Does anyone know if object 29058 has decayed already? Javi Zaragoza, Spain ---- "Björn Gimle" <b.gimle@chello.se> escribió: ============= > Current Space-Track elements seem to show this bottoming out at 138 km > altitude at about 15°N, 108°W at 23:43 UT this evening, shortly before > making a southerly pass at my 20 (Toronto, 43°N 79°W). > > Is a perigee of 138 km terminally low? > That depends more on the area/mass ratio of the object (roughly proportional to B* (col.55-61 of line1) and excentricity of the orbit (col.27-33 of line2). For a Molniya type orbit (high excentricity) a perigee of 75 km is not immediately fatal (it will be glowing red after perigee, and lose its solar panels). For a circular orbit and "normal" density I consider a mean motion of 16.55 as fatal - this corresponds to perigee=apogee=125 km. But for any near-circular orbit I use the ndot2 value (col.35-43 of line1) as a rule-of-thumb: divide 0.06 by ndot2 to get remaining days. I have one elset with ndot2 ~0.20 at ~06116.86 which would mean decay ~06117.19 An even better way is to plot 1/ndot2 for several recent elsets. ndot2 tripled between 06116.50 and 06116.86, which would make ndot2 infinite after about half that interval, at 06117.04 ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Thu Apr 27 2006 - 03:32:57 EDT