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SpaceX just got FCC approval to launch 7,518 satellites

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Re: SpaceX just got FCC approval to launch 7,518 satellites

#181

Post by bsder »

HarryHirsch wrote: post #138
notimetorelax wrote: post #118

Earlier quoted context omitted.

Which is fine, if there’s someone who can create it’s amazing if we can support them.

Back then the rocket scientists from JPL and MIT had dozens of aerospace contractors where they could go, and science would be moved forward. Nowadays, the rocket scientists join any of the dozens of hedge funds, but some go work for SpaceX. This is the stagnation of outsourcing.

> This is the stagnation of outsourcing.

This is the stagnation of paying your scientists poorly.

One of the reasons for so many microbreweries in San Diego was paying microbiology types so poorly. More than one microbrewer here has said: "Well, I was getting paid kinda crappy in biology. So, I started a microbrewery. Now I get paid about the same, don't have to put up with managers, and get to drink beer."

Re: SpaceX just got FCC approval to launch 7,518 satellites

#182

Post by dr_orpheus »

Rebelgecko wrote: post #129

Is there anyone who knows more about radio stuff that can explain why they want to have both Ku and V band for users? It it just a matter of having more spectrum? Or are some bands more suited to crowded areas, like a city where there might be lots of customers sharing bandwidth? Do you need different hardware for using the different frequencies?

There are a few possible reasons for using multiple bands. With the higher frequency of the V band you can very high data rates down to the ground. However, higher frequency RF will be very attenuated by rainfall [0]. So the Ku band could be used as a backup to the V band.

The V band (or optical links) will also likely be used for the inter-satellite communication.

You do typically need different hardware for using the different frequencies. With some of the more advanced software defined radios, you could use both of the at the same baseband within the same radio. But you will still need some sort of frequency conversion [1]. You will likely need different antennas for each band as well. And to get an efficient system you also want to add filters for each band.

[0] http://happy.emu.id.au/lab/rep/rep/9510/txtspace/9510_032.ht... [1] https://en.wikipedia.org/wiki/Low-noise_block_downconverter

Re: SpaceX just got FCC approval to launch 7,518 satellites

#183

Post by flukus »

spaceribs wrote: post #9
zjaffee wrote: post #3

Does anyone have any context on what sort of internet speeds satellite internet has been benchmarked to provide. I can't imagine the latency being anywhere near good enough to do many of the high bandwidth things people use the internet for today.

You'd be surprised, this article describes round-trip times to be 25ms to 35ms and gigabit speeds: https://arstechnica.com/information-technology/2018/02/space... Who knows if they'll actually reach these speeds/latencies in practice though, that remains to be seen.

Presumably those gigabit speeds are shared by the thousands/millions of people on your node. Wireless is a shared medium.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#184

Post by bargl »

jandrese wrote: post #147
bargl wrote: post #33

This is such a cool problem. We already have a ton of Geo sat which can do this kind of communication but they are super expensive and have a limited bandwidth. These satellites will actually have a ton of limitations in how much data they can send around and how they'll have to balance out their signals. Geo are easier to point to because, well they don't move. But these are going to be moving and changing all the t…

Motorola solved this problem with its Iridium constellation back in the 90s. Handoff between satellites isn't really that hard. Your phone knows where it is and what birds are overhead (and which are about to appear/disappear) so they can adjust automatically. Routing through the satellite constellation gets kind of hairy, but is also solvable via orbital mapping and some arcane routing algorithms. The real trick is…

Kymeta is coming out with a directional flat antenna. It wouldn't suit for a phone but I don't think these are meant for phones. I was not saying cell phone would have spinny disks on the top.

The last part is, where I think the real fun will emerge. Doing everything above but optimized based on the load of each satellite with a link budget computation involved will be cool. It may prove out that the optimization isn't needed but I think that kinda stuff is fun.

https://www.kymetacorp.com/markets/connected-car/kalo-trek/

Re: SpaceX just got FCC approval to launch 7,518 satellites

#185

Post by maxxxxx »

soared wrote: post #93
Rooster61 wrote: post #79

Earlier quoted context omitted.

I'm no stranger to the vast physical space at play here (amateur astronomer, here). I'm aware there is a LOT of room for this stuff to move around, but there is still a threshold, however high, to where the amount of debris would become dangerously numerous.

And you think that we can only fit <10k objects in an area larger than the surface of the earth?

There has been a collision between an Iridium satellite and another one before. It's a valid concern.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#186

Post by gbear605 »

Denzel wrote: post #158
test6554 wrote: post #146

Earlier quoted context omitted.

Anybody who sees a ceo who plans to spend a large chunk of company profits on colonizing mars for the sake of humanity might think to themselves, "I wonder if I can start a similar company, avoid the mars colonization expenses and undercut them on price."

You misunderstand just slightly, and through no fault of your own I might add since SpaceX’s messaging is deliberately murky here. SpaceX has no plans right now to colonize Mars. In fact, they keep saying, “Look! We want other companies or nations to step up and plan for how to establish a colony. We’re only going to do it if we absolutely have no other choice.” SpaceX is truly establishing a financially viable solar…

I think for Musk, Mars is more than just a milestone, but he’s able to be realistic enough that he knows that he SpaceX needs to focus on the rockets for now.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#187

Post by bargl »

tortarga wrote: post #140
bargl wrote: post #33

This is such a cool problem. We already have a ton of Geo sat which can do this kind of communication but they are super expensive and have a limited bandwidth. These satellites will actually have a ton of limitations in how much data they can send around and how they'll have to balance out their signals. Geo are easier to point to because, well they don't move. But these are going to be moving and changing all the t…

There was recently a video posted theorizing this here: https://www.youtube.com/watch?v=AdKNCBrkZQ4 Very interesting watch. Based off the paper: https://twitter.com/awm22/status/1044512585599602688

This is awesome thanks.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#188

Post by wolf550e »

51lver wrote: post #179
wolf550e wrote: post #165

Earlier quoted context omitted.

1-RTT TLS 1.3 handshake with small ECC keys and certificate chain optimized for size, and TLS shouldn't be a problem to sync mail over slow connection.

Simple and reliable pgp encryption will outlast tls 1.3, and rural users (quite reasonably) expect more life from their devices than city folks. No one is going to download and update with a 200MB image at 2400bps afterall.

pgp email is basically deprecated by the security community. Security people do not use and do not recommend pgp email. TLS is used by everything, and a version of it will be used for a long time, for example everything that will use IETF QUIC or HTTP3+ on top of IETF QUIC.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#189

Post by ambicapter »

zackbloom wrote: post #75
Rooster61 wrote: post #53

This scares me a bit. The idea of having LEO internet is great and all, but the idea of quadrupling the number of functioning satellites, all operating in different orbits but at a similar altitude seems incredibly dangerous to me. The article mentions the movie Gravity, which is a bit unrealistic as it portrays multiple large bodies in orbit all being at about the same altitude (which isn't the case in reality). Tha…

Think how big the Earth is. How hard it would be to find a Xerox machine in the Amazon or the middle of the Atlantic if someone stuck it there. Space is much, much, bigger.

Now imagine that Xerox machine is constantly moving at 17,000 mph. How interested would you be in figuring out where its going?

Re: SpaceX just got FCC approval to launch 7,518 satellites

#190

Post by ehead »

ryanmarsh wrote: post #71
dr_orpheus wrote: post #48

Earlier quoted context omitted.

The latency from the distance light travels does not vary that much. The rest of the ~600 ms latency is caused by the same thing as latency on ground systems (routers, etc.). And the processors on spacecraft are not particularly fast.

Who builds routers that go in space? Cisco? That's got to be some crazy hardware.

I believe companies like Boeing or Space Systems Lorale do that kind of work in their satellite design groups. Same with Orbital ATK.
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