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

[speedevil]

https://twitter.com/elonmusk/status/1127388838362378241

Now we know.  60!

I am amused!
In this thread I guessed;

If we want to fit such a satellite in a 4.6m diameter fairing, one idea that springs to mind is a pie wedge design, with a 60cm core.
If we imagine several whole pies stacked vertically at 1.3m spacing, with eleven satellites per pie, that comes out as 55 on 5 pies, with perhaps another 5 on top.

I think I can legitimately claim this as a guess of 60.
Though my guess on the packing style is very wrong apparently.

[Alexphysics]

Why not a static fire with payload attach and at the time of the launch window.  And if it goes well let it fly. 

Saves a few days and a cycle. They’ll need to a hundred or so launches like this so why not save a few days on each.

Seeing that stack just the payload configuration, payload faring separation and deployment is as much value as the satellites.

They review the static fire data via a quick-look review before giving the green light for the launch.  So, I presume there's a lot of data available that you can't make a split-second decision whether to launch or scrub.  Elon's already tweeted that if the static fire on Monday is good, they'll launch on Tuesday.  So the static fire only costs them ~24 hours to ensure the GSE, rocket and payload pass their test before doing it for real.

The launch is on wednesday, not tuesday, he corrected that later on a following tweet. We really don't know a thing about if they will have the payload on or not for SF.

[DistantTemple]

My bet is they follow their normal practice, and static fire with the payload off.
This is a particularly crucial launch, with lots of things they want to test, and likely lots of engineers waiting for validation/results before committing to the final(ish) design. Loosing this lot would be a significant hold up for the Starlink project.

[Jcc]

So these spacecraft are just flat. Probably, one side of it is a solar panel, the other on is the phased-array antenna. Electronics and tankage are in between. RCS thrusters at the edges.

Hard to imagine that working. Unless you give up a lot of efficiency in the solar arrays. And everything. More likely they will unfold somehow so the arrays, thrusters and antennas all point correctly.

[Jarnis]

IKEA flat pack comes to satellites. 

Competition probably, once again, doing a double take and having to go back to the drawing board on their long term plans...

[StuffOfInterest]

If my Googling is correct, this will be the 2nd most satellites launched at the same time, behind PSLV-C37 with 107, but it should be be far the most communication satellites to ever go up on a single launch.

When people were throwing numbers around earlier in the 30+ range for this flight I thought they were crazy.  Turns out they were low-balling.  Impressive.

[Jcc]

IKEA flat pack comes to satellites. 

Competition probably, once again, doing a double take and having to go back to the drawing board on their long term plans...

One web likely too far along to change their design and business plan. Bezos was waiting to see this before starting. Will the NG 7m fairing fit more sats or bigger ones?

[OneSpeed]

In the case of two stacks of 30:
The dimensions would be ~ 3m x 1.5m x .3m (9.8ft x 4.9ft x .98ft)
1.35 cubic meters

In the case of four stacks of 15:
The dimensions would be ~ 1.5m x 1.5m x .6m (4.9ft x 4.9ft x 1.96ft)
1.35 cubic meters

But because of the noted variations of edges shown it is unlikely  because the edges are too random to support the conclusion of double thick but square sized sats for four stacks of 15.

There is a third possibility. If it is two stacks of 30, each satellite appears to have two layers. It could actually be a single stack of 60 satellites (0.15m deep), with 30 pairs facing each other, and rotated 180° from each other. If the propellant tanks are sufficiently off centre, they could be twice the depth of each flat packed satellite.

[Yellowstone10]

If my Googling is correct, this will be the 2nd most satellites launched at the same time, behind PSLV-C37 with 107, but it should be be far the most communication satellites to ever go up on a single launch.

SpaceX's SSO-A mission launched 64 satellites, so this one's in third place at best. Probably the winner if you exclude Cubesats, though.

[smoliarm]

If my Googling is correct, this will be the 2nd most satellites launched at the same time, behind PSLV-C37 with 107, but it should be be far the most communication satellites to ever go up on a single launch.

SpaceX's SSO-A mission launched 64 satellites, so this one's in third place at best. Probably the winner if you exclude Cubesats, though.

Also, this launch of Soyuz had 72 satellites total:
date: Jul 14, 2017
sats: Kanopus-V-IK 1; TechnoSat; Flying Laptop; Norsat-1, -2; CICERO-1, -2, -3; Corvus-BC [×2]; MKA-N [×2]; Flock-2k [×48]; Lemur-2 [×8]; Mayak MKA; MKA-N [2]; Iskra-MAI-85; Ecuador-UTE-YuZGU
LV:  Soyuz-2.1a/Fregat-M

[ThePonjaX]

I don't think the place of this launch in the most satellites launched at the same time list is important.

They are going to need just 10 launch to get 600 sats in orbit, and 10 more for 1200. That's is incredible. 

Of course if everything goes well and etc, but this is really awesome. 

[ArbitraryConstant]

Looks like a stack of lawn chairs, each ready to pop open into a new shape.  But lawn chairs don't have propellant tanks and maneuvering thrusters. Remarkable engineering!

Maybe they don't unfold at all and they're just flying solar panels with propulsion and antennas.

edit: re comments this would limit power, do we know the power budget per satellite? maybe they adjust their angle somewhat using reaction wheels, their phased array antennas might be able to handle that.

[jaufgang]

Looks like a stack of lawn chairs, each ready to pop open into a new shape.  But lawn chairs don't have propellant tanks and maneuvering thrusters. Remarkable engineering!

Maybe they don't unfold at all and they're just flying solar panels with propulsion and antennas.

edit: re comments this would limit power, do we know the power budget per satellite? maybe they adjust their angle somewhat using reaction wheels, their phased array antennas might be able to handle that.

Yeah, I kinda expect these things to do some clever origami shape-shifting tricks after they deploy, but who knows.  Elon did refer to them in a tweet as "flat-packed" which seems to imply a distinct configuration for delivery. 

He also promised "more details on day of launch".  I suspect they'll release a video before launch that includes animations of the entire  deployment sequence and will show these details.

[meekGee]

So these spacecraft are just flat. Probably, one side of it is a solar panel, the other on is the phased-array antenna. Electronics and tankage are in between. RCS thrusters at the edges.

"Flat packed" is a term used to imply that they will unfold, but that in their folded state they achieve a very high density and are mostly planar.

I hope we get a glimpse of what unpacking looks like, but this will mean they have to unpack next to the booster...

[Mandella]

I guess this also gives another answer to the question "Why so many only partially functional sats on a test launch?"

The packing and unfolding is also being tested, along with multiple different variations on the individual satellites to see what works best.

[climbergilles]

So, how many sats will fit in Starship?

[gongora]

So, how many sats will fit in Starship?

This thread is for the upcoming launch.  General Starlink discussion should be conducted in the Starlink thread:
https://forum.nasaspaceflight.com/index.php?topic=36552.0

[ArbitraryConstant]

Looks like a stack of lawn chairs, each ready to pop open into a new shape.  But lawn chairs don't have propellant tanks and maneuvering thrusters. Remarkable engineering!

Maybe they don't unfold at all and they're just flying solar panels with propulsion and antennas.

edit: re comments this would limit power, do we know the power budget per satellite? maybe they adjust their angle somewhat using reaction wheels, their phased array antennas might be able to handle that.

Yeah, I kinda expect these things to do some clever origami shape-shifting tricks after they deploy, but who knows.  Elon did refer to them in a tweet as "flat-packed" which seems to imply a distinct configuration for delivery.

Here's my reasoning, this aspect ratio is very unusual for a satellite bus. Typically when a communications satellite unfolds something it's because the bus is more compact and hence efficient for propellant tanks etc and the additional surface area it wants is for functions like power and communications that want to fit more surface area in the limited dimensions of the fairing.

But in this case because the bus is so flat it already has a very large surface area for a bus of that mass. Unfolding trades something it already has lots of (surface area) and further limits something that's already constrained (inner dimensions for propellant tanks etc). The two systems that want lots of surface area, namely antennas and solar, already have lots. Moreover unlike a GTO satellite where the sun moves and the Earth doesn't, the Starlink bus can't use fixed antenna beams since it's moving over the Earth all the time, so if the whole satellite repoints itself a bit to capture more solar energy maybe that's something the antennas can deal with. It occurs to me that the satellites in a plane passing overhead would be aligned in more or less similar directions tilting towards the sun so this potentially wouldn't limit coverage at all, the base station would just need to talk to satellites closer to the horizon in the direction of the sun depending on latitude and time of day.

To summarize, something this bus needs anyway (reaction wheels) may be able to substitute to some extent for the mechanical complexity of deployable solar tracking arrays etc. This would never normally make sense but they're using a novel design to fit such a large number of satellites without a dispenser and in that fairly unusual circumstance I think it might make sense. They're basically floating 1U servers with solar on top and antennas below.

[ThomasGadd]

I have some questions. 

To deliver satellites into multiple planes the Merlin will have to fire for each adjustment.  Right? 

The procedure would be:  Initial burn, release first batch, next burn, release next batch, and so on until de-orbit burn.  Right?

What is the record for Merlin relights? 

My underlying question is how many planes will the initial mission populate? 

[niwax]

I have some questions. 

To deliver satellites into multiple planes the Merlin will have to fire for each adjustment.  Right? 

The procedure would be:  Initial burn, release first batch, next burn, release next batch, and so on until de-orbit burn.  Right?

What is the record for Merlin relights? 

My underlying question is how many planes will the initial mission populate?

More likely they'll either have one or maybe two planes per launch or drift the satellites into planes by themselves like Iridium does. This first launch might only be one plane, too, they won't be able to test 24/7 but it'll integrate into the final network.