SpaceX's Starlink, satellite flares, and spectacular twilight rocket plumes: EXPLAINED!

I want you to bear with me here for a moment and imagine that we are not in my garage that we are in space those are not cosmic washing machines these are not planet-sized bikes because I'm going to mix things up a little bit today and start this video with a quiz if this is the International Space Station and this is Earth how far away do you think the space station is to scale what's the altitude of the orbit I'll help you out a little bit and give you four different options the space station could be over here at the red arrow it could be here at the blue arrow which is exactly four Earth radii from Earth's surface it could be right here at the green arrow which is a radius and a half from Earth's surface or it could be all the way up here at the white arrow I asked this question because I used to think of orbits the wrong way and I feel like the typical depiction of space isn't very real well the channel intro plays go pause the video and drop an answer in the comments [Music] all right so now you're back I trust everybody made guesses for an added hint here's a graphic from a recent SpaceX webcast where they were sending astronauts to the International Space Station how close do you think their graphic is to reality if you pick the red arrow and you said the ISS was orbiting out here you are farther away than geosynchronous orbit interestingly enough that actually means that your orbit is so slow that Earth spins faster than you move around it so it looks like you're orbiting in the wrong direction unfortunately the energy required to get a payload all the way out to this orbit is massive the farther away you get from earth the more energy you need so very very few missions actually go past geosynchronous orbit the blue arrow is inside of you of synchronous orbit and it takes a lot less energy to get to this orbit the problem is the Van Allen radiation belts earth is surrounded by two shells of radiation known as the Van Allen belts and unfortunately this blue arrow is smack in the middle of the outer belt so if you parked a space station right here you basically slowly be cooking the astronauts on board and that would be bad so we don't put space stations here now that I've put this graphic up on the screen the green arrow is looking really good the inner Van Allen belt and the outer Van Allen belt have a gap in between them where there's a low radiation zone so you could absolutely Park a space station here and your astronauts would receive much lower doses of radiation just by living on the station however it's still actually too far away the farther you get from Earth's surface the harder you need to work the faster you need to go the more fuel you need to burn and the more expensive it is so if you want to put a large structure in Earth orbit you basically want it to be at the lowest possible altitude where there isn't an atmosphere to get in the way and believe it or not that is all the way in here it's a scale the white arrow is actually the orbit of the International Space Station it hardly even looks like we should call it space to the scale of the model that I'm holding in my hand mean the model is trailing through the ocean as we orbit the planet the International Space Station is like a football field sized chunk of metal that's zooming around earth at an unbelievably high speed and it's it's only that far off the surface and it keeps going that's just crazy space isn't you know necessarily outer space it's just outside the atmosphere and the atmosphere thins out really really quick airliners fly about here Mount Everest is about this tall and us humans can only survive below this altitude for any reasonable length of time it's kind of amazing that as a species we really can only populate this thin thin thin shell around one Rock flying through space for bonus points the space station also doesn't fly straight around earth's equator it's actually inclined at 51.6 4 degrees so it flies a little bit like this so satellite orbits by themselves are pretty interesting but that's not actually why I built this rig this entire contraption includes a very large globe with a gantry that allows me to let models of satellites orbit this globe at scale what are very low altitude orbits and the best part is that behind me I have the Sun being played by a very bright LED lightbulb all of this together is hopefully going to help me communicate to you the geometry behind satellite flare and how you can see sunlight and reflected off of objects flying through space while it's night time on earth and how this can be trouble for astronomers who of course don't want to see man-made objects causing light in the night sky because they want to look at natural lights in the night sky there's been a whole lot of news recently about so-called mega constellations of lots and lots of satellites being deployed by companies like SpaceX oneweb and Amazon SpaceX specifically has sort of already taken the cake in terms of launch rate at the time of this filming SpaceX has 540 Starling satellites in orbit around Earth and they have many many more launched planned to bring that number up to at least 12,000 satellites after the first batch of 60 launched last year I actually went out with a camera and was actually able to give some video of the Train of still deploying satellites it's pretty cool to be able to see a few satellites at night but tens of thousands of them might end up being a problem there's already been quite an outcry from the astronomical community because photographs taken by telescope cameras can be ruined by these satellites which end up looking like big streaks through the long exposure images so why do satellites produce light in the night sky normally if you see a light at nighttime like a car headlight or a lighted building or even the stars in the sky the object you're actually looking at is generating that light but the Starling satellites don't generate any light instead they reflect sunlight reflecting sunlight at night seems like a difficult thing to do but remember these satellites are 550 kilometres above Earth's surface and nighttime isn't based on location on the ground but instead the angle between the Sun and the ground this leads to some pretty awesome sights when large objects in the upper atmosphere can reflect sunlight while everything else looks dark this is a prime example of one of those really spectacular sunlit but at night time sort of objects I took this picture of a SpaceX launch shortly after dusk and this is actually just after the second stage separation so the idea here is that this is a huge plume of expanding gas that's being emitted from the second stage engine but the second stage is actually above that line over our heads where the sunlight can still shine although it looks like nighttime on the ground that means that despite the sky looking black because it's nighttime there's this thing this giant ball of gas that is illuminated above our heads and that looks really cool it's worth mentioning that even if it hadn't been nighttime where we were on the ground this cloud of gas would still have reflected sunlight but then again so would the atmosphere immediately above our heads so the light from the gas cloud would have been completely washed out by the blue sky that's why you don't see a big glowing plume like this at every single rocket launch it's there but you just can't see it you only get this when it's nighttime on the ground and daytime at the rocket satellite flare or satellite glint as it's sometimes called is when a satellite in orbit reflects sunlight back to Earth's surface so that we can see it in the sky for a long time the most spectacular examples of satellite flares came from the first generation iridium constellation which was a network of 82 satellites that provided satphone coverage across the entire globe they looked vaguely like this with one central core containing the electronics and guidance stuff there were some solar panels up top but most notably each satellite had these three large flat panel antennas pointed down towards Earth and those antennas are what actually provided the phone coverage these large panels were extremely reflective and because they were oriented for communication it was really easy to predict when they would reflect light back to your location so you could go outside at night and see one of these things fly over I even made a really kludgy video about photographing these flares a few years ago and managed to get an image with three different satellites in it which was kind of fun the Iridium satellites are in polar orbits so they basically travel north and south while the Earth rotates under them and they orbit at about twice the altitude of the International Space Station which in this scale would put the base of them about here basically as the satellite orbits earth these flat panel antennas act like mirrors for sunlight and each could reflect a spot of sunlight down onto Earth's surface that would trace a line until the satellite itself got far enough behind earth that it entered nighttime and was no longer illuminated by the Sun if you happen to be standing right here in the path of the reflection you would see the satellite show up it's a very bright spot for a brief moment as it moved across the sky it would only get really bright when that reflected beam was pointed straight at you so in long exposure it would look like a streak with a bright bulge in the center formed when that reflection lined up iridium flares were kind of because they were a unique thing and there weren't enough of them in the sky to disrupt real observations even so the next generation of iridium satellites that has just launched over the last couple of years actually has done away with that big three flat panel design and the satellites are going to be a lot dimmer that means we're not going to get the specular reflection or highly directional mirror like reflection from these new satellites but we can still see the diffuse reflection firm irregularly shaped objects this is a white sphere in orbit and if you notice from space we don't see it reflecting one intense spot on the Earth's surface more of a diffuse glow from the ground we can still see it it's just quite a bit fainter than the flare and that's because the same light that was once focused into a tight spot is instead being spread out over a very wide angle the new StarLink satellites look like flat panels but at least in the renderings I've been able to find they all point straight down so if we make that to scale here the flat panel is a little over an inch from the surface of Earth but you'll notice the reflected beam can't ever hit Earth's surface in order for the satellite to specularly reflect of this panel straight down onto earth it would need to be receiving sunlight normal to that surface meaning that would have to be facing the Sun meaning it would have to be directly behind earth meaning that the Sun wouldn't be visible so specular reflection really isn't the problem however like I said before we can still see the thing from Earth because it has enough irregular surfaces on it that it's also a diffuse reflector of light the Sierra to Lolo if I'm pronouncing that right Observatory in Chile took this image last November which was later published on Twitter you can see the streaks of light from the Starling satellites ruining this picture and this image caused quite a stir SpaceX's response has been to experiment with ways to reduce the diffuse reflection from their satellites their first effort was effectively to paint blak they tried this with two satellites and apparently reduced their brightness by about half which was an improvement but not anywhere near enough I have very little information about these darks at missions but I'm assuming they're not all of the features on the satellite could be coated with whatever they were using that was effectively black paint their most recent effort is to give every satellite its own little Sun umbrella if you can block the Sun from hitting anything reflective on the satellite you effectively put it inside of its own little patch of night time this is my tiny replica visor SAP sunshade and it does make the silver model look a whole lot darker they're currently testing this sunshade on a few satellites and apparently they're planning to implement sun shades on all satellites from the next launch onwards that leaves roughly 500 of these satellites currently in orbit with minimal reflection mitigation but the good news is that so close to Earth's surface these satellites will actually experience just a little bit of atmospheric drag so over a few years their orbits will decay and they'll get replaced by newer darker satellites I hope you found this discussion of the geometry of satellite flares interesting if you did like it please share this video and here's hoping that they figure this out because I really want low latency global internet from space to be a thing but I also really don't want pictures of the night sky to start coming with gridlines thanks for watching and remember to subscribe for more projects time lapses and astronomy [Music]

Channel: AlphaPhoenix

Views: 33,523

Keywords: Alpha, Phoenix, Alpha phoenix, Alphaphoenix, Spacex, Starlink, oneweb, amazon, kuiper, Leo, low earth orbit, satellite, internet, latency, speed, broadband, high speed internet, speed of light, travel time, communication, delay, Physics, optics, reflection, specular, mirror, diffuse, rough, surface, bright, light, Education, Astronomy, fieldofsattrails, satellite trails, trails, streaks, flare, flair, glint, image, telescope, camera, picture, Orbits, iss, international space station, altitude, misconception, space, atmosphere, drag

Id: aWpeN3cU17Q

Length: 13min 58sec (838 seconds)

Published: Mon Jul 06 2020