Mar 23 2021

Removing Space Debris

Right now there are about 3,000 active satellites in Earth orbit. About 1,000 of those satellites are part of the Starlink project to provide internet access everywhere on the planet, with a planned 42,000 total when complete. that is a massive increase in the number of active satellites. At the same time there another 3,000 defunct satellites that are no longer operational but remain in orbit. There is about 9,000 tonnes of total orbital debris, and we are tracking 30,000 objects of 10 cm or larger. But estimates are that there are millions of smaller objects in orbit.

In other words – usable Earth orbit is becoming crowded and hazardous. This is a risk to operational satellites, space stations, and any spacecraft hoping to get off Earth. Much of this debris is moving very fast relative to other objects with intersecting orbits. A lost bolt could destroy a satellite or punch a hole in the International Space Station (ISS). There is a concern that a serious collision, say between two satellites, would generate enough debris to cause a cascading event of further collisions.

There are now international agreements that make states responsible for anything they put into orbit for its lifetime. Companies and nations are supposed to arrange for the deorbiting of anything they put into orbit within 25 years of the end of its functional lifetime. However, the agreements have little teeth and compliance is low. This is just another example of allowing entities to externalize the costs of their own waste or downstream effects. It is also another example of how the assumption that natural resources are so gigantic we don’t have to worry about sustaining them. Space is really big, so who cares if we leave a lot of junk up there? Well, it took only a few decades for us to clutter low Earth orbit with enough debris to be a serious hazard.

There are lots of plans to cleaning up the debris, to at least get it to a stable level. Going forward, as I stated above, anyone putting a satellite into orbit is responsible for bringing it down. We just need to strictly enforce these agreements with consequences that are greater than the expense of compliance. Also, a lot of the debris is from discarded rocket stages. When a rocket puts a satellite into orbit, the final stage of the rocket itself necessarily is also in orbit. Unless the rocket is designed to then deorbit itself, it will stay there as space junk. Sometimes there is even fuel left over, which can explode, causing the single biggest problem of space debris.

Even if we put no further debris into orbit, which we are not close to achieving, we have the problem of existing space debris. There is no easy way to bring it down. It is often fast moving, in unusual orbits, tumbling, and spread out over great distances. It would take a lot of energy to track down and grab each piece of debris.

There are lots of proposed designs for such clean up. They generally involve either collecting the debris or slowing it down so that it deorbits and burns up in the atmosphere. There is even one plan to use ground-based lasers to shoot debris in order to slow them into deorbiting.

A Japanese company recently launched an experimental satellite to test what it is hoping will become a “deorbiting for hire” service. They will send up a small satellite that will attach to a decomissioned satellite and then fire rockets to slow them both down to burn up in the atmosphere. They characterize this as “garbage pickup” service – this is a great idea, especially if the international space community really starts enforcing space debris rules. Companies with defunct satellites could suddenly find themselves on the hook and looking for a way to take care of their space garbage to avoid huge fines.

This is where regulations can work with the free market. Simply attach an appropriate cost to what would otherwise be an unfairly externalized cost, and let the market find solutions. This is the idea behind charging for carbon release. The same principle has been proposed for plastic waste, which is also already a huge problem and getting worse.

We need a net-zero space debris policy – everything you send up into orbit you are responsible for bringing back down (or paying someone else to). Otherwise usable Earth orbit will not be sustainable over the long term.

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