VIEWS: 40 PAGES: 128 POSTED ON: 4/8/2010
2001 University of Tokyo CUBESAT Project University of Tokyo CubeSat Project CRITICAL DESIGN REVIEW April, 6, 2001 Intelligent Space Systems Laboratory University of Tokyo 2001 University of Tokyo CUBESAT Project ■Contents •Project Overview –CubeSat program, Organization, Management, Schedule •Mission Overview –Design Assumption, Mission Objective, Mission Profile, Success Level •System Design –Design Strategy & Concepts •Subsystem Details –Electronics, Power, Communication, Structure, Environment, Ground Segment •Concerns 2001 University of Tokyo CUBESAT Project Project Overview 2001 University of Tokyo CUBESAT Project ■CubeSat Program ・Proposed in University Space Systems Symposium. (Nov. 1998, Hawaii) ・International educational program to improve students’ skill of space engineering and project management. ・Quick and low cost development policy. ・10cm cubic satellite weighing less than 1kg. 2001 University of Tokyo CUBESAT Project ■Project Constraints ・10cm cubic shape, weight less than 1kg. ・Installed in the carrier called “P-POD”, developed by CalPoly. ・P-POD is to be installed in MPA (Multiple Payload Adopter), developed by One Stop Satellite Solutions Inc. ・Launched by Russian rocket “Dnepr” from Baikonur in November, 2001. ・Orbit 600-800km circular, 60 degree inclination ・HAM band operation 2001 University of Tokyo CUBESAT Project ■CubeSat Developers ・California Polytechnic State ・Taylor University U ・Dartmouth College ・Tokyo Institute of Technology ・Florida Space Institute ・University of Arizona ・Leland High School ・University of Tokyo ・Montana State University ・Wilcox High School ・Stanford University ・Stellar Innovations 2001 University of Tokyo CUBESAT Project ■CubeSat Program Organization Russia Launcher Provider OS2 Mission Organizer ISC Kosmotras OSSS Inc. Stanford U Carrier Provider CalPoly U.S.A. Japan Japan-side Agency Astro Reserch Co. CubeSat Developers U.S.A. Japan 10 Facilities ・U of Tokyo ・Tokyo Inst. of Tech. 2001 University of Tokyo CUBESAT Project ■Payload Configuration MPA Mass < 300kg Isogrid Spaceframe Deploys Payload Satellites Three-axis Stabilization Dnepr LV Launch weight 211 t Propellant amyl + heptyl Number of stages 3 P-POD LV diameter 3m Deployes 3 CubeSats LV length34m Reliability 0.97 Payload 400kg (800km) 1400kg (600km) (inclination 65deg) CubeSat 2001 University of Tokyo CUBESAT Project ■UT’s Project Organization Program Director ・21 active members Prof. Nakasuka ・General meeting every 1-2 week(s) ・Subsystem meeting every week Project Manager Y.Tsuda Electronics Communication Power Structure Environment Ground Seg. Y.Arikawa T.Ito N.Sako N.Miyamura P.Seo S.Ogasawara Y.Tsuda Y.Kato T.Eishima T.Ito N.Sako Y.Tsuda N.Miyamura T.Eishima Y.Arikawa S.Ogasawara K.Kanairo T.Murakami S.Ishikawa S.Ukawa S.Ukawa K.Muramatsu Y.Oda T.Murakami S.Ihikawa R.Funase I.Ikeda E.Hwan Y.Kuwata S.Hori K.Kanairo T.Yamamoto S.Ganryu 2001 University of Tokyo CUBESAT Project ■Development Milestone Development code : XI [sai] (X-factor Investigator) ・Basic functional check XI-I ・Technological demonstration for USSS conference ・Bread board model XI-II ・Validation of all technology to be used Communication test model, Mass model, CDR ・Engineering model XI-III ・Served to the integration & environmental testing ・Flight model & back up model XI-IV,V ・One for flight, the other for operation practice etc. 2001 University of Tokyo CUBESAT Project Mission Overview 2001 University of Tokyo CUBESAT Project ■“XI” Outlook Solar cells are to Antenna Latch be attached on Mechanism whole surface Antenna Flight Pin Hole Camera Hole photo: XI-II (BBM model) 2001 University of Tokyo CUBESAT Project ■Mission Description ■Mission Statement "To acquire the indispensable technology in developing super- small satellite system" ■Mission ・Gathering the satellite’s health information via beacon signal. ・Command uplink & data downlink. ・Telemetry data broadcasting service. ・On-orbit verification of the commercial-off-the-shelves (COTS) components. ・Imaging experiment as an extended mission. (TBD) ・Sending everyone’s message into space. 2001 University of Tokyo CUBESAT Project ■Success Level (1) ■Project‟s Minimum Success --- Acquiring the important technology and knowledge through designing and fabricating the spacecraft. ・Establishing overall work flow of the satellite development project. ・Establishing a methodology of spacecraft design. ・Raising the fabrication technique. ・Conducting several kind of testing and feeding back its results to the design. ・Keeping the project progressing smoothly so as to bring it to be the launchable condition. ■Mission Success --- Receiving signals from the spacecraft. ・Surviving in the actual launch environment. ・Successfully verifying the function of the communication system. ・Gathering house keeping data. 2001 University of Tokyo CUBESAT Project ■Success Level (2) ■Full Success --- Succeeding in uplink & downlink. ・Successfully commanding the spacecraft by uplink. ・Getting downlink data as a reaction to the command uplink. ■Advanced Success --- Successfully verifying the function of the advanced mission components. ・Verifying that sensors planned to be equipped as advanced mission components should work normally. 2001 University of Tokyo CUBESAT Project ■Mission Profile (1) ・Launched by Dnepr from Baikonur in Nov. 2001. ・MPA is put in 600-800km circular orbit with 60 degree inclination. ・MPA deploys some of its payloads & activates P-POD. ・P-POD deploys CubeSats. ・CubeSat starts operation after a certain elapsed time. 2001 University of Tokyo CUBESAT Project ■Mission Profile (2) 1. 2. 3. ■Post Ejection Stand-by ■Nominal Operation ■Telemetry Transmission Main OBC is activated Antenna is deployed. All This mode occurs as a reply while the other components including beacon to the uplink command from components are off. are activated except telemetry ground station. transmission system. 2001 University of Tokyo CUBESAT Project System Design 2001 University of Tokyo CUBESAT Project ■Basic Specifications ●Structure 10cm cubic, 1kg, Aluminum A7075 body ●Main Processor OBC PIC16F877 4MHz（Program memory 8k, RAM 368) Data Recorder EEPROM 32k + 224k ●Communication System Downlink 437.490MHz, FSK, AX.25, 1200bps, 600mW Uplink 145.835MHz, FSK, AX.25, 1200bps Beacon 436.8475MHz, CW, 100mW ●Power System Battery Manganese type lithium-ion battery, 8 parallel Solar Cells Single crystal silicon, 60 cells Bus Voltage 5V ●Attitude Control Passive stabilization using permanent magnet ●Sensors Voltage, Current, Temperature, Area sensor Structure PWR5V Power OBC Main Com1 DC-DC1 TX RX TNC ROM TX TNC TX Analog SW DC-DC2 TLM TLM OBC Com2 DC-DC3 OBC CMD uSW RX TNC RX Flight Pin ACK TLM Charge CW Gen CW Circuit PWR5V Flight Pin Solar Cell Digital Sensors Important Analog Antenna Latch Sensors Analog Sensors Battery 2001 University of Tokyo CUBESAT Project ■Internal Function Design Strategy ■Mother board intervenes inter- Structure subsystem signal & Subsystem power flow． Camera Module Electronics Subsystem Battery Data Handling Unit Mother Board Power Subsystem Power Unit Solar Cell Communication Subsystem Temperature Sensors Communication Unit 2001 University of Tokyo CUBESAT Project Structure Subsystem 2001 University of Tokyo CUBESAT Project ■Structure Subsystem 1. Body of CUBESAT 3. Antennae Deployment a) Assembly Mechanism b) Weight and Center Of Mass a) Magnetic Plunger c) Material b) Folding Method d) Size 2. Interface 4. Strength Analysis a) Flight Pin a) Behavior as b) External Input/Output Cantilever Beam c) Connector b) Ceiling panel’s vibration d) Kill Switch c) Load Estimation d) Countermeasure for vibration(Antennae) 2001 University of Tokyo CUBESAT Project ■Body of CUBESAT a) Assembly b) Weight and Center Of Mass c) Material d) Size z y Center Of Mass x 2001 University of Tokyo CUBESAT Project ■Assembly of XI-II +z panel ■First, Subsystem Panels to put up solar array on Boards are attached +y panel to Mother Board. ■Then,that module is attached to 4 pillars. ■Finally,Solar Cell panels covered The mainstay of XI-II +x panel CUBESAT’s surface. 2001 University of Tokyo CUBESAT Project ■Construction of subsystem board Electronic board Communication board ■Each subsystem board is attached to Power board Transceiver Mother Board. ■Battery and I/F Main motherboard connectors are Battery box also attached to Mother Board. I/F board Sub motherboard 2001 University of Tokyo CUBESAT Project ■Center Of mass z ■The difference of geometric center between center of mass is 7.8mm y (within 20mm) ■Total mass is 990g Center Of Mass (within 1kg) x 2001 University of Tokyo CUBESAT Project ■Material USE PRODUCT Main Structure A7075 PCB Glass Epoxy Battery Li-ion Rechargeable battery Solar Cell Si-Cell IC Plastic Packaged W ir in g Teflon coated Bolt,Nut Steel Antenna Convex tape ■A7075 is the same material of P-POD which means that thermal expansion is equal. 2001 University of Tokyo CUBESAT Project ■Front view of XI-II ■Solar cells mounted on EXTERNAL MOUNTING SURFACE do NOT exceed 6.5mm ■Antennae are also mounted on EXTERNAL MOUNTING SURFACE. 2001 University of Tokyo CUBESAT Project ■Bottom view of XI-II ■Antennae are mounted within 6.5mm. ■2 Kill Switches are mounted on this plane. 2001 University of Tokyo CUBESAT Project ■Interface a) Flight Pin b) External Input/Output c) Connector d) Kill Switch 2001 University of Tokyo CUBESAT Project ■Installation of CUBESAT ■3 CUBESATs can be installed in a P- POD carrier. ■We can get some experimental data from I/F hole before launch. 2001 University of Tokyo CUBESAT Project ■Interface System Micro V up Subsystem Switch Switch Unit Flight Pin V down Plunger Antenna Deployment Order Charge up Switch Unit Charge down Flight Pin 2 1 GND 2 Battery V 3 DCDC 5V for electronics External Interface 4 DCDC 5V for communication RJ-45 5 DCDC 10V 6 V operate 4V 7 External Tx 8 External Rx 2001 University of Tokyo CUBESAT Project ■Mother Board ■All Subsystem Boards are attached to Green connector. 2001 University of Tokyo CUBESAT Project ■Interface Board Before-Flight Pin Kill Switch RJ-45 Connector ■All External I/F is allocated to Interface Board ■Interface Board has some module as follows. • Kill Switch • Before-Flight Pin • External I/O Connector 2001 University of Tokyo CUBESAT Project ■External Interface No(Ext) Name Function 1 GND(1 ) Grou n d 2 BATT(2 ) Batte ry 3 E- DC(3 ) DCDC- Con ve rte r(for Ere c tric su bsyste m) ou tpu t 8,7,6,5,4,3,2,1 4 C- DC(4 ) DCDC- Con ve rte r(for Commu n ic ation su bsyste m) ou tpu t 5 Tx- DC(5 ) DCDC- Con ve rte r(for Te le me try Tran smitte r) ou tpu t RJ-45 Connector 6 EXT Tx(3 6 ) Exte rn al se rial Tx 7 EXT Rx(3 7 ) Exte rn al se rial Rx RJ-45 Plug 8 VTO CMOS Image se n sor NTSC sign al ■ We use RJ-45 connector. ■ Even if CUBESAT is installed in the P-POD , we can get the data witch the table shows. 2001 University of Tokyo CUBESAT Project ■Kill Switch OFF ON Kill Switch ■We use 2 Kill Switches in parallel for redundancy. ■When one of 2 switches is ON , all system can get power. 2001 University of Tokyo CUBESAT Project ■Flight Pin Switch 1 Switch 2 ■Switch1:Supplying power to the system. ■Switch2:OPEN/CLOSE battery charging circuit. 2001 University of Tokyo CUBESAT Project ■Antennae Deployment Mechanism a) Magnetic Plunger b) Folding Method 2001 University of Tokyo CUBESAT Project ■Antenna Deployment System ■Antenna is deployed using Electromagnetic Plunger fa +V is impressed fb The piece is captured by the magnet Magnetic Power decreases And the piece is released Electromagnetic Plunger fa = 3.5 [N] min. fb = 0.8 [N] 2001 University of Tokyo CUBESAT Project ■Antenna Deployment System Antenna Deployment Video 2001 University of Tokyo CUBESAT Project ■Strength Analysis a) Behavior as Cantilever Beam b) Ceiling panel’s vibration c) Load Estimation d) Countermeasure for vibration(Antennae) 2001 University of Tokyo CUBESAT Project ■Behavior as Cantilever Beam ■If CUBESAT experiences very strong vibration, it may behave as a cantilever beam. ■ In this case , the Harmonic Frequency is around 20[kHz] (witch is enough high, comparing to the launch vehicle’s frequency) 2001 University of Tokyo CUBESAT Project ■Ceiling panel’s vibration ■Harmonic Frequency is around 1 - 2 [kHz] ■The Harmonic Frequency largely depends on the thickness of the panel. ■The thicker the panel is designed , the higher the Harmonic Frequency becomes. 2001 University of Tokyo CUBESAT Project ■Ceiling panel’s vibration Thickness of panel ■ To avoid ceiling vs Harmonic frequency panel’s vibration we 3.0 1100 have to design it as 1080 2.5 possible as thick. Frequency(n=m=1)[kHz] 1060 ■ For this design , Total Mass[g] 2.0 1040 Total Mass is large Harmonic 1020 1.5 problem 1000 1.0 Harmonic 980 ■ Eventually,we have Frequency to choose around Total Mass 960 0.5 1.0-1.5mm 940 0.0 920 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Thickness of panel[mm] 2001 University of Tokyo CUBESAT Project ■Load Estimation P-POD ■ The 3rd CubeSat experiences maximum load while 2nd stage flight • The maximum stress is 0.011kgf/mm2 7.7g(max) (enough for Aluminum use) Maximum Stress 2001 University of Tokyo CUBESAT Project ■Countermeasure for vibration(Antennae) ■To complete any mission , fastening and deploying antennae is very important. ■It is difficult to simulate the behavior of the antenna , so we conduct some experiments to confirm the feasibility of this design. ■Fixing antennae with several points. 2001 University of Tokyo CUBESAT Project Electronics Subsystem 2001 University of Tokyo CUBESAT Project ■Function of Electronics Our Works • Health monitoring • Command & data-handling • Resetting DCDC • Antenna deployment • Controlling area sensors Our Goals • Satellite system management • Capturing images with area sensors 2001 University of Tokyo CUBESAT Project ■Block Diagram Rx-EtoC CW-CtoE Rx-TNC CW-TNC Rx-CtoE Thermometer CW-EtoC 0 to 7 MPX Tx-CtoE OBC MPX_SEL0 ~2 Tx-TNC Tx-EtoC Reset Signal (Power Sub Sys.) E-DCDC 5V SEL Detect OBC Program C-DCDC 5V & To Comm ROM Read/Write Sub Sys. Pins Battery Voltage Charge Current SCL Line ROM0 ROM0 Battery Charger IC Reset Signal ROM0 ROM0 ROM0 ROM0 ROM0 ROM0 SDA Line (Structure Mother Board) Solar Cell Current MPX 1 to 6 2001 University of Tokyo CUBESAT Project ■Command & Data-Handling CRNT /ROND /SOLA OBC TEMP /VOLT Fixed length = 17 bytes Uplink Command ANTD /CRNT /DCDC MTQC /POWR/ROMD Tx-TNC CW-TNC SOLA /TEMP /VOLT Ground Station in UT 2001 University of Tokyo CUBESAT Project ■Command & Data-Handling(2) ●Antenna deployment ●Requesting current data (Total , Solar Array , C-DCDC , E-DCDC) ●Resetting C-DCDC ●Resetting charging circuit ●Requesting EEPROM data ●Requesting temperature data (Battery , Solar Array , FM-Transmit) ●Requesting voltage data (Battery , Solar Array) 2001 University of Tokyo CUBESAT Project ■Command & Data-Handling(3) ●Current ----- 9 bytes (Total , Solar Array , C-DCDC , E-DCDC) ●EEPROM Data ----- Undecided ●Current & Temperature of Solar Array ----- 12 bytes ●Temperature ----- 8 bytes (Battery , Solar Array , FM-Transmit) ●Voltage ----- 2bytes (Battery , Solar Array) 2001 University of Tokyo CUBESAT Project ■Command & Data-Handling(4) Time 3 bytes Status 1 bytes Picture 1 bytes Voltage 2 bytes Current 9 bytes Additional Data 1 bytes 2001 University of Tokyo CUBESAT Project ■Components of Electronics For Thermometer JumperPin For ROM ROM READ/WRITE Pin For Camera ROM Module XI-II model 2001 University of Tokyo CUBESAT Project ■Components of Electronics-(2) OPAmp Module Program Pin Thermometer Module XI-II model 2001 University of Tokyo CUBESAT Project ■Components of Electronics-(3) PIC 16F877 • Clock :4MHz • Memory :8kword • RAM :368bytes • EEPROM :256bytes • Operative Voltage:2.0~5.5V ROM (24LC256) • I2C serial EEPROM • Memory :256Kbit(32Kbyte) • Max erase/write cycles:100,000 • Max write-cycle time :5ms • Max clock frequency :400kHz 2001 University of Tokyo CUBESAT Project ■Thermal Monitoring Thermal Sensor ( LM335Z ) Thermal Sensor Calibration ・Power consumption:5mW 40 y = 99.218x - 270.29 ・Measuring range :-40~100℃ 35 Temperature 30 ・Characteristic :10mV/℃ 25 20 ・Precision :±1℃ 15 10 data @ @ 5 linearized \ 0 -5 2.7 2.8 2.9 3 3.1 Voltage[V] Monitoring ・Temperature of Battery, Solar Panel(6) and Transceiver. ・AD converting a data & sending it to comm subsystem. 2001 University of Tokyo CUBESAT Project ■Function of Reset-(1) P.U. = Pull Up P.D. = Pull Down Pch FET Tx-DC Tx-TNC e P.U. P.D. c d P.U. a b Pch FET A E-DC OBC Nch FET SEL Detect e V in SEL Detect CW-GEN Pch FET A C-DC Rx-TNC Nch FET P.D. a b P.U. c d 2001 University of Tokyo CUBESAT Project ■Function of Reset-(2) For SEL tolerance, reset function is needed. Reset system requires high reliability so as CPU not to shut off continuously even in CPU malfunction case. If a=1&b=0 Two wire AND reset system using FET Switching Circuit • PchMOSFET Vin DCDC • NOT gate 2001 University of Tokyo CUBESAT Project Communication Subsystem 2001 University of Tokyo CUBESAT Project ■Communication System Diagram OBC Telemetry data Beacon data Sensors Up-link command AD Convert Tx TNC Negotiation Rx TNC PIC16C622 Morse encoder PIC16C711 AX25 Coded data PIC16C716 AX25 Coded command with Parity PLL PLL Modulator Morse Coded data Control Demodulator Control PTT Control MX614 MX614 PLL FSK modulated data Control FSK modulated command Nishi RF Lab. Nishi RF Lab. Nishi RF Lab. Custom made Custom made Custom made FM transmitter CW transmitter FM receiver switching Half wave length Half wave length dipole antenna Antenna SW monopole antenna 2001 University of Tokyo CUBESAT Project Telemetry Transmission System 2001 University of Tokyo CUBESAT Project ■Tx TNC (AX.25 encoder) ■Tx TNC：Micro controller PIC16C622 －program memory(EPROM) : 2 kbyte －data memory(RAM) : 128 byte －clock : 4 MHz －I/O port : 13 (4 AD Converters) －power consumption : 2.0 mA @ 5V ■Tx TNC receives telemetry data from OBC ■Puts Parity byte for error detection ■Encodes the telemetry data with AX.25 protocol PIC16C622 ■Sends encoded data to FSK modulator AX.25 Protocol ■This protocol is mainly used for data transmission by HAM ■Every Amateur Radio Station all around the world can decode our telemetry data!!! Flag Destination Source Control PID parity data parity data FCS Flag AX.25 frame structure(with Parity) 2001 University of Tokyo CUBESAT Project ■Tx TNC Program Start & Initialization No data from OBC ? Yes Receive data from OBC Packetize into AX25 format Send packet to FSK modulator 2001 University of Tokyo CUBESAT Project ■FM Transmitter ■FM Transmitter is used to transmit telemetry data ■Nishi RF Laboratory custom made transmitter －frequency: 437.490MHz －band width: 20kHz －RF output power: 1W －input power: under 6W －operative temp.: -30℃～+60℃ FM transmitter －volume: 90×60×10cm (including CW transmitter) FM transmitter System Diagram 2001 University of Tokyo CUBESAT Project Beacon Transmission System 2001 University of Tokyo CUBESAT Project ■CW Generator (Morse encoder) ■Morse encoder：Micro controller PIC16C716 －program memory(EPROM) : 2 kbyte －data memory(RAM) : 128 byte －clock : 4 MHz －4 AD Converters (8bit) －power consumption : 2.0 mA @ 5V ■CW generator receives beacon data from OBC ■Monitors sensor data independently from OBC (Countermeasure of OBC‟s hang up) PIC16C716 ■Generates Morse code ■Controls the KEY of CW transmitter ■Data rate : human decodable speed Beacon data format "UT1" "www.space.t.u-tokyo.ac.jp" "UT4" total I tmp. battery tmp. Panel tmp. tmp. tmp. tmp. tmp. tmp. "UT2" time1 time2 time3 "UT5" battery1 battery2 battery3 battery4 battery5 battery6 tmp. Panel tmp. Panel tmp. Panel tmp. Panel tmp. Panel tmp. Panel "UT3" Status Camera status battery V "UT6" 1 2 3 4 5 6 2001 University of Tokyo CUBESAT Project ■CW Generator Program Start & Initialization OBC ready No to send data? Yes Data Sampling Yes Counter < 10sec Receive data from OBC No Data sensing (AD Convert) UT1 www.space.t.u-tokyo.ac.jp UT2 AA BB CC UT3 DD EE FF Data Sending UT4 GG HH II UT5 JK LM NO UT6 PQ RS TU 2001 University of Tokyo CUBESAT Project Command Receiving System 2001 University of Tokyo CUBESAT Project ■Rx TNC (AX.25 decoder) ■Rx TNC：Micro controller PIC16C711 －program memory(EPROM) : 1 kbyte －data memory(RAM) : 64 byte －clock : 4 MHz －4 AD Converters (8bit) －power consumption : 2.0 mA @ 5V ■Rx TNC receives AX.25 encoded command from FSK demodulator PIC16C711 ■Decodes it and sends command to OBC OBC Reset System ■If the command is “Reset Command”, resets OBC ■Monitors OBC‟s current and resets OBC in case of SEL (Countermeasure of OBC‟s SEL) 2001 University of Tokyo CUBESAT Project ■Rx TNC Program Main Routine Start & Initialization Interruption Routine Receive Uplink command A/D convert „Total I‟ set „Receiving‟ flag „Total I‟ > Threshold ? Yes Command = “rset” No Yes or flag_rst = 1 ? flag_rst = 1 No Reset OBC OBC ready to receive? Yes Wait 10 [ms] flag_rst = 0 Send serial data to OBC clear „Receiving‟ flag 2001 University of Tokyo CUBESAT Project ■FM Receiver ■FM Receiver is used to receive up-link command ■Nishi RF Laboratory custom made receiver －frequency: 145.835MHz －input power: under 100mW －receive sensitivity: under -16dBμ －receive output: 16dBV typ. －operative temp.: -30℃～+60℃ FM receiver －volume: 50×60×10cm 2001 University of Tokyo CUBESAT Project ■Antenna Configuration Antenna for Transmitters 430MHz band Half wavelength dipole antenna Antenna for Receiver 144MHz Half wavelength monopole antenna 2001 University of Tokyo CUBESAT Project ■Antenna Pattern (Transmitter) Antenna Absolute Gain Transmitters' Half wavelength dipole Antenna (dBm) 5.00 The gain which 0.00 we can decode -5.00 the data in our -10.00 -15.00 ground station -20.00 -25.00 Gt Gt,req 2001 University of Tokyo CUBESAT Project ■Antenna Pattern (Receiver) Antenna Gain Receiver's Half wavelength monopole antenna (dBm) -20.00 -25.00 -30.00 -35.00 -40.00 -45.00 -50.00 -55.00 2001 University of Tokyo CUBESAT Project ■Link Budget (Telemetry Tx) Link Budget Telemetry (TDMA) Symbol UnitTelemetry Remark Frequency f MHz 437.400 Transmit P W 0.600 Parameter Transmit P dBW -2.218 Transmitter Line Loss Ll dB ` -3.000 Usually -1dB-3dB l Æ Transmit Antenna Half-Power Beamwidth t deg e 110.000 Ideal dip Peak Transmit Antenna Gain l Gpt dB 2.148 e Ideal dip CUBESAT Transmit Antenna Pointing Offset et deg 90.000 Uncontrolled Comm. System Transmit Antenna Pointing Loss Lpt dB -8.033 Transmit Antenna Gain Gt dB -5.885 Equiv. Isotropic Radiated Power EIRP dBW -11.103 Propagation Path Length S km 1439.940 50kbyte/1pass Space Loss Ls dB -148.434 Propagation & Polarization Loss La dB -0.470 Polarization (-0.3dB) Peak Receive Antenna Gain Grp dB 12.500 GS 435HS20 Æ Receive Antenna Half-Power Beamwidth r deg 29.000 GS 435HS20 UT‟s Receive Antenna Pointing Error er deg 15.000 Assumption Receive Antenna Pointing Loss Lpr dB -3.210 Ground Station Receive Antenna Gain Gr dB 9.290 System Noise Temperature Ts dBK 25.700 Data Rate R bps 1200.000 MX614 0 N Eb 0 Eb dB 21.390 Bit E r BER 0.000 Required Eb/N0 Req Eb/N0dB-Hz 13.000 FSK, BER=10-5 Implementation Loss dB -5.000 Margine dB 3.390 2001 University of Tokyo CUBESAT Project ■Link Budget (Command Rx) Link Budget Uplink Command Symbol Unit Uplink Remark Frequency f MHz 145.835 Transmit P W 20.000 Parameter Transmit P dBW 13.010 Transmitter Line Loss LlB dB ` -3.000 Usually -1dB-3 Transmit Antenna Half-Power Beamwidth t Æ deg 33.000 GS 144HS12 UT‟s Peak Transmit Antenna Gain Gpt dB 10.000 GS 144HS12 Ground Station e Transmit Antenna Pointing O f et degt 15.000 f Assumption Transmit Antenna Pointing Loss Lpt dB -2.479 Transmit Antenna Gain Gt dB 7.521 Equiv. Isotropic Radiated Power EIRP dBW 17.531 Propagation Path Length S km 1439.940 Space Loss Ls dB -138.894 Propagation & Polarization Loss La dB -0.470 Polarization (-0.3dB) Peak Receive A e Grp nt dB -2.521 Monopole Æ Receive Antenna Half-Power Beamwidth r deg 100.000 Monopole CUBESAT Receive Antenna Pointing Error er deg 90.000 Uncontrolled Receive Antenna Pointing Loss Lpr dB -9.720 Comm. System Receive Antenna Gain Gr dB -12.241 System Noise Temperature Ts dBK 31.100 Data Rate R bps 1200.000 0 N Eb 0 Eb dB 32.634 Bit E r BER 0.000 Required Eb/N0 Req Eb/N0dB-Hz 13.000 FSK, BER=10-5 Implemention Loss dB -5.000 Margine dB 14.634 2001 University of Tokyo CUBESAT Project Power Subsystem 2001 University of Tokyo CUBESAT Project ■Power Subsystem Charge Circuit A A A A A TNC OBC OBC Batteries Switching Switching DCDC Regulator Regulator Converter Electronics Communicati Tx Subsystem on Subsytem 2001 University of Tokyo CUBESAT Project ■Power Subsystem(CONT’D) ■Supply a continuous source of electrical power to loads. • Power source is solar panels. • Batteries are used for storage • Regulated DC power and unregulated power is supplied for loads. • Power consumption is monitored for SEL. 2001 University of Tokyo CUBESAT Project ■Power Regulation & Control ■Bus voltage: main 5[V] ■Regulated to 5V using switching regulators and DCDC converter ■Elect. subsystem power line & Comm. subsystem power lines are independent so that they monitor each other and shutdown in case of SEL 2001 University of Tokyo CUBESAT Project ■Source ■Power is supplied by body mounted solar cells. ■Cells are arranged on all 6 CubeSat surfaces. ■Average power 1228 [mW] (typ @ 80℃) 2001 University of Tokyo CUBESAT Project ■Solar Panel Bass bar ■Cell type : Si Crystal (SHARP) ■Efficiency : 16% ■10 cells in series / panel ■Cell size: +X :28.25x13.8mm -X,+Y,-Y:47.75x13.8mm +Z,-Z :47.75x15.8mm Photo:3 cells in series 2001 University of Tokyo CUBESAT Project ■Solar Array Layout (+X panel) +X panel: 4.5V x 172mA = 774mW (typ. @ 25 ℃) 4.5V x 162mA = 727mW (typ. @ 80 ℃) 2001 University of Tokyo CUBESAT Project ■Solar Array Layout (-X,+Y,-Y panel) -X,+Y,-Y panels: 4.5V x 297mA = 1336mW (typ. ＠ 25 ℃) 4.5V x 279mA = 1256mW (typ. ＠ 80 ℃) 2001 University of Tokyo CUBESAT Project ■Solar Array Layout (+Z,-Z panel) +Z,-Z panels: 4.5V x 340mA = 1530mW (typ. @ 25 ℃) 4.5V x 319mA = 1438mW (typ. @ 80 ℃) 2001 University of Tokyo CUBESAT Project ■Energy Storage ■Batteries will be used during eclipse and downlink ■Liion secondary batteries are selected. ■8 batteries are set in parallel. ■DOD is 3% ■Batteries only lifetime is 38 hrs 2001 University of Tokyo CUBESAT Project ■Liion battery Cathode Material Lithium Manganate Anode Material Carbon Operating Voltage 3.8[V] Discharge Capacity 780 [mAhr] Single Cell Spec. 2001 University of Tokyo CUBESAT Project ■Battery Charger ■3 candidates for Battery Charge Circuit MAX1679 MM1333 MM1485 •Small power dissipation •Small package (8 pins), •Small package (8 pins), •Const. Voltage & small power dissipation small power dissipation Current Charge Mode •Voltage&Temperature •Const. Voltage & •Pre-charge protection Current Charge Mode Temperature protection •Pre-charge, Timeout •No pre-charge func or •Large package (16 pins) •Need constant reset temperature protection and may be difficult to before IC‟s timeout assembly 2001 University of Tokyo CUBESAT Project ■Energy Consumption Components Power[mW] Frequency in use OBC 20 All times sensors 20 All times Tx TNC 20 During downlink Tx 6000 During downlink CW 300/125 All times (ON / OFF) CW TNC 20 All times Rx 125 All times Rx TNC 20 All times Camera 150 Sometimes Magnetic Plg. 800 Antennae deployment 2001 University of Tokyo CUBESAT Project ■Power Balance ■Points • Beacon can be sent by solar panels direct drive • Source and consumption must be balanced ■Solar cell average output 1228[mW] > Consumption at beacon use 900[mW] OK ■Maximum average supply power: 669[mW] > Average consumption 616[mW] OK 2001 University of Tokyo CUBESAT Project ■Attitude Control ■Objectives • To make CubeSat tumble in order to smooth thermal input • Point antennae to the ground station ■Methods • Use a permanent magnet and a libration damper 2001 University of Tokyo CUBESAT Project ■Control Mechanism ■Torque will be generated to align earth magnetic direction and Dipole CubeSat’s dipole Ground Moment Station Magnetic moment. Field ■ Libration is damped by energy dissipater. Antennae 2001 University of Tokyo CUBESAT Project ■Torquer Sizing Disturbance Torque[Nm] AirDrag 2.26E-10 Required Torque Solar Pressure 1.38E-9 1.0E-6 [Nm] Gravity Gradient 1.25E-8 To follow the change At 800km of magnetic field 1.0E-6 magnetic field Required Magnetic Dipole Moment 0.046 [Am^2] 2001 University of Tokyo CUBESAT Project ■Permanent Magnet Material Alnico-5 Magnetic Dipole Moment 0.05 [Am^2] Size φ4*25 [mm] Weight 2 [g] Residual Magnetic Flux Density 1300 [mT] 2001 University of Tokyo CUBESAT Project ■Libration Damper ■Libration damper dissipates energy to stable attitude change. • Dissipation caused by hysteresis loss and eddy current loss • High permeability iron is used for the damper • 3days are expected (8 days for worst case) to damp oscillation 2001 University of Tokyo CUBESAT Project Environment Subsystem 2001 University of Tokyo CUBESAT Project ■Environmental Tests (outline) Tried and Tested Future Works ■Heavy ion testing ■ Thermostat (PIC16F877 F84 C622 C774) EM-Plunger , Li -ion battery , C-MOS camera,Solar Panels ■Heavy ion testing (PIC16F877 C774 C622) ■ SEL testing DCDCs,OP-AMPs,Tx,Rx etc ■Li -ion battery testing (in a vacuum) ■ Vibration testing Solar Panels , EM-Plunger,EM ■C-MOS Camera testing (in a vacuum) ■ Thermal Vacuum Chamber XI-II α , EM , FM1 , FM2 2001 University of Tokyo CUBESAT Project ■Analysis (outline) ■ thermal analysis We construct a model of heat transfer by means of the node point method using C-programming. We will complete building 50nodes model and fixing the value of every parameter from XI- IIα testing. ■ SEE analysis We calculated SEE rate using the CRÈME software and provided reset functions to XI-IIα. ( http://crsp3.nrl.navy.mil/creme96/ ) 2001 University of Tokyo CUBESAT Project ■Tried and Tested ■Heavy ion testing ( at NASDA) 2000.09.12 source ; Calfornium (Cf252) Device Number Number Irradiation Fluence SEE Cross of SEU of SEL time[sec] [/cm^2] Section[cm^2/bit] F877 102 0 2502 332353 7.49272E-08 F84 101 3 1040 137956 3.57477E-07 C622 101 0 2599 344759 1.43046E-07 C774 101 0 2563 205669 1.19892E-07 (for quick look) 2001 University of Tokyo CUBESAT Project ■Tried and Tested ■Heavy ion testing ( at JAERI Takasaki) 2000.10.09 source ; 20Ne4+, 40Ar8+, 84Kr17+ Device SEU(Ne) SEU(Ar) SEU(Kr) LET=6.01 LET=15.1 LET=38.3 F877 1.6468E-07 2.1559E-08 ---- C622 8.4045E-10 9.6120E-09 ----- C774 1.8376E-08 2.4405E-08 4.1931E-08 ■Using CREME96 Results,We decided to use PIC16F877. Device SEUs/device/day F877 2.3514E-05 C622 1.26733E-06 C774 2.550029E-07 (height 600km,incrination=60°) cf. LET[MeV/(mg/cm^2)],SEU[cm^2/bit] 2001 University of Tokyo CUBESAT Project ■Tried and Tested ■ Vacuum chamber testing - Li ion battery test (2001.01.21 - 23 at UT-Arakawa Lab.) No deterioration observed in 10^-5 Torr evacuated chamber. 2001 University of Tokyo CUBESAT Project ■Analysis Quick look Height=600km Temperature of 6-nodes incrination =60° 6 nodes (CUBE planes) 10 Temperature[degree C] 8 mass density = Al density 6 T1 specific heat=920*9[J kg^-1K-1] 4 T2 conductivity=240[W m^-1K^-1] 2 T3 0 T4 ε=0.825 -2 0 20000 40000 60000 80000 100000 T5 α=0.805 -4 T6 -6 -8 time[sec] 2001 University of Tokyo CUBESAT Project ■Future Works We have a plan to execute EM-Plunger and XI-II α test with thermal vacuum chamber. (2001.04.10. - at ISAS Ohnishi Lab.) ~ Wires3 GND CW CW Vin(5V) Rx-TNC Rx-TNC ¨ BNCONS Battery Tx-TNC Tx-TNC GND OBC OBC Q flanged (Dsub50) Temperature sensor Serial Q flanged (Dsub50) Thermocouple sensor 9-wires A/D P flanged Q flanged (Dsub50) PIC 5V SW Mpx.B 2001 University of Tokyo CUBESAT Project ■Future Works Battery ON no yes OBC status(Serial) E5V C5V 10V Vop with checking telemetry yes Communication system status CW,Rx-TNC,Tx-TNC Executing partial test. yes no Running Long time Running Thermometer running OBC only for checking 2001 University of Tokyo CUBESAT Project ■Future Works CW Rx Tx ... Rx and Tx ... communicate 300 times per 5 minutes and suspend for 25 minutes . CW speak at all times. ... ... 2001 University of Tokyo CUBESAT Project ■Outgas Examination We choose following products from out-gas point of view. USE PRODUCT Wiring Fluorocarbon wires (H itachiC able Ltd. ) RTV LTV rubber KE1204(AL or BL) Rubber Si rubber KE9610/C-8B Bonding Agent SYLGARD184 ; FSXA-2869 USE TML CVCM WVR Wiring <0.1 <0.01 RTV 0.597 0.117 0.007 Rubber 0.846 0.052 0.736 Bonding Agent 1.740 0.660 0.040 ※However, they are not fixed yet. 2001 University of Tokyo CUBESAT Project ■Work Room Work Room Environment We will construct isolated work space to manufacture EM,FM1,FM2. (aiming at 1000-level clean room) ※Air conditioner HEPA Unit(SS-MAC) YAMATO science co. 2001 University of Tokyo CUBESAT Project Ground Segment 2001 University of Tokyo CUBESAT Project ■When can we contact?(1) Pass time for 1 week 1000 900 800 Pass time[sec] 700 600 500 400 300 200 100 0 Simulation passage time[hr] 2001 University of Tokyo CUBESAT Project ■When can we contact?(2) Åå } p 90 Maximum elevation angle (deg) 80 70 60 50 40 30 20 10 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 Pass # 2001 University of Tokyo CUBESAT Project ■When can we contact?(3) •There are 49 passes. which means we can contact with our CubeSat 6 or 7 times per day. •In those passes, 22 passes have an elevation over 20[deg]. •The longest pass time is about 900[sec]. •We have 1 or 2 chances to contact for 900[sec] everyday. 2001 University of Tokyo CUBESAT Project ■Necessary Time for Communication CW Beacon Downlink •CW Beacon is consist of 73 words. •If duty ratio is 0.3, it takes about 240[sec] to send 73 words. (60 words per minute ) FM Packet Telemetory downlink •Packet length is about 80 bytes. •Baud rate is 1200 [bps] , so it takes 0.54[sec] to receive a packet. 2001 University of Tokyo CUBESAT Project ■Operation Plan FM Packet 1200bps Uplink Command CW Beacon If we can receive the CW Beacon, we send Uplink Command once or twice a day. 2001 University of Tokyo CUBESAT Project ■How to handle Downlink Data We expect it may be difficult for us to receive and decode downlink data perfectly, so we prepare backup system to get something of traces of downlink data. •Recording CW Beacon & Telemetry Packet to Mini Disk. •Original TNC skipping CRC (check sum). 2001 University of Tokyo CUBESAT Project ■Ground Station Equipment(1) 144MHz/430MHz Antenna Transceiver, TNC, etc. 2001 University of Tokyo CUBESAT Project ■Ground Station Equipment(2) •144MHz/430MHz cross Yagi antenna [WHS32N, MASPRO] •430MHz cross Yagi antenna (TBD) •Antenna rotator & controller for azimuth [750FX, EMOTATOR] •Antenna rotator & controller for elevation [EV800, EMOTATOR] •VHF/UHF multi band all mode transceiver [IC-970J, ICOM] •VHF/UHF multi band all mode transceiver (Equipped for 9600bps packets) [IC-910D, ICOM] 2001 University of Tokyo CUBESAT Project ■Ground Station Equipment(3) •TNC [TNC505,TASCO] •TNC (With function to co-decode CW signal) [TNC555, TASCO] •TNC (Skipping CRC) [handmade] •Signal converter [I/F between PC and rotators] •Level converter [CT17, ICOM (I/F between PC and Tranceivers] •PC (OS:Window98) •MDLP mode MD recorder (TBD) [MDS-S50, SONY]×2 2001 University of Tokyo CUBESAT Project ■Ground Station Configuration Command TNC-505 144MHz uplink Telemetory IC-970J TNC 430MHz Telemetory downlink MD recorder PC MD recorder (Windows98) 430MHz CW downlink IC-910D TNC-555 CW beacon EV-800 Signal 750FX CT17 converter Frequency, Azimuth, Elevation http://www.space.t.u-tokyo.ac.jp/cubesat 2001 University of Tokyo CUBESAT Project ■Message Mission ■Message from all over the world will be microfilmed and packed in CubeSat ■Themes are • Dreams for space • CubeSat mission proposal etc. ■Messages are accepted by postal cards. ■Details are uploaded to WebPages 2001 University of Tokyo CUBESAT Project ■Program Timeline 3 4 5 6 7 8 9 10 11 FM Shipment (8/15) Launch TCDR FM Deadline CDR Mass Model Shipment (3/19) Long Range Comm. Experiment *postponed EM Deadline red char. : contract matter 2001 University of Tokyo CUBESAT Project ■Concerns (Electronics) ■We made a reset system for countermeasure against SEL, but still do not decide the SEL threshold current. How do we decide it and how much should we have a margin for it? ■For countermeasure against SEU, we will set only Watch Dog Timer. Is it enough? How can we detect SEU? 2001 University of Tokyo CUBESAT Project ■Concerns (Communication) ■When and by whom will our CubeSat‟s call sign be distributed? ■Only one frequency band is allocated for up-link command. If some developers uses the same protocol (ex. AX.25), how each Cubesat distinguishes its GS‟s command from other GS‟s command? Are there any regulations? ■Does our Cubesat require an impedance matching circuit between transceiver and antenna? ■Is it necessary to conduct a radiation environment test to FSK modulator-demodulator? ■Must our Cubesat equip space rated coaxial cable? Now, we are planning to use normal one (1.5D2V). 2001 University of Tokyo CUBESAT Project ■Concerns (Environment) ■the thermal vacuum testing regulation for Flight Model ■TML,CVCM limits ■the Vibration testing on Flight Model. 2001 University of Tokyo CUBESAT Project ■Concerns (Power) ■Is the use of a permanent magnet permitted? ■ When can we charge batteries last? 2001 University of Tokyo CUBESAT Project ■Concerns (Ground) ■How can we get the orbital information of our CubeSat?
Pages to are hidden for
"cdr"Please download to view full document