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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

#131

Post by [deleted] »

phkahler wrote: post #50
toomuchtodo wrote: post #44

Earlier quoted context omitted.

Not stupid. Sort of. The term you're looking for multilateration (edit: i'm twisting the term a bit for my own use here, it's not exactly multilateration but it's not exactly triangulation either). Without looking at the RF specd in the FCC docs or the satellite hardware part list, I'm not sure if you could do it on the receiver, but it would be straightforward for the constellation visible to the receiver to triangu…

The answer is probably yes, but it would be a side-effect since data transmission will be the primary purpose. Actually it may turn out to be pre-condition for getting the best throughput - i.e. knowing when and where the sats are and when your transmission window is to within a tight tolerance will be necessary and that's what you need for GPS.

[deleted]

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

#132

Post by davrosthedalek »

gsich wrote: post #117
phkahler wrote: post #46

Earlier quoted context omitted.

>> Think about switching your router every 10 minutes. Your cell phone switches towers all the time while you're on the road. My cellphone (republic) switches from WiFi to cellular network mid-call if I'm on it when I leave a building. This is not a new problem.

>My cellphone (republic) switches from WiFi to cellular network mid-call if I'm on it when I leave a building. This is not a new problem. Networking technology switching is unrelated to a call, which always uses cellular.

Not sure about republic, but many phones implement WiFi calling.

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

#133

Post by dzhiurgis »

dr_orpheus wrote: post #90
jimison wrote: post #36

Earlier quoted context omitted.

Perhaps their true market will be for industrial IOT devices that need to connect from all over the world. If I'm selling large HVAC units with cloud monitoring functionality, it'd be attractive to ship units that are pre-connected to SpaceX's satellite network. I wouldn't have to worry about setting up agreements with multiple cellular providers or having to depend on site-provided Wifi/ethernet. The point is, those…

There is definitely a market for this. Orbcomm already does this for a lot of machine to machine communication. However, their data rates are quite slow on the order of kbps.

Same with Iridium Certus/Next - their devices are rumoured to be tiny chips (even with current constellation the hotspot is just slightly larger than modern 4G ones).

You don't really need much bandwidth for most IoT apps.

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

#134

Post by mikeash »

Rooster61 wrote: post #85
biaachmonkie wrote: post #69

Earlier quoted context omitted.

Well since it's in LEO and since the sats will have been destroyed or damaged they won't be able to maintain their orbits, so the debris orbit will be decaying from the moment of the incident and should re-enter in a matter of a few months. The scenario I'm sure will be simulated by numerous people/orgs by the time this project is in full swing.

I'd think that only a fraction of the debris will head down into the influence of atmospheric drag. The rest would fly away at an angle that either takes it parallel to the path of the orbit, or higher in the orbit (however short that may last). These satellites, while in a LEO orbital configuration, I would assume would still be high enough to where there is a decent amount of room before significant drag comes into…

They’re already in place that has enough drag. The satellites will deorbit in months to years without periodic boosts. Debris will come down faster, since they have more surface area relative to their mass. A single impulse always results in an orbit that intersects the original orbit at the location of the impulse, so it’s impossible for a collision to raise debris entirely beyond that altitude.

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

#135

Post by PeterisP »

dzhiurgis wrote: post #123
PeterisP wrote: post #116

Earlier quoted context omitted.

It depends on what you mean by "email". "Doing email" as in SMTP/POP at 2400 baud is feasible, "doing email" as in accessing a https webmail service is not. You can communicate effectively over 2400 baud if (and only if) you use protocols and services designed for low bandwidth; luckily we have those protocols built and tested, even if we have mostly abandoned some of them.

Are you actually suggesting dropping SSL? Sure, Iridium is somewhat encrypted and indeed provide its own Facebook and Twitter apps.

Over 2400 baud? Yes, I probably would suggest dropping SSL and instead transmit pre-encrypted data over a very plain, very simple connection to avoid the overhead of SSL handshake (something like 5kb for current keysizes?) and its latency.

GPG-encrypted email over plain POP would work; and you can have automatic "remailers" on both sides of the link that handle the encryption/decryption once the communications are done over a "normal" connection.

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

#136

Post by nickik »

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…

I think this issue is over played a bit sometimes.

1. Satellites can kill themselves by dropping back into the atmosphere by their own propulsion system

2. Even if they fail, most of these are low enough that the time until they fall is reasonable short.

3. The objects are known and tracked so even if they are out of control, the others will avoid them.

4. We are moving into a world with cheap access to space and lots of satellites we need service satellites anyway and multiple are in development. This could be a legal requirement but even without it will develop because SpaceX doesn't want to have debris flying around on 'their' plane.

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

#137

Post by gpm »

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…

This is known as Kessler syndrome.

It could make orbital planes unusable, but is generally thought not to pose a substantial problem for launching through them, so worst case we just have to start putting satellites a bit higher.

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

#138

Post by HarryHirsch »

notimetorelax wrote: post #118
dv_dt wrote: post #92

Earlier quoted context omitted.

I read that as there is a lot of money that wants to piggyback on the success of SpaceX instead of fundamentally developing anything via their own investments.

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.

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

#139

Post by ALurchyBeast »

Rooster61 wrote: post #102
soared wrote: post #93

Earlier quoted context omitted.

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

<10K isn't the problem. It's when that 10K becomes much, much larger because of an unforeseen collision with an unrelated spacecraft/piece of space junk. It only takes one big collision to utterly litter that particular orbit, and thousands of slightly different orbits caused by the new trajectories of the various bits of the original spacecraft.

So whats your solution? Never put a bunch of satellites in space?

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

#140

Post by tortarga »

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

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