[meteorite-list] Airless Space Weathering Duplicated in Lab Environment

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 7 Sep 2015 23:19:46 -0700 (PDT)
Message-ID: <201509080619.t886Jk93006075_at_zagami.jpl.nasa.gov>

https://www.psi.edu/news/kimweathering

Airless Space Weathering Duplicated in Lab Environment
Planetary Science Institute
Sept. 3, 2015
 
Tucson, Ariz. - Using laboratory instruments typically used to make
semiconductor devices, space weathering of airless bodies in the Solar
System has been simulated, allowing researchers to better determine the
ages of their surfaces, states a new paper by Kimberly R. Kuhlman of the
Planetary Science Institute.
 
"Space weathering" is a catch-all term for what happens to surfaces
exposed to the environment of space over time. This includes the micrometeorite
impact damage and redeposition, effects of UV radiation, and the effects
of implantation of solar wind particles," said Kuhlman, lead author
of "Simulation of solar wind space weathering in orthopyroxene" that
appeared in Planetary and Space Science. "More space weathered surfaces
become redder and darker from the formation of nano-scale particles of
iron."
 
Bodies in the Solar System that exhibit space weathering include the Moon,
Mercury and asteroids.
 
Kuhlman shot hydrogen atoms at solar wind speeds into tiny, polished samples
of the common Solar System mineral orthopyroxene that had been placed
on top of a silicon wafer. She then examined the compositional changes
in the outer 20 nanometers of the implanted orthopyroxene using a scanning
transmission electron microscope (STEM), and for the first time discovered
the particles of iron beginning to form.
 
"This continuing work will allow us to estimate the rate at which these
'nanophase' iron particles form as a consequence of exposure to the
solar wind. Linking this to the spectroscopic effects will allow scientists
to infer the age of the body surfaces via remote sensing, which in turn
will inform our understanding of a wide range of physical processes in
the Solar System," Kuhlman said.
 
The project was funded by a grant to PSI from NASA's Lunar Advanced
Science and Exploration Research program.
Received on Tue 08 Sep 2015 02:19:46 AM PDT