Description

A brief description of the Story, relevance to its Epic (Mission Phases), and what its outcome shall look like

Solar panels mounted to the sides of FINCH were unable to provide sufficient power for the CubeSat. To alleviate this issue, the idea of deploying solar panels, which could increase the number we could have on the CubeSat, is being explored.

Research

1. Design and performance of a compact rigid-flex PCB-based deployable solar array for cube satellites (2026)

• 1U CubeSats- actually flight-tested in Binar-2,3,4 (solar arrays on positive and negative X-faces)
  • In orbit for 2 months
• Uses shape memory alloy (SMA) actuators made from nickel-titanium (NITINOL) to deploy the panels after orbital insertion (activated by sunlight)
• Single rigid-flex PCB that integrates solar panel support structure, hinges, and electrical routing
• “Rigid-flex”
  • Rigid- panels for mounting the PV cells
  • Flex- hinges between rigid panels
• Folded in an accordion pattern
• The design focuses on:
  • Better power-to-mass ratio
  • Better power-to-stowed volume ratio
  • high power generation density
  • reduced mechanical complexity
• Stowed (0.5 mm clearance)
  • Flex layer on top for ease of mounting actuators, so the separation between the first and second panels must be twice the panel thickness so that the hinges have the same curvature
• Implemented on 1U satellite
• Mathematical hinge models using Euler-Bernoulli elastica theory to predict deformation, curvature, and internal stresses (equations explained in detail)
• Optimizes the hinge geometry to satisfy strict CubeSat deployment constraints such as:
  • envelope dimensions
  • deployment angle
  • vibration tolerance
  • survivability over repeated cycles
• Compliant actuator for deployment using SMA
  • High strength
  • High output force
  • Large recoverable strain
  • Mechanical simplicity
  • Slow response time declared not an issue
• Uses SMA strips with a 45°C activation temperature so the arrays deploy only after exposure to sunlight in orbit
  • Has potential to fail from unfavourable tumbling and cannot be triggered at a desired time
    • Solution: backup heating circuit to deploy via joule heating
• Burn wire with thermal knife for deployment- 4 anchor points on PCB to allow for fully removable arrays
• Results: Average specific power of 66.9 W/kg, and average power-to-stowed volume ratio of 95.2 kW/m3
• Comparison: MMA Hawk- 121 W/kg, but usually below 80 W/kg