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Comment by ogre_codes | Hacker News Reader

Saying it will "Kill astronomy" is pretty hyperbolic.

It will likely affect some earthbound astronomy significantly, but much (most?) of the most important work in modern astronomy is satellite based.

I'm on the fence on this whole issue. It's not exactly clear what impact it will have on astronomy. Nor what impact it will have on making the internet pricing and availability. Where I used to live, the only options for internet access were expensive and really bad, the positive impact this might have is potentially quite big.

It's hard with a story like this to suss out what the long term effects will be so it's a big grey area.

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>It will likely affect some earthbound astronomy significantly, but much (most?) of the most important work in modern astronomy is satellite based.

I'm not an astronomer but I'm not convinced that that's the case. The number of space telescopes pales in comparison to the number of terrestrial observatories. Moreover, advances like adaptive optics have done a lot to close the gap between ground and space capabilities (for optical telescopes). Even once you've invested in expensive tech like adaptove optics, a telescope in space still costs an order of magnitude more than one on the ground (thats being really conservative. JWST has already cost ~10x more than the most expensive ground telescope ever, and the thing hasn't even launched yet)

There were a few space based radio telescopes in the past, but I don't think there are any now. Imagine building something like the Arecibo Observatory[1] or VLA[2] in space. And speaking of the VLA, some of the techniques for getting high quality results (e.g. interferometry without physically conjoining the receivers) are difficult if not impossible to do in space.

[1]: https://en.wikipedia.org/wiki/Arecibo_Observatory

[2]: 27 of these guys, which are able to move around precisely on rails to generate constructive interference with the different waves they're receiving: https://public.nrao.edu/wp-content/uploads/2016/04/vla_panor...

> I'm not an astronomer but I'm not convinced that that's the case.

I'm not entirely certain what the balance is here. I don't think my post made it clear that I'm not certain how big the effect would be, only that there is a tradeoff here which is hard to quantify.

I do know there is a lot of significant astronomy done by space telescope and that the importance of space astronomy is only growing.

Seems to me the answer is that those who benefit from the new satellite constellations (SpaceX, etc) should finance additional investment in astronomy to mitigate the effects.

> I do know there is a lot of significant astronomy done by space telescope and that the importance of space astronomy is only growing.

Former astronomer here. I would argue that the importance of space astronomy is actually decreasing. Satellite telescopes are most important at wavelengths that the Earth's atmosphere absorbs like IR, UV, and X-ray. At visible wavelengths satellite telescopes have been much less important over the past couple of decades due to the development of adaptive optics.

The main reason to put a visible wavelength telescope in space is that you avoid the smearing out of the source by the atmosphere. Adaptive optics solves this problem by correcting for the distortions induced by the atmosphere and bringing images to resolutions that are comparable to (though still not quite as good as) what you can achieve in space.

Since space telescopes no longer have the advantage of much greater resolution, there's much less of a compelling reason to use them for most research problems. (Some questions, of course, can only be tackled by using the highest resolution available.) On every other dimension space-based telescopes are inferior to ground-based telescopes. They are more expensive by many orders of magnitude, much, much smaller, and they cannot be changed once they're up (at least not easily). By contrast a ground based observatory can get substantially better over the course of a year by installing better detectors.

Adaptive optics have zero issues if you’re looking to make a cool picture, but they do introduce bias which is an issue for scientific instruments. That’s largely offset by more and larger telescopes for the same price, but it is very much a tradeoff based in launch costs which are falling.

IMO, over the next 30 years space based telescopes are going to play an ever larger role.

What about amateur astronomy? Are we now saying that only those with the means to afford space telescopes or expensive software can participate?

Are you an amateur astronomer or just trying to be the devil's advocate?

I'd be curious to know what the impact is on impactful amateur astronomy (as opposed to backyard hobbyists who are just engaged for personal pleasure). I know some amateurs use images created by public telescopes, I'm not sure how much meaningful work is done by amateurs using backyard equipment anymore.

Not being dismissive, genuinely curious.

Variable star observing is actually a place where amateurs really help, since it's about observation time, and not necessarily some hugely powerful telescope. And the more powerful a telescope is, the more people want to use it to point at all sorts of things, which makes it kind of expensive to use those telescopes for variable star observations which take a lot of time.

"Since professional astronomers do not have the time or the resources to monitor every variable star, astronomy is one of the few sciences where amateurs can make genuine contributions to scientific research." [0]

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

And the Betelgeuse deathwatch!

In recent news, the only confirmed interstellar comet in our solar system was found by a dude who worked at an observatory (not as an astronomer) and decided to build own telescope for fun in his spare time. It's one of only two known interstellar visitors we've had, and because he found it early enough the pros were able to make very detailed observations.

A decent number of asteroids and comets are still found by backyard astronomers.

If SpaceX works out, we'll probably see a lot more telescopes in space. Wouldn't be that expensive at that point for, say, a school class to launch a telescope cubesat.

I'd trade amateur ground astronomy for that.

I'm not entirely sure how you think looking at an image on a computer screen compensates for the experience of doing observations with your own eyes.

There are plenty of good pictures on wikipedia already, do looking at those compare to going out on a clear night and looking at the stars yourself?

A LEO satellite constellation will absolutely not prevent you from looking into the night sky with a telescope and seeing stars.

"Seeing a star" is a low bar to pass, especially if you get a telescope to help you.

The dead of night will be fine. But during (astronomical) twilight, the time when you are most likely awake and looking up, it will have ugly extra dots.

Also I'm sorry but I really, really don't care about a hobby if it gets in the way of the progress of the entire human race.

Imagine if a painter in Greece in some century BC convinced his fellow Grecians that building a harbor in the cove by their town was a bad idea because it ruined his paintings of the cove. How was he supposed to look at the marine life if you stuck wood and industry in the water???

This. Every change has some negative effect. The question is whether the net effect is positive or negative.

What makes a dot ugly?

Can adaptive optics be applied to filter out objects like Starlink satellites?

Don't think so. Adaptive optics works by changing the physical shape of the mirror. If you measure the atmosphere continuously and bend the mirror the right way, you can remove atmospheric distortion from the image. If anything, AO just gets you sharper images of the starlink satellites (or significantly worse ones if a satellite flies in front of the guidestar that you're using as a reference point to measure atmospheric distortions).

You can filter them out computationally without adaptive optics with enough frames captured.

Modern astronomy works at the edges of whats possible, a single frame might take hours. Needing multiple frames would mean multiple days per observation. It would mean no longer seeing faint and distant objects, limiting us to younger, closer and frankly far more boring objects. It would make observing variability impossible for certain timescales.

You need old distant objects for cosmology, observing the structure if the universe, big bang and stuff. You need variability for finding exoplanets, measuring distance and observing transitions such as supernovae.

Oh, and then a huge part is taking spectra, which means bouncing the light directly off a grating. Filtering transients is hard to impossible there. You need spectra for relative motion, magnetic fields, composition of matter and radiation and of course temperature.

Needing such filters would set astronomy back a few decades

Hey you're back! I asked you previously "That might work for imaging, but what's your fix for spectroscopy?" here: https://news.ycombinator.com/item?id=21577081

You replied "Optical, RF, or Xray?"

Then I said, "Let's start with optical." but then you disappeared!

So, what's your solution for long-slit optical spectroscopy?

Hey! I'm still waiting to hear back from the astronomer I paid to do the research. I still intend to report back with their DOI from the resulting paper. I recognize when I've exceeded my domain knowledge and need an expert.

To be clear, I think we're well in the realm of academic discussion; no one is stopping any global constellation due to astronomy concerns. As I've said many times in this thread and elsewhere, I think it's a growth opportunity for the astronomy community to move towards space based observation platforms, and with the plummeting cost of lift (ie SpaceX Falcon and Starship) I don't think that's an unreasonable position to hold.

No, they are too bright and will saturate the detector with even very short exposures. Best you can do is just discard the affected area, at worst you have to discard several exposures because the saturation effected the readout electronics.

Arecibo and VLA aren't affected by starlink at all. Those are radio telescopes. They don't even need to wait until nighttime to observe. It's only an optical/ir problem.

Starlink uses radio to communicate with the ground. A common complaint from radio astronomers is new radio satellite operators promising to not interfere with radio astronomy and then making no effort to follow through in that promise.

“It will likely affect some earthbound astronomy significantly, but much (most?) of the most important work in modern astronomy is satellite based.”

Not true at all. Ground based is much cheaper and easier to maintain and reconfigure with new and different equipment. Just look at the cost of the upcoming >30m telescopes vs the James Webb or Hubble.

On the plus side, SpaceX is making launches much bigger and cheaper, which will make space-based telescopes much more affordable. Cheaper launches = more, cheaper satellites.

That's good but I am not sure if the launch cost is where the money goes for telescopes.

You are right, but also wrong. Because the launch cost so much you spend even more move on the space telescope because you want it to work for a very long time to get the best value for your money.

And since you are going to spend so much money to launch it, you also add extra hardware to do other type of observations, so the cost of the telescope balloons upward but you are get more bang for the buck.

If on the other hand you have cheap launches then you can send up the minimum telescope needed since you can always send up a better one or even a very different one if you later discover the need.

Today because of high costs, we need to design the scopes to meet all the possible needs we can think of and afford, result very expensive space scopes.

I guess we would have to look at the actual costs and trade offs. Personally I am still not convinced that launch cost is the biggest problem but I am sure astronomers are crunching budget numbers right now and will adjust plans if it makes sense.

A ground-based telescope will always be way cheaper than one in orbit.

Why make this more expensive than it needs to be? Researchers are already strapped for cash.

> but much (most?) of the most important work in modern astronomy is satellite based.

You're going to have to point out which source you pulled that out of! As a simple example, more than half of the Nobel prizes awarded for astronomy since 2000 are for discoveries made with ground based detectors. And of those awarded to satellite experiments, none was actually competing with a ground based experiment, so satellites mainly bring different, not better, capabilities.

...ground based detectors...

When I encounter this phrase I think of things like the neutrino detector in Antarctica, which of course isn't affected by satellites at all. How much contemporary astronomy relies on visible-light telescopy?

A very large fraction. Optical is still the most important band, probably followed by radio, x-ray, IR and gamma ray in that order. And less then 10% of optical is done using satellites.

It will kill astronomy pretty good.

The key point is usable observation time. Our current handful of satellite telescopes provide 24h of time a day. Each terrestrial telescope provides maybe 8h. However, there are a magnitude more telescopes on Hawaii alone than in space. You would need to get a hundred satellite telescopes to begin to replace earthbased observation time.

And that doesn't even begin to talk about the possible instruments, mirror sizes, astronomical costs of buulding and running satellites, etc.

It really won't.

Satellites are invisible if they're in the Earth's shadow. By the time useful observation can begin, there's an enormous swath of the sky that will have zero visible satellites in it.

Diversify your observation targets. There's more than one interesting thing to science at any given moment. If that means spreading out your observations so you spend two hours a night observing four targets as opposed to four hours a night on two targets, so be it.

At the very worst, this means astronomers will need to do more work during the day shift scheduling and prioritizing. This isn't a new problem. I remember reading a back page article in Astronomer magazine sometime in the late 90s with a page of BASIC code. Someone wanted to optimize a computer controlled telescope to make one observation of 100 or so stars every night. You need to roughly minimize the total Manhatten distance between every two observations, while also eliminating observations below the horizon and penalize observations low in the sky. So the author wrote a program to roughly approximate the traveling salesman problem with the additional constraints. In the 90s. In BASIC. In one page. It might be NP complete to get the perfect solution, but good enough is pretty good.

Add an additional constraints penalising observations where they might be impacted by satellites. Hire an intern working on their degree who's taken an optimization course and have them do it for you.

>And that doesn't even begin to talk about the possible instruments, mirror sizes, astronomical costs of buulding and running satellites, etc.

We're going to have to start thinking bigger if we want to leave this rock. Might as well start now.

The real risk is Elon's companies dissolving and the satellites adding pollution for no real gain. If I could trade observatory time for (working) world-wide internet, I'd take the latter with no hesitation.

As much as I sympathize, most of the cosmos aren't really going anywhere. It'll be there after we build hundreds of telescopes.

Starlink is not for consumers, so you cannot get it anyways. It's for enterprise at this point.

The amount of important work in modern astronomy that is satellite based is limited, as pointed out elsewhere on this thread.

For now. Do the Elon Musk analysis from first principles. The future of astronomy is clearly outside of Earth's gravity well and atmosphere.

Yes, but the current budgets clearly are not.

He's working on that ;)

/s (jeez, your sense of humor folks...)

Well, he is. For the Luddites in these threads, it's enough to cite the JWST as a reason to keep doing things the same old way, over and over, in space and on Earth.

Of course, the reason why people who enjoy lecturing others about why something can't be done differently or shouldn't be done differently seem to gravitate to a site called "Hacker News" is one of those universal mysteries that can't be answered with a computer or a telescope.

How is that clear? What principles did you use?

Because access to space is insanely expensive.

Don't fight the people who are trying to fix this.

Also dangerous and inflexible.

Most astronomy is long exposure which the eventual mega constellation is particularly harmful too because there's no way currently to deal with the light reflecting off them.

You know they don't use film plates for those exposures anymore, right? They stack images digitally. Removing satellite trails is the easiest part of the post processing flow, or it damned well should be.

Digit and film single long exposures are functionally identical and for very dim objects you still need long exposures because the amount of light reaching the sensor is very low. You can't image stack if the object is too dim to appear in the shorter exposure's you're stacking.

My impression is that a lot of interesting "leads" are generated by ground based telescopes and only then examined in more detailed by space based telescopes. If you kill off the generating mechanism, then effectiveness of space telescopes could also decline a lot.

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