You don't fully vent your tanks before the burn. 2nd stage has a handful of ways of ejecting gas. Though the engine, as a burn, though the engine, as a purge or chill, through the non propulsive vents or through the ACS nozzles. You also need to vent both tanks at once or at similar rates, or you can load the common dome in a way that causes an explosion (see F9R dev 1, ultimate fate.) So most likely what you saw was the full tank vent, or a possible ACS maneuver. It's been almost a decade since I was involved in this so my memory is fuzzy. If you want any more ideas, I can cross post this to the Arocket mailing list. On Wed, Jun 5, 2024, 8:07 PM ronlee--- via Seesat-l < seesat-l_at_lists.seesatmail.org> wrote: > 1) Background: Starlink 6-64 launched on a Falcon 9 rocket at > 10:37:18 PM EDT on 31 May 2024 (02:37:18 UT on 1 June 2024) from > SLC-40 in Florida. > > I have seen at least one event on four other occasions and am close > to knowing when the primary event occurs. The primary event occurs > low in the west and consists of a bright central object and gaseous > surrounding area. It is an easy naked eye object. I will call it > Event 1. > > On this launch I was expecting Event 1 to occur about T+01:29:25 > > The second event (Event 2) I had only seen once and was a few minutes > after seeing Event 1 and is a quick ejection of gaseous appearing > material. > > 2) Observing location: Falcon, Colorado USA > > -104.5614, 38.9478 N, 2073 meters > > 3) Timing: I am using the launch time of 02:37:18 UT as T=0. The > two events occur about 90 minutes after launch or roughly T+01:30:00 > (HH:MM:SS). > > Event accuracy has possible errors of several seconds due to having to > look > at a timing app on my phone after the event and not positively seeing > the > actual start of either event. > > 4) Deorbit event observations on 1 June 2024 (UT): > > Event 1 was first observed with binoculars at approximate azimuth 270 > degrees > and four degrees elevation. I saw it appear over the roof line of a > house to > the west at 4:06:25 UT on 1 June or T+01:29:07. It could have been > visible > sooner. It soon became the normal easy naked eye object before entering > Earth shadow around 4:08:40 UT. > > I watched it dim as it entered Earth's shadow and continue to scan > looking > for Event 2 which amazingly I did see at 4:09:06 UT. I do not > understand > why I was able to see it being in Earth shadow. It seemed to be an > ejection > up/towards the zenith. > > 5) Element set: The following was provided pre-launch by Dr Kelso and > was used to generate look angles/timing. > > STARLINK-G6-64 STACK Launch 0237 UT 1 June 2024 > 1 72000C 24106A 24153.15438634 .00042590 00000+0 85478-4 0 09 > 2 72000 42.9985 66.4093 0006180 254.5220 124.2177 15.98668964 18 > > Launch: 2024-06-01 02:37:00 UTC. > Deploy: 2024-06-01 03:42:18.980 UTC. > > 6) Re-entry warning notice > > A1855/24 NOTAMN > Q) FAJO/QWMLW/IV/BO/W/000/999/4144S02938E999 > A) FAJO B) 2405310059 C) 2406060316 > D) 31 MAY 0059-0553, 01 JUN 0033-0527, 02 JUN 0006-0500 2340-0434, 03 > JUN 2314-0408, 04 JUN 2248-0342, 5 JUN 2222-0316. > E) AREA BOUNDED BY (4256S 00224W, 4045S 00221W, 3210S 05700E, 3515S > 05700E): SPACEX STARLINK 6-64 ROCKET RE-ENTRY OPS TAKING PLACE. > APPLICABLE AIRSPACE DOWNGRADED TO GLASS G. > F) SFC G) UNL > > F1901/24 NOTAMN > Q) YMMM/QWMLW/IV/BO/W/000/999/1610S08231E999 > A) YMMM > B) 2405310059 C) 2406060316 > D) 2405310059 TO 2405310553 > 2406010033 TO 2406010527 > 2406020006 TO 2406020500 > 2406022340 TO 2406030434 > 2406032314 TO 2406040408 > 2406042248 TO 2406050342 > 2406052222 TO 2406060316 > E) ROCKET LAUNCH WILL TAKE PLACE > FLW RECEIVED FROM GOVERNMENT OF UNITED STATES OF AMERICA: > HAZARDOUS OPS WILL BE CONDUCTED FOR ATMOSPHERIC RE-ENTRY AND > SPLASHDOWN OF LAUNCH VEHICLE FALCON-9 STARLINK 6-64 WI THE FOLLOWING > AREAS: > 2033S 07500E > 0746S 08927E > 0853S 09228E > 2422S 07500E TO BEGINNING > PRIMARY LAUNCH 240531 > BACKUP AS PER FIELD D > F) SFC G) UNL > > Graphical depiction of re-entry area: > > https://forum.nasaspaceflight.com/assets/60937.0/2286726.jpg > > 7) Discussion of events: I have not been certain whether Event 1 was > the > deorbit burn. If it is then Event 2 is probably a venting of propellant > or other gases/liquids. Then yesterday I finally considered that Event > 1 > is the deorbit burn and we are seeing an inverted jellyfish. > > Examples of the jellyfish effect from the second stage during ascent: > > https://i.imgur.com/KlGOFSu.gif > > https://pbs.twimg.com/media/FgHu9rhUoAASjUa?format=jpg&name=large > > https://pbs.twimg.com/media/FmjLasvX0AYjJMe?format=jpg&name=900x900 > > Can anyone confirm that Event 1 is likely the deorbit burn or provide > a reason for what we are seeing? > > Graci > Ron Lee > > _______________________________________________ > Seesat-l mailing list > https://lists.seesatmail.org/mailman/listinfo/seesat-l > _______________________________________________ Seesat-l mailing list https://lists.seesatmail.org/mailman/listinfo/seesat-lReceived on Wed Jun 05 2024 - 21:15:44 UTC
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