Class
Article
College
College of Science
Presentation Type
Poster Presentation
Abstract
The Long Duration Exposure Facility (LDEF) was a NASA mission designed to view the long-term effects of space exposure which flew in the Low Earth Orbit (LEO) environment from 1984 to 1990. The mission was originally planned to last 9 months but, after a series of delays resulting from the Challenger explosion, remained in space for 69 months before it was recovered. LDEF results are very noteworthy as the number of long exposure materials available for study is limited by the expense required to launch and retrieve them. USU received a plate that flew on the LDEF mission and has analyzed it with regards to surface characteristics, optical reflectivity, and electron emission. Secondary electron emission may generate large enough electrical potential differences in spacecraft to cause electrostatic discharges which may result in enormous damage, anomalies in mission performance, or even total mission failure. Secondary electron emission as a material property also has important applications in scanning electron microscopes, plasma systems, and high voltage systems. Secondary electrons are generated by inelastic scattering events when a material is struck by highly energetic electrons'for example by those from space plasma fluxes'whereby internal electrons are excited enough to be liberated from the material. Secondary electrons may be generated from photons, electrons or ions, but the secondary electron yield (SEY) from electrons is usually the largest for space applications. SEY measurements have been made for select portions of an LDEF plate to identify the effects of contamination from outgassing and long-duration exposure to the space environment. SEY is known to be affected by factors such as surface roughness, oxidation, and contamination all of which evolved for LDEF, as it was bombarded by radiation and small orbital debris.
Start Date
4-9-2020 12:00 PM
End Date
4-9-2020 1:00 PM
Secondary Electron Yield Analysis of Contamination Found on Long Duration Exposure Facility Panels
The Long Duration Exposure Facility (LDEF) was a NASA mission designed to view the long-term effects of space exposure which flew in the Low Earth Orbit (LEO) environment from 1984 to 1990. The mission was originally planned to last 9 months but, after a series of delays resulting from the Challenger explosion, remained in space for 69 months before it was recovered. LDEF results are very noteworthy as the number of long exposure materials available for study is limited by the expense required to launch and retrieve them. USU received a plate that flew on the LDEF mission and has analyzed it with regards to surface characteristics, optical reflectivity, and electron emission. Secondary electron emission may generate large enough electrical potential differences in spacecraft to cause electrostatic discharges which may result in enormous damage, anomalies in mission performance, or even total mission failure. Secondary electron emission as a material property also has important applications in scanning electron microscopes, plasma systems, and high voltage systems. Secondary electrons are generated by inelastic scattering events when a material is struck by highly energetic electrons'for example by those from space plasma fluxes'whereby internal electrons are excited enough to be liberated from the material. Secondary electrons may be generated from photons, electrons or ions, but the secondary electron yield (SEY) from electrons is usually the largest for space applications. SEY measurements have been made for select portions of an LDEF plate to identify the effects of contamination from outgassing and long-duration exposure to the space environment. SEY is known to be affected by factors such as surface roughness, oxidation, and contamination all of which evolved for LDEF, as it was bombarded by radiation and small orbital debris.