It's very unlikely that SpaceX, who has to be concerned about space debris every time they launch, didn't think about the collision risk while they were designing their satellite system.

In fact they petitioned the FCC(?) to lower the constellation's altitude for the very reason that, in the case of a malfunction, the satellite's would orbit would degrade more quickly. A carefully tracked constellation of satellites would be much easier to avoid than the random chunks of shrapnel left behind by other mishaps.

EDIT: a few typos

I think they lowered the orbit because Starlink latency was/is not competitive.

Lowering orbit doesn't substantially reduce latency, building more satellites does.

Building more satellites doesn't reduce latency. Are you referring to the ISL?

Adding more ground stations and building more satellites does reduce latency, because there will be a satellite closer to "halfway between" you and a ground station, which defines the shortest possible path.

If there is just one (non-stationary) satellite in your sky, the geometry is probably pretty crummy, so light-speed delay is greater. Also, link budget is worse, so probably data rate is lower too.

Yes, once you have a ton of satellites, adding more doesn't improve latency much.

Having more satellites lets you communicate in a straighter line. Lower altitude lets you hug the Earth more closely. Higher altitude lets you see more neighbors. I'd wager the low altitude satellites are for last mile communication moreso than global linkage. I mean, otherwise they'd have no use for the higher altitude ones? An optimal low latency link around the planet would mostly alternate low-high-low-high-low in sequence, if there aren't enough low altitude nodes to use them exclusively. But maybe you could crush this argument by doing the actual math in this case.

You are referring to the ISL in these satellites, that are not in the first batch, nor are there any plans to change that soon from what I've seen. So without the ISL, their latency is certainly not lower by adding more satellites. The difference in latency from different altitudes LEO is negligible.

compared to geostationary sats, starlinks are 1/30 of the distance, and thus 1/30 of the latency

They didn't lower it from geostationary, so this is--while correct--irrelevant.

It makes a difference there, sure, but SpaceX lowered orbits from 1,150 to 550km. Half the latency, but only by about as much as traffic between LA to SF incurs.

I was a bit wrong in my initial estimate. More satellites can't improve latency by much once they get dense enough, and it looks like Starlink has enough such that the altitude would be on the same scale as distance. Still doesn't matter for the typical home user. Like, I get 21 ms ping to servers in my local city.

> Still doesn't matter for the typical home user.

One very important market they're going after is global arbitrageurs.

The funny part is that by providing low latency service to them, they are (hopefully) going to be able to fund SpaceX longer to build rockets to get human colonies off-planet.

It’s almost like a Gibson or Stephenson novel.

Do you have any evidence of this? I work in algorithmic trading/finance and I'm relatively certain that this isn't true.

> Do you have any evidence of this?

My only evidence is a very basic evaluation of their publicly stated capabilities.

> I work in algorithmic trading/finance and I'm relatively certain that this isn't true.

It sounds like you have a much better informed opinion than I do.

With my limited knowledge, I see no reason why SpaceX wouldn't aggressively go after that market, but like I said, my knowledge is limited.

> Still doesn't matter for the typical home user.

550km vs 1,150km might not matter, but it matters a ton vs 40,000km. Even without the bandwidth limits, I wouldn't be able to use geostationary internet for my normal usage.

Starlink has been LEO since it was first announced, so how bad geostationary internet may be is not relevant to the discussion about why SpaceX lowered the altitude.

right i didn’t know that

I was under the impression that Starlink latency is actually very competitive with terrestrial fiber. Why do you say it wasn't or isn't? Everything I find suggest Starlink will have low latency.

For most usages yes. For gaming though it's right on the edge: theoretical minimum at 350km orbit is 40ms roundtrip, which would work for most games. But many complications, including position of the satellite, latencies within the networking components, packet loss etc, can easily slow this to 100ms+, which is unsuitable for many online games.

No, the round trip for electromagnetic waves at 350km it’s about 2 ms not 40. The lowest orbit of the satellites though would be 550km and not 350km, but it would still be less than 4ms. From where did you get the 40ms figure that it’s wrong by an order of magnitude?

I don't know where they got that figure from, but it is unrealistic to not also expect a decent amount of latency to be introduced by the transmission hardware, particularly under load. I have no idea how much, but this has generally been the case with most systems of this sort.

Electromagnetic waves travel at essentially the speed of light. The speed of light is roughly 300km per millisecond. So if they are 550km up, that’s roughly 4ms round trip. Even with horrible inefficiency, it won’t likely increase that by 10x.

It can’t be both?

> charlatan like Musk

If Musk was a charlatan, we wouldn't have this problem. Musk would have failed to put spacelink satellites in orbit and we wouldn't have this problem.

The reason why we have this problem is precisely because Musk isn't a charlatan.

> I also know a lot of people directly involved in SSA and all of them are very concerned with how much these new constellations are going to increase the risk of collisions

Just because they are concerned doesn't mean they are against SpaceX or Musk. Every venture is open to concern.

> SpaceX cultists

Is NASA and the US government SpaceX cultists? You act like Musk just sent this satellites up there without any warning or government approval. He didn't.

All you've done is toss ad hominems at Musk, SpaceX and those who support this venture.

I call Musk a charlatan because he tries to pass himself off as something he isn't. His physics and engineering knowledge is nowhere near the level he boasts about, and he often states things that an SME would find laughable were they not eaten up without question by so many ill-informed cultists. It's dangerous, and unfortunately it's probably going to result in even more harm to people before he's reigned in.

And to clarify, the SSA folks I was referring to are against these types of constellations particularly in the context of the speed and lack of oversight (and no, FCC/ITU spectrum approval has nothing to do with oversight and regulation of the physical objects in orbit) of these ventures.

> Yes, I’m an astronomer and I can tell you this SpaceX statement is pure BS. The astronomy community absolutely thought of this before any of these satellites were launched. I’ve personally talked about it at public outreach events (and it was members of the public who brought it up) and topic has definitely come up at professional meetings...but there is just a general feeling of powerlessness, both from the point of how do you fight a company like SpaceX and a charlatan like Musk, and also from the point of many members of the public don’t care.

Why aren't you talking about any of the other constellations that are being built? They're all planning huge numbers of satellites, many of which are larger or in higher orbits than SpaceX's satellites. You can't single out Elon Musk's companies just because of a personal vendetta if you're actually trying to be fair and attack this from a technical perspective.

Many of the other constellations look unlikely to be completed.

>charlatan like Musk

I'm not a fanboy by any means but the guy built two companies and launched a car from his factory into space from a rocket his other business built. He's personally spearheading the early stages of commercial space exploration. I don't know that I'd describe him as a charlatan.

Starting companies, even successful, relatively technical companies, does not preclude a person from being a charlatan. The charlatan part comes when he publicly dismissed the concerns of experts and claimed there wouldn't be a problem, but of course there was a problem.

> charlatan: a person falsely claiming to have a special knowledge or skill

"publicly dismissed the concerns of experts" i.e falsely claiming to have special knowledge

Musk did not found Tesla, but would like you to believe that he did: https://www.quora.com/Did-Elon-Musk-found-Tesla-1

Maybe 'charlatan' is unfair, but he's certainly more of a sales-and-hype man than a real engineering type. I don't understand why so many technical people are snowed by his razzle dazzle.

What I have observed over the years is that Musk routinely burrows into engineering considerations, for better or for worse, most especially at SpaceX but also with regards to manufacturing, specifically, at Tesla. He is an engineering enthusiast with a well documented skillset.

Regardless of how we characterize Musk, however, reducing the issue at hand to a pro/anti Musk ad hominem argument is a distraction and a waste of time. It is suddenly relatively cheap to put a huge number of small satellites in low earth orbit. This creates a conflict with astronomical interests. What remains is a policy debate worth having.

SpaceX's statement may be ignorant, erroneous, or even deceitful. I have no doubt that the astronomy community identified the problem immediately and has been trying to bring it to public attention. However, as with light pollution at both optical and radio frequencies, they are relatively powerless compared to the interests with which they are in conflict. If the FCC is the arbiter of how many satellites a company can launch into LEO, they have already lost. This was a regulatory and legislative battle that they needed to be fighting, and probably were fighting, and basically had very little chance of winning unless they were somehow able to mobilize public support for earth-based astronomy against the telecommunications industry.

And so what? founding a company is the easiest step (a little bit of money and paperwork). executing to make it the world leader in electric mobility is what really matters. So your point is really irrelevant.

While true, the company was founded in July 2003 and Musk joined in February 2004. The first Roadster prototypes were revealed in 2006.

Acting like he hitched his flag to an already successful company is disingenuous.

And then there was paypal.

It's not clear to me how active Elon was with PayPal, I really think it was much more Peter Thiel that made it successful (although I am not claiming expertise). Elon founded x.com which merged with what become PayPal, but as PayPal started to become successful it was Peter Thiel at the helm. That doesn't mean Elon wasn't instrumental to its success, only that I cannot find much evidence that he was instrumental to its success.

https://en.wikipedia.org/wiki/PayPal#Early_history

> In October of that year, Musk made the decision that X.com would terminate its other Internet banking operations and focus on the PayPal money service.[25] In the same month, Elon Musk was replaced by Peter Thiel as CEO of X.com. The X.com company was then renamed PayPal in 2001,[26] and expanded rapidly throughout the year until company executives decided to take PayPal public in 2002.

No, he wasn't a first-day founder. But he joined not to long after and it was his private money and him as a CEO which built Tesla.

"Founder" is a label decided by the company, not by outsiders. Many Silicon Valley companies have "founders" who were not there on Day 1.

Founder is a word that has meaning, we shouldn't let companies dictate our use of language.

It's fun to watch people up and downvote me for just relaying what Silicon Valley founders have actually been doing for decades. I totally agree that it's a surprise to most people how it works, but I don't think "they" are going to change. It just is.

I find the "did Musk found Tesla thing" petty and unnecessary. Without Musk it would have been a footnote in history.

But I dislike your assertion that just because SV companies feel free to rewrite their history, we should consider that canonical.

It's totally valid to point out that Musk wasn't a founder, though using it as some kind of slight is juvenile.

eBay is free to claim it was invented to sell Pez dispensers and we're free to point out that's PR spin. Neither side is in the wrong.

I didn't assert that, nor did I say it was invalid to not understand the inside-Silicon-Valley use of "founder".

I was just explaining how to not embarrass yourself.

With all respect, I can't read your previous posts without taking the meaning I did, but the fault may be mine.