Author Topic: Starlink v2 mini satellites  (Read 67105 times)

Online vaporcobra

Re: Starlink v2 mini satellites
« Reply #40 on: 02/28/2023 03:55 am »
Lots of changes.  The mirror film over the phased arrays, the deployment rods staying attached to the second stage.  Can't tell what the fold-out pieces on top of the solar arrays are.

To add to this, the rectangular object sticking out from the crossbeam is likely a big chunk of aluminum honeycomb that crushes against the tank wall to stop the 'ladder' from bouncing back up.

Offline Asteroza

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Re: Starlink v2 mini satellites
« Reply #41 on: 02/28/2023 04:04 am »
Can't tell what the fold-out pieces on top of the solar arrays are.

My eyesight isn't that bad yet, but what fold out pieces are you referring to?

Offline catdlr

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Re: Starlink v2 mini satellites
« Reply #42 on: 02/28/2023 04:13 am »
Can't tell what the fold-out pieces on top of the solar arrays are.

My eyesight isn't that bad yet, but what fold out pieces are you referring to?

The best I could see was the two Argon thrusters pointed 45 deg from each other at the top of the solar arrays. Unless that crack that runs down the entire length of the solar array folds outward?
« Last Edit: 02/28/2023 04:15 am by catdlr »
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Offline blach

Re: Starlink v2 mini satellites
« Reply #43 on: 02/28/2023 05:15 am »
2000W/kg is REALLY good specific power, I think?

The Busek 600W hall thruster is 2.6kg.

All the stats are pretty impressive considering argon fuel.

SpaceX is getting good at building them, not a surprising development factoring in the gigantic numbers of them they must build now. (Must be multiples the rest of the world combined?)
Overall it does better using argon than the Busek does using Xenon fuel. Plus its ISP increase over that of an Xenon Hal thruster will need 30% less fuel for same total Delta-V.

added: Correction For the V2 sats. That is >50% less fuel for same DV. From the Isp*9.8*LN(wet/dry) where using argon only 20% of V2 sat mass is fuel.

The V2 will be a "lively" as in highly and quickly maneuverable sat vs the V1's due to the much higher acceleration rates even with same number of thrusters and 2X the total mass. Giving the V2s about 2X the acceleration over that of V1 for same number of thrusters.

I'm not sure this is correct. It might actually be a good bit slower to reach operational orbit:

https://twitter.com/lougrims/status/1630309641434398722

Offline woods170

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Re: Starlink v2 mini satellites
« Reply #44 on: 02/28/2023 09:11 am »
Stupid question: How many per launch? This has a huge impact on concerns regarding space debris and astronomical impact.

Stack looks to be 20 high but it's not clear if there are multiple satellites in each layer.
SpaceX tweeted 21 per launch:

https://twitter.com/SpaceX/status/1629898239066480640?t=mNgtxYvARzRcMzgET8K5rA&s=19
The PLF volume wise can support 30 sats but mass wise will be around 20 depending upon factors such as launch site, launch azimuth and targeted inclination and seasonal weather.

They might upgrade to Extended Fairing with Recovery.
That would necessitate using Falcon Heavy as the combined payload stacks' wet mass is the constraint not the fairing. The stack is 9 minis short of the of the v1.0 stack height which was two parallel stacks of 30 totalling 60.

You are assuming that the V2 mini's have the same "height" (or rather lack thereof) as the v1.0 sats. I can tell you that your assumption is incorrect. The V2 mini's are somewhat "thicker" than the v1.5 sats and notably thicker than the v1.0 sats. Also, the way how the tension-release mechanism of the connected tension rods is set up,  removes a few feet of useable room near the top of the fairing. Both factors combined is why in the same height of payload envelope only 21 layers of V2 minis can be stacked, against 30 layers of v1.0s.

Offline TrueBlueWitt

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Re: Starlink v2 mini satellites
« Reply #45 on: 02/28/2023 11:58 am »
You can tell the v2's were designed for Starship with being enclosed all the way to orbit.. They are like typical Sats in their ability to withstand aero-loads/heating. You could see there was a much bigger delay in Fairing Deploy than with the earlier v1.x Starlinks. This likey cost them an additional 1-2 Starlinks they could lift to orbit.

Offline Robotbeat

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Re: Starlink v2 mini satellites
« Reply #46 on: 02/28/2023 12:24 pm »
2000W/kg is REALLY good specific power, I think?

The Busek 600W hall thruster is 2.6kg.

All the stats are pretty impressive considering argon fuel.

SpaceX is getting good at building them, not a surprising development factoring in the gigantic numbers of them they must build now. (Must be multiples the rest of the world combined?)
Overall it does better using argon than the Busek does using Xenon fuel. Plus its ISP increase over that of an Xenon Hal thruster will need 30% less fuel for same total Delta-V.

added: Correction For the V2 sats. That is >50% less fuel for same DV. From the Isp*9.8*LN(wet/dry) where using argon only 20% of V2 sat mass is fuel.

The V2 will be a "lively" as in highly and quickly maneuverable sat vs the V1's due to the much higher acceleration rates even with same number of thrusters and 2X the total mass. Giving the V2s about 2X the acceleration over that of V1 for same number of thrusters.

I'm not sure this is correct. It might actually be a good bit slower to reach operational orbit:

https://twitter.com/lougrims/status/1630309641434398722
Heís exaggerating the efficiency difference and the time to reach orbit. Efficiency of Xenon at that Isp would be about 65%, Krypton in between like 57%. But the Isp was increased from before which reduces the efficiency hit.

SpaceX gets a really good power to weight ratio with this thruster. If they also improved the solar arrays, then there may have been no hit to time to reach station at all. In spite of the higher Isp and lower efficiency.
« Last Edit: 02/28/2023 12:26 pm by Robotbeat »
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Offline gongora

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Re: Starlink v2 mini satellites
« Reply #47 on: 02/28/2023 12:27 pm »
Can't tell what the fold-out pieces on top of the solar arrays are.

My eyesight isn't that bad yet, but what fold out pieces are you referring to?

There are two surfaces on top covered with mirror film, I'm assuming those fold out and face the ground.

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Re: Starlink v2 mini satellites
« Reply #48 on: 02/28/2023 07:23 pm »
https://twitter.com/sciguyspace/status/1630659589673721864

Quote
Fascinating thread here on why SpaceX shifted from using Krypton to Argon to fuel its Starlink spacecraft. The new thrusters were designed, built, tested, and flown in about 550 days.

twitter.com/lougrims/status/1630302082526769153

Quote
As promised here is a thread on SpaceX announcement about their new Hall thruster for Starlink V2 mini. Trying to go over the figures they published and why it's kind of a unique thruster. Please excuse in advance typos, I had a long day of meetings. twitter.com/SpaceX/status/Ö

https://twitter.com/longmier/status/1630463541949132800

Quote
Nice writeup Lou. This was a tricky one for us to solve for sure.

twitter.com/lougrims/status/1630464757147787265

Quote
I can imagine! You probably can't take about it but I would be curious to know when the switch to argon was decided. Also love those molded brackets on the reaction wheel. Cool to see that volumes are high enough that "CNC all the things" is not the best solution anymore.

https://twitter.com/longmier/status/1630626524318797825

Quote
556 days from thruster clean-sheet to orbit.

Offline Asteroza

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Re: Starlink v2 mini satellites
« Reply #49 on: 02/28/2023 11:13 pm »
Can't tell what the fold-out pieces on top of the solar arrays are.

My eyesight isn't that bad yet, but what fold out pieces are you referring to?

There are two surfaces on top covered with mirror film, I'm assuming those fold out and face the ground.

Ah, eyes got tricked, thought I was seeing the horizon directly when that was actually the reflection off the mirrored panel.

I think the mirror panel part is covering the pieces of the small antennas and their frame. But, it's on both sides, so I wonder about line of sight issues with at least one ISL laser beam director...

Offline russianhalo117

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Re: Starlink v2 mini satellites
« Reply #50 on: 03/01/2023 01:55 am »
No, there is not nearly enough Xenon, and itís way too expensive to use Xenon.
Xenon as what is used for spacecraft underwent isotopic beta decay from Iodine via the Iodine to Xenon cycle. There is however it is nearly all trapped inside rock, the mantle and water, however its free atmospheric abundance is variable through degassing and regassing though it is presently on a decreasing trend. Argon comes from rock as well as originates from Potassium Argon cycle. Carbon becomes Nitrogen over time. It is all a cycle subject to physical reaction and geologic time. Xenon and Iodine love heat while under pressure to regas the rock. To move upwards a combination of the geologic elevator and water bring the final product and its variations of Xenon to the surface. Subduction , hydrothermal vents and eruptions are some of natures ways to degas Xenon from the rock.

Offline russianhalo117

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Re: Starlink v2 mini satellites
« Reply #51 on: 03/01/2023 02:10 am »
Stupid question: How many per launch? This has a huge impact on concerns regarding space debris and astronomical impact.

Stack looks to be 20 high but it's not clear if there are multiple satellites in each layer.
SpaceX tweeted 21 per launch:

https://twitter.com/SpaceX/status/1629898239066480640?t=mNgtxYvARzRcMzgET8K5rA&s=19
The PLF volume wise can support 30 sats but mass wise will be around 20 depending upon factors such as launch site, launch azimuth and targeted inclination and seasonal weather.

They might upgrade to Extended Fairing with Recovery.
That would necessitate using Falcon Heavy as the combined payload stacks' wet mass is the constraint not the fairing. The stack is 9 minis short of the of the v1.0 stack height which was two parallel stacks of 30 totalling 60.

You are assuming that the V2 mini's have the same "height" (or rather lack thereof) as the v1.0 sats. I can tell you that your assumption is incorrect. The V2 mini's are somewhat "thicker" than the v1.5 sats and notably thicker than the v1.0 sats. Also, the way how the tension-release mechanism of the connected tension rods is set up,  removes a few feet of useable room near the top of the fairing. Both factors combined is why in the same height of payload envelope only 21 layers of V2 minis can be stacked, against 30 layers of v1.0s.
That was all a very quick guestimation before pictures became available.
The tension rods height, per a friend, of the forward release mechanism can be adjusted for the intended number of sats and are not at the maximum loading capacity but close. For this flight, and maybe others, cameras were flown on select tension rods with the blue cabling running to them and the stacks forward release mechanism.

Offline woods170

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Re: Starlink v2 mini satellites
« Reply #52 on: 03/01/2023 07:35 am »

https://twitter.com/longmier/status/1630626524318797825

Quote
556 days from thruster clean-sheet to orbit.

And THAT is why the rest of the world is unable to compete with SpaceX.
« Last Edit: 03/01/2023 07:38 am by woods170 »

Offline ZachF

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Re: Starlink v2 mini satellites
« Reply #53 on: 03/01/2023 04:20 pm »
Something fun/interesting to think about, the eventual photovoltaic capacity of the Starlink system might be measured in *gigawatts*!

https://twitter.com/virtuallynathan/status/1630941027317186560?s=21

1 GW generation at 50% capacity is roughly comparable to Latvia or Lithuania.
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Re: Starlink v2 mini satellites
« Reply #54 on: 03/01/2023 05:48 pm »
Pretty impressive coming from a ~800kg satellite. (16,900kg/21 = 804kg).

From Wikipedia's Falcon 9 Launch List:

27 February 2023,
23:13[491]   F9 B5 ♺
B1076.3[492]   CCSFS,
SLC-40   Starlink Group 6-1[493] (21 V2 Mini satellites)[494]   ~16,900 kg (37,300 lb)   LEO   SpaceX   Success   Success
(drone ship)
An East Coast Starlink launch to their Generation 2 network. First launch of downsized Starlink V2 satellites - officially referred to as the F9-2 bus, but colloquially known as "Starlink V2 Mini." This flight marked the 100th consecutive landing success of a Falcon 9 booster since 16 February 2021.

Offline Robotbeat

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Re: Starlink v2 mini satellites
« Reply #55 on: 03/01/2023 06:34 pm »
Something fun/interesting to think about, the eventual photovoltaic capacity of the Starlink system might be measured in *gigawatts*!

https://twitter.com/virtuallynathan/status/1630941027317186560?s=21

1 GW generation at 50% capacity is roughly comparable to Latvia or Lithuania.
24% is actually doable for commercial silicon cell panel-level efficiency at 1AM or AM1.5, ie 1000W/m^2 at sea level and the equator. But space has higher intensity sunlight AM0 (air mass zero) of 1367/m^2. However the slightly different spectrum means a little lower efficiency. Maybe 21% efficiency, so the net effect is still to have about 287W/m^2 solar power at the panel level. Itís possible he actually under-estimated total power per satellite (although I suspect itís close as maybe Starlink solar panels are not as optimized in area). It could be 73.4kW per Starlink v2 full size satellite. (Trying to find the FCC documentÖ Which isnít made any easier by the fact that deep-linking to FCC document attachments does not work in spite of people continuing to try deep-linking to those documents here. PLEASE attach the document PDF when linking to the FCC site!

Edit: Iíve attached the document in question.
« Last Edit: 03/01/2023 06:42 pm by Robotbeat »
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Offline Robotbeat

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Re: Starlink v2 mini satellites
« Reply #56 on: 03/01/2023 06:49 pm »
Note that because the satellites are orbiting around 530km altitude, about 510km above vast majority of the atmosphere, their time in sunlight is over 60%, not just 50%.

Anyway, letís say 40,000 satellites at 73.4kW each and with a 60% capacity factor. 77.2TWh of energy made over 5 years.

Letís say it took 800 Starship launches to get them there. That required on the order of 800,000tonnes of methane, which if fully burned produces 2.75 kg of CO2 per kg of methane, so about 2.2Mtonnes of CO2. Thatís 28.5 grams of CO2 emitted per kWh of electricity produced on the Starlink satellites (which displaces perhaps a similar amount on the ground? Maybe half that because maybe half of the energy is used for stationkeeping). Not bad compared to the US average of over 360grams of CO2 per kWh.

Or put another wayÖ 800,000 tonnes of methane at 55.5MJ/kg is 44.4 Petajoules (4.44e16J) which the average 1.76GW pays back in about 0.8 years or 10 months. The solar arrays produce more electrical energy than it took fuel energy to launch the rocket within 10 months. Again, not too shabby!

It may not be space based solar power with actual energy beaming, but offloading telecoms energy to orbit isnít bad, either.
« Last Edit: 03/01/2023 07:07 pm by Robotbeat »
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Online DanClemmensen

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Re: Starlink v2 mini satellites
« Reply #57 on: 03/01/2023 06:56 pm »
Note that because the satellites are orbiting around 530km altitude, about 510km above vast majority of the atmosphere, their time in sunlight is over 60%, not just 50%.
Not because the are above the atmosphere, but because they spend less than half the time in the Earth's shadow.

Offline Robotbeat

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Re: Starlink v2 mini satellites
« Reply #58 on: 03/01/2023 07:08 pm »
Note that because the satellites are orbiting around 530km altitude, about 510km above vast majority of the atmosphere, their time in sunlight is over 60%, not just 50%.
Not because the are above the atmosphere, but because they spend less than half the time in the Earth's shadow.
Yes, of course, I took that to be implicit. I included the atmosphere as part of the thing that can produce a shadow. Clouds and stuff can produce a shadow.
« Last Edit: 03/01/2023 07:09 pm by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Re: Starlink v2 mini satellites
« Reply #59 on: 03/01/2023 07:15 pm »
Not sure if this was mentioned here but from 6-1, SpaceX separated the fairings much later at ~98km altitude compared to much lower altitudes with the Starlink V1.5 launches (the latest V1.5 launch out of Vandenburg separated at ~85km). I wonder if this is a case of SpaceX playing it safe for the first launch with V2 mini sats or if the new sats truly do have less tolerance for lower atmospheric heating. I mean, when the V2 sats launch on starship they dont have to experience any atmospheric heating or drag because, well, the satellites arent exposed to space until deployment.

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