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SpaceX satellites could blight the night sky, warn astronomers

theguardian.com

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Re: SpaceX satellites could blight the night sky, warn astronomers

#31

Post by aeternus »

batbomb wrote: post #28
thecrumb wrote: post #5

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.

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.

Re: SpaceX satellites could blight the night sky, warn astronomers

#32

Post by jasonhansel »

Robotbeat wrote: post #22
jasonhansel wrote: post #20

Earlier quoted context omitted.

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…

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.

Re: SpaceX satellites could blight the night sky, warn astronomers

#33

Post by aeternus »

nonnontrivial wrote: post #11

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/

Re: SpaceX satellites could blight the night sky, warn astronomers

#34

Post by jasonhansel »

givinguflac wrote: post #14
mdorazio wrote: post #3

Earlier quoted context omitted.

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 posi…

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…

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.

Re: SpaceX satellites could blight the night sky, warn astronomers

#35

Post by jasonhansel »

Robotbeat wrote: post #10
vbuwivbiu wrote: post #9

Earlier quoted context omitted.

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 mor…

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

Re: SpaceX satellites could blight the night sky, warn astronomers

#36

Post by Rebelgecko »

pfdietz wrote: post #17
vikramkr wrote: post #2

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…

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.

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

Re: SpaceX satellites could blight the night sky, warn astronomers

#37

Post by batbomb »

aeternus wrote: post #31
batbomb wrote: post #28

Earlier quoted context omitted.

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.

Re: SpaceX satellites could blight the night sky, warn astronomers

#38

Post by greggeter »

errantspark wrote: post #18

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 plan…

Windmills in the hundreds north of Abilene, TX are gorgeous, too... at first. Then it's overload. Then you wish for the plains to be back the way they were.

Re: SpaceX satellites could blight the night sky, warn astronomers

#39

Post by perilunar »

batbomb wrote: post #37
aeternus wrote: post #31

Earlier quoted context omitted.

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 yo…

>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.

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