Open Source Cubesat Platform

for Heliogyro Deployment Testing

Authors: Artur Scholz (1,2), Jer-Nan Juang (1,3) Affiliation: (1) National Cheng Kung University, (2) LibreCube Initiative (3) National Institute of Aerospace Venue: The Fourth International Symposium on Solar Sailing 2017 Location: Kyoto, Japan Date: Tuesday, 17th January 2017, 12:15-12:30

Credits: U.S. Centennial of Flight Commission

Credits: NASA Langley

Solar Sail Concepts

Credits: Wikipedia

NASA HELIOS project

Project lead at NASA Langley Research Center

HELIOS is precursor for future heliogyro missions

Based on a previous MIT study, but uses miniaturized (CubeSat) technologies

Accomplishments: Coupled FEM modal analysis Blade controller design and analysis Modal tests in vacuum chamber Sail fabrication (preliminary)

Sail Deployment

Most recent research on heliogyro focuses on sail control. Need more attention on deployment, it is most vital for mission success. Examples of heliogyro sail deployments:

1967 MacNeal

2013 Janhunen

1990 Blomquist

Deployment Process

Deployment process of Heliogyro is particularly demanding: Sail packaging and fixation

Satellite detumbling

Satellite spin-up

Sail deployment

Sail control

Credits: NASA

Research Topics

Deployment experiment design must focus on: Sail blades

Deployment mechanism

Deployment monitoring

Avionic system

Credits: NASA

Our Proposal

Open Source / Open Research

CubeSat Platform

Open Hardware

LibreCube is a non-profit organization to enable and support:

Community for exchange and collaboration of open

source CubeSat projects

Standardization to ensure compatibility and facilitate collaboration

Reference architecture for a generic CubeSat missions

Open and free tools for mission design and operation

Open Software

Modeling and simulation of all aspects of HelioGyro deployment and control shall make use of freely available and open source software. Makes it possible for anyone to reproduce the results and to contribute The simulation ecosystem is based on the Python programming language and its many scientific libraries:

• Matplotlib – plotting • Numpy – numerical processing • SciPy – scientific computing • SimPy – algebraic computation, incl. Lagrangian/Kane’s method • etc.

Preliminary Research Results

Description of the forces maintaining a gravity gradient stability

https://en.wikipedia.org/wiki/Space_tether

θ

r

Simulation I: Zero Tension

• Zero tension

• Equations of motion

Pelaez, J. (1995). On the Dynamics of the Deployment of a Tether From an Orbiter-Part II. Exponential Deployment. Acta Astronautica, Vol. 36, No.6, Elsevier Science, Ltd

Non-dimensional Angle and Angular Velocity

Non-dimensional time τ

Angular Velocity

Time (sec)

RPM

Angle

Time (sec)

deg

Non-dimensional Deployed Length

Non-dimensional time τ

Deployed Length

Time (sec.)

Initial/ejection velocity: 1 m/sec Initial length: 1 m m

Non-dimensional Tension

Non-dimensional time τ

Conclusion

• Heliogyro has low technological readiness level (TRL)

• Propose research in Open sharing Properly acknowledge contributions

• Rely on open source hardware and software

• Initial research results provide confidence on sail

deployment from spinning CubeSat

Thanks for Your Attention!

Q & A

Position Vector

• The center of mass of the cubesat will be taken as the origin O; the x axis lies in the local vertical and points to the zenith; the y axis lies in the tangent to the trajectory, and the z axis is normal to the orbital plane.

• From the circular motion of the cubesat follows the constant angular velocity of the cubesat frame relative to a geocentric inertial frame:

• Position vector of the end mass in terms of the body polar

coordinates (r, θ) is

Lagrange’s Equations of Motion

• Potential energy with the end mass m

• Kinetic energy with hub + end mass m

• Lagrangian • Lagrange’s equations

Equations of Motion

• Keep up to the second-order terms • Equation of motion for the string

• Equation of motion for the angle

Non-Dimensional Equations of Motion

Non-dimensional parameters Equation of motion for the string Equation of motion for the angle

Deployment Design Process

• Define an equation to describe the deployed length in time:

satisfying the initial condition

• Solve the following equations of motion

• Compute the non-dimensional tension force

• Search for a deployment equation that provides a stable deployment trajectory and minimizes the vibrational motion of string.