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Starlink's laser system is beaming 42 petabytes of data per day

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Re: Starlink's laser system is beaming 42 petabytes of data per day

#111

Post by qayxc »

gnrlst wrote: post #103
latchkey wrote: post #88

I sit in my hot tub at night and see 1-2+ satellites go over every single time I'm out there. Which also makes me wonder how many of the shooting stars I've seen recently are just old starlinks burning up.

How do you spot a satellite? I've never seen one.

If the seeing is good it's actually possible to spot up hundred satellites with the unaided eye. Due to light pollution, it's unlikely to spot one in most places, though. The ISS at least should be easily visible due to its size, even in places that aren't particularly dark.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#112

Post by flir »

gnrlst wrote: post #103
latchkey wrote: post #88

I sit in my hot tub at night and see 1-2+ satellites go over every single time I'm out there. Which also makes me wonder how many of the shooting stars I've seen recently are just old starlinks burning up.

How do you spot a satellite? I've never seen one.

Even in a city you stand a chance if you've got high walls around you. A courtyard garden for example. Just lie back and stare up.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#113

Post by moffkalast »

nightpool wrote: post #105
moffkalast wrote: post #96

Earlier quoted context omitted.

Don't all satellites orbit in the same direction? Launching retrograde is just throwing away free velocity.

In the context of the full article ( https://en.wikipedia.org/wiki/Iridium_satellite_constellatio... ), it's clear they're talking about the polar orbits used by the Iridium constellation, which have "seams" around the Atlantic and the Pacific as the "first" set of satellites passing north-to-south overlap with the "last" set of satellites coming back south-to-north on the other side of their orbits. So of the 6 orbi…

Ah I didn't realize they have all of their stats in polar orbits, that's interesting. Starlink is mostly equatorial afaik, the higher latitudes aren't very well covered.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#115

Post by qwertox »

gnrlst wrote: post #103
latchkey wrote: post #88

I sit in my hot tub at night and see 1-2+ satellites go over every single time I'm out there. Which also makes me wonder how many of the shooting stars I've seen recently are just old starlinks burning up.

How do you spot a satellite? I've never seen one.

It's usually a somewhat like a fast moving little but visible star. Fast as in it would usually cross 1/4 of the visible sky within 20 seconds or so.

You should try to find one once, with the help of an app. It's not that difficult.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#116

Post by Scoundreller »

oh_sigh wrote: post #108
Scoundreller wrote: post #23

So which points are getting “faster than fibre” latency because of this? Extra distance up and down, but make up for it on the long-haul. Won’t beat HF radio though.

It's possible for starlink to beat radio, because radio can't always go straight to the target. If I wanted a radio link from NY->Tokyo, what would that path look like?

True, it would be bouncing around between ground and the atmosphere (when it works at all).

Re: Starlink's laser system is beaming 42 petabytes of data per day

#117

Post by amlozano »

moffkalast wrote: post #96
Scoundreller wrote: post #21

Earlier quoted context omitted.

Indeed Iridium had to deal with the same thing (or I guess, didn’t): “ Cross-seam inter-satellite link hand-offs would have to happen very rapidly and cope with large Doppler shifts; therefore, Iridium supports inter-satellite links only between satellites orbiting in the same direction.” https://en.m.wikipedia.org/wiki/Iridium_satellite_constellat...

Don't all satellites orbit in the same direction? Launching retrograde is just throwing away free velocity.

The Iridium satellites are in what you might call "parallel" orbits, if you stretch the meaning of the word a little bit.

The wikipedia link above explains it well:

""" Orbital velocity of the satellites is approximately 27,000 km/h (17,000 mph). Satellites communicate with neighboring satellites via Ka band inter-satellite links. Each satellite can have four inter-satellite links: one each to neighbors fore and aft in the same orbital plane, and one each to satellites in neighboring planes to either side. The satellites orbit from pole to same pole with an orbital period of roughly 100 minutes.[8] This design means that there is excellent satellite visibility and service coverage especially at the North and South poles. The over-the-pole orbital design produces "seams" where satellites in counter-rotating planes next to one another are traveling in opposite directions. Cross-seam inter-satellite link hand-offs would have to happen very rapidly and cope with large Doppler shifts; therefore, Iridium supports inter-satellite links only between satellites orbiting in the same direction. """

The 'seams' have interesting implications for latency when I was working on Global Data Broadcast.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#118

Post by aqfamnzc »

latchkey wrote: post #110
gnrlst wrote: post #103

Earlier quoted context omitted.

How do you spot a satellite? I've never seen one.

To me, they look like little white dots moving across the sky. Brightness can change as they move too. It'll start off bright and then as it goes away it eventually disappears entirely. Since I usually sit in the same position in the hot tub, I've come to notice that I usually see one of them cross a pretty specific path from north to south, so I've gotten used to looking in that part of the sky as I'm sitting there.…

I guess they disappear as they approach the horizon because the light is spread/absorbed too much by going through more atmosphere?

Re: Starlink's laser system is beaming 42 petabytes of data per day

#119

Post by latchkey »

qayxc wrote: post #104
latchkey wrote: post #88

I sit in my hot tub at night and see 1-2+ satellites go over every single time I'm out there. Which also makes me wonder how many of the shooting stars I've seen recently are just old starlinks burning up.

> Which also makes me wonder how many of the shooting stars I've seen recently are just old starlinks burning up. Probably close to none. The lifetime of the satellites is about 5 years give or take. According to this page [1], a total of 355 satellites have deorbited over the past roughly 5 years. That's an average of about 71 per year or about one every 5 days. Since planned disposals are done over uninhabited area…

No, I love this data! Thank you.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#120

Post by latchkey »

aqfamnzc wrote: post #118
latchkey wrote: post #110

Earlier quoted context omitted.

To me, they look like little white dots moving across the sky. Brightness can change as they move too. It'll start off bright and then as it goes away it eventually disappears entirely. Since I usually sit in the same position in the hot tub, I've come to notice that I usually see one of them cross a pretty specific path from north to south, so I've gotten used to looking in that part of the sky as I'm sitting there.…

I guess they disappear as they approach the horizon because the light is spread/absorbed too much by going through more atmosphere?

I actually see them disappear long before they get to the horizon. My guess is just less reflected light on whatever is shiny on the satellite.
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