kerbiloid

Starlink (updates and concerns)

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On 11/5/2019 at 12:35 AM, Listy said:

The big challenge for Starlink if it really does want to expand beyond serving rural westerners, is that mobile internet in the developing world (in Asia at least, which is by far the most affluent and populous 'developing' region) is already pretty fast, almost ubiquitous, and insanely cheap (cents per gigabyte cheap). Plus, you don't need to buy and carry a special base station around with you. The idea that there are billions of people just waiting to get online in the developing world but can't because there's no phone line nearby doesn't reflect today's reality - everywhere in the world, most people almost certainly live within the range of a phone tower these days. Today it's much more likely that people who remain offline either see no need for the internet, or they can share a phone with a family member who does have internet, or its simply unaffordable - in which case, they won't be able to afford Starlink either.

Telecommunication companies outside the west also tend to be fairly young and a lot more dynamic than the dinosaurs we are used to - much like a certain upstart rocket company that's popular around here in fact :). Certainly in Asia, if Starlink comes close to being competitive, those companies wont just sit still - they'll respond by dropping prices even more, and rolling out thousands of new phone towers faster than Elon can chuck satellites in the sky. If that happens it will be a win for consumers, but it might not be a win for Starlink.

Mobile internet is fast there its plenty of people around, not there its not. 
Guess 3rd world are less strict on coverage rules too, like in Norway it was an demand that you had to cower areas who was not profitable.
But you are correct in one part, Starlink does not provides cell phone services so they do not compete in that market. 
The only overlap is cases there you only have expensive or slow mobile internet but can afford an starlink antenna 

One major use case of initial starlink is actually to link up cell towers not connected to the backbone. 

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Saw the Starlink-2 train pass almost directly overhead tonight. Was able to see about 30 of the 60 satellites during the ~10 minute pass - the sun had only recently set so the sky was still quite bright. Most satellites that I saw were spread out with 20-30 second gaps between each one that I could see, but there were a few clumps of 3-4 close together still. Most seem to be slowly spinning/tumbling at the moment, with brightness varying from invisible/very dim to fairly bright (4-5 reached Sirius level bright) over about a 10-20 second period.

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59 minutes ago, Jacke said:

If I recall correctly, all the issues with astronomy and the Starlink satellites have occurred while the offended satellites were still raising their orbits, right? Regardless, the article seems to be complaining about problems that SpaceX has said they're working on fixing, but then it whines that they haven't been able to instantly implement those fixes. One of it's proposed solutions is literally something Elon Musk has said they're trying to do (reduce reflectivity). The concerns are valid, but it sort of completely ignores that SpaceX has had their head honcho directly respond to those concerns and offer some solutions they're working on. 

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1 hour ago, Jacke said:

There are some legitimate concerns for ground-based astronomy, particularly wide field work.

21 minutes ago, Raven Industries said:

If I recall correctly, all the issues with astronomy and the Starlink satellites have occurred while the offended satellites were still raising their orbits, right? Regardless, the article seems to be complaining about problems that SpaceX has said they're working on fixing, but then it whines that they haven't been able to instantly implement those fixes. One of it's proposed solutions is literally something Elon Musk has said they're trying to do (reduce reflectivity). The concerns are valid, but it sort of completely ignores that SpaceX has had their head honcho directly respond to those concerns and offer some solutions they're working on. 

Some of the issues can be dealt with, but it's really a matter of reducing their albedo, not eliminating it. If they can get them nominally to 6.5 mag, then they are not visible---to the naked eye. Astronomers will be able to see them almost regardless of mitigation (it'll depend on illumination, integration time on the sensors, etc).

All that said, I think this was bound to happen eventually assuming it's the only way to have low latency comms worldwide at low cost. Yeah, we could bury fiber everywhere, but how much would that cost? If sat constellations are the solution that physics allows, and that simultaneously reduces cost, it's inevitable. We'll need more space telescopes. The usual answer to this is that we have many, many terrestrial telescopes, and just the one space telescope, so adding another, or 2, etc, doesn't solve the issue. I think the solution is to have as many as we need such that people can easily use them. Maybe they can be cheaper if launch costs are almost nothing.

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10 minutes ago, tater said:

Maybe they can be cheaper if launch costs are almost nothing.

This. 

In order to work at all economically, Starlink needs radically reduced launch costs. Those same radically reduced launch costs will allow lofting many "cheap" space telescopes, maybe even based on the Starlink buss itself (coulda sworn I saw this mentioned somewhere).

One way or another, the world will be a very different place in a hundred years, or a thousand. Sooner or later it'll just end up looking like Coruscant anyway. -_-
If we don't nuke ourselves into Tatooine first...

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3 hours ago, Raven Industries said:

The concerns are valid, but it sort of completely ignores that SpaceX has had their head honcho directly respond to those concerns and offer some solutions they're working on. 

If I had a dime for every time some corporation CEO promised they were working on fixing something that never ended up getting fixed, I would already be retired and driving around in my Ferrari.

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12 hours ago, tater said:

We'll need more space telescopes.

This.

Edited by Wjolcz

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12 hours ago, tater said:

We'll need more space telescopes

We need FarSide optical and radio telescopes, although that two-week day might be a bummer

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Just now, StrandedonEarth said:

We need FarSide optical and radio telescopes, although that two-week day might be a bummer

Makes sense for radio, less sense for optical in many ways, particularly when we start landing more on the Moon (dust).

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Do note that space telescopes have their own limitations. For one, making them as big as the largest Earth-based ones would require the BFR just to fit the mirror assembly in. Adaptive optics practically eliminate the effects of atmosphere, so the only way of making a space telescope with the same capabilities as recent terrestrial ones would be to use a mirror of the same size. The largest telescope currently under construction will have a 30m mirror, even with a folding mechanism, that's a lot mirror for a rocket to carry.

EDIT: Looks like the 40m one has already started and is actually further along. There was also a 100m diameter telescope under serious consideration. Matching that with a spaceborne telescope would be rather though.

Edited by Dragon01

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Astronomers should attach a gigawatt laser to the telescope at the ocular end.

Let the star wars begin!

Edited by kerbiloid

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14 hours ago, mikegarrison said:

If I had a dime for every time some corporation CEO promised they were working on fixing something that never ended up getting fixed, I would already be retired and driving around in my Ferrari.

Heh, true. I'm a bit more optimistic though. If that does happen, then I'll be happy to lambaste SpaceX with everyone else. 

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6 hours ago, tater said:

Makes sense for radio, less sense for optical in many ways, particularly when we start landing more on the Moon (dust).

The moon is not dusty in the way that this implies. With no atmosphere, particles will settle immediately rather than being transported around.

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57 minutes ago, mikegarrison said:

The moon is not dusty in the way that this implies. With no atmosphere, particles will settle immediately rather than being transported around.

I understand the Moon quite well. The issue is twofold. One, any nearby landings will scour the telescopes, as ejecta from the landing engines is thrown laterally at near engine exhaust velocity (a few km/s). Optics are highly sensitive to this, obviously. Two, given the high velocities and small particulates, they can travel vast distances before settling. So even landings on the other side of the Moon are an issue. They never lose their lateral velocity, they stop via hitting terrain (or the telescope) since it's an airless world. Lunar orbital velocity is ~2.something km/s. Dust could literally never come back in some instances, or be in a VERY low orbit and slam into things on the other side of the Moon. Not a big deal for many structures, but bad for optics.

Surveyor 3 was badly etched on the side facing the LM, for example.

 

EDIT: I'd add that "settling" implies dust that looks like what we see on landings like Starhopper or F9 on Earth. What actually happens is that the particles are blasted out in straight lines close to the lander, and are only bent into their curved trajectories by the low gravity of the Moon. To the extent they settle (what goes up must come down), it's actually slower than on Earth, where the lateral velocity is killed almost immediately by air resistance.

 

Edited by tater

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Fair enough. I did think about the particles actually getting put into a low orbit, but I didn't think it was all that likely. If evidence says otherwise, then so be it.

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Just now, mikegarrison said:

Fair enough. I did think about the particles actually getting put into a low orbit, but I didn't think it was all that likely. If evidence says otherwise, then so be it.

Yeah, This was discussed at meetings even back in the 80s and 90s that I went to. A prof of mine was all in for radio astronomy farside, but optical made less sense. No reason not to just put it in space, really. Also, the thermal issues are just as bad on the surface, but different---in space, you have the day/night temp issues across the spacecraft (one side in sun, the other freezing), but at least it's constant. You get the same temp range on the surface, but 14 days at a time. So deeply cold, then incredibly hot. You could use heat pipes and use the surface for some level of thermal management, I suppose, but I think it ends up coming out in the wash, or it might even be better in space. Radio is not as picky, since the wavelengths are so much longer that it takes a lot of expansion/contraction to be a decent % of a wavelength.

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On 12/4/2019 at 5:39 PM, Jacke said:

And since it's in Forbes, this issue also made it onto TV's Global News National edition.

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6 hours ago, tater said:

Radio is not as picky, since the wavelengths are so much longer that it takes a lot of expansion/contraction to be a decent % of a wavelength.

And that's a purpose for the Moon. Covering it with countless antennas made of local metals. As the antennas themselves are mostly rather simple parts.

Edited by kerbiloid

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11 hours ago, tater said:

I understand the Moon quite well. The issue is twofold. One, any nearby landings will scour the telescopes, as ejecta from the landing engines is thrown laterally at near engine exhaust velocity (a few km/s). Optics are highly sensitive to this, obviously. Two, given the high velocities and small particulates, they can travel vast distances before settling. So even landings on the other side of the Moon are an issue. They never lose their lateral velocity, they stop via hitting terrain (or the telescope) since it's an airless world. Lunar orbital velocity is ~2.something km/s. Dust could literally never come back in some instances, or be in a VERY low orbit and slam into things on the other side of the Moon. Not a big deal for many structures, but bad for optics.

Surveyor 3 was badly etched on the side facing the LM, for example.

 

EDIT: I'd add that "settling" implies dust that looks like what we see on landings like Starhopper or F9 on Earth. What actually happens is that the particles are blasted out in straight lines close to the lander, and are only bent into their curved trajectories by the low gravity of the Moon. To the extent they settle (what goes up must come down), it's actually slower than on Earth, where the lateral velocity is killed almost immediately by air resistance.

 

I know the particles could go kilometers but did not thought they would go so thousands of km, note that this would be very tiny dust particles, not much an problem for an spaceship, but bad for optic. 
On an base you will have an landing pad and also an barrier to stop this, but this would not work other places, but think risk is pretty low.

Micrometeorites hitting the moon would be an larger source and they can throw larger stuff if hitting at an shallow angle. 
An fun thing in KSP is to crash something on the Mun with very shallow angle and orbital speed, if its something complex it will generate an cloud of derbies on various trajectories. 

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2 hours ago, magnemoe said:

I know the particles could go kilometers but did not thought they would go so thousands of km, note that this would be very tiny dust particles, not much an problem for an spaceship, but bad for optic. 
On an base you will have an landing pad and also an barrier to stop this, but this would not work other places, but think risk is pretty low.

Yeah, they usually show bases with landing areas inside berms. Some particles bounce off the berm, and head up, away from the base (and with much reduced velocity after the impact).

Near a base, the debris can be quite large (but slower). The guy I quoted the tweet from is probably the leading expert on exhaust plume regolith interactions on Earth. He's the guy NASA is having work with SpaceX on Starship for CLPS on this subject (huge engine impact on the Moon, and how it affects landing operations, since it actually digs deep holes (which then fill in once the thrust stops)).

 

2 hours ago, magnemoe said:

Micrometeorites hitting the moon would be an larger source and they can throw larger stuff if hitting at an shallow angle. 
An fun thing in KSP is to crash something on the Mun with very shallow angle and orbital speed, if its something complex it will generate an cloud of derbies on various trajectories. 

Yeah, even natural pelting could impact optical telescopes. It's possible to mitigate the effect, obviously. Have telescopes with covers that can be stowed after landers operate for some time period, etc. The question is what is gained by putting them on the surface vs space?

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4 hours ago, tater said:

The question is what is gained by putting them on the surface vs space?

Do you mean a robotic platform? If so, probably not much is gained. People, however, might like to work in a place where there is an up and a down.

And if there is an issue of blocking all emissions from Earth, the far side of the moon is ideal.

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