Are we putting up too many satellites?

Chris Smith put the question to North Carolina State astrophysicist Katie Mack, and chemist Kate Biberdorf has a question about space junk too...

Katie - This is a very kind of heated discussion happening among astronomers and space technology people and those who are actually putting these satellites up there. From the astronomer side, one of the things that we worry about with all of these satellites like the Starlink satellites where there's, I think, more than 1000 of them up there now, and there's going to be possibly as many as 10,000 or more, the problem is that those get in the way of our observations. And when we are trying to study deep sky objects and we have to stare at something for a very long time with a telescope when lots and lots of satellites are crossing through the image, you get these stripes that are really hard to deal with for certain kinds of observations. And so the fact that they're somewhat problematic for certain kinds of observations, both visual observations and also potentially radio, because they're also beaming back information to earth and that can give us radio interference when we're doing radio observations with space that can be an issue for astronomers. And then there's also a growing concern that it's just changing the way the night sky looks, and so it's a kind of, for people who have a beautiful dark sky and can watch the stars, it's going to look different when there are lots of little tiny points of light that are moving across the sky all the time. And that's a question of, you know, what's our responsibility to the world to maintain the pristine nature of the night sky, this global resource. So I think it's a complicated question, and there are just lots of aspects of it, and there are really big discussions happening all the time about can these things be controlled? How should we control them? Who should have authority over what gets put into orbit? And it's something that's going to get more and more important over time as more of these things are going up.

Chris - Kate?

Kate - Didn't the ISS just get damaged from space junk? I mean, aren't we worried about that too?

Katie - I mean, we do worry about space junk. Space junk can be anything - it could be a screw that fell out when somebody was doing a repair on something, and there's a lot that's being tracked all the time. And these little satellites, as there are more and more of those, we need more and more systems to mitigate the possibility of collisions. And collisions are still pretty rare, like there's still not so much up there that you have to worry about this stuff too much, but we do need to have kind of a more robust system for if there is going to be a near encounter. Because at the moment each satellite owner could say, "I don't really want to move my satellite. Why don't you move your satellite?" And there have been situations where there's been a conflict over who has to fire their attitude adjustments to move the thing. Or sometimes they can't, sometimes these things don't have the ability to adjust themselves. And then you have to worry about the possibility of an actual collision which can cause really major damage even if it's just between two robotic satellites that don't even come near people, those can damage other satellites and damage the space station and so on. And so that's also something that people are worried about.