Astrophysicist Marla Geha has been doing some trash talking lately.
Nothing unseemly or untoward, to be sure. Just friendly reminders that orbiting garbage is starting to clog up Earth’s satellite lanes like a halo of space waste.
Geha says we might want to do something about it — like take out the trash. Growing pockets of space debris already have an effect on scientific space missions, she noted, and pose a safety threat to manned missions. In November, for example, a Russian anti-satellite test put astronauts at the International Space Station (ISS) at risk because of the debris it generated.
Geha, a professor of astronomy in Yale’s Faculty of Arts and Sciences, recently agreed to be a judge for the Clear Constellation competition, in which teams of college undergraduates will submit designs for innovative ways to remove space debris. Rubicon, a software company specializing in waste removal and recycling, is sponsoring the competition and offering a $100,000 first prize.
Geha spoke with Yale News about the contest, the extent of the space junk problem, and the need for solutions.
How much orbiting debris are we talking about here?
Marla Geha: NASA is tracking more than 27,000 individual objects, but there are more than half a million pieces of space junk orbiting the planet. Each one of those pieces is moving along at 17,000 miles per hour.
What sort of material is it? How long has it been accumulating?
Geha: It’s everything from parts of working satellites that were launched a few weeks ago to a wrench that somebody dropped 20 years ago, to bits of satellites that exploded and even derelict satellites. Almost everything is still there.
In terms of when it began, the first artificial satellite around Earth was Sputnik, launched in 1957. While Sputnik itself burned up in the atmosphere a few months later, a satellite launched just a few months later in 1958 remains in orbit. Since then, there has been an exponential number of things launched. In particular, when we’re talking about space debris, it’s material in low-Earth orbit or geosynchronous orbits where many of our satellites reside. There are these hotspots — or highways — that satellites like to be in, so if there is junk in that area, it’s a threat to all of the satellites there, whether they’re working or not.
Space may be large, but because satellites are in fairly specified areas, it’s becoming crowded. Certainly, the recent Russian anti-satellite test showed how crowded those regions can be.
What is your reaction to that incident? Were you surprised it happened?
Geha: There have only been a few of these events — intentional, anti-satellite tests — and it was clear that they were real mistakes. Most people thought we had learned it’s a very bad idea. Russia endangered its own astronauts on the ISS by doing that test.
But it wasn’t illegal. There are United Nations treaties saying you can’t do harm to astronauts — but exploding a satellite is not illegal.
What impact does space junk have on scientific research?
Geha: For my own work, space junk means that the Hubble Space Telescope and some of the other astronomical satellites are at increasingly higher risk of impact. Satellites, including derelict satellites, are also starting to show up in data from ground-based telescopes. We may be imaging a galaxy, for example, and suddenly you see lines going across the image from a satellite going by. You just have to throw the image out. That is happening more often. With big observatories that are going to scan the entire sky, if you have to throw out a large number of images, it drastically reduces the amount of science you’re able to do.
The biggest immediate impact to the public, actually, is just the sheer number of low-orbit satellites that are polluting the night sky with light pollution. There has been work done to put coatings on satellites to make them less reflective and tilting them in such a way that they are slightly less bright. It’s an interesting question: Who owns the night sky?
Does space junk have an effect for those of us who aren’t astronauts or astrophysicists?
Geha: As of today, your GPS is not going to go down because of this. But there are scenarios where the number of objects could easily cascade. Imagine an explosion of a single satellite. Instead of one piece of space junk, you have 1,000 pieces all over the place, which could then cause another satellite to explode, and then another. It could become a situation where it does become a threat to all of the satellites that we rely on. Without some careful thought, this could eventually be a threat to our modern, technology-driven way of life.
How did you get involved in the Clear Constellation competition?
Geha: I teach a course called ASTR160 “Frontiers and Controversy in Astrophysics.” In the class, we were discussing rocket science and satellites, and learning about the UN treaties that exist to somewhat regulate the launch of satellites. That’s when I got an email asking me to judge this competition. I thought this would excite my students and raise awareness.
The idea of the contest is to find novel ways to de-orbit debris and basically do garbage collecting.
These are all going to be undergraduate teams, associated with a college or university. They have to submit a letter of intent to submit a proposal by December 31 and then there will be information sessions, and the final proposals are due March 31.
But beyond space garbage collecting, I do think the true path forward is regulation. Let’s do some small tweaks now — like putting a small rocket on every satellite to de-orbit it responsibly — so there isn’t a massive problem in five or 10 years.