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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

#241

Post by pvaldes »

gus_massa wrote: post #208
pvaldes wrote: post #94

Perhaps putting a camera at the outer side of each satelite and a screen at the facing-to-earth side transmitting what the camera sees could help. Plus google advertising benefits, of course.

The amount of light blocked by the satellite is too small. The problem is that the satellite reflects a lot of light from the sun.

Maybe they could use a broken/plicated/spiky surface that does not reflect so much light. That definitely would reduce the amount of light reflected.

Maybe could be designed to act as a heat exchanger also or be used as a system to mitigate the improbable impact of a small debris

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#242

Post by 0-_-0 »

dayjobpork wrote: post #213
0-_-0 wrote: post #158

Earlier quoted context omitted.

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?

We wouldn't get planet-scale internet

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#243

Post by welterde »

0-_-0 wrote: post #186
welterde wrote: post #165

Earlier quoted context omitted.

If the conditions are quite stable that might work (or if one can live with limited accuracy), but conditions tend to change over time (moon position, thin clouds and of course the seeing - how much the atmosphere distorts the image) so nothing is as straightforward as one might hope for. In space that approach would work quite well indeed, but then you wouldn't need it in the first place.. Edit: Even if one still ha…

How much does the bloom extend in the image fom the streak? Can you measure it in arcminutes or is it optics dependent? Is the bloom present if you cover up the satellite exactly? (Is it caused by the sensor, or would diffraction around a shutter cause it as well?) I think you could mitigate the problems with conditions changing if (instead of blocking out the streak in the image with some per-area shutter) you track…

If no light falls onto the detector then there is no blooming. And of course there will be diffraction from the shutter edges as well, so engineering it will be quite a challenge (one can take hints from coronographs). If the satellites does end up on the sensor then the dimension of the streak depends on the optics, how bright it is, the used detector, plate scale, etc. (if you are extremely unlucky you might have internal reflections too and they might end up who knows where on the detector - optics is hard).

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#244

Post by welterde »

valuearb wrote: post #216
simion314 wrote: post #164

Earlier quoted context omitted.

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 t…

You are forgetting that the telescope has to work in space. Big thermal swings, no easy air cooling, no AC outlet to get your power from, no convenient anchoring point for your telescope to push against to point a certain direction, no just bolting several racks full of off-the-shelve electronics to the telescope (none of them work in vacuum), no possibility to repair or upgrade anything, ...

Having to use lightweight materials is the least of your worries (and not even that expensive - and sometimes done for ground-based instruments as well).

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#245

Post by svara »

valuearb wrote: post #222
svara wrote: post #37

Living in a city, I didn't understand how big a deal this was until I got a view of the clear night sky in a less populated area recently. The satellites are already visible by eye everywhere, and there are only 655 Starlink satellites. There's approval for 12000, and SpaceX is seeking approval for 30000! If they're all going to be this reflective, satellites will be the main thing we see in the night sky a few years…

Starlink is only ever visible at dusk or dawn. It’s orbits are so low they are in the earths shadow for the rest of the night. And new Starlink have visits limiting their reflectivity even during dusk and dawn.

> And new Starlink have visits limiting their reflectivity even during dusk and dawn.

I hope this really does work; as far as I could tell no such satellite has yet reached its final orbit.

It boggles the mind that this seems to be an afterthought to something this potentially consequential.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#246

Post by simion314 »

valuearb wrote: post #209
simion314 wrote: post #45

Earlier quoted context omitted.

Will those american billionaires pay say for more European satellites to compensate? What if this were Chinese satellites would you have the same opinion? It would be great if this billionaires would also launch scientific satellites payed from their pocket to compensate, then I would change my mind.

Elon has already cut the cost of putting scientific payloads in space by nearly 80%, what else do you want him to do?

Don't shit on others plate and then offer a discount on cleaning products.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#247

Post by dr_dshiv »

welterde wrote: post #96
dr_dshiv wrote: post #74

Earlier quoted context omitted.

This paper suggests otherwise, what are your thoughts? Optical aperture synthesis with electronically connected telescopes https://www.nature.com/articles/ncomms7852

Like I said interferometers exist but they are very limited in their capabilities. For example the VLT interferometer is limited to observing objects that are brighter than 18th magnitude (and that's using multiple 8m telescopes! Using the auxiliary telescopes which are still 2m you are limited to about 10th magnitude). Something that is easily within the reach of a single telescope less than 50cm in diameter (single…

Thanks, this Wikipedia page has more -- and consider adding! https://en.m.wikipedia.org/wiki/Astronomical_interferometer

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#248

Post by SiempreViernes »

valuearb wrote: post #235
SiempreViernes wrote: post #34

Earlier quoted context omitted.

> It is this author’s opinion that any correlation between mass and space telescope cost is a coincidence. From "Survey of cost models for space telescopes" https://doi.org/10.1117/1.3430603

A decade old study, using only NASA telescopes, using only super expensive launch systems. Now the Falcon Heavy can lift over double the payload mass of the Space Shuttle to orbit, for less than 1/40th the cost per pound.

> using only super expensive launch systems.

And _yet_, despite launch cost supposedly being suuuuper large, weight played no clear role in total cost. Not sure how that is a counter argument?

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#249

Post by valuearb »

Balgair wrote: post #236
valuearb wrote: post #229

Earlier quoted context omitted.

No, it’s not. Starlink satellites are only visible at dusk and dawn, they are in the earths shadow during prime viewing hours. And SoaceX has already added visors to make new Starlink satellites nearly invisible.

> nearly invisible In what wavelengths?

In all the best wavelengths first dawn/dusk observations.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#250

Post by valuearb »

welterde wrote: post #244
valuearb wrote: post #216

Earlier quoted context omitted.

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 t…

You are forgetting that the telescope has to work in space. Big thermal swings, no easy air cooling, no AC outlet to get your power from, no convenient anchoring point for your telescope to push against to point a certain direction, no just bolting several racks full of off-the-shelve electronics to the telescope (none of them work in vacuum), no possibility to repair or upgrade anything, ... Having to use lightweigh…

I didn’t say it was easy, just easier.
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