Don Gardner responded to my post: > > I am not certain which would be more likely to have darkened; the > > Spectra-1000 or the yarn. The former is described as having "high > > resistance to chemicals, water, and UV light": > > I would suspect that atomic oxygen is reacting with the > polyetheylene (Spectra 1000). Does atomic oxygen have much of an effect at TIPS' initial altitude of 1030 km? The following page: http://www.irs.uni-stuttgart.de/RESEARCH/SYSTEMS/FIPEX/irsfipex.htm has a URL to a graph relating Atomic Oxygen Fluence vs Altitude, for minimum, nominal and maximum solar activity: http://www.irs.uni-stuttgart.de/RESEARCH/SYSTEMS/FIPEX/bild4.htm Please note that TIPS' deployment and most of its fading occurred near solar minimum, when atomic oxygen fluence would have been at its lowest. The graph extends to 900 km, a bit short of TIPS' initial altitude, but it shows that the atomic oxygen fluence at solar minimum would have been at least 100,000 times less at TIPS' altitude than, say, ISS' altitude of 400 km, where we know atomic oxygen is a serious problem. Surface recession also appears to be about 100,000 times slower. This does not prove that atomic oxygen could not have been TIPS' darkening agent, but clearly altitude and solar flux must be important factors. Ted Molczan ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www.satellite.eu.org/seesat/seesatindex.html
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