10 August 2005 Utah State University Logan, UT

Transcription

1 19th Annual AIAA SmallSat Conference The *.Sat CubeSat Bus When Three Cubes Meet Eric P. Lee, *.Sat Project Manager and Matthew D Ortenzio, Stevan M. Spremo, Belgacem A. Jaroux (Stanford University) Ignacio Mas, Dan Saldana (Space Technology Center) 10 August 2005 Utah State University Logan, UT

2 Introduction Today s Primary Goals The *.Sat CubeSat Bus and context as a standard High-level overview of standard services provided by the *.Sat CubeSat Bus *.Sat Mission Statement To provide a standard CubeSat Bus as a support platform for educational and scientific space experiments. Nomenclature *.Sat CubeSat Bus (covers Ground Segment and Space Vehicle) GeneSat-1 Mission and Payload 10 August 2005 SSC05-VI-4 / 2

3 What is a CubeSat? Picosatellite 100mm x 100mm x 100mm (about four inches!) 1kg mass (about 2.2 pounds!) CalPoly P-POD Launcher Poly-Picosatellite Orbital Deployer Secondary payload, up to five per launch Standard form-factor and LV interface developed in 2001 by Stanford and Cal Poly Adopted by 70+ universities worldwide and growing 10 August 2005 SSC05-VI-4 / 3

4 Why a Standard CubeSat Bus? Form-factor is very well-defined Standard services within these parameters are feasible Flight heritage (QuakeSat, upcoming Dnepr cluster launch, etc.) Limited resources on academic programs Academic calendar Varying student schedules/plans Finite funding pool Reduce need to reinvent the wheel University missions all require Bus Services Science and Tech missions aboard CubeSat Design iterations are costly in time and resources Allows focus on payload and mission design/operations 10 August 2005 SSC05-VI-4 / 4

5 Basic Requirements Standard Bus Adherence to the CubeSat Design Specification Modular configuration Primary Payload 1.0, 1.0, 1.0 Primary Payload 1.5, 1.0, 0.5 Primary Payload 2.0, 1.0 (no active ADCS) Standardized interface(s) Bus Module LEO Orbit Fly as secondary payload Bus Module One-year Design Cycle Four academic quarters Secondary Payload Secondary Payload Bus Module Reality dictated otherwise COTS parts if feasible 10 August 2005 SSC05-VI-4 / 5

6 *.Sat Heritage NemaSat Program, /1.0/1.0 Configuration C. Elegans primary payload Secondary not determined NemaSat Program, early /1.0/1.5 Configuration E. Coli payload Active ADCS module as secondary *.Sat Bus program, mid /2.0 Configuration GeneSat-1 microbiology payload Payload/Bus undergoing final integration testing Slated for early-mid 2006 launch 10 August 2005 SSC05-VI-4 / 6

7 NASA/Ames Astrobionics GeneSat-1 Payload Self-contained genetic research experiment Multiple wells, fluidic media Optical density sensor system Fluorescing protein Gene-expression in E. coli bacteria Micro-g environment Space radiation In-Situ Genetics Experiments on Nanosatellites (ISGEN) GeneSat-1 is a precursor to the future ISGEN missions (bigger bird) Will fly other increasingly complex organisms Opportunities for multiple future launches 10 August 2005 SSC05-VI-4 / 7

8 Spacecraft layout Triple Cube 100x100mm footprint 340mm long 3kg mass P/L Module Bus Module 10 August 2005 SSC05-VI-4 / 8

9 Bus Layout C&DH Batteries EPS Wedgelock Plate Antenna Payload I/F Backplane ADS Gyros/Accels 10 August 2005 SSC05-VI-4 / 9

10 Alternate Bus Layout Z-axis coil C&DH Batteries EPS Magnetometer ADCS PCB Patch Antenna Sun Sensor WedgeLock Plate Payload I/F Backplane ADS Gyros/Accels 10 August 2005 SSC05-VI-4 / 10

11 System Interfaces Primary Payload Digital/Analog/I2C I/O Unregulated Power Solar Arrays Bus Module 2.4 GHz Link Ground Station Digital/Analog/I2C I/O Unregulated Power Secondary Payload 10 August 2005 SSC05-VI-4 / 11

12 Standardized Interfaces to Payload(s) Structural/Mechanical Bus module conforms to CubeSat Spec at interface Alodined aluminum structure provides thermal/electrical continuity 50-pin payload interface connectors Electrical Power (EPS) Body-mounted solar cells (8.2 W pp) Li-ion battery pack (4300 mah BOL) Power delivery to P/L(s) and Bus Unregulated Voltage to P/L(s) Regulated Voltage for Bus subsystems (3.3 and 5V) Single-point ground for entire S/V Hardware-based fault mitigation and hysteresis battery protection 10 August 2005 SSC05-VI-4 / 12

13 Standardized Interfaces to Payload(s) Command and Data Handling/Software 16 basic/required commands, up to 256 commands total PIC18 MCU running Salvo RTOS-based system software Software based SEU mitigation and onboard WDTs 2MB onboard storage for each payload I 2 C-based data link from Bus to P/L(s) Communications/Ground station 2.4 GHz ISM band transceiver (115kbps internal datarate) Monopole or micro-strip antenna designs 6-meter dish at Stanford 18-meter dish also available at SRI Mercury Ground Station software (Internet-based infrastructure) Approx. 15 minutes access per day, 2MB/day downlink capability depending on orbital parameters 10 August 2005 SSC05-VI-4 / 13

14 Additional Bus Services to Payload Attitude Determination and Control (ADCS) Onboard 3-axis ADS via accelerometers and rate gyros Passive magnet/hysteresis rod system Active control system in development (0.5 cube option) Thermal Control (TCS) Provisions for active/passive thermal control Batteries have onboard heating elements Largely dictated by orbital parameters and P/L requirements Onboard sensors/telemetry Bus and P/L Temperature Regulated and unregulated voltages Current draws by Bus and P/L subsystems Command result histories/codes 10 August 2005 SSC05-VI-4 / 14

15 Lessons Learned Requirements Management Customer involvement with design process Parallel development with payload team Maintaining standard capability vs. Mission Requirements Adequate capability for variety of missions Flexibility Changing payload requirements Varying launch windows and orbits Limited Launch Opportunities Domestic vs. International Not The Standard Could be developed as such A standards-based approach is viable in the University setting with a real customer-built payload 10 August 2005 SSC05-VI-4 / 15

16 Thank you! Key supporters NASA/Ames Astrobionics John Hines, Bruce Yost, Elwood Agasid, Dan Saldana Space Technology Center (STC) Dave Engelbert Stanford University Space Systems Development Lab (SSDL) Professor Bob Twiggs CalPoly CubeSat Team Professor Jordi Puig-Suari Santa Clara University Team Professor Chris Kitts Lockheed Martin Space Systems Company Dr. Dave Klinger, Mark Crowley, Eric Tapio 10 August 2005 SSC05-VI-4 / 16

17 More Pictures Lithium Ion Battery EPS Board Four Solar Panels Integrated Test 10 August 2005 SSC05-VI-4 / 17