Re: N of MIR
Dave Cappellucci (dcappell@rmii.com)
Sat, 28 Oct 95 19:13 MDT
> I have some TL of MIR for the year 1995
> I'm surprised to see how the "N" of MIR
> always increases. Specialy from day 291 to 300
> It's more visible on a curve I made of it.
> Is it a coincidence that N never decreases
> for the TL I have?
> How could I get more TL of MIR in just one file
> if possible?
>
> Day N N./2
>
>138 15.56561 0.00007202
>195 15.57069 0.00001252
>205 15.57125 0.00002002
>228 15.57236 0.00001565
>230 15.57245 0.00001589
>237 15.57281 0.00001322
>242 15.57325 0.00006883
>248 15.57363 0.00003035
>258 15.57424 0.00003351
>268 15.57499 0.00003780
>275 15.5755 0.00002780
>276 15.57557 0.00002366
>279 15.57592 0.00003320
>289 15.57662 0.00002048
>290 15.57675 0.00002939
>291 15.5769 0.00004119
>300 15.57882 0.00009490
>
>Alphonse POUPLIER 100723.2613@compuserve.com
>
What you are seeing is normal decay behavior. Mir is a very large object and
is subject to significant atmospheric drag. If allowed to continue
unchecked, Mir would eventually re-enter the earth's atmosphere and burn up.
What keeps this from happening are periodic station-keeping maneuvers
performed to either increase the period (decrease the mean motion),
circularize the orbit or both. You can see this by plotting the orbital
period over a long period of time. What you will see are fairly regular
discontinuities that appear whenever a maneuver is performed. It is also
interesting to plot eccentricity vs time and apogee/perigee vs. time. These
plots show when circularizing maneuvers are performed.
I believe you can find some fairly large files in the Celestial Archives
(archive.afit.af.mil) containing historical elsets for Mir and other
satellites. Some of these files go back several years.
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- Dave Cappellucci http://www.usa.net/~dcappell -
- Acappella Publishing http://www.usa.net/acappella -
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