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

Mon Apr 2 00:17:04 UTC 2018

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

On Sun, Apr 1, 2018 at 5:15 PM, Greg D <ko6th.greg at gmail.com> wrote:

> Ah, interesting site.  Wouldn't it be fitting if it returned to the launch
> site.  Looks like it might pass just under...
>
> For a change, Australia isn't a target this time :).
>
> Greg  KO6TH
>
>
>
> Roger wrote:
>
> 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-tiang
>> ong-1-space-st
>> >> ation-will-crash-to-earth-this-weekend
>> >> <https://www.theguardian.com/science/2018/mar/30/chinas-tian
>> gong-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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