the terrestrial accumulation zone.

Koslov, N. N.↗
NASA NTRS2026

Isotopic Evidence for A Cold and Distant Origin of 3I/Atlas

Interstellar objects provide the only directly observable samples of icy planetesimals formed around other stars, and can therefore provide insight into the diversity of physical and chemical conditions occurring during exoplanet formation1−3. Here we report isotopic measurements of the interstellar comet 3I/ATLAS, which reveal an elemental composition unlike any Solar System body. The water in 3I/ATLAS is enriched in deuterium, at a level of D/H = (0.98 ± 0.06)%, which is more than an order of magnitude higher than in known comets, while its range of 12 C/ 13 C ratios (141–191 for CO 2 and 123–172 for CO) exceeds typical values found in the Solar System, as well as nearby interstellar clouds and protoplanetary disks. Such extreme isotopic signatures indicate formation at temperatures ≲ 30 K in a relatively metal-poor environment. When interpreted with respect to models for Galactic chemical evolution, the carbon isotopic composition implies that 3I/ATLAS may have accreted as long ago as 12 billion years, following a period of intense, early star formation. 3I/ATLAS thus represents a preserved fragment of an ancient planetary system.

Martin A Cordiner↗
NASA NTRS2026

Isotopic Signature of Organic Molecules from Beyond the Solar System: An Enriched Methane D/H Ratio in the Interstellar Object 3I/ATLAS

Interstellar objects are interlopers from other planetary systems, and their volatile compositions provide a glimpse into planet formation around their host star. We present near-infrared spectra of the coma of interstellar object 3I/ATLAS measured with the James Webb Space Telescope. Our results demonstrate an unexpectedly high D/H = (3.31 ± 0.34)% for methane and represent an exceedingly rare detection of deuterated organic molecules in an interstellar object. This D/H ratio is a factor of 14 ± 2 higher than that measured in comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft, the only other comet for which CH3D has been detected, yet the ratio of deuteration in methane compared with water is consistent for both comets within 1.2σ. The D/H ratio in methane is observationally unconstrained in extrasolar sources to date, but the enriched ratio in 3I/ATLAS is most similar to those measured in other organic molecules toward primitive environments. The high D/H ratios of water and methane in 3I/ATLAS are a natural consequence of formation in a high D/H elemental ratio environment as a result of locally cold conditions in the protoplanetary disk and prior interstellar cloud. Thus, 3I/ATLAS formed in an environment very different from that in which our Sun and planets originated.

Interstellar Object 3I/ATLAS↗