FRL's Demonstration and Science Experiments (DSX) rogram Quest for the Common Micro Satellite Bus 21st Annual Conference on Small Satellites August 13-16, 16, 2007 Logan, Utah N. Greg Heinsohn DSX HSB Program Manager Microsat Systems Inc. (303) 285-1848 gheinsohn@microsatsystems.com
Introduction The Demonstration and Science Experiments (DSX) is AFRL s fourth space science technology experiment (SSTE4) Comprised of elements provided by AFRL, NASA, academia, and many contractors DSX will pave the way for new capabilities in Space surveillance in high ground of MEO Small satellites with significant operational capabilities Protection of space assets from radiation environments Modular spacecraft platforms Three major research areas Physics of VLF electromagnetic wave injection Space weather in the poorly characterized MEO environment Characterization of environmental effects on materials and electronics
Spacecraft Overview Built around EELV (ESPA) Ring Two modules are derivatives of TechSat 21 also used for TacSat-2 mission Same structural design for both Avionics Module and Payload Module Z booms are 8 meters 16 meters tip to tip Y booms are 27 meters 54 meters tip to tip VMAG Payload Module Wave Interaction Experiment Space Weather Components Space Environmental Effects Experiment Z Axis Antennas VLF Receive Eight meters TASC Y axis antennas VLF electric Field Transmit & Receive 27 meters Avionics Module Attitude Control system Power Thermal Control Communications Command & Data Handling Space Weather Components ESPA Ring Primary Structure Interfaces between EELV and Upper Satellite Innovative approach demonstrates versatility of bus design to accommodate a variety of spacecraft mission
Launch Configurations Avionics Module ESPA Ring ESPA Configuration Payload Module Primary Payload (placeholder) Payload Module Stacked Configuration Avionics Module DSX on ESPA in EELV Fairing DSX in Minotaur IV/V Fairing DSX in Falcon 5 Fairing Modular design compatible with ESPA on EELV and dedicated launch vehicles, Simplifies payload integration
Avionics Module Components Solar Array Interface Sun Sensor (3) SEAKR Avionics Reaction Wheels (3) Helix Antenna (6) Comm Electronics Components.... Transponder Omni Patch Antenna (2) Torquers (3) Li-Ion 30 Ah Battery (2) HEPS Experiment ESPA Photometer & Radiometer (4) Payload Electronics Computer System
Payload Module Components HIPS Z-Boom (2) NASA SET-1 PAYLOAD LIPS TATU (2) TASC LEESA VMAG DPU RSH (2) HST BBR RECEIVER WIPER TCU SET CREDANCE MODULE VMAG CONTROL ELECTRONICS IMU Y-Booms (2) CEASE Magnetometer ESPA
Structural and Telecom Designs 2x S/L Band Tx/Rx HSB IAS Transponder ReceiverDiplexer S-Band Input Tx Output 10 db Coupler -10 db port SPDT Switch Splitter 6x MGATx 2x SP3T Switch Avionics Module Structure Payload module very similar 10 sides composite sandwich panel carbon fiber/polycyanate face sheets High stiffness design Aluminum foil outer surface for equipotential grounding DSX Telecom Subsystem Communications through AFSCN L band uplink, S band downlink 2 patch antennas provide 4 pi coverage for uplink and downlink 6 MGA antennas oriented such that an antenna is always pointed at Earth for high speed down link when arrays are pointed at Sun
DSX Avionics & Power Design stowed deployed Integrated Avionics System Provides power switching Provides all C&DH functions RAD 750 Processor Command & data via RS-422 Supports discrete I/O, analog and element unique interfaces Power System Single wing array with 3 panels 4.27 m^2 Triple junction cells Designed for significant radiation deterioration in MEO orbit 60 amp hour Li-ion battery 28 +6/-4 VDC
DSX Flight Software, Thermal & ADCS Flight Software VxWorks operating system CCSDS protocol Modular design Easily adaptable for future missions Four major components Startup Code Stand-alone C Code Space Vehicle Management Software Optional Software Payloads Thermal Simple design High heritage components Software controlled heaters Reconfigurable set points Sized for 50% duty cycle AD590 temp sensors in radiation cans for shielding from MEO environment Attitude Determination and Control Three-axis stabilized precision pointing platform very large inertias provide a significant challenge highly reliable flight-qualified components Attitude determination provided by sun sensors, magnetometer and inertial measuring unit Control provided by reaction wheels and torque rods Two primary modes Magnetic field track for science collection Sun track for power collection
DSX Team Program Office Systems Engineering Integration and Test Launch Segment Spacecraft Bus Equipment VLF Wave Particle Interaction Experiment Space Weather Experiments AMP TEK R Space Environmental Effects PROPULSION DIRECTORATE Assurance Technology Corp Antennas