SpaceX F9 : Starlink 5 (v1.0 L4) : Feb. 17, 2020 : Master Thread

[gongora]

Master thread for the fifth Starlink launch (fourth Starlink v1.0 launch).

Check the Starlink Index Thread for links to more Starlink information.

NSF Threads for Starlink v1.0 Flight 4: Master

NSF News Articles for Starlink:
https://www.nasaspaceflight.com/?s=Starlink

Succcessful launch Feb. 17, 2020 at 10:05:55am EST (1505 UTC), on Falcon 9 (booster 1056.4) from CCAFS SLC-40.  ASDS landing was unsuccessful.  Targeting deployment orbit of around 190x380km.  The booster supporting this mission previously launched the CRS-17 mission in May 2019, the CRS-18 mission in July 2019, and the JCSAT-18/Kacific1 mission in December 2019.

Payload: A batch of 60 Starlink satellites with Ku-band and Ka-band antennas.

Please use the Starlink Discussion Thread for all general discussion on Starlink.

L2 SpaceX:
https://forum.nasaspaceflight.com/index.php?board=60.0

[zubenelgenubi]

Cross-post:

http://www.launchphotography.com/Delta_4_Atlas_5_Falcon_9_Launch_Viewing.html

<snip>
FALCON 9

<snip> Then, a Falcon 9 is slated to launch another Starlink mission from pad 40 on late January. And a Falcon 9 with another batch of Starlink satellites from pad 40 is slated for late January or February earliest.

[LandingZone-1]

http://www.launchphotography.com/Delta_4_Atlas_5_Falcon_9_Launch_Viewing.html

The next SpaceX Falcon 9 rocket from Cape Canaveral will launch another batch of 60 Starlink satellites from pad 40 on February TBA. The launch window for Starlink missions is instantaneous and the launch time gets 21.5 minutes earlier each day.

[Comga]

http://www.launchphotography.com/Delta_4_Atlas_5_Falcon_9_Launch_Viewing.html

The next SpaceX Falcon 9 rocket from Cape Canaveral will launch another batch of 60 Starlink satellites from pad 40 on February TBA. The launch window for Starlink missions is instantaneous and the launch time gets 21.5 minutes earlier each day.

But we can’t just extrapolate “21.5 minutes earlier each day” from today’s Flight 3 to Flight 4 because they want these to distribute the 3 new planes from a different initial ascending note, no?

Is there a pattern in McDowell’s plots that gives us a clue as to what will be the time of launch on, say, two weeks from today from which the 21.5 minute progression will be valid?
Is there a pattern in how SpaceX is filling out this initial constellation?

[Comga]

twitter.com/planet4589/status/1220249033442316288

A new visualization of the Starlink constellation showing the orbital plane of each satellite versus time:

https://twitter.com/planet4589/status/1220249519868301312

The  Y axis here is in a coordinate system rotating at 4.487 degrees/day, the nodal precession rate for a satellite in the nominal 550 km orbit.  Satellites in the operational constellation are therefore horizontal lines in this graph.

twitter.com/planet4589/status/1220249818293063685

Satellites at different orbital heights precess at different rates, thus changing ascending node relative to the 550 km rotating coordinate system.
  The deployment rod debris objects are marked in green.

https://twitter.com/planet4589/status/1220250244312698880

Here is a zoom in showing that the initial launch are now shifting plane (because their orbits have been lowered a bit) and at top right) some of the V1.0-L1 sats have reached the op orbit and are now horizontal in the plot

The first plot suggests that the 3rd V1 launch was right between the previous 2. If it had been off to one side or the other, it might have been a clue.
There is no clear next step I can see.

[envy887]

But we can’t just extrapolate “21.5 minutes earlier each day” from today’s Flight 3 to Flight 4 because they want these to distribute the 3 new planes from a different initial ascending note, no?

Unless they change the insertion altitude or the orbit-raising rate, the day-to-day change in launch time will always be the same.

The exact time will vary depending which planes they want the launch to fill, but the day to day change will always be about 20 minutes.

[Comga]

But we can’t just extrapolate “21.5 minutes earlier each day” from today’s Flight 3 to Flight 4 because they want these to distribute the 3 new planes from a different initial ascending note, no?

Unless they change the insertion altitude or the orbit-raising rate, the day-to-day change in launch time will always be the same.

The exact time will vary depending which planes they want the launch to fill, but the day to day change will always be about 20 minutes.

Yes
Launch time depends on which planes they intend to fill.
I was hoping there was an obvious pattern to this, but I can’t recognize one in the data as plotted.
Can anyone see one?

[zubenelgenubi]

Cross-post; my bold:

http://www.launchphotography.com/Delta_4_Atlas_5_Falcon_9_Launch_Viewing.html

FALCON 9

The next SpaceX Falcon 9 rocket from Cape Canaveral will launch another batch of 60 Starlink satellites from pad 40 on mid-February TBA, in the daytime. The launch window for Starlink missions is instantaneous and the launch time gets 21.5 minutes earlier each day. Other upcoming launches include: A Falcon 9 is scheduled to launch the next Dragon resupply mission to the ISS from pad 40 on March 2 at the earliest, at 1:45am EST. The launch window is instantaneous. The launch time gets 22-26 minutes earlier each day. And another Falcon 9 will launch another Starlink mission from pad 39A on early March TBD.

[Alexphysics]

Ben Cooper mission page says February 15th at 10:46am

http://www.launchphotography.com/Starlink_4.html

[Barley]

http://www.launchphotography.com/Delta_4_Atlas_5_Falcon_9_Launch_Viewing.html

The next SpaceX Falcon 9 rocket from Cape Canaveral will launch another batch of 60 Starlink satellites from pad 40 on February TBA. The launch window for Starlink missions is instantaneous and the launch time gets 21.5 minutes earlier each day.

Why the instantaneous launch window? 

The plane can be changed at about 0.3 degrees per day by waiting at the lower insertion orbit for an extra day.  A one hour launch window would delay reaching the operational orbits by less than 2 months.  At least for the early launches that is still well before the constellation is complete enough to be operational so no time would be lost.

There should be a tradeoff between the added difficulty of an instantaneous window and operating the satellites.  An instantaneous launch window implies that maneuvering the satellites is more difficult.

For that matter is there any reason to fill the planes in a particular order?  Instead of waiting a little less than a day for a specific plane, can't they just wait a few hours for the next empty plane (or however many empty planes are filled by one launch).

[envy887]

http://www.launchphotography.com/Delta_4_Atlas_5_Falcon_9_Launch_Viewing.html

The next SpaceX Falcon 9 rocket from Cape Canaveral will launch another batch of 60 Starlink satellites from pad 40 on February TBA. The launch window for Starlink missions is instantaneous and the launch time gets 21.5 minutes earlier each day.

Why the instantaneous launch window? 

The plane can be changed at about 0.3 degrees per day by waiting at the lower insertion orbit for an extra day.  A one hour launch window would delay reaching the operational orbits by less than 2 months.  At least for the early launches that is still well before the constellation is complete enough to be operational so no time would be lost.

There should be a tradeoff between the added difficulty of an instantaneous window and operating the satellites.  An instantaneous launch window implies that maneuvering the satellites is more difficult.

For that matter is there any reason to fill the planes in a particular order?  Instead of waiting a little less than a day for a specific plane, can't they just wait a few hours for the next empty plane (or however many empty planes are filled by one launch).

Falcon can't really hold or recycle once they start loading prop about 35 minutes before launch, so an hour long window isn't really more useful than an instantaneous one.

[Norm38]

All Dragon missions to ISS have instantaneous launch windows, as do other payloads.  It's not something special for Starlink, it's routine.  So they may as well keep at it.

[abaddon]

Falcon can't really hold or recycle once they start loading prop about 35 minutes before launch, so an hour long window isn't really more useful than an instantaneous one.

That's not true, they can align within the window before fueling to e.g. better fit in a gap in the weather, wait for a lightning strike hold to clear, etc etc.  Many Falcon 9 launches have had non-instantaneous windows, and that has proven useful on occasion to allow them to launch rather than scrubbing for the day.

In fact, they just did this with the in-flight abort test...

[Comga]

The IFA is not relevant because it didn’t have a target orbit, of course.
If they extend the Starlink launch window on the early side I think that guarantees that the satellites would have to spend more time drifting.
If the extend the window on the late side the satellites can’t easily be drifted back. AIUI. 
Better to keep the windows instantaneous and delay launch until the weather has better overall probability.
Like SpaceX just did.

[abaddon]

The IFA is not relevant because it didn’t have a target orbit, of course.

The IFA is absolutely relevant if you read what I quoted, which was saying that irrespective of orbit, a window was not helpful due to sub cooling.  The IFA proves this is wrong.  Many other flights have had windows and some have had adjustments within windows, if you still want to exclude the IFA for some reason.

Your other comments would be better targeted at @Barley's post, I'm just addressing the specific comment that SpaceX can't adjust within a window due to subcooled fuel and oxidizer.

[envy887]

Falcon can't really hold or recycle once they start loading prop about 35 minutes before launch, so an hour long window isn't really more useful than an instantaneous one.

That's not true, they can align within the window before fueling to e.g. better fit in a gap in the weather, wait for a lightning strike hold to clear, etc etc.  Many Falcon 9 launches have had non-instantaneous windows, and that has proven useful on occasion to allow them to launch rather than scrubbing for the day.

In fact, they just did this with the in-flight abort test...

Sure, but because prop load commits them to either launch or scrub for the day, the max they can shift in a 1 hour window is 25 minutes which isn't real likely to be enough to find a hole in the weather.

IFA had a 4 hour window, and IIRC they had a chance to extend that even more if the weather wasn't cooperating at the end. That kind of wait would put a Starlink launch way out of plane.

[abaddon]

The max they can shift in an hour window is an hour.  They can target the start of the window, or they can start prop load at +25 to target the end of the hour window, or anything in between.

Again, I’m not arguing Starlink windows can or can’t be shifted, just that prop load doesn’t make all SpaceX launch windows instantaneous, which is clearly not the case.

[ZachS09]

When will they reveal which booster will be used for Starlink-4?

If it’s scheduled for mid-February, the booster name should be announced in a week or so.

[AndrewRG10]

When will they reveal which booster will be used for Starlink-4?

If it’s scheduled for mid-February, the booster name should be announced in a week or so.

They seem to be reusing boosters in progression of how they last flew. We had B1049 then B1051 from Starlink and Radarsat. If we assume they continue we should see a FH sidebooster fly. From the 'leaked' spacex update, B1048.5 is meant to fly March so we can guess B1052.3 is Starlink and maybe B1053.3 as Saocom 1b, if not that then B1059.2 will fly Saocom 1b

[whitelancer64]

When will they reveal which booster will be used for Starlink-4?

If it’s scheduled for mid-February, the booster name should be announced in a week or so.

They seem to be reusing boosters in progression of how they last flew. We had B1049 then B1051 from Starlink and Radarsat. If we assume they continue we should see a FH sidebooster fly. From the 'leaked' spacex update, B1048.5 is meant to fly March so we can guess B1052.3 is Starlink and maybe B1053.3 as Saocom 1b, if not that then B1059.2 will fly Saocom 1b

It would be interesting to see 52 / 53 fly standalone missions!