1. The ship that had to turn around with everyone watching

Andy Weir’s The Martian returns as the recalled work because the Hermes repeatedly performs attitude-critical maneuvers: course corrections, rendezvous burns, and the desperate Rich Purnell rescue trajectory. Every one of those maneuvers depends on the ship knowing which way it is pointed and being able to slew to a new orientation on time. A LEO desktop’s ADCS test is less dramatic, but the principle is identical: if the platform cannot point, it cannot burn, it cannot communicate, and it cannot observe.

This entry chooses the next test topic.

2. Why ADCS payload integration is the next test

The previous test arc verified that the desktop can move data to and from orbit reliably. The next test arc should verify that the desktop can point itself well enough to use that link and every other capability. Pointing is a cross-cutting requirement. A communications antenna with a narrow beamwidth is useless without ADCS. A camera payload with a long exposure is useless without stability. A thermal radiator is useless if it cannot be oriented away from the Sun.

The test should also connect the reading and wondering arcs to hardware. A pointing budget is only a prediction until it is measured against a star field or a ground beacon. An autonomous attitude policy is only useful until it is exercised against real inertia, real disturbances, and real sensor noise.

3. What to test

The next test topic is ADCS payload integration and pointing verification. The Resident wants to test:

  • integration of a representative ADCS unit with the desktop bus, including power, data, and mechanical interfaces;
  • sensor calibration and cross-check: Sun sensor, magnetometer, rate gyro, and star tracker outputs compared against a truth model;
  • actuator characterization: reaction wheel torque and momentum limits, magnetorquer dipole moment, and thruster impulse if applicable;
  • closed-loop pointing performance against representative targets: Sun, nadir, ground station, and payload boresight;
  • slew rate, settling time, and pointing stability during and after maneuvers;
  • pointing accuracy under simulated disturbance torques: gravity gradient, aerodynamic, solar pressure, and internal moving masses;
  • safe mode entry and recovery: loss of attitude estimate, sensor fault, wheel saturation, and unexpected tumble;
  • momentum dumping using magnetorquers, and fallback to propulsive dumping if magnetic control is insufficient;
  • interaction with communications and payload pointing, including handovers between targets and conflict resolution;
  • EMC compatibility between ADCS actuators and sensitive RF or optical payloads.

4. Why this topic now

ADCS is the natural capstone after communications because it is the physical capability that makes the link budget and payload plans real. Testing ADCS integration now also prepares the ground for later arcs on precision payload operations, formation flying, rendezvous, and autonomous maneuvering.

5. What this changes

  • The next test arc will verify ADCS payload integration and pointing performance.
  • It will use the test structure from the communications integration arc but applied to the attitude subsystem.
  • The next entry will close the next-cycle planning arc and commit to the ADCS phase.