[amsat-bb] Tiangong Re-entry (0000 UTC +/- 2.5 hrs)

[Roger]

http://www.aerospace.org/CORDSuploads/TiangongStoryboard.png

Shows it on what's expected to be it's last orbit.


73, Roger
W7TZ
CN83ia
Grid Busters
w7tz.webs.com

On Sun, Apr 1, 2018 at 5:03 PM, Greg D <ko6th.greg at gmail.com> wrote:

> I just updated the keps on gPredict, and Tiangong-1 disappeared from the
> list.  Where'd it come down, or are rumors of its demise ever so
> slightly exaggerated?  Heavens-above still thinks it's up there.
>
> Greg  KO6TH
>
>
> Robert Bruninga wrote:
> > Since this is journalism, I think you and some others are right.  If one
> > simply looks at latitude as a number, then the latitude near the
> > inclination will have a higher probability of appearing.  But the best
> > feedback came from Ralph W0RPK who pointed out this page which is
> tracking
> > the orbit with updated predictions:
> > http://www.aerospace.org/CORDSuploads/TiangongStoryboard.png
> >
> > And the USA is about as far as you can get from the predicted impact.
> The
> > USA is 12 hours out of cycle with the orbit.
> >
> > The prediction there is currently showing about 0000 UTC which is 8 PM
> EDT
> > plus or minus 2.5 hours. (which is about 3 orbits worth).  And although
> > those orbits cover a vast Pacific and Atlantic oceans, a good portion of
> > them cross the middle east through Russia and china.
> >
> > Bob, WB4APR
> >
> > On Sun, Apr 1, 2018 at 11:26 AM, Gary Bender, WS5N <ws5n at wildblue.net>
> > wrote:
> >
> >> I was thinking the favoring of higher latitudes for reentry was because
> >> the apparent sine wave of the ground track naturally slows down in
> >> "latitude velocity" as it peaks at 43 degrees and reverses.  Add in the
> >> rotation of the earth under it and you end up with a bit more dwell time
> >> above 38 degrees.  It is changing latitude much faster between the
> >> extremes.  (Or maybe I am over thinking it.)
> >>  --
> >>     Gary, WS5N
> >>
> >> ----- Original Message -----
> >> From: "Robert Bruninga" <bruninga at usna.edu>
> >> To: "amsat bb" <amsat-bb at amsat.org>
> >> Cc: "TAPR APRS Mailing List" <aprssig at tapr.org>
> >> Sent: Saturday, March 31, 2018 5:55:17 PM
> >> Subject: Re: [aprssig] [amsat-bb] Tiangong Re-entry on Heavens bove
> >>
> >>> Hi Bob, do you know the object number by chance?
> >> No, but this link shows that the higher probabilities or re-entry are
> >> between about 38 to 43 degree latitudes north and south.
> >>
> >> https://www.theguardian.com/science/2018/mar/30/chinas-
> tiangong-1-space-st
> >> ation-will-crash-to-earth-this-weekend
> >> <https://www.theguardian.com/science/2018/mar/30/chinas-
> tiangong-1-space-st%0Aation-will-crash-to-earth-this-weekend>
> >>
> >> Im not sure why those would be slightly higher.  43 degrees is its
> maximum
> >> excursion (matches its inclination)...  Maybe its because as it passes
> >> over the equatorial bulge, it sees the higher drag and that will start
> the
> >> demise which will occur then 20 minutes later?
> >>
> >> Bob
> >> -----Original Message-----
> >> From: Robert Bruninga
> >> Sent: Saturday, March 31, 2018 9:16 AM
> >> Subject: [amsat-bb] Tiangong Re-enetry on Heavens bove
> >>
> >> You can see the live track of Taengong to re-enter in the next 24 hours
> on
> >> http://www.heavens-above.com/
> >>
> >> Just remember, as it suffers increased drag, it will speed up and be
> ahead
> >> of classic predictions.
> >>
> >> But at least you can see when you are under the orbit as to whether it
> is
> >> worth going outside.  I 'd go out several minutes before the prediction
> >> since we dont know how quickly they are updating the elements as it
> speeds
> >> up.
> >>
> >> and even if it is daytime, you will see it if it comes in in your
> area...
> >>
> >> Bob
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