01/28/2022

It’s A Bird. It’s A Plane. It’s An Astronomical Photo Bomb.

10:37 minutes

four images collaged together. they are of the night sky, showing white streaks from satellites
(Top left) Satellite streaks run across an image of the whirlpool galaxy, Messier 51. (Top right) A flare from the Iridium satellite constellation. (Bottom left) In November 2019, Padraic Koen captured Starlink satellite streaks. (bottom right) Taken on March 25, 2020, Patrick Hevs captured streaks potentially from Starlink. Credit: Anecdata/Satellite Streak Watcher/CC-BY 4.0

Anyone who’s spent any time gazing at the stars at night has had the experience of seeing an occasional satellite whizz by—a sighting that usually happens around twilight. But if you’ve been out in the dark lately, you may have noticed that there’s a lot more traffic in space these days. With keen eyes, you might spot a series of dots moving in a straight line. That line is a “train” of satellites in low earth orbit, launched to provide broadband internet access from space. 

Starlink is the main company behind such efforts currently, with thousands of satellites in orbit already, but other players, such as Amazon, are joining the market as well. The companies behind them say they can provide high-speed broadband internet access to rural areas that might be out of range of a fiber optic cable or a good cellular connection. 

But just as you can see those lines of glowing dots, astronomers and their telescopes can see them too, making their jobs more difficult. The problem is especially acute in long-duration exposures of the night sky—in which the dots become bright streaks across an entire image. Over the past few years, astronomers and some of the companies behind the large satellite constellations have been trying to find ways to mitigate the optical interference the satellites can cause.

Dr. Bruce Cameron, the director of the System Architecture Group at MIT, describes the capabilities of some of these huge satellite constellations, and who might stand to benefit from them. Dr. Connie Walker, a scientist with NSF’s NOIRLab and the co-chair of four panels looking at the impact of these satellite constellations on astronomy, joins guest host Miles O’Brien to discuss the challenges these constellations could pose in the future, and her hopes for collaboration with industry to solve the problems.


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Segment Guests

Connie Walker

Connie Walker is an astronomer in NSF’s NOIRlab, and was co-chair of 4 panels looking at the question of LEO Constellations. She’s based in Tucson, Arizona.

Bruce Cameron

Bruce Cameron is Director of the System Architecture Group at MIT in Cambridge, Massachusetts.

Segment Transcript

MILES O’BRIEN: This is Science Friday. I’m Miles O’Brien. Anyone who’s spent any time gazing at the stars at night has had the experience of seeing satellites whiz by. But if you’ve been out in the dark lately, you may have noticed there’s a lot more traffic in space these days, bumper to bumper traffic. It’s actually called a train of satellites, a group of satellites in low Earth orbit launched to provide broadband internet access from space. Elon Musk’s Starlink is the main one, with thousands of satellites in orbit already. And there are other players, such as Amazon, in the market as well.

But just as you can see those lines of glowing dots, astronomers and their telescopes can see them, too, making their jobs more difficult. Joining me now are two guests. Dr. Connie Walker is a scientist with the National Science Foundation’s NOIRlab, and she was the co-chair of four panels looking at this question. Dr. Bruce Cameron is the director of the System Architecture Group at MIT. He and his colleagues studied the network capabilities of some of these huge satellite constellations. Welcome to you both.

BRUCE CAMERON: Thanks for having us.

CONNIE WALKER: It’s a pleasure to be here.

MILES O’BRIEN: Good to have you. Bruce, thousands of satellites going into orbit. The term that people are using is that it’s the industrialization of space, all of this to provide internet service. What are the advantages of this type of internet network architecture?

BRUCE CAMERON: Well, for anybody who’s lived on a rural satellite connection in the past, this is not your grandparents’ satellite internet. The significant difference between what we’ve traditionally done and what these new constellations are doing is that they’re closer.

So a traditional satellite internet connection goes all the way out to geostationary orbit, which is some 35,000 kilometers away. By contrast, this new generation is very close, similar in orbit to the International Space Station, in what we call low Earth orbit, which can be somewhere on the order of 500 kilometers up. And with that, because it’s closer, it’s faster.

MILES O’BRIEN: Closer, faster, but because it’s whizzing by at about 17,500 miles an hour, you need a lot of them to provide continuous service. Is this something that is going to change people’s lives in these rural areas or in emerging countries?

BRUCE CAMERON: I think that’s yet to come. This is really an interesting time in the satellite world because there’s so many of these going up. The market is predominantly rural and difficult to access areas, as you pointed out. In fact, SpaceX applied to be part of the Rural Opportunities Development Fund and receive subsidies from the US government for providing internet into rural areas.

But when we look at the populations that are of interest here, these are dominantly North America and European audiences that already have some level of connectivity to the internet. By contrast, roughly 50% of the world’s population, 4 billion people, don’t have reliable internet communications. 35% have essentially spotty or sometime access. And fully 15% of the world’s population has no access to the internet.

But that is not the target market against which these constellations are being invested in. These are primarily being invested in to provide rural internet access and then potentially internet access on aircraft and on cruise ships for the developed world.

MILES O’BRIEN: When we talk about, say, countries like India where there is much less internet capability and service, are there better ground-based alternatives, whether it’s fiber optic or 5G cellular, for example, that might be more cost effective for everybody involved and might not crowd up the night skies?

BRUCE CAMERON: Certainly. Any way you cut it, this is easier to do on the ground than it is in space, right? Space is an expensive way to solve this problem. And in a densely populated country like India, there are tremendous number of terrestrial opportunities. They may not be fiber right away, but whether they are point to point networks or whether they are traditional copper lines like we have here in the US, there are lots of other ways to grow the internet access capability of a developing country.

MILES O’BRIEN: So let me get this straight then. It’s tens of thousands of satellites serving kind of a narrow niche of a market. Is that the way you envision it? Or is this going to be broadly available to lots of people?

BRUCE CAMERON: Well, I think there’s some fascinating policy questions to come from this, right? This is not a government-owned program, right? So it is a for-profit series of corporations– Amazon putting up a network, OneWeb putting up a network, Telesat. And these companies are looking to figure out what the largest market is by revenue to deliver against this.

Rather than a question of how might we increase the level of internet access for the global population, it so happens that because, as you point out, these satellites are in low Earth orbit– they’re whizzing by, we need lots of them to provide coverage– we sort of get global coverage for free, if you want to think about it that way, when we invest in the developed world in this type of network.

MILES O’BRIEN: All right, Connie, you’ve been patient as we’ve been discussing all these little technological nuances. Help us shed a little light, if you will, on what the problem is from your perspective as an astronomer.

CONNIE WALKER: Well, first, I’d like to comment that the astronomers do understand that there’s a lot of benefits to broadband access that these satellite constellations provide. However, it has been shown that if the numbers and the brightness of the satellites cannot be minimized, they will create problems for our publicly funded large telescopes and cause the loss of science.

MILES O’BRIEN: Well, give us an example. I know for one example that comes to mind is an observatory which is under construction right now, the Vera C. Rubin Observatory in Chile. And I understand because of the nature of its mission, kind of widescale, long time exposures, these satellites whizzing by may have a real impact.

CONNIE WALKER: Yes, the Rubin Observatory will have an extremely wide field of view and have very sensitive detectors, a billion times more sensitive than our eyes can see. And they’ve got to create a movie, basically, of everything that’s changing in the universe over a 10-year period. So it’s going to be an amazing thing. For them, they have this incredibly huge camera, and that camera is left open, basically.

When the satellites traverse across the sky, there’s a trail that’s created. Not just a single spot– it doesn’t just take a picture at that moment– but there’ll be a trail that goes across the image. And that is what produces the problem. Given the number of satellites that are going to be launched the next few years, it’s going to come to a point very soon that every second or maybe every third image that’s taken with these cutting edge telescopes that are coming online will have at least one satellite trail running through them.

MILES O’BRIEN: Is there a way to make the satellites less reflective?

CONNIE WALKER: Well, the good news is that we’re actually working with industry to produce solutions. And some of those solutions have been implemented already by a company. And they have thought of two different ways of lowering the brightness of the satellites.

And they have actually tried those, and they’ve worked to a certain level. In terms of what astronomy needs, it’s not quite there yet, but they’re still working at it. They’re doing things like coating the surfaces of the satellite and also putting up visors to shield from sunlight, and so that we don’t actually see that anything’s reflected off of the satellite. We see something much less reduced.

MILES O’BRIEN: We should give credit due on that. That is Elon Musk’s Starlink that is doing that.

CONNIE WALKER: Yes, that is Elon Musk and SpaceX and the Starlink satellites.

MILES O’BRIEN: But they still are launching numerous satellites that are not coded in that manner, correct?

CONNIE WALKER: Well, they have not been coating their satellites as far as I know since visors have been used. And actually, they’re now thinking of a third way of doing things because they actually need to have inter-communications between satellites, and so they might not be able to use the visors. So they’re now trying to come up with new solutions, which you have to give them lots of credit for this. There’s ways of taking their satellite and having it on what they call a knife edge, so you don’t see the whole satellite.

You can also try– and they haven’t quite done this yet, but it’s been talked about– actually adjusting on orbit if you’re going over an observatory so that not as much will be reflected towards the observatory. So there’s a bunch of mitigation techniques. And there’s more that we’ve been trying to create and agree on.

MILES O’BRIEN: Yeah, you’re a scientist, and we’ve been talking about astronomy, but the stars and the heavens in the night sky have great spiritual meaning to many cultures. And to what extent are we dishonoring that long history and heritage?

CONNIE WALKER: Oh, to a great extent. I mean, light pollution in general affects everything, from humans to animals to our cultural heritage to the how important the night sky was a millennia ago, to even 110 years ago when lights were first used as streetlights. Culturally, Indigenous populations rely on the night sky. Animals for migration rely on the night sky. So it affects it greatly. And even if you’re just out there to enjoy the view of the night sky, it’s going to be very impacted if we cannot minimize the brightness of these satellites.

MILES O’BRIEN: So are you optimistic that you’ll not reach a point where the satellites are completely ruining the night sky for the likes of you?

CONNIE WALKER: Yes, I’m optimistic that we can mitigate it to a certain point. And it may not be perfect, but we’ll do the best we can to do things like use software to remove as much of the satellite trails or work with the companies to know, for instance, where they are going to be with their satellites in the night sky and when and try to avoid them, to create software to do that. So there’ll be a number of different mitigation techniques that we’ll be able to, I think, involve. It will be a compromise for astronomy. We will not get entirely what we want, but I think that’s the way of life in general.

MILES O’BRIEN: Well, thank you. We’ve run run out of time. Thanks to both of you, actually, for joining me today. Dr. Connie Walker is a scientist with NSF’s NOIRlab, and Dr. Bruce Cameron is the director of the System Architecture Group at MIT.

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Miles O’Brien is a science correspondent for PBS NewsHour, a producer and director for the PBS science documentary series NOVA, and a correspondent for the PBS documentary series FRONTLINE and the National Science Foundation Science Nation series.

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