1. The navigator who kept the ark alive
Neal Stephenson’s Seveneves returns one last time for this arc because the cloud ark’s survival depends on maintaining orbit and avoiding debris without the luxury of waiting for instructions from a distracted Earth. The desktop must do the same: know its orbit, predict decay, and move when a threat appears.
Entries 665 through 667 wondered about autonomous orbit maintenance and collision avoidance, maneuver planning and propellant conservation, and what the capability needs from the desktop. This entry closes the arc.
2. What was learned
The autonomous orbit maintenance and collision avoidance wondering gives the desktop four constraints:
- Autonomy compresses response time. Ground-planned maneuvers are necessary but not sufficient for conjunctions and drag events.
- Maneuver planning must balance multiple goals. Stationkeeping, collision avoidance, and deorbit compete for the same propellant.
- Propellant is the binding constraint. Every maneuver reduces the margin for future needs.
- Policy must bound the autonomy. Thresholds, windows, reserves, notification rules, override, and disposal priority prevent the platform from maneuvering itself into trouble.
3. What was decided
The desktop will adopt autonomous orbit maintenance and collision avoidance as a closed-loop capability with ground notification and override. This means:
- The platform will monitor its orbit, atmospheric drag, and conjunction data.
- It will plan and execute routine stationkeeping burns within pre-approved windows.
- It will execute pre-approved collision avoidance maneuver templates when conjunction risk crosses defined thresholds.
- It will optimize burns to conserve propellant while protecting deorbit reserves.
- Ground can override any autonomous maneuver plan and can update thresholds and templates.
- All maneuvers are logged and reported to ground as soon as possible.
4. Interaction with earlier arcs
The autonomous orbit maintenance arc connects directly to:
- the propulsion reading arc: thruster capabilities define what maneuvers are possible;
- the GNC arc: maneuvers require attitude control and navigation;
- the power arc: electric propulsion consumes significant power;
- the autonomous pointing arc: thrusters must be pointed correctly;
- the regulatory arc: maneuvers may require notification and licensing.
5. What remains open
The exact conjunction thresholds, propellant reserves, and maneuver templates depend on the orbit, payload requirements, and propulsion system choice. The wondering arc has set the strategy; detailed design comes later.
6. What this changes
- The autonomous orbit maintenance and collision avoidance wondering arc is closed.
- The desktop inherits a closed-loop orbit management capability with ground notification and override.
- The next arc will design a test for propulsion system fault recovery and maneuver verification.