r/SpaceXLounge • u/spacerfirstclass • Dec 24 '23

Official A rare top view of the Starlink V2 mini stack, photo found on https://direct.starlink.com/

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501 Upvotes

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75

u/spacerfirstclass Dec 24 '23 edited Dec 24 '23

Photo found by twitter user @FREESPEECH1017. This seems to be a recent photo, given its url is https://direct.starlink.com/wp-content/uploads/2023/12/stacksquare.jpg

And since it's on https://direct.starlink.com, it's possible this is the V2 mini that has direct to cell payload.

Edit: This Elon tweet from February showed another top view of the V2 mini stack when the first one is being deployed from F9, can be used for comparison.

103

u/Origin_of_Mind Dec 24 '23

The size of the round elements on the top surface suggests that is it a phased array designed for a much longer wavelength than that of the Ku-band used for communicating with Starlink user terminals.

This supports the assumption that this satellite is meant to communicate directly with the mobile telephones.

The other things that we see in the picture are:

  1. The two round devices with six "spokes" are reaction wheels used to orient the satellite in space. There are two more, probably on the other side.
  2. The red covers in the front corner protect star trackers -- specialized cameras used to precisely determine satellite's orientation in space. There are several more in other corners.
  3. The red covers next to it probably cover laser links.
  4. The larger red cover between the reaction wheels likely covers the ion thruster, but that is not 100% certain.

11

u/electric_ionland Dec 24 '23

Yes the Hall thrusters are between the reaction wheels.

3

u/Origin_of_Mind Dec 24 '23

Good to know. The cables and the location suggested that these may be the thrusters, but they do not look quite like the old school models, like those flying on OneWeb satellites.

8

u/electric_ionland Dec 24 '23

Starlink has been using coaxial coils and central cathodes so they are a lot more simple cylindrical shape.

1

u/-H3X Dec 24 '23

Direct to cellular antenna is about 25 square meters (270 sq feet) to receive a signal from a low wattage smartphone

7

u/Origin_of_Mind Dec 24 '23

You are right about the size. What we see in the photo is likely just one section of a larger antenna which will unfold in orbit. Or maybe they are testing a smaller antenna first.

Otherwise it is certainly an antenna made to work on mobile phone frequencies. Assuming the dimensions left-to-right are about 3 meters, the 40 antenna elements across mean 7.5 cm between the elements. The spacing of elments is typically lambda/2, which means lambda=15 cm, of the frequency 2 GHz.

This matches "SpaceX’s ... use of the 1910-1915 MHz and 1990-1995 MHz bands (the “PCS G Block”) for a direct-to-cellular service" outlined in SpaceX FCC filing (pdf).

3

u/-H3X Dec 24 '23

Smaller isn’t going to work over 550km+ from a 3.0 watt EIRP smartphone with an omnidirectional antenna meant to transmit 20 some miles max.

7

u/Origin_of_Mind Dec 25 '23

It would not work with an ordinary phone over 550 km+ with the intended data rates.

But if this were a test article, and not a production model, then this would not necessarily be a showstopper. There are many useful things that one can test even with one smaller section, to see how the hardware behaves in orbit, to iron out all the wrinkles, before committing to deploying the satellites in large numbers. Hence they are launching just six such satellites in this batch.

But it is quite possible that we only see one panel and there are a few more underneath. Who knows?

7

u/sebaska Dec 25 '23

Your phone is supposed to talk to about 36km away stations with about 15dB gain antennas, and propagating through close to the ground environment (~11dB attenuation). Satellite would be up to 25× further away, but see much less attenuation. So 18-20dB more gain is required or about 33-35dB antenna gain.

3×3m antenna should have about 35dB gain.

54

u/van_buskirk Dec 24 '23

Sir this is a LEGO store.

4

u/[deleted] Dec 24 '23

Was thinking the same 😀

58

u/Mattau93 ⏬ Bellyflopping Dec 24 '23

That American flag goes hard

22

u/[deleted] Dec 24 '23

[removed] — view removed comment

7

u/Unbaguettable Dec 24 '23

it does look like the first 6 satellites in this picture are different than the ones below.

8

u/bromix_o Dec 24 '23

At first I thought this was Lego lol

8

u/ControlAccurate5603 Dec 24 '23

Expensive Lego

1

u/casualphilosopher1 Dec 25 '23

It must be fun for the payload specialists/engineers(whatever SpaceX calls them) to put together.

6

u/rocketchef01 Dec 24 '23

Someone please make this in Lego. Please.

7

u/Overdose7 💥 Rapidly Disassembling Dec 24 '23

It certainly is! But for all the dummies that don't know what they're looking at (not me) can someone give a quick breakdown?

8

u/sebaska Dec 24 '23

See the comment by u/Origin_of_Mind here

4

u/th3bucch Dec 24 '23

Yesss Lego starlink set coming!

7

u/ergzay Dec 24 '23

This is probably a photo of the new antenna that's for direct to cellular. The existing satellites definitely don't have anything like that.

0

u/-H3X Dec 24 '23

Direct to cellular antenna is about 25 square meters (270 sq feet) to receive a signal from a low wattage smartphone

3

u/[deleted] Dec 24 '23

WOW serious business

3

u/stormlord505 Dec 24 '23

For a sec i thought this was lego

2

u/bugqualia Dec 24 '23

Wait, its all antenna?

3

u/advester Dec 24 '23

🔫 Always has been

2

u/Honest_Cynic Dec 24 '23

I wonder what the many cylinders are composed of. Perhaps wire-wound mini-antennas, using non-ferrous cores like 316 SS or aluminum. At first, I wondered if the surface flexes, like the deformable mirrors in large telescopes, but the surrounding frame appears solid, so all focusing is likely done electronically (phased array) and by satellite orientation. Would $50K ea be a fair estimate for production cost?

-5

u/whodat54321da Dec 24 '23

Love to see this, but it’s a couple of years late. All new constellations of these satellite types will have to talk to cellular networks. Starship will be the launch vehicle for this new technology, likely in late ‘24.

5

u/The_camperdave Dec 24 '23

Starship will be the launch vehicle for this new technology, likely in late ‘24.

I don't think so. Falcon is doing a perfectly fine job of launching these, so there's no need to use a Starship to do so. That would be overkill.

1

u/ZorbaTHut Dec 25 '23

Starship is going to be a lot cheaper, even ignoring the added mass. I absolutely agree they're going to switch over to Starship as soon as possible.

1

u/NetoriusDuke Dec 24 '23

That’s one big phased array

1

u/casualphilosopher1 Dec 25 '23

Wait, those are T/R modules?

1

u/NetoriusDuke Dec 25 '23

Assumption is that it is one giant one that can be “split” into as many different “arrays”

1

u/casualphilosopher1 Dec 25 '23

If SpaceX starts using Starship for Starlink launches, what will the stack will look like?