PDR-Preliminary design review. 2 May 2012. Luis Carrillo Vanessa Elleson Ian Neel Sam Mutschler Andrew Tucker David Wallace. Table of Contents. Concept of Operations Work Breakdown Structures (WBS) Communications Structures Power Systems
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PDR-Preliminary design review 2 May 2012 Luis Carrillo Vanessa Elleson Ian Neel Sam Mutschler Andrew Tucker David Wallace
Table of Contents Concept of Operations Work Breakdown Structures (WBS) Communications Structures Power Systems Guidance Navigation and Control Command and Data Handling Visual Data Configuration Management Project Schedule Cost Budget
Concept of Operations • Launch • Initialization • Simultaneous release of Texas A&M satellite and Target • Stop “moving” within two minutes of release from ESPA Ring (3.5.1) • Rotational Rates: ±0.5 [deg/sec] • Translational Rates: ±2 [cm/sec] • GPS Functionality • Calculate Relative Navigation Solution and Absolute Position • Maneuver 1-RCS Test (3.5.2) • Maneuver 2-Approach Target (3.5.3) • Maneuver 3-Move around Target (3.5.4) • Maneuver 4-Dock with Target (3.5.5)
Low data rate (ldr) system • Astrodev Helium 100 • VHF/UHF Amateur Frequencies • Up to 38.4 kbps data rate • 3 W RF output • AX.25 Packet Acknowledgement • Flexible monopole antennas released by burning through monofilament wire • Two Units, VHF Up, UHF Down/Crosslink • Either can function as uplink in emergencies • 18.7 dB UHF / 14.4 dB VHF Link Margin with Ground Station at 250 mi (400 km) altitude, 10o elevation 10
high Data rate (hdr) system • ClydeSpace CPUT-STX-805-001 • 2.4 GHz Amateur Frequencies • 1 W RF output • Up to 2 Mbps data rate (1/8 will be used) • High Gain Patch Antenna (8 dBi) • 4.0 dB Link Margin with Ground Station at 250 mi (400 km) altitude, 10o elevation
Download budget assumptions • 12 min 43 sec available ground pass time per day, calculated with orbit tracking software • 20 % Packet Loss Rate (PLR) • 50% Ground Passes Missed
Communications on the move • New application of satellite telephone technology currently under development by AggieSat Lab • Utilizes Iridium Satellite Communications Network • Communicate without line of sight • Iridium model 9523 Internet Modem • > 21% orbit coverage at 250 mi (400 km) altitude • Approximately 6600 Mb data over estimated mission lifetime (4.2-6.4 months, 41.5 Mb/day)
Download times • Thumbnails generated to downlink all images captured • Thumbnails used to select Full Resolution Images for Downlink
Launch Vehicle • Falcon 9 Launch vehicle • Circular orbit from 200 – 2000 km • Inclinations from 28.5 – 51.6o • LEO Mission accuracy • Perigee/Apogee ± 10 km • Inclination ± 0.1o • Right Ascension of Ascending Node ± 0.15o
Launch Environment • Maximum axial acceleration 6 g • Maximum lateral acceleration 2 g • Fundamental bending mode greater than 10 Hz • Fundamental axial mode greater than 25 Hz • Temperature exposure up to 200 oF
Separation system • Lightband Separation system by Planetary Systems Corporation • 15” diameter Lightband • 6 springs
Material selection • Aluminum 6061-T6 for all structural components • High strength to weight ratio • Low cost • Easy to machine • Standard satellite bus material • Parts ordered from onlinemetals.com
Internal Layout Upper Face Iridium Radio Right Face STX HDR Radio He 100 Radio (x2) Front Face Bottom Face Rear Face ECB GPS IMU Left Face CDH Unit Sun Sensor
Analysis Assumptions • Structural mass of 72.18 lbs and applied mass distributed over fuel tank of 71.12 lbs • 14 g axial acceleration, 4 g lateral acceleration • Factor of safety: 2
Static Analysis • Results • Max stress of 34.394 ksi • Max displacement of 0.214”
Power Generation • Solar Cells • Spectrolab UTJ Gallium Arsenide cells • Max power output 31.5 W/ft^2 • Body mounted panels with active solar alignment for optimal energy harnessing
Power Generation Y X Z Theta (rotation about the Z axis) Phi (rotation about the X Axis)
Power Distribution • Clyde Space SmallSatmodular electrical power system • Provides benefits such as maximum power point tracking for solar panels • Power distribution unit featuring dc-dc converters for conversion from solar power to supply power to other subsystems • Safety circuitry for over voltage and over current protection. • Expected efficiency of 95% • Modular for addition of various supply voltages
Power Storage • Secondary Batteries • Lithium ion cells • Panasonic CGR-18650E • Typical capacity 2500 mAh, 3.7V • Maximum charge rate 0.7C • Battery of 8 cells in series for desired 30V, • Two of these strings in parallel to increase capacity and limit Depth of Discharge for increased battery life. • Two batteries included for redundancy
Power Storage • Battery Performance • Operational temperature range • Charge (32º to 140º F) Discharge (-4º to 140º F) • Battery monitored and heated by power supply system to maintain optimal charging and discharge rates
Future Work • Battery duty cycles for better battery sizing • Simulation of system in orbit to more accurately determine power requirements for various flight phases • Current estimates are worst case scenario Battery box design and placement • Design of battery enclosure and insulation
