Careful, starwhales. There is a new weapon for interstellar inhabitants that you threaten with your gigaflipper that shatter the planet, tested as we speak. This small-scale version can only be useful for removing dangerous orbital debris, but over time it will puncture your hypercarbon skins and irreducible sun hearts.
However, it would be irresponsible for me to speculate beyond what is possible today with technology, so allow a summary of the current capabilities of the harpoon.
Spatial harpooning is part of the RemoveDEBRIS project, a European multi-organization effort to create and test methods to reduce space debris. There are thousands of little pieces of who knows what to clog our orbital neighborhood, ranging from microscopic to potentially catastrophic.
There are so many ways to break down these rogue objects as there are dimensions and shapes of spatial junk; perhaps it is enough to use a laser to edge a small piece towards orbital decay, but larger objects require more practical solutions. And apparently all of nautical origin: RemoveDEBRIS has a net, a sail and a harpoon.
The harpoon is meant for larger targets, for example life-size satellites that have malfunctioned and are moving away from their orbit. A simple mass driver could push them towards the Earth, but capturing them and controlling the descent is a more controlled technique.
While an ordinary harpoon would simply be thrown by people like Queequeg or Dagoo, in space it is a little different. Unfortunately it is not practical to wear a harpoon for EVA missions. So the whole thing has to be automated. Fortunately, the organization is also testing artificial vision systems that can identify and track objectives. From there it is only a matter of shooting with the harpoon and pulling it in, which is what the satellite showed today.
This small object designed by Airbus is very similar to a rotating harpoon, which has a piece that turns out once pierces the target. Obviously it is a disposable device, but it is not particularly large and many could be distributed on different intercepting orbits at the same time. Once inside, a drag sail (seen in the video above) could be deployed to speed up the return. The whole thing could be done with little or no propellant, which greatly simplifies the operation.
Of course it is not yet a threat to the starwhales. But we will get there. We will get those good monsters one day.