Starlink, Spacex, American Astronomical Society discussed on Astronomy Cast

Astronomy Cast


His strong castor wheaton fact space journey through the cosmos. We help you understand. Not only what we know but how you know what we know. Brazil Razer Cain publisher of University with me as always Dr Pamela Gate a senior scientist for the Planetary Science Institute and the Director of Cosmo quest and so again this week. We are at the American Astronomical Society Meeting and the other big issue that was hanging over the entire conference is the impact Ah Starlink and the various satellite constellations that are in the process of getting launched. There's already one hundred. Eighty satellites in space from Starlink making it the largest satellite provider in the world. And there's going to be thousands tens of thousands more satellites so starner's WanNa we know what was going to be the impact. What mitigation strategies are there? And what does the future look like. When there are tens of thousands of satellites orbiting the earth? What does it mean for astronomy? All right let's into the episode all right so so here. We are back at the American Astronomical Society Meeting in Honolulu Hawaii and and we last episode. We talked about the big controversy of the construction of the thirty meter telescope. Here on the on the Hawaiian islands the Bit other big controversy. That's going on is of course. The starling constellation and literally just a couple of days ago. SPACEX launched launched the third batch of starling satellites another sixty satellites into space. And I it is safe to say. Hey that astronomers are outraged. I think that's an under Sabin. Yeah and there. There were three different arguments. Demint put forward and I have to admit at the top of this episode. I am somewhat biased. I desperately want to see the digital divide to be overcome and low cost Internet Internet to be available globally and Starlink promises. That and so a lot of what we're GONNA talk about. Today the issue comes down to whether or not you trust. Trust Elon. Musk to actually implement the low cost in the low cost Internet so the three arguments that we heard today against Starlink And one was a cultural problem of old but the children if you see satellite zipping around in the sky will people still fall in love with the stars. Will your experience visiting a dark sky site. Turn you off to astronomy if you see satellites and the cry of outrage. We heard was that people won't be inspired by the sky if they see manmade objects now I have to admit I distinctly remember exactly exactly where I was the first time I saw satellite. I I was up in the mountains of the caucuses camping beside a glacier and and I was sitting on a rock all by myself because being a teenager is hard and I was fifteen and sometimes you need to sit on a rock by yourself from your fifteen and and the satellite. I just saw something moving in the sky and I realized what it was and that realization of I'm alone on orrock beside a glacier but there's a satellite moving through my stars that at the age of fifteen was amazing moment and this idea that satellites make it impossible for people to fall in love with the stars. I I don't think that's the case. But it was one of the arguments arguments put forward and getting together to the second but but sort of like from a practical technical standpoint win. The starlings are first launched launched. They are actually very bright there about magnitude two or three which makes them easily visible to the unaided eye from many spots on the earth and they look like this train of moving across the sky. Call this this string of pearls and end and then as the starlings raise their altitude up to their final position of about five hundred fifty kilometers altitude the dimmed back to about a five magnitude which is at the very limits of the human. I can see in Nice dark dark skies and and but of course in the eyes of a of an astronomer that is incredibly bright. Eight of fifth magnitude star is very bright star in in the eyes of telescope and then the other problem is that when when when they pass across the sky they will really only be visible to astronomy when they are low on the on the horizon during the summer months. So when it's when the night is the longest the night is the shortest. You're going to get really. You're only going to be able to see these satellite right. Aided the right after twilight and right before sunrise. And and that's it you have to be and then for the for the rest of the night there won't be any satellites delights but as the nights get longer the satellites get brighter over C- over the entire night sky and so they're anticipating baiting that over some of the the big observatories in Chile and in the Northern Hemisphere. When you're in the middle of the longest nights you're gonNA see these? These satellites run across the entire sky. So so there's no question that these are going to be very bright objects that are going to move through your field of view and I leave streaks and one of the things that people keep bringing up is there's already thousands of pieces of stuff. There's eighteen thousand thousand tracked pieces that you can pull from the database right now. Eighteen thousand seven. I think you can pull from the database and you can track the position using celestis and other other things like that. Yeah so there you know we know and to adding another twelve hundred. which is the goal for link? So so let's narrow this down even further so there's eighteen thousand things up there. Prior to the launch of Starlink only two hundred objects were naked eye visible. So Oh you can only look up two hundred different things in heavens above and go outside and see them with the unaided eye with Starlink. They're adding well over for a thousand by the end of this year to the list of things that will be visible to the unaided eye and its brightness that is really the problem. I was an observational astronomer. For a number of years before realizing I am the rain God in those years years that are as an observational astronomer. I had myriad satellites go through my images but because they were low brightness objects there'd there'd be the straight line of pixels that well I couldn't see stars in but that line was the size on the sky. I that the satellite was on the sky. We starlink what's happening is these well captured. photons that are reflected off of the satellite delight. There are so many of them that they saturate the pill pixels spill over to adjacent pixels wiping out a larger swath of your detector than the satellite alone would wipe out. And when you saturate a pixel that saturation can cause the next. Several images to have ghosts hosts of that satellites passage still visible so not only. Are you wiping out. A larger percentage of pixels with that satellite but you're wiping them out across multiple images. Yeah and and so you know a lot of these these these satellites as they pass the field of view view can overwhelm the sensor and essentially make an entire observing frame worthless and the speed that they're moving is of great concern into these dreamers as they as they move through it's about. How quickly is this thing moving through your field of view? And how long do you have to not be able to take data data while this while the satellite is is moving through so so they're they're quite concerned just about overall in the time domain as well and of course the the big observatory that's going to be the most effective is the newly renamed. That's a different controversial. I know that's like a third the Third Controversy Jersey. We won't get into that but the newly but we. I think we can all agree. That the Vera Rubin Observatory is a wonderful Navarine Observatory and that is going to be the. That's that's going to be the facility that's going to be deeply affected because it just is staring wide eyed at the sky for all all night capturing as much as they can as deeply as a canon so every frame is GonNa have starlings and one ebbs and all this past them and this is this this is a problem of because it has a giant field of you. The probability that there's going to be a Starlink in any one image goes up if you have a small field of view. There's the potential that you can time your images to avoid having star Lincoln them but because this is a huge field of view. You your ability to do. That is greatly reduced. And they're going to end up picking up. STARLA starlings left and right and here's a question starts to become one of mitigation so folks are working with spacex to see okay. What do we need to do to reduce the brightness of these objects so that they aren't blowing out the detectors? Yeah there's more than that so so Someone from spacex actually gave a presentation this morning and that was actually a bit of a surprise and they didn't do a very good job of letting us know that this is is going to happen. There weren't a lot of people we have the whole ballroom and there wasn't a lot of people they're listening to her her talk. They mentioned essentially a couple of mediation strategy. So the first first thing is with this first launch they have. They've applied some darkening materials to one of the sixty satellites to see if the some of their ideas to make them to have a lower Albedo lower flexibility. And before you laugh at the fact that it's only one the thing you have to take into mind mind is these suckers were already largely built in preparation and turning around and re fabricating that takes time and so my suspicion. My hope is that that they were only able to fabricate one with the new materials fast enough to be able to test and I think it's you know. No this is how you perform an experiment right. Is You you isolate. The variable does putting all this material on one of the satellites make darker than the rest and and we'll find out what happened happens so so that's the first thing they did is experimenting and and this is a good sign. I mean this is like literally. This is the first time I think that any satellite constellation Elation has ever had a conversation with Strana mors and said what can we do to minimize our impact on your science. I don't there's you know the two hundred others others that we mentioned plus all the eighteen thousand. No one's ever tried to make them not bright in the eyes of strimmers so till the first strategy is to try at a paint them so there will be the second thing is to provide an open source real time. Location of all of the satellites in the Constellation and to communicate with the other networks. And anyone out there. Who is who is going to be relying on knowing the position? These starlink so in theory as the as the Constellation gets built your of your telescope operator. You're going to know when a Starlink is going to be passing through your detector and you'll be able to shut detector down. Wait for the starling. Pass opened the doctor again. And continue to get your to get your data so you won't necessarily get that that if you've got a very precise amount of time you'd be able to use it carefully. Navigating around satellite as coming by the other thing is they're going to provide a very specific and I forget what the technical term was but essentially the the launch trajectory of each new constellation as they go up so when that first trail is starting to head off into space and it is going to cause horrible streaks in any telescope any amateur Astra photographer is going to get this as well. They're going to sit there. You're going to know when that when Constellation is going to be passing through where it's going to be just to to plan your observing observing time around those starlink launches and it only you know it's only a few months or really. It's only a few days a week that they're in this trail l. and these are the spread out and shift themselves to that higher orbit but but the second problem that we're talking about one of the additional parts to to this is well so far SPACEX has been extraordinarily in in terms of trying to build a relationship saying look yes. We're going to work with you. Here's all ways we're going to work with you. SPACEX is just one of a myriad of companies looking to do this and so is China when they start launching their constellations..

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