Texas A&M is conducting research into the idea of a using a slingshot technique to throw space junk into a decay orbit.
The slingshot satellite, or Sling-Sat as they’ve named it, would intercept a piece of space debris, “catch” it, and then “throw” it back towards the Earth and into a decay orbit.
The Sling-Sat would absorb the momentum of the piece of debris while catching it and would thus be provided with a very beneficial and energy-saving boost, which would propel the Sling-Sat towards its next target.
The Sling-Sat would be provided with a secondary boost while “throwing” the piece of debris towards the earth– a Newtonian opposite-reaction.
This proposed debris-capturing device would also feature retractable arms, which would allow it to adjust its rotational speed.
I see several good ideas emerging here:
- Making use of the object’s momentum to save propellant/energy.
- Converting the object’s momentum into smaller-arc angular momentum. Hopefully the transfer from (relatively) linear to angular momentum would also help reduce the amount of kinetic energy exerted on the capturing device.
- Using the reactionary momentum from the “throw” to propel the capturing device towards its next target.
I also see several points of concern:
- If the piece of debris is at too high velocity relative to the capturing device, then the outcome of the impact, or “catching”, is likely to be disastrous and counter-productive (creating more space junk).
- Throwing the debris into a decay orbit to burn up on re-entry is a rather wasteful goal. It would be better if the resources within the debris could be captured and utilized (the metals, propellant, technology, etc.).
- After “catching” a piece of orbital debris, the capturing device may still require a substantial amount of energy to stabilize and orient itself properly to “throw” the object into a decay orbit.
Overall, it is an intriguing an idea that is worth some thought. I believe some of the concepts it brings to light may be useful in design of the final Space Junkmobile.