by Chris Peterson » Tue Apr 07, 2020 4:11 am
alter-ego wrote: ↑Tue Apr 07, 2020 2:18 am
Chris Peterson wrote: ↑Mon Apr 06, 2020 12:51 pm
geckzilla wrote: ↑Mon Apr 06, 2020 9:23 am
Er, this is quite contrary to all that I've read about them. Darkening them hasn't helped (there's one test dark sat, and it looks the same as the rest) and the huge social benefit just ain't there. The constellation can't support that many users or that much bandwidth. The entire thing is a bit of a sham, if you ask me.
The measurements of the darkened satellite suggest that this approach will, in fact, drop the satellites below the blooming threshold of the Rubin Observatory. Without it they would lose about a third of their survey exposures. But they're working closely with Musk and the Starlink people, and the PI seems pretty optimistic that they'll be able to deal with it. Most other astronomy isn't much impacted.
I'm optimistic too, but not as much as Musk. He has expressed commitment to reducing the impact on astronomy and has stated that they would reduce the impact to "zero". The great news is he wants to fix it, and he's certainly capable.
However, as far as the first attempt with Darksat, there is a way to go, but there are other ideas.
Space News wrote: However, the company’s claim that DarkSat has achieved a “notable reduction” in brightness is not necessarily supported by recent observations. In a paper posted to the online preprint server arXiv March 17, astronomers using a small telescope in Chile measured the brightness of DarkSat and compared it to another Starlink satellite without darkening treatments.
They found DarkSat was about 0.88 magnitudes, or 55%, dimmer than the ordinary Starlink satellite.
That falls far short of what many astronomers are seeking. In a March 11 panel discussion organized by the American Astronomical Society, Tony
Tyson, chief scientist for the Vera Rubin Observatory under construction in Chile, said that simulations of the Starlink satellites showed that not only would the satellites make bright streaks on images taken by the telescope, but create other image artifacts by saturating pixels in the detector.
“
If we could make those particular spacecraft, the Starlinks, darker by 10 to 20 times, it may remove many of these artifacts,” he said. “It won’t remove the main trail — it will always be there — but it would remove the artifacts so that we might be able to get the science out of the data.”
To be clear, most projects either have a low probability of a satellite passing through, or can be timed to avoid them. The major issue is with wide field surveys, and for those, satellite tracks are not a problem unless they are bright enough to cause blooming. That's the goal of the darkening efforts. Not to make tracks go away, but avoid deep saturation, which ruins large sections of the image.
[quote=alter-ego post_id=301094 time=1586225907 user_id=125299]
[quote="Chris Peterson" post_id=301060 time=1586177494 user_id=117706]
[quote=geckzilla post_id=301055 time=1586165009 user_id=124138]
Er, this is quite contrary to all that I've read about them. Darkening them hasn't helped (there's one test dark sat, and it looks the same as the rest) and the huge social benefit just ain't there. The constellation can't support that many users or that much bandwidth. The entire thing is a bit of a sham, if you ask me.
[/quote]
The measurements of the darkened satellite suggest that this approach will, in fact, drop the satellites below the blooming threshold of the Rubin Observatory. Without it they would lose about a third of their survey exposures. But they're working closely with Musk and the Starlink people, and the PI seems pretty optimistic that they'll be able to deal with it. Most other astronomy isn't much impacted.
[/quote]
I'm optimistic too, but not as much as Musk. He has expressed commitment to reducing the impact on astronomy and has stated that they would reduce the impact to "zero". The great news is he wants to fix it, and he's certainly capable.
However, as far as the first attempt with Darksat, there is a way to go, but there are other ideas.
[quote="[url=https://spacenews.com/spacex-claims-some-success-in-darkening-starlink-satellites/]Space News[/url]"] However, the company’s claim that DarkSat has achieved a “notable reduction” in brightness is not necessarily supported by recent observations. In a paper posted to the online preprint server arXiv March 17, astronomers using a small telescope in Chile measured the brightness of DarkSat and compared it to another Starlink satellite without darkening treatments. [color=#0000FF]They found DarkSat was about 0.88 magnitudes, or 55%, dimmer than the ordinary Starlink satellite.
[/color]
That falls far short of what many astronomers are seeking. In a March 11 panel discussion organized by the American Astronomical Society, Tony [color=#0000FF]Tyson, chief scientist for the Vera Rubin Observatory under construction in Chile, said that simulations of the Starlink satellites showed that not only would the satellites make bright streaks on images taken by the telescope, but create other image artifacts by saturating pixels in the detector.
[/color]
“[color=#0000FF]If we could make those particular spacecraft, the Starlinks, darker by 10 to 20 times, it may remove many of these artifacts[/color],” he said. “It won’t remove the main trail — it will always be there — but it would remove the artifacts so that we might be able to get the science out of the data.”
[/quote]
[/quote]
To be clear, most projects either have a low probability of a satellite passing through, or can be timed to avoid them. The major issue is with wide field surveys, and for those, satellite tracks are not a problem unless they are bright enough to cause blooming. That's the goal of the darkening efforts. Not to make tracks go away, but avoid deep saturation, which ruins large sections of the image.