USSF-52 OTV 7 estimated elset

The Aeronautical navigation warning for the Pacific area makes it clear that it relates to the OTV launch

!CARF 12/275 ZAK AIRSPACE DCC EROP X1729 USSF52 REENTRY STNR ALT
RESERVATION WI AN AREA DEFINED AS 405500N1460200W TO 423800N1383600W
TO 513400N1415700W TO 495100N1504200W TO POINT OF ORIGIN SFC-UNL
CAUTION SPACE LAUNCH / HAZARDOUS OPS AND POSSIBILITY OF FALLING
SPACE DEBRIS 2312121253-2312121354

My own earlier analysis was based on
initial orbit - LEO at 51°.6
Second orbit - HEO at 63° inclination
Falcon 9 disposal orbit - HEO at 74° inclination

It put the Falcon 9 over the Pacific drop zone right in the narrowed-down window of the new nav warnings.

I rationalised the 74° orbit as being the result of a depletion burn where excess propellant over the amount needed to cause re-entry is expended on the inclination change.

There's actually a large family of orbit possibilities from LEO upwards that will overfly the re-entry area at the required time. It's governed simply by the RAAN and rotation of the Earth after launch.

Bob Christy

> On 11 Dec 2023, at 18:51, Marco Langbroek via Seesat-l <seesat-l_at_lists.seesatmail.org> wrote:
> 
> hi all,
> 
> After discussions with Jonathan McDowell and Ted Molczan, I have slightly revised my orbit estimates for USSF-52 OTV 7, which should launch in about 6 hours from now, around 1:14 UTC (12 December).
> 
> I used the fact that the Navigational Warning for the apparent second stage deorbit area south of Alaska was later re-issued as NAVAREA XII 854.
> 
> This NavWarning contains a time constraint that the original did not have (the original opened at launch time): it opens at 12:53 UTC (Dec 11). With the 4-minute shift in launch time between Dec 11 and Dec 12, that becomes 12:49 UTC (Dec 12).
> 
> So I constructed an orbit that arrives over the area of NAVAREA XII 854 around 12:49 UTC. This means I had to increase the apogee altitude from 35188 km to 37700 km.
> 
> The resulting orbit has a daily precession of 4m 22s, matching the 4-minute shift in launch time (from 1:18 to 1:14 UTC) between 11 and 12 December, as Ted Molczan noted in a private communication.
> 
> This is the resulting estimated elset:
> 
> USSF-52 OTV 7                  for launch on 12 Dec 2023 01:14:00 UTC
> 1 70000U 23999A   23346.07013889  .00000000  00000-0  00000-0 0    06
> 2 70000 074.0000 325.5453 7407989 135.5462 360.0000 02.15472011    09
> 
> 
> I also slightly revised the initial low orbit USSF-52 is launched into before doing the dogleg into HEO.
> 
> My initial estimate with ~48 degrees orbital inclination was based on the azimuth of area A from NAVAREA IV 1414. After comments by Jonathan, I tried to get something that better fits Areas B and C as well, and arrived at 51.5 degrees orbital inclination:
> 
> 
> USSF-52 initial orbit          for launch on 12 Dec 2023 01:14:00 UTC
> 1 70001U 23999A   23346.05138889  .00000000  00000-0  00000-0 0    03
> 2 70001 051.5000 354.4138 0011414 048.2332 322.9851 16.30015116    06
> 
> 
> Note that this all strongly hinches on whether the area south of Alaska is indeed related to USSF-52 and not something else. This is not 100% sure.
> 
> The elsets should be treated as ballpark figures only, and there is always the possibility of subsequent further orbital adjustments of the payload post-release.
> 
> 
> - Marco
> 
> 
> -----
> Dr Marco Langbroek  -  SatTrackCam Leiden, the Netherlands.
> e-mail: sattrackcam_at_langbroek.org
> 
> launchtower:    http://launchtower.langbroek.org
> Station (b)log: http://sattrackcam.blogspot.com
> Twitter:        _at_Marco_Langbroek
> -----
> 
> 
> _______________________________________________
> Seesat-l mailing list
> https://lists.seesatmail.org/mailman/listinfo/seesat-l

_______________________________________________
Seesat-l mailing list
https://lists.seesatmail.org/mailman/listinfo/seesat-l