Starlink v2 reached the brightness reduction target recommended by astronomers | Hacker News Reader

Starlink v2 reached the brightness reduction target recommended by astronomers

arxiv.org

122 pointsbilsbie76 comments

Please don't editorialize the title. The title is

> Starlink Generation 2 Mini Satellites: Photometric Characterization

I'm a professional astronomer and I don't know what the "brightness reduction target recommended by astronomers" is. I do know that a 7th magnitude source will likely saturate most large research telescopes, rendering a good chunk of that data useless.

Here's a link to the IAU website about an agreement between the NSF and SpaceX to set a target of below 7.0 magnitude for Starlink.

https://cps.iau.org/news/nsf-and-spacex-sign-agreement-to-mi...

I don’t normally change it but in this case it seemed too esoteric.

People wouldn’t know why they should be interested.

Could you link to where this claim is made? I don’t see it in the article.

https://pay.reddit.com/r/spacex/comments/14bhto5/observation...

But title is incorrect?

Can someone explain to me how the title as it appears here relates to the linked paper.

"Therefore, the Mini satellites are fainter than Gen 1 Starlink satellites despite their larger sizes. "

OK, but no mention of "the brightness reduction target recommended by astronomers" anywhere. If there is a missing source please can we see it?

It seems like the wrong title. I couldn't find any support for it in the paper.

The paper does say 'Their goal is to “make its second-generation satellites invisible to the naked eye when they are on station”.' Which to me sounds like "make it so ordinary folks don't notice" and has very little to do with astronomy. It's a nice improvement but doesn't solve the problems.

Edit linked elsewhere in the discussion: https://cps.iau.org/news/nsf-and-spacex-sign-agreement-to-mi...

They talk it about that on the reddit thread

https://pay.reddit.com/r/spacex/comments/14bhto5/observation...

My parents recently got starlink internet in a developing country with measured 70mbits down and 12mbits up. It costs about the same as wired internet, which is available where they live. But the speed is higher and they can run it on a battery so the internet stays up even when the power goes down, which happens often.

I think it’s a game changer for people in rural areas and cabins, people in RVs, people on boats, etc.

I’ve worked remote my whole career, but now it is possible for me to do that from anywhere on earth with starlink service. That’s amazing to me.

I'm guessing it will also make airline passengers more productive.

It's good that these expectations are set, and even better that they are met.

We'll probably have more constellations of satellites in the future, so it's good that there are clear goals to hit to limit their negative effects.

Funnily enough, I saw a train of Starlink sats from their most recent launch (which was Sunday I think?) on Tuesday night in the skies over northern Utah. I assume this reduction is for normal nighttime hours, and not the times immediately after sunset/before sunrise when they can catch the light while still ascending to their final orbit?

Edit: the launch was early in the morning on Monday

It’s for their operational orbit. During deployment and orbit raising (while you can see the train) they won’t necessarily be in stealth mode yet.

Starlink brightness concerns are mostly for around dawn and dusk. During the night, since they're pretty low, they're mostly in complete shadow. However, the darkness design is for operational altitude and attitude; during orbit raising, they are in an unusual mode.

I have what might be a controversial opinion. Sacrificing terrestrial visible light astronomy for a well developed worldwide satellite communication constellation seems like an easy trade. Astronomers can still do terrestrial radio astronomy, and as far as I know, it seems like the utility of orbiting telescopes far outweigh the utility of terrestrial telescopes.

Yeah I tend to agree. My opinions on the internet in general have soured greatly in the last few years, but even still enabling things like telehealth to rural areas seems like an overall win.

I didn't quite understand what this meant from the headline. The introduction in the paper clears it up. The TLDR is that astronomers are concerned they won't be able to do space observations with so many satellites in the way, but SpaceX has optimized for some parameter the indicates this will not be an issue.

The black paint also makes for stealthier capability in SpaceX's military satellites

https://wikipedia.org/wiki/Starlink#Military_capabilities

There's no stealth in space. Any sort of running electronics or photovoltaics will emit heat that can be easily picked up by spaceborne sensors. The strategic advantage for military satellites is going to be the fact that Starship can launch literal orders of magnitude more of them than the launch systems of rival countries, not the fact that they're painted black and thus marginally harder to spot from the ground with Mk. I Eyeball.

Is there a good reference on tracking satellites from their thermal signature? Couldn't find anything.

This is the most comprehensive debunking I’ve seen of the “stealth in space” concept: http://www.projectrho.com/public_html/rocket/spacewardetect....

This is one of the classic online nerd arguments, much of which is documented there. I’m a little terrified of reigniting the whole thing here and now to be honest, but if people want to get into it, have fun.

SBIRS is intended to use infrared to track ballistic missiles through all stages of flight, including decoys and debris released during the mid-course phase in space (so we know it's meant to be extremely sensitive, not limited to tracking hot rocket engines during the boost phase) Seems like a good bet that orbital systems with such sensors could be used to track LEO satellites too.

That’s weird, every ork knows purple paint makes it stealthy.

Guess they take "black projects" seriously!

There's an interesting question concerning why (most) US stealth aircraft are black. Black isn't the best color to make an aircraft invisible at night; a dark blueish gray is best for that. One possibility is that the radar absorbent material is inherently black so they don't have a choice, and indeed the U-2 was originally a dark blue color before it received a new black RAM paint. That is probably the real reason I think, but another possibility is that when missile and radar technology made visual intercepts less relevant, they were freed to paint these secretive aircraft a less optimal black, which everybody knows is the proper color for secretive aircraft.

Incidentally the new B-21 apparently won't be black. Maybe they have a new RAM paint formulation that doesn't force the choice of black.

Whatchu talkin' 'bout Willis? Neither the B-2, nor the F-22, nor the F-35 are black, they're all this bluish gray you mention, same as most non-stealth aircraft. The only stealth aircraft I can think of that was black was the F-117.

You're right that the F-22 and F-35 aren't black, but neither are they the blueish gray I'm talking about which is much darker: https://dragonladyhistory.com/2019/04/30/u-2-black-paint/ The B-2 also isn't very blueish, it's more on the dark gray end of the scale but I can see how that's subjective.

And you're forgetting the U-2 and SR-71, which lacked full blown RCS reduction geometry but were still fitted with the black RAM coating (the SR-71 also had some stealth geometry; that was the purpose of the chines.)

These will be still easily bright enough to be seen through a light pair of binoculars, so the claim that they won’t interfere with astronomical observations is a real stretch.

The problem with Starlink vs other satellites isn’t just the individual brightness but the vast number of them, and that they are often visible in a swarm.

Brightness reduction is nice but it's still important to also consider the energy required to keep starlink running: https://twitter.com/rdrimmel/status/1563158073694310401

I wonder if that guy has worked out the energy required to build the ground infrastructure to bring communications to all of Earth.

As I understand it, the cost of fiber repair has gone down and we should be able to wire everywhere that has grid electricity with high speed fiber very economically, but it doesn't happen for rent seeking and bureaucratic reasons. That would still leave the oceans and some more remote areas that don't have power.

In addition to rent seeking and bureaucracy, attempts to expand ground infrastructure are plagued by obstructionism by the giant telecom incumbents, not only in the form of legalized monopolies for some areas, but also by such underhanded methods as weaponization of environmental regulations with fake environment preservation groups and stoking NIMBYism in residents. It's nearly impossible to get anything done in some parts of the US especially.

Add most of Canada to the list too.

A lot of places have no grid electricity worth calling that. And of those that do, there is no financially feasible way to wire them up with fiber.

A big portion of the population of those can be covered by cell towers and relays cheaper than launching cell towers into space that only last a few years.

Also does't work when your infrastructure is destroyed faster than it can be repaired, like we can see in Ukraine currently.

In my small New Englandntown it would cost about $2,500 per household. We have about 2,000 homes.

Starlink isn't a good fit for towns that big, as it would overflow the rough limit of 300 dishes per cell (maybe changed with some of the recent fights with Dish?).

I don't want starlink. I'm old fashion I want fiber. I was just throwing out pricing for rural broadband installs in New England. I realize now my initial comment neglected that important detail.

That's a good point. One way to look at Starlink is as a proxy to the cost of government bureaucracy and oligopolies and monopolies that restrain trade. It's actually cheaper and more effective to build Starlink than it is to arbitrate all of that terrestrial mess.

Ah yes, because Musk is a philanthropist and is doing this for earth as a whole. That's why for poorer, thrid world countries, he'll... keep charging the usual rate, making Starlink a non-starter in those countries ?

Starlink is a rich idiot's toy, not a solution to bring communications to everyone.

It’s expensive because of capacity limits and this is why it is stated for use in remote areas.

They do price discriminate to a cheaper price for poorer countries (in Ukraine it went the opposite despite being a poor country, where they tried to jack the price up by thousands of percent, but we don't know the terms of the recent pentagon deal to say what price it finally went through at).

No it isn't, the "energy costs" are negligible. That link is a joke, he's fear mongering about the effect of satellites falling back to earth but can't point to any specific harm; "Effect? WE HAVE NO IDEA." Classic Fear, Uncertainty, Doubt; aka FUD.

That thread claims the Starship launches for Starlink are "expected to have a significant effect on the atmosphere," but for support it links to an article about the black soot emitted by kerosene-fueled rockets like Falcon. Starship is fueled by methane, a much cleaner-burning fuel.

Talk about grasping at straws. Come on.

This comment is the most egregious case of whataboutism I've seen in a while.

Whataboutism refers to a Soviet-era habit of rhetorical distraction, i.e. "The USSR does something terrible," to which the reply was, "Whatabout the terrible things the US does?"

How does the comment you're referring to add up to that?

Light pollution is fixed ,but WHAT ABOUT co2 is what I meant.

That's... not whataboutism, it isn't an attempt to distract from an accusation or problem, it's the opposite of that in fact.

I honestly don't get your point, you probably misunderstand me, we might disagree, but this is not the opposite case of whataboutism.

This advancement is objectively good, it's one of the issues raised later in the twitter thread even, and (s)he chooses to change the focus to another subject.

This is called "moving the goalposts", not whataboutism.

Whataboutism would be "Yeah, well, who cares what Starlink does, NASA launches rockets all the time and no one complains about their emissions"

Why do you have to launch by rocket? Why not something like spinlaunch(1), perhaps powered in situ by stored renewable energy?

1. https://www.spinlaunch.com/

Spinlaunch is a joke. No payload is built to withstand those kinds of forces during a launch and the added weight to reinforce them to do so makes it uneconomical.

They are even offering to pay companies the extra cost to reinforce their payloads to try and get customers and they still can't get anyone to do it.

> They are even offering to pay companies the extra cost to reinforce their payloads to try and get customers and they still can't get anyone to do it.

It certainly can't help that Spinlaunch can't put anything into space.

I was gonna say. Wut? They have a demo that probably fooled all the investors lol.

Well, spinlaunch doesn't exist yet. It also imparts _much_ higher accelerations on its payloads than a rocket does, and a rocket is already appreciable.

Spinlaunch would destroy these satellites, and still requires some amount of rocket to get to orbit.

sadly spinlaunch is bogus and the whole concept doesn't really work out. [0]

[0] https://youtu.be/9ziGI0i9VbE (Spinlaunch: BUSTED! by Thunderf00t)

That video actually explicitly says that the concept _can_ work, he's just skeptical that the current company is likely to achieve it. I wasn't particularly impressed. Yeah, maybe spinlauch the entity _won't_ achieve it. Most people who try to do very hard things fail. But the only way we advance is because sometimes they don't.

Thunderf00t isn't science, it's a youtube channel who wants to get views.

He also busted Starlink because apparently technology costs never reduce, and single geostationary satellites have infinite bandwidth

YouTube channels are bogus, but he's not wrong. It's wildly unlikely. Any actual project would require not just a payload that can handle insane stresses, but also rockets for orbital insertion. Rockets that can handle those kinds of ludicrous launch stresses are hard to conceive.

I can't prove that it's impossible, but the gap between the requirements and even the most extreme conception of what's feasible is so immense as to basically dismiss out of hand. They're welcome to keep trying, but it absolutely will not happen soon and is not worth the level of attention it receives.

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