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How satellite ‘megaconstellations’ will photobomb astronomy images

nature.com

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Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#211

Post by dayjobpork »

valuearb wrote: post #206
vanderZwan wrote: post #124

Earlier quoted context omitted.

> which I would say is trivial I'm frankly amazed at the arrogance on display here. Do you honestly think you know better then the entire field of astronomy?

If the entire field of astronomy is so educated on the subject, why do most not know Starlink was never visible except at dawn or dusk, and it’s already implemented successful mitigations for those tones with visors?

Unless Musk has secretly invented Romulan cloaking technology, being invisible doesn't help when you are trying to look at the stuff behind

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#212

Post by liability »

valuearb wrote: post #210
liability wrote: post #196

Earlier quoted context omitted.

I wasn't thinking of OFAC, I was thinking of this: https://en.m.wikipedia.org/wiki/China_exclusion_policy_of_NA... If NASA is forbidden from working with organizations affiliated with China, it seems to me that SpaceX working with China might imperil their collaboration with NASA. Then again maybe not, I don't know the answer.

Answer is no. SpaceX is not NASA.

I know SpaceX is not NASA, that's not a valuable insight.

Edit: It seems the situation is not nearly as clear as you believe: https://www.satellitetoday.com/government-military/2020/08/2...

Considering a less direct relationship with China already has some congressmen evidently perturbed, I think there is a decent chance SpaceX would refuse any contracts with China if for no other reason than to avoid provoking Congress further.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#213

Post by dayjobpork »

0-_-0 wrote: post #158
welterde wrote: post #149

Earlier quoted context omitted.

Sure. And for small field of view things that might be the future. But if you are looking at large chunks of the sky at some point with enough satellites the shutter will have to stay shut for the whole duration of the exposure.. so not really a good solution for that.

What if SpaceX funded research into shutters that cover part of the CCD? Is that a possible solution?

What if spacex just didn't pollute the sky for an entire planet?

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#214

Post by mdorazio »

DoingIsLearning wrote: post #76
reitzensteinm wrote: post #42

Earlier quoted context omitted.

I personally believe that pervasive high speed internet even in remote locations will do more for humanity than the scientific cost of these satellites. However, this conversation has basically been skipped over. Maybe you're right and I'm wrong. The constellations are being launched, and there's zero chance of shutting them down once they're serving a commercial role. Considering the abundant red tape in the modern…

On top of the points made by q3k, about this being a US centric issue, being projected as a global issue, why do you believe this implementation will be able to deliver global pervasive internet? The obejective is noble but can you provide any realistic data or estimates of how this infrastructure can scale to more than a few million users and _still_ be high bandwith. Beyond that your bandwith will go down as you ad…

1) Why do you think people in subsaharan Africa, for example, won't be able to use it?

2) The only limitation on bandwidth (and thus users) is the number of satellites in orbit. If the constellation bandwidth is saturated, launch more satellites and you get more bandwidth.

3) I guess you'll just ignore the use cases for the tens of millions of non-rich people who literally can't get decent internet because it doesn't exist where they live?

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#215

Post by kanox »

verytrivial wrote: post #15

The article covers the mitigations already in place and how they only partially resolve the issue. These satellites are low, bright (at dawn/dusk) and very soon to be incredibly numerous. Yes, it is possible for data workflows to post-process these streaks away, but not all configurations allow this, and whereas previous intrusions were somewhat rare and could be ignored that simply won't be the case due to three com…

>> The article covers the mitigations already in place and how they only partially resolve the issue.

> So in April, SpaceX instead began launching Starlinks with a sunshade to block sunlight that would otherwise reflect off its antennas, which are the main source of the Starlinks’ brightness once they have reached their final positions.

> So far, only one of these ‘VisorSat’ Starlinks has finished the journey to its final orbit of 550 kilometres above Earth. Amateur astronomers have reported that the sunshade appears to make the Starlink fainter than it would otherwise be.

> But astronomers are still awaiting further confirmation that the modifications have a significant effect, says Meredith Rawls, an astronomer at the University of Washington in Seattle. Regardless, SpaceX is now launching all of its Starlinks with the sun-shielding visor.

It seems that the impact of the sunshade mitigation is not yet fully measured?

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#216

Post by valuearb »

simion314 wrote: post #164
BurningFrog wrote: post #159

Earlier quoted context omitted.

SpaceX is lowering satellite launch cost by 90% for anyone, Chinese or otherwise. This should start a golden age of space astronomy, even if Elon doesn't give away some telescope launches as PR.

The launch costs is just a small part of the total costs. You destroy my house and I should be happy you offer me a discount when I buy new blueprints from you.

Historically this has only been true because of the immense cost of building super lightweight payloads using super expensive super light materials to fit in very limited payload mass requirements.

Falcon 9 is a heavy launch system that can lift up to 50,000 lbs of payload to orbit, similar to the Shuttle.

Falcon Heavy is a super heavy launch system that can put 140,000 lbs of payload in orbit.

Starship is designed to be significantly cheaper than both of the Falcons, and to put over 200,000 lbs of payload in orbit with a far larger fairing size (though Falcon Heavy is getting a larger fairing shortly).

These are all game changers the scientific and commercial space customers haven’t yet taken advantage of.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#217

Post by valuearb »

q3k wrote: post #25
verytrivial wrote: post #15

The article covers the mitigations already in place and how they only partially resolve the issue. These satellites are low, bright (at dawn/dusk) and very soon to be incredibly numerous. Yes, it is possible for data workflows to post-process these streaks away, but not all configurations allow this, and whereas previous intrusions were somewhat rare and could be ignored that simply won't be the case due to three com…

You won't be alone on that hill. This issue is yet another reminder that capitalism only appears to work because you assume infinite resources on a finite planet.

Capitalism is terrible, it’s just far better than anything else we’ve ever tried.

It’s only real Achilles heel is tragedy of the commons (like this), which is a problem for the isms as well.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#218

Post by mdorazio »

welterde wrote: post #144
pas wrote: post #138

Earlier quoted context omitted.

Take many short expo images, and integrate them. This way you will have smaller streaks. Yes, the sats will occlude things anyway, and their brightness is a big problem, but they are fast moving, they can be mitigated by moving to may short expo images combined. Yes, it's an undue burden, SpaceX should do more, but they can't solve it completely.

The readout time for astronomy CCDs is typically between 2 and 30s (going faster produces more noise), so there is a lower limit on how short you can make exposures. In LEO the apparent movement of satellites is around 3.6 arcmin per second, which means for an average sized detector that covers maybe 20 arcmin it takes about 6s to produce a streak that covers the full length of the detector (bit longer depending on t…

I'm not sure you're thinking about it the right way. Or maybe I'm not. It seems you're assuming that every exposure you take will have a streak in the same spot from a satellite. It's more realistic that a large portion of exposures will have no streak at all, or that if you re-exposed a detector on the same piece of sky, any streak it would see the second time would be in a different place than the first. So if you expose twice and do some basic interpolation to remove the streaks, you would end up with an equivalent zero-satellite image from two exposures.

What am I missing?

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#219

Post by kanox »

DoingIsLearning wrote: post #76
reitzensteinm wrote: post #42

Earlier quoted context omitted.

I personally believe that pervasive high speed internet even in remote locations will do more for humanity than the scientific cost of these satellites. However, this conversation has basically been skipped over. Maybe you're right and I'm wrong. The constellations are being launched, and there's zero chance of shutting them down once they're serving a commercial role. Considering the abundant red tape in the modern…

On top of the points made by q3k, about this being a US centric issue, being projected as a global issue, why do you believe this implementation will be able to deliver global pervasive internet? The obejective is noble but can you provide any realistic data or estimates of how this infrastructure can scale to more than a few million users and _still_ be high bandwith. Beyond that your bandwith will go down as you ad…

> On top of the points made by q3k, about this being a US centric issue, being projected as a global issue, why do you believe this implementation will be able to deliver global pervasive internet?

Rural internet access is absolutely not an US-centric issue, many parts of the world have much worse infrastructure. Being opposed to new technologies because "I already have fast internet" is unbelievably narrow minded.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#220

Post by kanox »

xwdv wrote: post #205
reitzensteinm wrote: post #42

Earlier quoted context omitted.

I personally believe that pervasive high speed internet even in remote locations will do more for humanity than the scientific cost of these satellites. However, this conversation has basically been skipped over. Maybe you're right and I'm wrong. The constellations are being launched, and there's zero chance of shutting them down once they're serving a commercial role. Considering the abundant red tape in the modern…

> I personally believe that pervasive high speed internet even in remote locations will do more for humanity than the scientific cost of these satellites. If the internet was simply a wellspring from which one could obtain knowledge you may be correct. But most likely, the internet will instead be used to proliferate bigoted and intolerant opinions, while spreading lies and misinformation in the form of crude memes.…

So because you don't like the internet other people shouldn't get it?
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