SpaceX satellites could blight the night sky, warn astronomers | Hacker News Reader

SpaceX satellites could blight the night sky, warn astronomers

theguardian.com

Obviously high-bandwidth satellite internet is important. Speaking from a place in the USA where we only have one option for pretty crappy DSL internet (at $60 a month), I would probably even be among the first to try and get it! Before you criticize scientists as having tunnel vision for attempting to stymie global world progress, consider that astronomers are not and have never been in a position to have any regulatory power on this issue. At most they can inform the public of the side effects.

There was a similar situation when a Russian private company sent up a satellite that would deploy reflectors to purposefully make it one of the brightest objects in the night sky[1]. I image some astronomers breathed a sigh of relief when the reflectors didn't properly deploy.

In radio astronomy, there are a few small protected bands to keep some portions of the spectrum quiet for scientific purposes. There is no such "spectrum allocation" for optical astronomy. Like chopping down the rain forest or putting plastic in the ocean, we may improve our quality of life through external costs. Governmental regulation permits us to partially control for these externalities. Perhaps if we find ourselves in a big mess like with CFC's and destroying the ozone layer, we will have a public call-to-action to create regulations.

So, what's the rub? Ground based telescopes are vastly cheaper than space-based alternatives for optical and radio astronomy. The difference in cost is often more than two orders of magnitude. If ground based telescopes become less efficient or less productive, there will simply be fewer scientific discoveries made within a flat budget. If the public is required to increase the budgets of NASA, NSF, ESO, and ESA to maintain their desired level of scientific output, then that in itself is an external cost that SpaceX and other companies are passing on.

[1] http://spaceflight101.com/soyuz-kanopus-v-ik/mayak/

Wondering if these satellites follow a fixed path. If so, and there are few enough of them, the nextgen land-based optical telescopes will just have to factor this into scheduling.

Has SpaceX said anything about the paths they will follow? Can they change mid-deployment?

They all have Xenon thrusters and can move, however will do so only when needed to dodge other satellites or debris. Changing their orbit significantly is prohibitively expensive.

You can see the general pattern in a really cool webgl animation on the main site: https://www.starlink.com/

Interestingly (if somewhat unfortunately), this is already done for some radio telescopes. Some satellite down-links are strong enough to damage the receivers, so their visibility has to be taken into account when considering what frequencies to observe at what times.

From a minute of googling, there’s roughly 5k satellites in orbit right now. Most of those are in a slightly higher orbit than Starlink’s (LEO) so they’re incrementally farther away, but would be in a better position to catch sunlight in the night sky.

And yet I, probably like everyone else who isn’t an astronomy enthusiast, haven’t ever looked at a light in the sky and known it was a satellite. They’re subtle, not dominating the night sky by any means, at least insofar as an untrained modern human can tell. Starlink would up the number of satellites by ~2x, perhaps, but would that be enough to change the basic equation?

> at least insofar as an untrained modern human can tell

Perhaps, but that's irrelevant to this discussion which was initiated by competent experts in their field. Not like protests against 5G which are based on dodgy YouTube videos.

Starlink will have a significant impact on the global night sky based solely on the approval of one agency of one country of 8% of the World's population. Even if you as a layman don't perceive it to be a problem in your daily life, doesn't that just seem... wrong? If North Korea had taken such a step there would be sanctions.

There's also 10,000+ aircraft (and over a million people!) in the air at any time, and those planes have nav lights and strobes that are much brighter than satellites.

Is it worth protecting ground based astronomy here though? Obviously the science is immensely important, but so is the internet, I dont buy this idea about the lack of consensus being an issue. Certainly the scientists should have had their say, and perhaps this should have been put up for a more public debate before the project was initiated, but I don't think that the go ahead to the project should be contingent on consensus from the scientific community. It should be contingent on approval from a regulatory body that is appointed/controlled in some democratic way and reflects the will of the population, and if the benefits to society outweigh the risks, then it should get the go ahead regardless of consensus by astronomers.

Possibly unpopular opinion: no, I don't think it's worth protecting ground-based astronomy. I could be wrong, but the majority of the important visual/IR astronomical observations from the last decade seem have come from space-based instruments, not ground-based ones. We need to put more instruments in orbit, not worry about fundamentally limited ones on the ground.

Additionally, this seems to me like an overall positive effect for the public at large. Being able to see satellites zooming across the sky is pretty cool, provides educational opportunities beyond what normal stargazing offers, and reminds people that there's something to aspire to (and look forward to) beyond what's on the ground.

I recall reading about how 5g might interfere with weather forecasting and hurricane tracking, that's the kind of reason that would be compelling to me to stop the satellites (such as if we need ground based telescopes to detect asteroid threats), but unless there is some ground based telescope use case that needs to be ground based and can't be done better with satellite anyway, then perhaps we should be having a different conversation: should we in fact be directing more funding towords satellites to get better space telescopes in the air and simultaneously improve research while future proofing against the inevitable filling of the night sky by satellites as launch costs continue to come down?

While obviously we're making more advanced measurements with space-based instruments, the value of the night sky for the average human cannot be overblown. Many people don't know what they're missing, having never lived outside of broad scale light pollution. While I don't think we necessarily need to worry about all ground-based telescopes, I do think that the average person being able to look at the sky and see the stars is something we should never give up on.

I agree with this sentiment 100%. Looking up at the sky and seeing a massive chains of satellites would be a lot like finding piles of trash along a hiking trail.

The thirty-meter telescope [0] will be ground-based and adjust for atmospheric distortions with adaptive optics.

It will have 144 times the light-collecting area of Hubble. Nice graphic comparing the new generation of extremely large telescopes here: [1].

[0] https://en.wikipedia.org/wiki/Thirty_Meter_Telescope

[1] https://en.es-static.us/upl/2018/04/comparison-telescope-mir...

>I don't think that the go ahead to the project should be contingent on consensus from the scientific community.

Something that could have immense impact on astronomy, the interest of the population in the cosmos, and a permanent change to the night sky shouldn't have some consensus, at least morally?

>It should be contingent on approval from a regulatory body that is appointed/controlled in some democratic way and reflects the will of the population,

Do those exist, much less in the current US administration?

>and if the benefits to society outweigh the risks, then it should get the go ahead regardless of consensus by astronomers.

...unless there is a way to accomplish the same thing for 99% of the population that is better implemented or doesn't affect the sky.

I dont think that they should have veto power, or that there is an inherent moral responsibility. That doesnt mean that I think starlink is justified, there should have been more debate and to tour point I certainly dont believe that the current regulatory standards were sufficient. What I believe is that it is up to astronomers to make their case to the public (starlink had plenty of advance notice) about why it is important to stop starlink, and that if the public is not convinced, there is no obligation to have any sort of consensus, moral or otherwise, from astronomers before launching. They don't own the sky any more than SpaceX does. The same point you made for the value of space based internet applies to the astronomers as well - do they need ground based telescopes or would space based telescopes be equally capable without affecting the sky by shutting down attempts to increase internet access and provide better connectivity via satellite? Obviously, both sides want the night sky for their own use, and if there is no way that a constellation of satellites will not interfere with astronomy, then both groups need to make their case. And if society decided astronomy was more important than space internet, I would be equally unopposed to shutting down these sorts of projects without the consensus of the companies investing in them. We do absolutely need a better regulatory framework though.

AFAICT this would affect even casual stargazers, not just astronomers.

In the sense that, yes, you can see satellites in space. As a casual stargazer myself, spotting satellites is one of the fun parts of stargazing.

Spotting satellites can be fun, but seeing dozens of them at all times (which is what the article claims) would be rather unpleasant.

The article is incorrect. Most of the satellites will be in very low orbits (340km) such that past astronautical twilight, you won't be able to see them except near the horizon (and even then only if you're near astronautical twilight) as they won't be sun lit. And even in astronautical twilight, you'll only be able to see about a dozen or so under good conditions. The higher orbit satellites will be less bright.

On a really dark sky near astronautical twilight, you can already usually see a few satellites in orbit, and some are far brighter.

We're becoming a spacefaring species. That's exciting, and part of it means we'll be able to see more satellites.

It's worth noting that the original tweets grossly exaggerated this problem. I think it's worth trying to minimize albedo of the satellites, but this was a completely predictable result that was obvious from the first minute anyone discussed a large LEO constellation (seeing as we already have satellites). I don't know why it took so long for the astronomy community to actually bring it up. Perhaps because the initially deployed satellites flared a lot in their pre-operational condition, but I'm a little disappointed in how fast a lot of mistruths of this situation traveled around the internet.

Given that a large number of people reported them as UFOs, it seems likely that they're fairly visible.

Personally, I'd find this a nuisance, not a source of excitement. I find it unfortunate that, when trying to enjoy nature, we are so completely unable to escape evidence of human habitation and technology.

They were much brighter and closer together right after deployment than in operation. Already, they've spread out and are now aligned in operational configuration so they're far less noticeable than at first. On par with typical satellites. I spotted them night before last, and it was difficult to see them.

As far as being able to detect evidence of human habitation and technology, that has been the case since the beginning of the Space Age. Choosing to find it a nuisance is, of course, a personal choice, not really something anyone can argue with you about.

That sounds awesome IMO.

The importance society places on something can be judged by how much money it's willing to spend on it.

The NSF budget for astronomy is $250M/year.

Revenue projections for Starlink reach as high as $50B/year.

Astronomy isn't limited to the US and the NSF is not the only funding agency in the US. Sure, the annual cost isn't $50B/year, but that's a shitty metric to use, it is textbook tragedy of the commons.

It properly captures what populations, acting through their governments, think of the importance and value of astronomy.

It doesn't capture the value of individuals looking up and seeing stars. But I suspect the continued migration to highly illuminated cities shows that value isn't very high either.

The global market for ice cream is already $60B/year.

Your point? If the world had to choose between astronomy and ice cream, it would choose the latter.

As a landowner in a dark sky zone, I can’t decide if the trade-off is worth it.

It’d be nice to have Internet way out there. But at the cost of my (and everyone else’s) pure night sky?

Someone ought to do a simulation of what this would look like with the full constellation. I love stargazing, I take days long trips to go to dark sites just so I can enjoy the sky. I imagine it would be quite beautiful to see that the implied lattice around the earth as sun glints off the solar panels.

I'm personally so excited to see these, I think it will be a breathtaking, tangible emblem of one of the first planet-scale systems that humans have built.

> His estimates suggest that once the first 1,584 satellites are launched, for which the trajectories have already been made public, there will be about 15 satellites clearly visible above the horizon for three to four hours after sunset and before sunrise.

Oh no, 15 tiny lights in the sky. Not really a blight.

Actually, this is a good point.

I care about light pollution a lot and think most people are missing what I had when I grew up (Canadian/American border in the 90's). I wish cities had strict codes and <1% of the waste light they do now.

But dark skies are not dark at all - there are about 10000 visible stars. A few moving dots is not going to ruin the experience.

Wouldn't be a problem if we didn't let telecomms fuck us in the ass so badly that we need this.

Has anyone yet built an AR simulator app of what SpaceX informs us will be their satellites’ visibility with correctly-aimed panels at various times of day, dusk, and night?

Not too worried about it. They have a shelf life and I imagine their design will improve over time.

I'd rather see some regulations against all the lights in the Walmart/shopping mall/grocery store parking lots which have completely ruined the night sky in my area.

after their shelf life SpaceX will send more up. That's our night sky ruined as long as SpaceX exists and any competitors.

That's not accurate unless you think the current satellites (many of which are far brighter, such as ISS and Iridium flares) already "ruin" the night sky.

I watched a recent pass of the Starlink satellites, and now that they're oriented near their operational directions, I could barely see them. I only noticed them because I knew right where to look. Unlike the flashing lights of passing aircraft which were a lot more distracting.

Iridium has about 85 satellites in service.

SpaceX satellites are much closer and they are planning something around 7,500 of them.

Might not be too hard to look in just the right place with that many floating around.

SpaceX will also be serving orders of magnitude more customers than Iridium. Being closer also means they'll pass in the Earth's shadow earlier in the night than Iridium.

These SpaceX satellites were reported as UFOs, so they were clearly quite visible to people not looking for them.

ISS is also sometimes reported as a UFO. It's often brighter than Venus.

The shelf life isn't the problem. The problem is quantity in the sky (this will continuously be relaunched) and how bright they are. This will ruin many long exposures for many existing telescopes, but you can do some amount of image subtraction if you do many short exposures. That's might be a problem for some instruments depending on their readout electronics.

It's also a global problem.

The video in the article is not representative. Solar sails were not in the final position and the satellites were not in their final (higher) orbit. It was also taken during the short time-window that the sun was still illuminating the satellites.

Regardless, we should be moving our telescopes to space. Much less interference of all kinds.

The amount of light will still be appreciable and will affect many kinds of observatories around the world, even at magnitudes less brightness.

You also can't slew a telescope in space like you can on ground, it would be extremely cost prohibitive in terms of fuel.

"moving telescopes to space" is the equivalent of "let them eat cake" comment in this funding environment. It sounds like a wonderful proposition until you realize how many observatories we have on the ground and their utilization and how expensive it would be to replicate half that utilization. It's already not easy getting time on a telescope, if everybody had to be crammed on 15 space observatories costing $1B/each, there would be no observational time for grad students or post docs let alone funding for research. You also kill follow up observations on temporal events.

Of course, maybe the government could reach an agreement with SpaceX to send up the observatories for free and send some money the way of the astronomers for seriously messing up the sky, but there's no reason to expect SpaceX to be a good citizen of the night sky.

>You also can't slew a telescope in space like you can on ground, it would be extremely cost prohibitive in terms of fuel.

You can use reaction wheels instead for zero fuel use.

not quickly

>there's no reason to expect SpaceX to be a good citizen of the night sky.

Seems like they are willing to do more than most:

https://twitter.com/elonmusk/status/1132908915144794113

https://twitter.com/elonmusk/status/1132908689860415488

https://twitter.com/elonmusk/status/1132902372458418176

One more reason to utilize the far side of the moon for some seriuos astronomy! Am I rite?

Billboards from LEO. I'm not a fan but it could monetize key tech for space travel.

As a defender of space travel and Starlink: Nobody in their right mind wants that. Public reaction would rightly be swift and negative. Starlink provides a useful, widely available service and the fact you can see them is a side effect (they're not very bright operationally, so it's not really a negative). But a billboard is effectively legal graffiti.

This is such an incredibly short-sighted view from astronomers. The same tech that is going to enable SpaceX to launch thousands of satellites is exactly what will enable (and fund) the expansion of humans into space — which will be more of a boon to astronomy in the long term than any number of large ground-based telescopes.

I'm perfectly happy to permanently screw over ground-based astronomy if that's what it take to get us into space.

Just build the damn telescopes in space. And stop thinking single-mirror scopes like Hubble — you could build huge multiple-segment mirrors in space — much bigger than anything on earth.

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