Solar Array Tracking Mechanism
Dual-Axis Solar Array Drive Assembly (SADA)
A dual-axis solar array drive assembly is a gimbaled tracking mechanism that continuously orients solar arrays toward the Sun across the 336-hour lunar day to maximize energy capture. Driven by stepper motors and harmonic gear reducers, the mechanism tracks at approximately 0.5 degrees per hour with closed-loop pointing accuracy under 0.5 degrees. Operating on the Moon requires drive joints to survive 100 years of thermal cycling across temperature extremes from -173°C to +127°C, relying on solid film lubricants like molybdenum disulfide. Drive bearings also require sealed or labyrinth protection against mechanical wear caused by abrasive lunar dust accumulation.
Dual-axis tracking system that orients solar arrays toward the Sun for maximum energy capture
Purpose
Maximize solar energy collection by continuously tracking the Sun across the 336-hour lunar day
Context
Child of L2-PWR-SOL within the Lunar Ark power generation system
Principles
- ▸Dual-axis gimbal provides azimuth and elevation tracking for full hemisphere coverage
- ▸Stepper motors with harmonic drive gear reducers provide high-precision pointing
- ▸Slip ring or flex harness transfers power across rotating joint without cable wrap
- ▸Sun sensor feedback provides closed-loop pointing accuracy <0.5 degrees
Typical implementations
- ▸ISS Solar Alpha Rotary Joint (SARJ) single-axis 10m wingspan tracking
- ▸Dawn spacecraft solar array drive assembly (dual-axis)
- ▸Moog Type 3 Solar Array Drive Assembly for GEO satellites
- ▸Honeybee Robotics solar tracking mechanisms for planetary landers
Lunar considerations
- ▸Lunar dust accumulation on drive bearings requires sealed or labyrinth protection
- ▸336-hour day means very slow tracking rate (~0.5 deg/hr) reducing mechanism wear
- ▸Temperature extremes (-173C to +127C) require wide-range lubricants or solid film lubricants
- ▸Must survive 100 years of thermal cycling at drive mechanism joints
Specifications
Functional
| primary function | Dual-axis tracking system that orients solar arrays toward the Sun for maximum energy capture |
Physical
| materials | Titanium gears, MoS2 solid lubricant, Maraging steel shafts, Kapton flex cables |
Interfaces
Provides
- Oriented mounting platform for solar array panels
Requires
- Sun position ephemeris and pointing commands
- Power for drive motors (~20W)
Cite this entry
Lunar Ark Codex. "Solar Array Tracking Mechanism" (L3-PWR-SOL-TRACK). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-PWR-SOL-TRACK
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.