I think there are a couple of issues compounding the problem with calculating the decay rate using the flux values. First, the flux values are not very good predictor of atmospheric density. NASA is moving towards a different approach using atmospheric models calibrated using on-orbit satellites. See the following papers for more info on this HASDM model: http://esa-spaceweather.net/spweather/workshops/eswwII/proc/Session2/doornbos_esaspaceweatherweek2005.pdf http://sol.spacenvironment.net/~JB2006/pubs/JB2006_AIAA_2002_4887.pdf http://www.cosis.net/abstracts/COSPAR02/03151/COSPAR02-A-03151-1.pdf Dr. Bowman's current research is into calculating better Cd curves for a variety of different shapes that are commonly found in the satellite catalog. Secondly, remember that B-star isn't just drag. It's actually the sum total of all the perturbations on the object. The General Perturbations model used to produce the TLEs just lumps all these together with drag being about 75% of B-star. This is also why you might sometimes see a positive B-star - radiation pressure or other factors could actually boost the orbit for a very light, reflective object. The Special Perturbations models are much more accurate for predicting decay as they model most of the perturbations independently, however these aren't published on space-track so we are sort of screwed :) -- Brian Weeden ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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