SpaceX F9 : Starlink v0.9 : May 23, 2019 - DISCUSSION

[Dappa]

Now all of those need to separate a bit, and deploy their rather large solar sail, and orient themselves, and manage to not run into each other one orbit later, when every single one of their orbits will want to intersect the same point in space.

This may be the first ever actual traffic jam in space?

The beauty of this deployment method, is that all satellites have a slightly different speed because the stack was tumbling end over end. So after one orbit they'll all get some separation from each other, and it only gets better over time.

[butters]

The astonishing simplicity of this does a lot to reset expectations about LEO constellations. Deploying massive constellations looks so much more practical than it did just a few weeks ago. It suddenly seems almost certain that there will be several tens of thousands of satellites in LEO by the end of the 2020s providing next-generation communications and earth observation services.

It looks like an instantly-obvious embodiment of an idea that signals to markets that a new product category has arrived, like when Steve Jobs demonstrated "slide to unlock" on the first iPhone and everybody knew that smartphones would be the next big thing.

[drzerg]

Now all of those need to separate a bit, and deploy their rather large solar sail, and orient themselves, and manage to not run into each other one orbit later, when every single one of their orbits will want to intersect the same point in space.

This may be the first ever actual traffic jam in space?

they will not. only ones that have exact same orbital period will come together. if they start from one point only satelites with exact same speed from the point of separation exept of inclination will come together. it could be pair from one layer. allother have different orbitalspeeds and periods.

[kaiser]

It looks like the real deployment happened during the 30 second "expected loss of signal". There was a long brace holding the stack together, that was missing after the stream came back on. I guess SpaceX wants to keep that piece of the mechanism for everybody else to figure out.

Yes. The convenient loss of signal is a cover-up  No way they could lost the signal like that. That's some trade secret they want to protect!

To be fair that's the point in time where you work to ensure that there isn't a loss of signal, since it's critical to success. That's the place your really really want data.

[Steven Pietrobon]

Here's before and after shots of deployment. One thing I noticed is the hoops at the corner of the satellites. These align with the black thing on the stage just above left centre. Perhaps there is something that holds these hoops together which comes apart for deployment. There's also a half loop attached above the loops half way up the stack, which does not appear to be there after deployment.

[king1999]

Really pretty website: https://www.starlink.com

[theinternetftw]

Really pretty website: https://www.starlink.com

The globe logo at the top is WebGL and you can spin it around.  Cute!

Edit: For a good time, hold Right or Left arrow.

[su27k]

A pretty accurate simulation of deployment in KSP, and he predicted it before seeing the actual deployment

[theinternetftw]

Probably just a whimsical variable name, but here's a commented out bit of the starlink logo code:

      var lightMars = new THREE.PointLight( 0xCCCCCC, 1, 1000 );
      lightMars.position.set( 0, -20, -10 );
      //scene.add( lightMars );

[Asteroza]

Really pretty website: https://www.starlink.com

The globe logo at the top is WebGL and you can spin it around.  Cute!

Edit: For a good time, hold Right or Left arrow.

That explains why my browser almost locked up, since it doesn't deal with WebGL very well...

Here's before and after shots of deployment. One thing I noticed is the hoops at the corner of the satellites. These align with the black thing on the stage just above left centre. Perhaps there is something that holds these hoops together which comes apart for deployment. There's also a half loop attached above the loops half way up the stack, which does not appear to be there after deployment.

Was there some sort of pole through the rings perhaps? The video cutout just before deployment might have hidden a pole ejection, but there was no such debris in view when the video came back so not sure. or it could have been a tension cable through the center of the ring stack, and an explosive bolt at the top freeing it for winching back to the payload adapter.

[tyrred]

Here's before and after shots of deployment. One thing I noticed is the hoops at the corner of the satellites. These align with the black thing on the stage just above left centre. Perhaps there is something that holds these hoops together which comes apart for deployment. There's also a half loop attached above the loops half way up the stack, which does not appear to be there after deployment.

Hoops are in slight compression with each other, cumulatively enough to hold the stack together?  The black release mechanism withdraws; compression is released gently and the whole stack pushes itself gently away?

The black release mechanism looks retracted in the second image...

I'm usually wrong.  YMMV

[Bananas_on_Mars]

I‘ve thought it might have been something as simple as a fully unwound spring coil, used to strap down the satellites against the payload adapter. Release it on the payload adapter side and it might shoot out into space. Not a problem if done retrograde.

Maybe we will see something in the TLEs, some unexplained additional objects...

[Semmel]

My interpretation: The white rod that is visible in the before-deployment shot could be a cable that holds the sats down. The rings of the sats provide the mechanical support towards the pazoad adapter. The cable is under tension, pulling the sats down. The rings are fit into each other so that they cant shift during launch. Release the cable at the top and roll it up with a pre-tensed spring rod. This can be very quick and the satellites are free instantaneously. The rings also provde a shielding so that the end of the cable cannot flap around while being rolled up.

@edit:
Let me add an other option. The images from the integration facility show a bar on the outside, above the outside rings of the satellites. This could be a simple restrainer that holds the entire stack together. On deployment, it opens like a flower and outside the view of the camera.

[Semmel]

Holy crap I just saw the Starlink satellites fly overhead!  Seen 45 degrees above the northern horizon from Moscow, Idaho at 12:25AM on 2019 May 24.  They were in a line, kind of like a string of diamonds in that you could sort of see a line of them but individual ones would brighten, then dim, such that it looked like I was seeing movement within the line.  They dimmed at maybe 20 degrees over the horizon. 

Presumably they're illuminated over the pole since it's midnight here?  I didn't in any way expect to see them but I just happened to catch them as I got out of my car! 

It's 4 hours since launch, so the timing seems about right for their plane to have rotated over to here from KSC.  Unfortunately, now they're headed over the Pacific Ocean.  Maybe they can see them in Hawaii or New Zealand?  Good luck, and let us know if you do.

At the time of launch, we had already near sunrise in Berlin. So there was no point in looking for them, especially since they were not deployed yet, they wouldnt have looked like much. By tonight, they are probably already busy rising their orbit, so would have dispersed all over the place. Not sure they look as impressive if they float by one at a time. Ill give it a try if the weather behaves.. its a 50%/50% chance according to the weather forcast. But at least Nomadd is not in town, so chances should be pretty good

[Alexphysics]

Now all of those need to separate a bit, and deploy their rather large solar sail, and orient themselves, and manage to not run into each other one orbit later, when every single one of their orbits will want to intersect the same point in space.

This may be the first ever actual traffic jam in space?

Cubesat deployments like this have occurred before.

Yep.
But not 60 cubesats at once, each with a 10m+ long solar panel to deploy.

Starlink satellites are not Cubesats

[Alexphysics]

That was one heck of a light show with the grid fins right after the entry burn, up until loss of video.

I wonder of this was their most difficult landing yet, at least for block 5 (due to the high mass of the payload)? I can;t recall seeing the ASDS this far out before. To be honest, I would not have been surprised had this landing failed. I'm also wondering if this was a 3-engine landing.

I am hoping that the sat deployment goes well, and that there is video.

This was probably like a normal GTO landing. If you can't recall seeing landings this far out from the launchpad you may have missed a ton of GTO missions...

[WindnWar]

This launch was about equivalent in weight to the Apollo-Soyuz test mission launch or some of the Skylab crew missions. Pretty impressive given the first stage was recovered too.

[envy887]

That was one heck of a light show with the grid fins right after the entry burn, up until loss of video.

I wonder of this was their most difficult landing yet, at least for block 5 (due to the high mass of the payload)? I can;t recall seeing the ASDS this far out before. To be honest, I would not have been surprised had this landing failed. I'm also wondering if this was a 3-engine landing.

I am hoping that the sat deployment goes well, and that there is video.

This was probably like a normal GTO landing. If you can't recall seeing landings this far out from the launchpad you may have missed a ton of GTO missions...

GTO missions use a due east launch azimuth which puts them far out at sea. This was a more northerly launch up the East coast, like an ISS launch but most ISS launches are RTLS. The only recent similar launch would have been DM-1.

[spacenut]

Congradulations on Starlink deployment.  Can't wait for the future launches so I can get on it. 

[edzieba]

The periodic foil pulsing is not the same as that seen before. The past missions have seen the foil move in response to gas releases from the MVac during startup, shutdown, and purging events. The pulses seen in the Starlink launch are very periodic, synchronised across all camera shots, and affect the foil on the lowest visible Starlink satellite. The foil movements on the Starlink satellite rule out gas release within the foil-covered engine section as the source of these particular periodic pulses.

Pulses start at T+180s, with a frequency of ~1.2Hz, at a relatively high amplitude.
At T+240 the pulses are very clearly visible affecting the Starlink foil. Frequency is now down to ~1Hz
T+300, pulses are noticeable lower amplitude, frequency is now down to ~0.5Hz
T+370, pulses are extremely low amplitude, ~0.3Hz
T+440, pulses are now very difficult to detect below the normal movement of the engine section foil, but still obvious on the Starlink foil.
After SECO1, pulses are not evident (though I have not had the chance to scrub full the full footage)
T+2624 we see MVac chilldown venting, but tellingly not accompanied by any periodic movement of either the engine bay foil nor Starlink foil
T+2725 we have what I think is the 'smoking gun': pulsing the all visible foil sections (including on Starlink) in combination with cold-gas RCS firings

(This is as much as I can do on my lunch break, timing of each pulse to sync to telemetry will have to wait until another day. )

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My hypothesis is the foil movement is due to RCS thruster firings. The reducing frequency coincides nicely with stage's angle of attack converging towards it's final attitude during the burn. The MVac nozzle is the main method of controlling AoA, so RCS firings are likely for fine adjustments (essentially error correction) to avoid hunting oscillation of the MVac nozzle. As the stage angle converges to the target and the engine is throttled back, so to do the RCS corrections reduce in frequency and amplitude.