TOP.02 // ADCS
Attitude Determination & Control (PMAC, B-Dot & 3-Axis)
Passive permanent-magnet alignment, Aharoni demagnetization limits on HyMu-80 hysteresis rods, B-dot magnetorquer detumbling, and CubeSat 3-axis reaction wheels.
1. SatWiki Encyclopedia Specifications (4)
- SQ-SS-007
Passive magnetic attitude control (PMAC)
A permanent magnet that aligns one axis with the geomagnetic field and soft-magnetic dampers that drain the spin. It needs no power, software or sensors, which is why most 1P PocketQubes use it, but its physics scales badly into a 50 mm cube.
- SQ-SS-003
Attitude determination and control (ADCS)
Measures the orientation of the spacecraft and turns it where the mission needs it. From magnetometers and magnetorquers to star trackers and reaction wheels, small-satellite ADCS covers pointing from tens of degrees to arcseconds.
- SQ-EN-002
Space environment
What low Earth orbit does to a small satellite: a thermosphere whose density follows the Sun, atomic oxygen, trapped and solar radiation, a dipole-like magnetic field, strong thermal forcing and debris. PocketQubes feel each effect more strongly per kilogram.
- SQ-EN-007
Magnetic cleanliness
Controlling parasitic current loops, ferromagnetic fasteners and nickel-plated battery cases that otherwise dominate disturbance torques on 50 mm picosatellites.
2. Interactive Lab Calculators & Workbenches (2)
3. Technical Notes (4)
- NL-TN-2026-011
Disturbance torques at PocketQube scale
We evaluate the four environmental disturbance torques—gravity gradient, aerodynamic drag, solar radiation pressure and residual magnetic dipole—for a 50 mm 1P PocketQube across 350 to 700 km altitude and show why residual current loops and battery ferromagnetic cases dominate picosatellite attitude dynamics.
- NL-TN-2026-010
Passive magnetic attitude control for a 1P: sizing the magnet and damper rods
We formulate the coupled magnetostatic design rules for passive magnetic attitude control (PMAC) inside a 50 mm PocketQube: sizing the permanent dipole against aerodynamic torque, keeping the magnet's stray field below the apparent saturation field of the hysteresis dampers, selecting rod aspect ratio to overcome shape demagnetization, and bounding the final dead-band angle.
- NL-TN-2026-018
3-axis reaction wheels, star trackers and momentum dumping in CubeSat ADCS
While 1P PocketQubes and 1U educational CubeSats rely on passive magnetic stabilization or B-dot detumbling, imaging and optical-downlink CubeSats require 3-axis reaction wheels paired with miniature CMOS star trackers. We formulate the Euler rigid-body wheel exchange equations, size wheel momentum capacity against secular disturbance torques, and derive continuous magnetorquer momentum desaturation.
- NL-TN-2026-003
Magnetic detumbling with B-dot: a 1U and a 1P compared
The first job of a small satellite after separation is to remove the angular rate the deployer gave it. We derive the B-dot law, which needs only a magnetometer and magnetorquers, show why it can never increase rotational energy, and simulate rigid-body detumbling in a 500 km Sun-synchronous orbit with a tilted-dipole field. From about 9.6°/s, a 1U with 0.05 A·m² coils falls below 1°/s within minutes, while a 1P with 0.005 A·m² board coils takes about one orbit; both converge to a residual rate of the order of twice the orbital rate. We close with a flight-code sketch and design rules for PocketQubes.
4. Research Monographs (2)
5. Engineering Course Modules (2)
- MODULE 05
Disturbance Torques, PMAC & B-Dot Detumbling
Why residual magnetic dipoles dominate 1P disturbance torques, sizing hysteresis rods for PMAC, and active B-dot magnetorquer laws.
- MODULE 12
3U/6U CubeSat 3-Axis Reaction Wheels, Star Trackers & S/X-Band Downlinks
Scaling from 1P magnetic detumbling to arcsecond star trackers, reaction wheel momentum desaturation, deployable 20–60 W solar wings, and 50–150 Mbps X-band Earth observation downlinks.