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SpaceX launches another 60 Starlink satellites while setting two reuse records

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Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#151
post #109

Earlier quoted context omitted.

Netflix claims an UHD stream is 25 Mbps. This is probably the most demanding use case for your average consumer, but it may not be a rare use case in the near future. Each satellite can support 800 UHD streams. That doesn't seem sufficient if each satellite covers a large geographic area. This suggests to me a low data cap and/or rate, perhaps comparable to DSL.

12,000 satellites is the current FCC approved launch figures, I believe. 20Gbps per satellite but I don't know if that's full duplex or how much is divided between terminal/gateway, so lets divide that in half. For simplicity let's say they only sell consumer-grade 100Mbps connections, which are oversubscribed 100x as is typical. Divide the possible number of customers by 3 to account for uneven geographic distributi…

You're forgetting that this is a satellite constellation- I'm not sure what the orbital parameters are offhand, but I'd divide that number by at least 4 (and maybe up to 20), based on number of satellites over the service area(s) at any given moment.

Last I saw, they were reconfiguring deployment plans to go for higher density constellation in the lower latitudes before worldwide coverage, so I'm not sure if this is even knowable at this point.

Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#152

Earlier quoted context omitted.

I'd feel about the same as I do when Comcast wants to use my own cable modem as a public wifi hotspot. At this point I'd just like to have a built-in wifi hotspot for my own usage in my car. My Chevy can do this. My fancy high-tech Tesla cannot.

What if you were paid some/all of the profit via micropayments when people used your tesla/modem hotspot?

That would make it more palatable. And QOS so that anybody in my car using the hotspot has priority for traffic.

Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#153
post #109

Earlier quoted context omitted.

Netflix claims an UHD stream is 25 Mbps. This is probably the most demanding use case for your average consumer, but it may not be a rare use case in the near future. Each satellite can support 800 UHD streams. That doesn't seem sufficient if each satellite covers a large geographic area. This suggests to me a low data cap and/or rate, perhaps comparable to DSL.

12,000 satellites is the current FCC approved launch figures, I believe. 20Gbps per satellite but I don't know if that's full duplex or how much is divided between terminal/gateway, so lets divide that in half. For simplicity let's say they only sell consumer-grade 100Mbps connections, which are oversubscribed 100x as is typical. Divide the possible number of customers by 3 to account for uneven geographic distributi…

This first round of sats have 20Gbps but the next gen will be much faster.

Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#154
post #57

Earlier quoted context omitted.

I've been having this hard to articulate notion that humanity hasn't really begun to fathom the changes that will come with "cheap" launch vehicles. We have better than half a century where space launch was so expensive, and so rare, that this had an impact on the payloads themselves. Perversely it caused the payloads to become so highly engineered (for a variety of reasons) that they also became ultra-expensive in-l…

> billions upon billions of dollars to basically put a large 1 MP sensor at the end of a tube with a digital radio for communications. That's such a gross over-simplification of what the Hubble platform is and what it is capable of that it annoys me. First, there are _six_ scientific sensor packages on the Hubble craft. These have been swapped out and upgraded several times during its life with a process that allowed…

I think your response almost perfectly exemplifies the kind of luddism that's going to get washed away in the tsunami of stuff heading north up the gravity well.

We know today that the Hubble instrument cost about $4.7 billion, and lifetime costs as of 2010 are around $10 billion [1] which doesn't appear to have included launch costs (1 initial launch and I believe 5 servicing missions) which at around $450 million per launch is quite a bill of around $2.7 billion in total program launch costs.

One might try to make the argument that shuttle missions involved multiple mission objectives for each launch (and thus the total cost shouldn't be borne by the HST alone). However, HST servicing missions were designed around the shuttle, making it mandatory for the servicing mission and thus the entire cost is a minimum regardless of other shuttle duties.

For example, STS-61, the mission to repair the HST (plus a few other odds and ends) required one of the most complex mission profiles in history. I can't find solid figures on how much the mission cost, but I'm guessing it was on the order of around $1 billion dollars, launch costs included. I think it could be argued that such a complex mission was worth the cost in terms of maybe crew and mission planning experience, but my central argument is, in a cheap launch future, such a mission (and all servicing missions) would be entirely pointless -- which not only would be cheaper, but allow more advanced sensing packages to be put up over time with less of a risk to the lives of the astronaut crews.

Suppose Falcon-9 Heavy technology existed when the Hubble was launched. Here might be a take on an entirely different program:

1 - Separate satellites for each orthogonal sensing package. Say maybe, 1x FOC/FOS, 1x GHRS/HRS, 1x HSP, and 1x WFPC. So a constellation of 4 satellites to start with.

2 - Let's build all missions off of a single designed "things in a can" platform so we can realize cheaper costs over time. Let's assume an expected life-span of 4 years (the time between STS-61 and STS-82). So we can reduce the per device cost from $4.7 billion/per to probably something more in line with reality. Maybe $250 million/per so we can at least gold plate it a bit, but keep it within the original budget per instrument.

3 - Launch mass of the original HST was about 11.1 metric tonnes. Since we're getting rid of stuff, we can shave that down to probably 4 - A F9Heavy can shove 63,800 kg to LEO, which is about where the HST sits (with periodic reboosts during servicing missions). That means we can put the entire constellation up in one launch with room to spare.

5 - So no we're now in program year 5 and total cost (minus ground station and staff and such) is $1.09 billion. Even with a complete failure of one of the satellites, the replacement cost is $300 million ($250 for another satellite + $50 for an F9 launch). At 5 years in, with an equivalent optics failure as the HST, we're at $1.39 billion for a program of greater capability and one failed device.

6 - Over the years, the HST servicing missions added the ACS, COS, NICMOS, STIS, and the WFPC2 and WFC3 instruments. The COSTAR was never needed, and never needed to be replaced by the COS. That's two servicing missions that never had to happen at all! We've just shaved off almost another billion dollars from the program. For that cost, we can almost repeat the entire first launch and shove another 4 satellites of the the same capability in the air. So we do that and we're extend the life of the HSP and the WFPC missions beyond what actually happened and we're at a total cost of around $2.5 billion.

7 - We go ahead and do two more F9Heavy launches to clear out the mission backlog and now we have 14 satellites conducting mission, in orbit, for almost exactly the cost of just the original HST device, and no lives risked on servicing missions. With the remaining funds, we can deorbit failed satellites, engineer better/different sensing packages, and put another 14 satellites in orbit. Hell, there's enough spare launch capacity in the flight plan to put a couple JWSTs, CXOs, and roadsters up as well.

8 - We don't know what Starship launch costs might be, but they could significantly expand these kinds of mission profiles. Musk's crazy claim is $2 million per, and could shove maybe 6-8 HST-class satellites up in one go.

9 - For $2 million per launch, why the hell are we putting up $250 million dollar devices? Why not get crazy, set up an assembly line for "things in a can" space sensing devices and crank them out at $500,000 per can and radio setup with a "bring your own sensor" policy? Who the fuck cares if the STIS mission didn't pan out? Deorbit the sucker and put two more up next month!

At the scale of nation states and large corporations, it means space platforms become as disposable as they de facto actually are.

[1] https://www.nasa.gov/pdf/499224main_JWST-ICRP_Report-FINAL.p...

Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#155
post #131
post #109

Earlier quoted context omitted.

12,000 satellites is the current FCC approved launch figures, I believe. 20Gbps per satellite but I don't know if that's full duplex or how much is divided between terminal/gateway, so lets divide that in half. For simplicity let's say they only sell consumer-grade 100Mbps connections, which are oversubscribed 100x as is typical. Divide the possible number of customers by 3 to account for uneven geographic distributi…

Another calculation is revenue per satellite per customer served. Would 100k per month per satellite finance these things long term?

This seems like the important metric.

Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#156
post #18

4th reuse. Wow didn't realise they were that deep in already. Thought reuse was still conceptual

They've done it 22 times. https://en.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_He...

He means 4th reuse of _the same booster_. Not the 4th reuse of any and all Falcon 9s (if that's what you were getting at).

Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#157
post #98

Earlier quoted context omitted.

Starlink apparently won't be a fixed concept. 5 year sat lifecycle means its likely we'll see rapid year-over-year turnover and hence macro-level iteration on the specs and design.

RF and the Atmosphere being what they are and the non-variable parts of this equation mean there are significant real physical and abstract legal limits for any project attempting to put "bandwidth in orbit."

What are some ballpark figures on the theoretical / practical limits?

Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#158
post #109

Earlier quoted context omitted.

Netflix claims an UHD stream is 25 Mbps. This is probably the most demanding use case for your average consumer, but it may not be a rare use case in the near future. Each satellite can support 800 UHD streams. That doesn't seem sufficient if each satellite covers a large geographic area. This suggests to me a low data cap and/or rate, perhaps comparable to DSL.

12,000 satellites is the current FCC approved launch figures, I believe. 20Gbps per satellite but I don't know if that's full duplex or how much is divided between terminal/gateway, so lets divide that in half. For simplicity let's say they only sell consumer-grade 100Mbps connections, which are oversubscribed 100x as is typical. Divide the possible number of customers by 3 to account for uneven geographic distributi…

($800m a month * 12month * 5month sat lifespan)/12000 sats = of 40m revenue per satellite

150kg sat to launch at $2,719kg/leo costs $0.4m

Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#159

Earlier quoted context omitted.

That's interesting that they say 100% of the components will burn up on reentry— is this an updated design? That wasn't true for the previous batch

If this becomes really common, do any of the materials on the satellites present a health or environmental concern?

No.

Re: SpaceX launches another 60 Starlink satellites while setting two reuse records

#160
post #135

Earlier quoted context omitted.

Sounds speculative. Given link bandwidths and likely error rates, it seems better to allow the higher layers to retransmit than to optimize for correcting burst errors. Especially given Starlink's goal to control latency.

I haven't seen a link budget. Do you have a link for one about the "likely error rates"? My guess is Starlink is going to need FEC for Doppler effects and multipath in urban environments. Maybe they will be able to overcome multipath with modulation. But Doppler shift will be significant with LEO. The latest 802.11n standards have been increasing physical layer frame sizes, not decreasing them. I don't know of any mo…

Not commenting on error correction, but your speculation about multipath reveals that you fundamentally fail to understand how starlink is meant to work.

Starlink allows high bandwidth density on the ground, and at the satellites because every antenna in the system is an extremely capable steerable phased array. Every transceiver can fully distinguish between signals of equal power and frequency that differ whose sources differ at least 10 degrees.

Reflections from buildings are irrelevant when the antenna must already be capable of picking the correct transmission out of the 50 or so equally powerful beams on the same frequency that only differ in angle.

Also, since every terminal already needs to be constantly aware of the position of every satellite, the correct answer to doppler is not fancy error correction, it's modulating the transmission to eliminate it, or just expecting it at the receiver.

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