Transcript CubeSat Design for Solar Sail Testing Applications

CubeSat Design for Solar Sail
Testing Applications
Phillip Hempel
Daniel Parcher
Paul Mears
Taffy Tingley
The University of Texas at Austin
October 11, 2001
Presentation Outline
Project
Goal
Budget
Management
Structure
Future Work
Satellite
Systems
Conclusion
Project Goal
 Design a Test Platform for Solar
Sail Propulsion Technology
– Measure Thrust
– Measure Solar Sail Efficiency
Management Structure
 Daniel Parcher
– Project Manager
– Tracking Systems Department Head
– Electronics Department Head
 Phillip Hempel
– Mechanical Systems Department Head
 Taffy Tingley
– Propulsion Systems Department Head
 Paul Mears
– Orbital Trajectory Department Head
CubeSat Project Background
 Sponsored by Stanford University
 Utilizes picosatellite satellite
Designs that perform some
scientific task
 Different CubeSat launches provide
different initial conditions
Constraints
 CubeSat Prescribed Constraints
– 10cm Sided Cube
– 1 Kg Weight
– Timing System to Delay Power-On
– Space-Flown Materials
 Adopted Constraints (for Simplicity and Reliability)
– No Attitude Control
– No Powered Systems (except required Timer)
– No Communications Systems
Presentation Outline
Project
Overview
Budget
Management
Structure
Future Work
Satellite
Systems
Conclusion
CubeSat Required Systems
 Timer
– RDAS accelerometer/timer
– Voltage outputs to trigger
system events
 Casing
– Aluminum
– Kill Switch
– Attached CC reflectors
Tracking / Communcations
 No Satellite Communication
 Tracking performed with corner cube reflectors
– determine position, rotation, acceleration
 Corner cube reflectors to be supplied by
Banner Engineering Corp.
Mechanical Systems
Phillip Hempel
Satellite Components
 Frame/ Corner Cube Reflectors
 Kill Switch/ Timer
 Sail
 Inflation Capsule
 Capillaries
 Hardening Strips
Frame
 10 cm Sided
Cube
 Corner Cubes
Panels to be
Placed on Sides
Corner Cube Reflectors
 Flat-Plate Reflectors
 Attached to Frame
 Released Prior to
Inflation
 In the Plane of the
Solar Sail
Kill Switch/Timer
 Kill Switch Triggered by Release
 Begins Timer Sequence
 Controls All Timing Sequences
Solar Sail Properties
 Aluminized Mylar
 Circular Shape
 Area of 100 m^2
Example of Aluminized Mylar Structure
Capillaries

Tubes attached to the surface
of the solar sail
 Capillaries will be placed
placed strategically for
structural rigidity
 Tubes are inflated by nitrogen
from capsule
Total Length = 272 ft.
Diameter
= 0.5 in
Inflation Capsule
 7.6 cm Long
 3.8 cm Diameter
 86 cm^3 Volume
 60.5 psi
 Placed in the Center
of the CubeSat
Hardening Strips
 Thin tape-like strips
 Strips will be placed strategically in
a spider web pattern on the sail
 Strips harden with solar radiation
exposure
Total Strip Length = 308 ft.
Cut-Away CubeSat
Sequence of Events
 P-Pod Release/ Deactivate Kill





Switch
Waiting Period
Side Panels Unlock
Inflation Begins
Inflation Ends/ Rigidization Occurs
Solar sail reaches final shape
Propulsion
Taffy Tingley
Solar Sail Material Selection
Encounter Satellite
Solar Blade Solar Sail
Solar Sail Material Selection
Cosmos I
Star of Tolerance
Satellite
Aluminized Mylar
 High Strength to Weight Ratio
 Tested
 Cheap!
 Double Reflective
ABAQUS
Finite Element Design
 Monitor regions where high stress occurs
- Add tear strip or tension line to sail
 Monitor rigidity
 Model several perturbations and situations
 Perform thermal analysis
 Monitor effects of additional components
 All in 3-D
Future Propulsion Work
 Integrate deployment apparatus into FE model
 Install Tear Strips into FE model
 Perform Thermal Analysis
Orbit Simulation
Paul Mears
Solar Radiation Pressure
 Electromagnetic
radiation flux
 Photon energy
 Momentum
exchange
produces force
per unit area
ΔV
Sail Thrust
Function of: T = f (A, S, e, q)
where
A = sail area
S = Power (scaled Watt)
e = reflectivity
q = angle of incidence
T  (S  A cosθ) (1  ε 2  2ε cos 2θ)
Sail Thrust Vector
Sail
-Fr
Fi
Sun
θ
FT
Fr

Thrust Acts in the direction
Normal to the Sail
 Sail Normal makes an angle q
with the Sun Position Vector
 Thrust is generated by
Incidental and Reflected Light


T  T  SN
 
θ  a cos(SN  u)
  
T  Ti  Tr
ŜN
4-Body Problem
Z
Y
X

SPV  S

MPV  M

r1

r2
ECEF Coordinate System (x, y, z)
(1) Earth (2) Sun (3) Moon
(4) Satellite (T) Thrust

r3

ˆ
SN , T
Forces on the Satellite
The gravitational
forces of all the
planets effect the
satellite, as well as
thrust

 i 
Fi 
ri
3
ri

ri
i

F1 (Earth)
Z
Y
X

F3

F2 (Sun)

T (Thrust)
FBD: Satellite


 i 
FTotal  T    3 ri i = 1, 2, 3
ri
(Moon)
Initial Conditions of Orbit
 Injection will occur at perigee
 Orbit will be highly elliptic with apogee at
42000km
Rp = 7178.14 km
Ra = 48619.23 km
Resulting Orbital
Elements
Vp = 10.19 km/s2
Va = 3.04 km/s2
e = 0.743
a = 55797.37 km
Orbit Propagation: Perturbing Forces
Earth Forces Only
Earth, Sun, Moon Forces
Orbit Propagation with Thrust
Earth, Sun, Moon Forces
All Gravitational Forces
plus Thrust
Future Work in Orbit Simulation
Rotating Thrust Vector


SN
Zˆ
α  α0  α t

β  β0  β t
α( t )
Xˆ
(t )
Yˆ
Presentation Outline
Project
Overview
Management
Structure
Satellite
Systems
Budget
Future Work
Conclusion
Budget
• Personnel
• Testing
• Materials
• Launch
• Total
- $15,633
- $ 2,000
- $ 5,000
- $50,000
- $72,653
Future Work
 Hardware integration
– Part size and weight definition
and orientation within the
satellite
 Deployment system timing
 Finite element analysis
 Orbital simulation
– Rotating thrust vector definition
– Orbital trajectories simulation
Conclusion
 PaperSat is developing a picosatellite design for





CubeSat
Design will test solar sail propulsion technology
Design will not incorporate attitude control
Deployment system uses compressed gas
Solar sail will be reflective on both sides
Position, acceleration, and orientation will be
measured from ground stations
http://www.ae.utexas.edu/design/papersat/
Acknowledgements
 Dr. Wallace Fowler
 Dr. Cesar Ocampo
 Dr. Eric Becker
 Meredith Fitzpatrick
 Previous CubeSat Design Groups
Questions?