3 ms·

I am by no means a rocket scientist, but wouldn't a de-orbiting requirement be as simple as including a few small chemical thrusters with a dedicated fuel sourc

I am by no means a rocket scientist, but wouldn't a de-orbiting requirement be as simple as including a few small chemical thrusters with a dedicated fuel source reserved for de-orbiting? I have no idea how much force it takes to actually move a given amount of mass out of orbit, and I assume it is different depending on the height of that orbit. So maybe doing this would simply add too much weight in the form of fuel storage to be feasible. In my head though, orbits are fragile and it shouldn't take a lot to nudge something into a death spiral towards the atmosphere.

SonicScrub 5y ago
This works great for a small-subset of the space-debris problem: satellites in low-earth orbit that have reached their end-of-life. For example, Starlink satellites maintain a small reserve propellant for their maneuvering thrusters to be executed at EOL. This activity will likely be mandated by regulatory bodies in the coming years (and definitely should be). However performing this task becomes much more difficult to do as orbits get higher. The higher the orbit, the more fuel is required to perform a de-orbit, and the more fuel is required to lift THAT fuel into the orbit in the first place. Propellant requirements scale exponentially with increased mass. Beyond a certain orbital altitude, it becomes prohibitively expensive. In addition, the bulk of the space-junk problem is not defunct satellites, but fragments from previous collisions, and stage-separations (screws, scraps, paint-chips, etc). Satellites (even defunct ones) are easily trackable, and have known trajectories. Random 10 cm pieces of metal are not. While mandating EOL maneuvers for low-earth satellites is definitely a solution to part of the problem, it is not the full solution.
LeifCarrotson 5y ago
Orbits are circles or ellipsoids, not spirals. It takes a ton (possibly literally) of propellant to change your orbit from a circle in GEO to an ellipse that intercepts the atmosphere. If you don't have enough, you've not put it in a deorbiting spiral, simply an oval that will stay up for about as long as the original satellite's circular orbit. Rocket scientists work in terms of 'delta V', meaning an amount of energy gives you a particular change in velocity. GEO to LEO takes on the order of 6 km/s (oversimplifying because orbital mechanics are complicated), meaning you need a rocket engine that's capable of accelerating your satellite from 0 to 13,400 miles per hour. That's really expensive and difficult.

SonicScrub 5y ago

This works great for a small-subset of the space-debris problem: satellites in low-earth orbit that have reached their end-of-life. For example, Starlink satellites maintain a small reserve propellant for their maneuvering thrusters to be executed at EOL. This activity will likely be mandated by regulatory bodies in the coming years (and definitely should be). However performing this task becomes much more difficult to do as orbits get higher. The higher the orbit, the more fuel is required to perform a de-orbit, and the more fuel is required to lift THAT fuel into the orbit in the first place. Propellant requirements scale exponentially with increased mass. Beyond a certain orbital altitude, it becomes prohibitively expensive. In addition, the bulk of the space-junk problem is not defunct satellites, but fragments from previous collisions, and stage-separations (screws, scraps, paint-chips, etc). Satellites (even defunct ones) are easily trackable, and have known trajectories. Random 10 cm pieces of metal are not. While mandating EOL maneuvers for low-earth satellites is definitely a solution to part of the problem, it is not the full solution.

LeifCarrotson 5y ago

Orbits are circles or ellipsoids, not spirals. It takes a ton (possibly literally) of propellant to change your orbit from a circle in GEO to an ellipse that intercepts the atmosphere. If you don't have enough, you've not put it in a deorbiting spiral, simply an oval that will stay up for about as long as the original satellite's circular orbit. Rocket scientists work in terms of 'delta V', meaning an amount of energy gives you a particular change in velocity. GEO to LEO takes on the order of 6 km/s (oversimplifying because orbital mechanics are complicated), meaning you need a rocket engine that's capable of accelerating your satellite from 0 to 13,400 miles per hour. That's really expensive and difficult.