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Building a Space-Based ISP

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Re: Building a Space-Based ISP

#11

Post by azernik »

HALtheWise wrote: post #4

The article ends with this nugget about C++ shared memory state management, but I don't have the background to know exactly what they're referring to. Does anyone recognize this pattern and feel able to explain it to mere mortals? > “We also have different tools so that any state that is persisted through the application is managed in a very particular place in memory. This lets us know it is being properly shared be…

Essentially:

They have one address range for shared (i.e. subject to syncing across all replicas) memory, and a separate one for non-shared (single-replica) memory.

Cross-replica data is presumably subject to their agreement algorithm, checking that the different computers reach the same (within some error bars) results; you want to arrange things so that there are frequent checkpoints at which the conflict resolution system can say "a bad write happened at this point, I should disregard whatever this computer said from that point until it recovers".

i.e. you want local memory to use as scratch space for performance reasons, but to make sure that there isn't a long runway for errors to happen and decisions to be made before the shared-memory checker notices a mistake. To ensure this happens, you want manual control over which memory allocator handles which data.

Re: Building a Space-Based ISP

#12

Post by azernik »

VWWHFSfQ wrote: post #9
cute_boi wrote: post #7

"Starlink is currently in orbit at 340 miles" Can we please stop using miles etc :( I am tired when people makes mistake like this.

what should they use

Kilometers.

If they're writing for a US audience and absolutely need miles, put one or the other in parens after the "main" one.

Re: Building a Space-Based ISP

#13

Post by admissionsguy »

mnd999 wrote: post #2

Puff piece. Starlink is fundamentally not about providing broadband to anyone. It’s landgrabbing a finite resource - low-earth orbit space - before it’s worth is recognised by those who should be regulating it. The broadband itself might be nice or it might be awful. It doesn’t actually matter because that was never the point.

Is it scarce, though? Couldn't you put more constellations at the same orbits +/- a couple of kms? In any case, I would expect the spectrum rights to be much scarcer than the space, and they are well regulated.

Re: Building a Space-Based ISP

#14

Post by marsokod »

p1mrx wrote: post #10
nynx wrote: post #3

Starlink is super exciting from an emerging technologies perspective —— (relatively) cheap satellite production, commercialized laser links, commercialized phased-array tx/rs, among others. These open up very interesting possibilities down the road. These posts always have a thread about people wanting to work for spacex, but because of my pseudo-anonymity, I don’t feel bad about starting it: Does anyone know if spac…

I think the most exciting part is their use of electric ion propulsion to maintain low earth orbit. If SpaceX ever goes bankrupt or something, the satellites will passively deorbit within 5 years or so.

No need for that actually. They will deorbit within a year if left completely dead, and within a couple of month if they have a single button "start deorbiting" that uses the electric propulsion.

But more importantly, their propulsion allows them to launch at a very low orbit. This is a very good method for a constellation as they can see all the early failures (the beginning of the bathtub curve) happen at a very low orbit and reduce the cost of ground testing.

Their orbital debris management strategy is one of the best I have seen.

Re: Building a Space-Based ISP

#15

Post by jsharf »

mnd999 wrote: post #2

Puff piece. Starlink is fundamentally not about providing broadband to anyone. It’s landgrabbing a finite resource - low-earth orbit space - before it’s worth is recognised by those who should be regulating it. The broadband itself might be nice or it might be awful. It doesn’t actually matter because that was never the point.

The alternative is waiting literally 10-20 years for anyone else to catch up.

Re: Building a Space-Based ISP

#16

Post by krapht »

azernik wrote: post #12
VWWHFSfQ wrote: post #9

Earlier quoted context omitted.

what should they use

Kilometers. If they're writing for a US audience and absolutely need miles, put one or the other in parens after the "main" one.

People who get irritated over units of measure are themselves irritating. It is not so hard to round, double it 4 times and then divide by 10.

Re: Building a Space-Based ISP

#17

Post by wmf »

mnd999 wrote: post #2

Puff piece. Starlink is fundamentally not about providing broadband to anyone. It’s landgrabbing a finite resource - low-earth orbit space - before it’s worth is recognised by those who should be regulating it. The broadband itself might be nice or it might be awful. It doesn’t actually matter because that was never the point.

So what is the high-value use of low-earth orbit other than broadband and why doesn't SpaceX do that directly?

Re: Building a Space-Based ISP

#18

Post by cryptonector »

jsharf wrote: post #15
mnd999 wrote: post #2

Puff piece. Starlink is fundamentally not about providing broadband to anyone. It’s landgrabbing a finite resource - low-earth orbit space - before it’s worth is recognised by those who should be regulating it. The broadband itself might be nice or it might be awful. It doesn’t actually matter because that was never the point.

The alternative is waiting literally 10-20 years for anyone else to catch up.

Or, hey! slow SpaceX down with regulation!1!!

Re: Building a Space-Based ISP

#19

Post by cryptonector »

marsokod wrote: post #14
p1mrx wrote: post #10

Earlier quoted context omitted.

I think the most exciting part is their use of electric ion propulsion to maintain low earth orbit. If SpaceX ever goes bankrupt or something, the satellites will passively deorbit within 5 years or so.

No need for that actually. They will deorbit within a year if left completely dead, and within a couple of month if they have a single button "start deorbiting" that uses the electric propulsion. But more importantly, their propulsion allows them to launch at a very low orbit. This is a very good method for a constellation as they can see all the early failures (the beginning of the bathtub curve) happen at a very lo…

And launching to lower orbits means higher payload to orbit per launch which means they can launch more of their constellation per launch. (Although they probably a larger constellation at those orbits just due to how short the orbital periods are.)

Re: Building a Space-Based ISP

#20

Post by cryptonector »

admissionsguy wrote: post #13
mnd999 wrote: post #2

Puff piece. Starlink is fundamentally not about providing broadband to anyone. It’s landgrabbing a finite resource - low-earth orbit space - before it’s worth is recognised by those who should be regulating it. The broadband itself might be nice or it might be awful. It doesn’t actually matter because that was never the point.

Is it scarce, though? Couldn't you put more constellations at the same orbits +/- a couple of kms? In any case, I would expect the spectrum rights to be much scarcer than the space, and they are well regulated.

Exactly, spectrum is the scarce resource here, and it already is regulated. There is no need for additional regulation regarding that, and there already is regulation of orbits between FCC and FAA.
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