Oops - the perils of writing a reply on-line without checking your figures or formulae. I dismissed the correct formula, because I calculated /2 instead of *2 : In message <9703221039.AA25724@cds.plasma.mpe-garching.mpg.de>, I wrote: >>Q decreases at higher MM. For elliptic orbits, Q is much higher, >>but seldom more than 2*(16.6-MM) > Alan Pickup corrected me: >Using King-Hele's definitions, Lifetime = Q/ndot > >Elsets give you ndot2 which is half ndot, so Lifetime = Q/(2*ndot2) > >Q is about about 0.1 rev/day for a circular orbit at 16.2 revs/day MM >(mean motion). However, at 15.8 revs/day (as per this object) it is >closer to 0.14 (using King-Hele's graphs). >Taking ndot2 = 0.00044 and Q = 0.14 about day 97080: > Lifetime = 0.14 / (2 * 0.00044) days = 159 days With the correct definition, Qmax for elliptic orbits should be 16.6-MM. ------------------------------------------------------------ -- b_gimle@algonet.se +46-8-7428086 (home) -- -- 59.22371 N, 18.22857 E AND member of : -- -- http://www.algonet.se/~b_gimle seesat-l / seesat-d -- -- bjorn@tt-tech.se +46-8-59095783 (office)-- ------------------------------------------------------------