Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

SpaceX just got FCC approval to launch 7,518 satellites

fastcompany.com

Post reply on HN
Print view View original

81–90 of 290 posts

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

#81

Post by dr_orpheus »

biaachmonkie wrote: post #69
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…

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.

This is not true of the orbit that the SpaceX satellites are going in to. LEO is a bit of a general term that covers altitudes anywhere from 100 km to 2000 km. While it is true that something at 400 km altitude will deorbit in a few months, they will be orbiting at an altitude of 1100-1300 km. At that altitude it will take hundreds of years from them to deorbit. The drag goes down exponentially as you get in to higher orbits. The FCC filing says that the SpaceX satellites will have enough fuel remaining in order to deorbit the satellite after the satellite has reached its usable mission life.

This was a big concern for NASA though. Their typical guidelines were that commercial satellites have to have >90% reliability to deorbit the satellite. But they want to increase this for the SpaceX satellites because if 10% (~400) of the satellites end up failing then they are effectively up there forever.

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

#82

Post by anvandare »

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…

SpaceX gave their proposals for this (very valid) concern here:

https://licensing.fcc.gov/myibfs/download.do?attachment_key=...

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

#84

Post by elteto »

phkahler wrote: post #46
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…

>> 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.

Satellites shooting lasers to talk to each other and create a global network in space is not a new problem?

Damn, I guess we ran out of interesting problems to solve then /s.

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

#85

Post by Rooster61 »

biaachmonkie wrote: post #69
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…

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 play. Otherwise, it would not be economical to have these in orbit as they would decay and need to be replaced too quickly to justify the cost.

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

#86

Post by dr_orpheus »

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.

Cisco has built routers for space multiple times before. The first time was way back in 2003: https://en.wikipedia.org/wiki/CLEO_(router)

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

#87

Post by ubercore »

Rooster61 wrote: post #77
wufufufu wrote: post #61

Earlier quoted context omitted.

This is a well informed answer to your question: https://www.quora.com/Why-dont-satellites-crash-into-each-ot...

Thank you for the article, but it really doesn't answer my question. That thread's answers assume that we are talking about the current situation we have around the Earth. We have no precedent for this many satellites orbiting at the same altitude, but at different latitudes/longitudes (which negates the safeguard that they are moving at the same speed, it doesn't matter if they can intersect). The satellites would a…

First, check out the video explaining the orbits: https://www.youtube.com/watch?feature=youtu.be&v=AdKNCBrkZQ4...

Doing some quick math, the shell in which they'll be orbiting has a surface area of 373,367,808km. With ~7000 satellites, an even distribution would leave them 533,382 km between satellites. All the satellites have station keeping thrusters to keep them in LEO with drag. Keeping them from running into each other is probably pretty simple, in comparison to the other challenges they'll need to solve.

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

#88

Post by bargl »

phkahler wrote: post #46
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…

>> 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.

Well dang. That's a really good point. I remember early cell phones that would drop signal when running between towers.

The hard part here is that you have to target the beam at the satellite. It's not a wide angle beam that's used it's a focused beam. (This might not be true based on what they implement)

But for Geo it's a targeted beam. So this isn't a perfect corollary, and my example was pretty bad lol.

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

#89

Post by Rooster61 »

dr_orpheus wrote: post #81
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.

This is not true of the orbit that the SpaceX satellites are going in to. LEO is a bit of a general term that covers altitudes anywhere from 100 km to 2000 km. While it is true that something at 400 km altitude will deorbit in a few months, they will be orbiting at an altitude of 1100-1300 km. At that altitude it will take hundreds of years from them to deorbit. The drag goes down exponentially as you get in to highe…

Not to mention a struck satellite (probably) no longer has the capability to deorbit, at least not in a controlled manner.

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

#90

Post by dr_orpheus »

jimison wrote: post #36
dr_orpheus wrote: post #12

Earlier quoted context omitted.

Yeah, a significant portion of the latency is just the distance to the existing satellites in geosynchronous orbit. For light to get out and back to the geo belt is around 240 ms, excluding any other factors. Getting up to the promised gigabit speed will be significant challenge. The original demo satellites that SpaceX launched only had data rates of ~15 Mbps.

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.
Post reply on HN