NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
Cosmic Ray Exposure Ages of Stony Meteorites: Space Erosion or Yarkovsky?Space erosion from dust impacts may set upper limits on the cosmic ray exposure (CRE) ages of stony meteorites. A meteoroid orbiting within the asteroid belt is bombarded by both cosmic rays and interplanetary dust particles. Galactic cosmic rays penetrate only the first few meters of the meteoroid; deeper regions are shielded. The dust particle impacts create tiny craters on the meteoroid's surface, wearing it away by space erosion (abrasion) at a particular rate. Hence a particular point inside a meteoroid accumulates cosmic ray products only until that point wears away, limiting CRE ages. The results would apply to other regolith-free surfaces in the solar system as well, so that abrasion may set upper CRE age limits which depend on the dusty environment. Calculations based on N. Divine's dust populations and on micrometeoroid cratering indicate that stony meteoroids in circular ecliptic orbits at 2 AU will record 21Ne CRE ages of approx.176 x 10(exp 6) years if dust masses are in the range 10(exp -21) - 10(exp -3) kg. This is in broad agreement with the maximum observed CRE ages of approx. 100 x 10(exp 6) years for stones. High erosion rates in the inner solar system may limit the CRE ages of Near-Earth Asteroids (NEAs) to approx. 120 x 10(exp 6) years. If abrasion should prove to be approx. 6 times quicker than found here, then space erosion may be responsible for many of the measured CRE ages of main belt stony meteorites. In that case the CRE ages may not measure the drift time to the resonances due to the Yarkovsky effects as in the standard scenario, and that for some reason Yarkovsky is ineffective.
Document ID
20140010049
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Rubincam, David Parry (NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
July 23, 2014
Publication Date
February 12, 2014
Subject Category
Geosciences (General)
Report/Patent Number
GSFC-E-DAA-TN13991
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
Yarkovsky
Space Erosion
Meteorites

Related Records

There are no records associated with this record.
No Preview Available