NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Cometary origin of carbon and water on the terrestrial planetsAn early high-temperature phase of the protosolar accretion disk is implied by at least three different telltales in chondrites and confirmed by peculiarities in the dust grains of Comet Halley. The existence of this high-temperature phase implies a large accretion rate hence a massive early disk. This clarifies the origin of the Kuiper Belt and of the Oort cloud, those two cometary populations of different symmetry that subsist today. Later, when the dust sedimented and was removed from the thermal equilibrium with the gas phase, a somewhat lower temperature of the disk explains the future planets' densities as well as the location beyond 2.6 AU of the carbonaceous chondrite chemistry. This lower temperature remains however large enough to require an exogenous origin for all carbon and all water now present in the earth. The later orbital diffusion of planetesimals, which is required by protoplanetary growth, is needed to explain the origin of the terrestrial biosphere (atmosphere, oceans, carbonates and organic compounds) by a veneer mostly made of comets.
Document ID
19920038310
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Delsemme, A. H.
(Toledo, University OH, United States)
Date Acquired
August 15, 2013
Publication Date
January 1, 1992
Publication Information
Publication: Advances in Space Research
Volume: 12
Issue: 4, 19
ISSN: 0273-1177
Subject Category
Space Biology
Accession Number
92A20934
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available