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How bad are satellite megaconstellations for astronomy?

leonarddavid.com

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Re: How bad are satellite megaconstellations for astronomy?

#61

Post by _dain_ »

rickydroll wrote: post #43
_dain_ wrote: post #28

Earlier quoted context omitted.

> That needs some citations. The James Webb Telescope's mirror is 6.5m in diameter. It took decades and billions of dollars of overruns and a prayer to launch and work correctly. There is no hope of most hardware repairs. Because it had to get launched folded up, because the launch vehicles were so space- and mass-constrained. The unfolding mechanism was enormously complicated and added to much of the cost. Now we ca…

https://en.wikipedia.org/wiki/Extremely_Large_Telescope The 39-meter primary mirror has 798 1.4-meter segments, each individually adjustable. The scaffolding required to hold all the segments is "significant" and must be assembled in orbit. We would stick this out next to the James Webb at L2, which means we would need the ability to travel to L2 to construct this mythical orbital extremely large telescope. With our…

For one thing, before this decade is out we will have the lift capacity to get an ELT-worth of mass to L2. And the lack of need to correct for atmospheric distortion would simplify the design considerably.

But it's beside the point. Such a singular mega-telescope would no longer be the only way to do astronomy in space. A world of radically lower launch costs gives more possibilities. We could have a fleet of thousands of independent small/medium sized space telescopes. That way, we wouldn't have to carefully ration imaging time between competing astronomy projects anymore. High quality data would become cheap and abundant, procured on-demand.

Re: How bad are satellite megaconstellations for astronomy?

#62

Post by rickydroll »

1) Most research is performed on the thousands of smaller telescopes (0.5-2 m.) scattered worldwide at private and public institutions. Even with the multitude of telescopes in the size range, there is still significant contention for scope time.

2) Space telescopes will never be disposable and will always require some form of service, even with high-reliability construction.

3) low Earth orbit is a limited resource and should be managed as a worldwide Commons. Allowing private corporations to occupy space is another way to privatize profit and push losses onto the public purse. Do you think any of these private companies will clean up the orbital messes they create, or will they act like they have to date?

4) Satellite Internet solves the billionaire's problem of extracting more money from users. Terrestrial methods for Internet access are good enough in all but the most remote communities. The main problem with terrestrial Internet is funding buildout Via private companies in a natural monopoly environment.

Re: How bad are satellite megaconstellations for astronomy?

#63

Post by hagbard_c »

bmitc wrote: post #26
marcosdumay wrote: post #10

Earlier quoted context omitted.

Yes, the future of astronomy is in space. If the satellites don't disrupt it, light pollution will anyway, or best case, it will be disrupted by atmospheric pollution. There's no lack of clear skies in space.

That needs some citations. The James Webb Telescope's mirror is 6.5m in diameter. It took decades and billions of dollars of overruns and a prayer to launch and work correctly. There is no hope of most hardware repairs. That mirror size pails in comparison to what can be accomplished via ground based observatories for much, much cheaper. And the available modes of operation are completely different between space and…

If the promises made for new launch systems like SpaceX' Starship (and maybe even, one day, in some unknown future, Bezos' Blue Origin manages to launch something larger than a phallic pond hopper?) it should become radically less expensive to launch larger telescopes into orbit and/or to e.g. the moon.

Re: How bad are satellite megaconstellations for astronomy?

#64

Post by ajford »

LeoPanthera wrote: post #6
tetris11 wrote: post #2

I know it's a blessing for people who live out in the sticks to have internet.... but is that really such a large use-case to justify entire fleets of these things? How hard is it to run km of wire from the nearest town? To me, these were built for the sole purpose of surveillance, and internet is an afterthought. Edit: yes yes it's expensive, but the easiest solution the world came up with was for some guy to invest…

> How hard is it to run km of wire from the nearest town? If it's not hard, why hasn't it happened already?

Because telecoms keep pocketing the money instead of actually building out broadband. https://www.huffpost.com/entry/the-book-of-broken-promis_b_5...

Re: How bad are satellite megaconstellations for astronomy?

#65

Post by ggreer »

bmitc wrote: post #30
oh_my_goodness wrote: post #16

Earlier quoted context omitted.

Hard enough that some people are putting up satellites instead. EDIT: Say there's some way to put in fiber at $10k per km. Even then, ten million users at 1km per user makes $100 billion.

To me, these are capitalistic solutions looking for problems. It's the whole startup mentality. Let's just throw a bunch of shit in space and see if it ends up being useful for anything. This idea of connecting the world is as false as the other hundred millions times that's been sold.

Useful for anything? Starlink useful to its 2.7 million subscribers. And it's already profitable. As of last year, SpaceX makes more in subscription fees than it costs to build and launch the satellites. The economics will only become more favorable when SpaceX improves their launch capabilities with Starship.

Re: How bad are satellite megaconstellations for astronomy?

#66

Post by a2l3aQ »

Starlevel004 wrote: post #29
tetris11 wrote: post #2

I know it's a blessing for people who live out in the sticks to have internet.... but is that really such a large use-case to justify entire fleets of these things? How hard is it to run km of wire from the nearest town? To me, these were built for the sole purpose of surveillance, and internet is an afterthought. Edit: yes yes it's expensive, but the easiest solution the world came up with was for some guy to invest…

[flagged]

Not a great point of view when the cities don't grow all that much food.

Re: How bad are satellite megaconstellations for astronomy?

#67

Post by gammarator »

StellarScience wrote: post #42

There certainly is a real concern for astronomers, but the photo illustrations used in the article are selected to make things seem worse than they really are. They're wide field of view, long-duration exposures. That used to be the way astronomers imaged space, with film systems a century ago. But these days astronomical telescopes tend to have much narrower fields of view (like tiny soda straws peering into one par…

> They're wide field of view, long-duration exposures. That used to be the way astronomers imaged space,

Sorry, but one of the two example images (https://noirlab.edu/public/images/iotw1946a/) is a single 333-second exposure with a modern survey camera, the Dark Energy Camera. This is not particularly long nor does it represent some outmoded observational strategy. Large, wide-field imaging sky surveys (such as the upcoming Rubin Observatory) are among the highest-profile ground-based astronomy projects today.

Masking and stacking can mitigate the problem but it does not of course compensate for the lost area and sensitivity. And the brightest satellites (like BlueWalker) saturate the readout electronics and spoil the whole exposure.

Narrow field instruments (such as spectrographs) have less geometric chance of seeing a satellite but tend to take longer exposures (tens of minutes), so there is a greater loss of telescope time when a streak does happen.

Even space telescopes are affected by streaks (https://www.space.com/hubble-images-spoiled-starlink-satelli...).

> It takes a bit more work and software

Equivalently, it takes more money and time. That just means less science, given flat to declining funding from Congress.

Re: How bad are satellite megaconstellations for astronomy?

#68

Post by throwaway11460 »

hehdhdjehehegwv wrote: post #15
Almondsetat wrote: post #12

Earlier quoted context omitted.

Exactly my thoughts. Scientists drool at the few telescopes we have in orbit. If we could launch more of them for less money at the expense of a busier night sky I don't think they would want to miss on that

[flagged]

SpaceX single handedly made my whole family excited about space exploration. My mother watches every launch and landing, keeps track of Starlink satellites passing by and runs out with her phone camera every time they are visible.

She even started to learn English because she wanted to understand what they're saying on the live streams. I am fixing some production bug at 4 AM and suddenly she's texting me like "you're watching the launch too???". And last time I forgot to send her the link to the latest Starship test she nearly grounded me.

She is a seamstress who never cared about any of this until she saw the first landing of Falcon Heavy, proclaimed that we live in a fucking scifi and became the biggest Elon Musk fangirl I know.

Re: How bad are satellite megaconstellations for astronomy?

#69

Post by ericd »

iwontberude wrote: post #23
ericd wrote: post #11

Earlier quoted context omitted.

Yeah, I’m not sure why trenching is so expensive, I think PG&E was quoting something silly like millions per kilometer. I’m planning on doing like a tenth of a kilometer in a day with a $400 trencher rental pretty soon. I’m sure it’s not apples to apples, but the delta there seems pretty baffling. For me, the biggest hang up has just been that I’m required by the state to get it inspected before I put in the conduit,…

It might cost money to figure out where to prioritize resources

Yeah, but if the planning that’s meant to make things efficient is using up almost all the money, seems like maybe we need to rethink how we’re doing things.

Re: How bad are satellite megaconstellations for astronomy?

#70

Post by Starlevel004 »

a2l3aQ wrote: post #66
Starlevel004 wrote: post #29

Earlier quoted context omitted.

[flagged]

Not a great point of view when the cities don't grow all that much food.

Neither do most ruraloids and especially not the ones actually paying for the satellites.
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