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This report concerns several research tasks related to the origin and evolution of planetary atmospheres and the large-scale distribution of volatile elements in the Solar System. These tasks and their present status are as follows: (1) we have conducted an analysis of the volatility and condensation behavior of compounds of iron, aluminum, and phosphorus in the atmosphere of Venus in response to publish interpretations of the Soviet Venera probe XRF experiment data, to investigate the chemistry of volcanic gases, injection of volatiles by cometary and asteroidal impactors, and reactions in the troposphere; (2) we have completed and are now writing up our research on condensation-accretion modeling of the terrestrial planets; (3) we have laid the groundwork for a detailed study of the effects of water transport in the solar nebula on the bulk composition, oxidation state, and volatile content of preplanetary solids; (4) we have completed an extensive laboratory study of cryovolcanic materials in the outer solar system; (5) we have begun to study the impact erosion and shock alteration of the atmosphere of Mars resulting from cometary and asteroidal bombardment; and (6) we have developed a new Monte Carlo model of the cometary and asteroidal bombardment flux on the terrestrial planets, including all relevant chemical and physical processes associated with atmospheric entry and impact, to assess both the hazards posed by this bombardment to life on Earth and the degree of cross-correlation between the various phenomena (NO(x) production, explosive yield, crater production, iridium signature, etc.) that characterize this bombardment. The purpose of these investigations has been to contribute to the developing understanding of both the dynamics of long-term planetary atmosphere evolution and the short-term stability of planetary surface environments.
The present volume on the origin and evolution of planet and satellite atmospheres discusses the chemistry of interstellar gas and grains, planetary accretion, cometary composition, the inventories of asteroid volatiles, key similarities and differences among the terrestrial planets' atmospheric compositions, and planets' atmospheric escape and water loss. Also discussed are planetary atmosphere-planetary interior evolutionary coupling, the atmospheric composition of the outer planets, the structure and composition of giant planet interiors, the tenuous atmosphere of Io, the sources of the atmospheres of the outer solar system's satellites, the present state and chemical evolution of the Titan, Triton, and Pluto atmospheres, and the thermal structure and heat balance of the outer planets.
The James Webb Space Telescope (JWST) is a large-scale space telescope mission designed to study fundamental astrophysical questions ranging from the formation of the universe to the origin of planetary systems and the origins of life. JWSTs orbit design is a Libration Point Orbit (LPO) around the Sun-EarthMoon (SEM) L2 point for a planned mission lifetime of 10.5 years. The launch readiness period for JWST is from Oct 1st, 2018 November 30th, 2018. This paper presents the first launch window analysis for the JWST observatory using finite-burn modeling; previous analysis assumed a single impulsive midcourse correction to achieve the mission orbit. The physical limitations of the JWST hardware stemming primarily from propulsion, communication and thermal requirements alongside updated mission design requirements result in significant launch window within the launch readiness period. Future plans are also discussed.
The James Webb Space Telescope (JWST) is a large-scale space telescope mission designed to study fundamental astrophysical questions ranging from the formation of the universe to the origin of planetary systems and the origins of life. JWSTs orbit design is a Libration Point Orbit (LPO) around the Sun-Earth/Moon (SEM) L2 point for a planned mission lifetime of 10.5 years. The launch readiness period for JWST is from Oct 1st, 2018 November 30th, 2018. This paper presents the first launch window analysis for the JWST observatory using finite-burn modeling; previous analysis assumed a single impulsive midcourse correction to achieve the mission orbit. The physical limitations of the JWST hardware stemming primarily from propulsion, communication and thermal requirements alongside updated mission design requirements result in significant launch window within the launch readiness period. Future plans are also discussed.
The collisional ejection and the coaccretion hypotheses of lunar origin are examined in the context of theories of planetary accretion and of siderophile element abundances in planetary mantles. The information concerning the possible dynamical environments within which the terrestrial planets may have grown and the known abundances of siderophile and chalcophile elements in the mantles of the earth, the moon, and the hypothetical shergottite parent body is used to evaluate the existing hypotheses of lunar origin. The analysis indicates that none of the existing theories concerning lunar origin is fully consistent with observed siderophile element abundances in the lunar and terrestrial mantles.
Solar wind mechanism for origin of planetary rotation, discussing previous calculations of angular velocity and couple acting on planet
Measurements of deuterated methane show that Titan's atmosphere is enriched by at least several times in deuterium compared to the major planets. Potential causative factors for this enrichment are condensation to form tropospheric methane clouds, fractionation occuring over a hypothetical CH4-C2H2 ocean and between the ocean and the clathrate crust beneath, fractionation which occurred during the formation of Titan and fractionation occuring as a result of the evolution of Titan's atmosphere. The greater part of the observed fractionation is probably derived from the formation of Titan and the subsequent evolution of Titan atmosphere driven by photochemistry. The latter process is developed here for the first time. The D/H ratio in a planetary atmosphere is one readily available measure of the origin and evolution of the hydrogen bearing volatiles on the planet. Comparison between D/H ratio in the inner solar system and the outer solar system may pose important constraints on current theories.
The origin and maintenance of planetary magnetic fields are discussed. The discussion is not limited to dynamo theories, although these are almost universally favored. Thermoelectric currents are found to be a possible alternative for Jupiter. Two energy sources for dynamos are considered: convection and precessionally induced fluid flow. The earth is the most favorable planet for precessionally driven dynamo, although Neptune is a possibility. Jupiter is likely to have a convectionally driven dynamo, as may Saturn, but the relevant properties of Saturn are not yet well known. Conclusions for each planet are given.
Main sequence star rotation and planetary system origin
There has been a long-standing perspective in the planetary engineering community that the use of planetary protection sterilization techniques such as dry heat microbial reduction (DHMR) have led to significant mission failures in the past. This perception has led to a hesitation to craft mission designs that incorporate sterilization beyond the component-level. Via interviews with long-standing members of the planetary engineering community across the Agency, we have identified the root historical missions that have driven this perspective. The source, or Origin Story, which has been passed down to subsequent generations of engineers, is the failures tied to the early series of the Ranger missions. In this presentation, we examine the details behind the Ranger failures, the majority of which are non-planetary protection sterilization-related, and bring to light the myth of this perception.
NASA Planetary Program for study of origin, evolution, planetary composition, and prospects of extraterrestrial life in solar system
Several components of planetary noble gases, including CCFXe (Xe-X), s-process Kr and Xe, and Ne-E, are now thought to have had a presolar origin. It is proposed that the 'normal planetary' noble gas component, which contains most of the planetary Ar, Kr, and Xe, is also presolar. This component was trapped in carbonaceous mantles as the mantles formed on grain surfaces in the molecular cloud. The presolar dust grains and their carbonaceous mantles were then incorporated into primitive meteorites. This model naturally explains: (1) the affinity of 'normal planetary' noble gases for carbonaceous material in primitive chondrites; (2) the near absence of He and Ne in the 'normal planetary' component; (3) the elemental fractionation patterns of the 'exotic' and 'normal planetary' components; (4) the similarity of the isotopic compositions of 'normal planetary' and trapped solar Ar, Kr, and Xe; (5) the high noble gas content of the 'normal planetary' gas carrier; (6) several aspects of the chemistry of the 'normal planetary' gas carrier; (7) the correlation of planetary noble gases with the fine-grained material in primitive chondrites; and (8) the widespread occurrence of the planetary fractionation pattern throughout the solar system.
Primordial and episodic theories for the origin of comets are discussed. The implications of the former type for the origin of the solar system are considered. Candidate sites for the formation of comets are compared. The possible existence of a massive inner Oort cloud is discussed.
Inert gases released by stepwise heating of unaltered, strongly magnetic, and weakly magnetic samples from the 0-64 micron and the 105-250 micron fractions of a disaggregated and sieved sample of the Allende meteorite reveal the occurrence of both solar and planetary neon. The origin of the solar neon is thought to be implantation of solar wind ions. The origin of the planetary neon remains unresolved. Heavy isotope enriched components of krypton and xenon have been detected and there are some indications that a light krypton component may also be present. Other than a larger concentration of Xe-129 in the weakly magnetic samples, the signatures of the magnetic separates are isotopically very similar.
Earth-moon system origin assuming moon was formed from terrestrial material ejected from earth during rotational instability
Planetary nebula condensation, examining stability of thermal equilibrium