I saw Space News' An object is now orbiting alongside China’s Shijian-21 debris mitigation satellite recently about a "new object" orbiting near a relatively newly launched satellite. The article says it's currently classified as an apogee kick motor, and states the following:

Apogee kick motors usually perform a final maneuver after satellite separation so as to not pose a threat to active satellites through risk of collision.

This makes sense to me, as keeping the motor attached would mean a shorter lifetime due to the additional mass, and having stray debris wandering around an orbit seems undesirable.

This led to two questions:

  • How is this maneuver done?
  • How common is this maneuver historically and among currently-operating rockets?

For the first question, I've found a few interesting bits of information, but nothing complete. Maneuvering the kick motor like a "normal" satellite/rocket after its burn seems like an obvious answer, and Rocket Lab's kick stage appears to use this approach, but I haven't been able to find out how common this approach is or whether it's a relatively recent development. In addition, it doesn't seem feasible for something like the Star 48, since it seems much simpler technology-wise and I'm not sure how maneuvering/reignition would work for a solid motor. Are there other separation/disposal options for this or other cases?

As for the second question, I haven't been able to find anything, though I'm not sure I'm looking in the right places.

  • $\begingroup$ Huh, I've never heard of such a thing. Always assumed the separation mechanism wouldn't be worth the mass. Following this question. $\endgroup$ Nov 9 '21 at 0:27

One example (I do not know if it is typical) was the Inertial Upper Stage (IUS) used to boost space shuttle launched payloads into their final orbits.

The multi-solid-stage IUS also had a liquid fueled reaction control system (RCS). This RCS was used to fly the IUS away from the payload after separation. Here is an example from STS-93 which launched the Chandra (aka AXAF) observatory on an IUS.

...the final IUS coast phase and included the IUS/Chandra separation event and a special final RCS burn. The special RCS burn was included to provide the combined functions of a collision/contamination avoidance maneuver (CCAM) and RCS burn-to-depletion (BTD). The CCAM/BTD was designed to preclude physical contact and to minimize contamination of Chandra by IUS SRM outgassing or RCS thrusting.

Source: Flight Results of the Chandra X-ray Observatory Inertial Upper Stage Space Mission


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