Growth and redistribution FO condensible materials in the protoplanetary nebula the earliest stages of planetary formation - growth by sticking, and primary accretion of 100KM primitive bodies - are…

The federal contract award NNX17AL60A was issued by the National Aeronautics and Space Administration (NASA) to the SETI Institute, a non-profit research organization, to conduct research on the growth and redistribution of condensible materials in the protoplanetary nebula during the earliest stages of planetary formation. This cooperative agreement, valued at $519,486.00, aims to improve understanding of the physics and properties related to the formation of primitive planetesimals. The research involves implementing physical processes into computational models, studying porous/fractal growth and planetesimal formation, and analyzing transport of anomalous oxygen isotopes and depletion of volatile elements in chondrites. This award is not associated with any set-aside designation. The SETI Institute has received multiple contract and grant awards from NASA and the National Science Foundation to support its scientific research and analysis related to astrobiology, planetary science, and the search for extraterrestrial intelligence.

Growth and redistribution FO condensible materials in the protoplanetary nebula the earliest stages of planetary formation - growth by sticking, and primary accretion of 100KM primitive bodies - are poorly understood, and yet profoundly important because the particles making up primitive (unmelted) planetesimals actually witnessed the early protoplanetary nebula and provide our only ground truth about its properties. Our research is somewhat unusual because IT intimately combines state of the art global models of growth by sticking, and radial transport, of porous aggregate particles (constrained by limited experiments on ideal materials) with problem-focussed studies of some of the most longstanding puzzles of meteoritics. The processes of physics and the properties of meteorites speak in two different languages, but we need both to understand the earliest stages of planet formation. Underneath IT all, planet formation is geology, in the sense that IT can be resistant to clean mathematical solutions. The techniques we propose are necessarily numerical, with parameters based on physical processes which have sometimes been studied more rigorously by others. The underlying processes can be messy, and we introduce them only when previous work has shown them to have significant implications. We believe this overall program represents a significant step forward toward replacing the usual cosmic abundance, minimum mass nebula with a more realistic initial setting for planet formation.we propose five basic tasks, denoted by their section numbers: (6.1) implement a few key physical processes into the code, including external mass loss and/or gain from disk winds or infall; (6.2) study variations on the process of porous/fractal growth and determine the implications for the primary formation of planetesimals; (6.3) study the transport of anomalous heavy oxygen isotopes from the outer nebula into primitive chondrites, comparing model timescales with observed ones; (6.4) test a new hypothesis for the longstanding problem of the systematic depletion of the moderately volatile elements in chondrites and planets; (6.5) understand the substantial depletion of chondrites (including carbonaceous chondrites) in carbon relative to cosmic abundance. The work will provide realistic initial conditions for primary accretion of planetesimals and planets in the inner and outer solar system, and a protoplanetary disk context for primitive meteorite properties that is now lacking, including a connection between observed properties and nebula timescales. In the end, on timescales far longer than those of this proposal, our goal must be to explain all of this geology in the context of the same nebula evolutionary scenario.