一般

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1 Micro Sun Sensor with CMOS Imager for Small Satellite Attitude Control Keisuke Yoshihara, Hidekazu Hashimoto, Toru yamamoto, Hirobumi Saito, Eiji Hirokawa, Makoto Mita Japan Aerospace Exploration Agency Kota Magoshi Magoshi Corp. 19 th ANNUAL AIAA/USU CONFERENCE ON SMALL SATELLITES

2 Contents Introduction General description of the MSS Concept Functionality and Architecture Design target and Current Status Substantial test results Radiation test for COTS APS Optical performance test Summary Japan Aerospace Exploration Agency (JAXA) / STDRC 1

3 Introduction JAXA s research and development program for next generation small satellite bus technology On-board computer, attitude sensor, reaction control system etc Newly-developed components and subsystems are planed to be installed in the MicroLabSat-II for on-orbit demonstration. Micro Sun Sensor MicroLabSat-II Japan Aerospace Exploration Agency (JAXA) / STDRC 2

4 Concept of the MSS The general concept of the MSS is to achieve good balance of size, mass, power consumption and performance. Design concept of the MSS Adoption of the CMOS APS as detector - MSS s simplicity and lower power consumption. FPGA based signal processing - Simplicity and compactness of the digital electronics. - Flexibility in the implementation of the signal processing. Using COTS APS, optical filter and EEPROM - The state-of-the-art commercial parts are high performance and lower cost. - Radiation hardness is not guaranteed is verified by radiation test. Japan Aerospace Exploration Agency (JAXA) / STDRC 3

5 Concept of the MSS Measurement principle Sunlight incident on the APS through a cross-shaped slit. The coordinates of the intersection of sun image are computed. (Centroid calculation acquires sub-pixel resolution and accuracy) Two axis solar aspect angle is derived from the intersection coordinates. Boresight Sun incidence Evaporated cross- shape Slit Non- browning glass ND filter Cross- shape Slit Green filter Mask Sensor Elect ronics board CMOS image sensor Slit image CMOS APS Chassis Intersection point (H, V) Transfer function calculation Sun incident direction (θ, φ) Japan Aerospace Exploration Agency (JAXA) / STDRC 4

6 Functionality and Architecture Function and technology Output of pixel coordinates of sunlight intersection for solar angle Solar calculation in OBC. Raw pixel data output for APS test. Direct access (read/write) to ROM and RAM. Overcurrent detection and reconfiguration. Optical Filter and Slit CMOS APS Electronics architecture Signal processing and command /telemetry handling functions are implemented in a single FPGA. CMOS/TTL serial data interface. (RS-422 is also available) Telemetry Command Power Supply RAM EEPROM Interface Filter Image data XO FPGA Voltage regurator Micro Sun Sensor Block Diagram Japan Aerospace Exploration Agency (JAXA) / STDRC 5

7 Design Target and Current Status Design Target Item Dimension Mass Power FOV Performance Specifications 60mm(W) * 60mm(D) * 60mm(H) 330g 5VDC, < 1.5W (nominal) 90 90deg <0.1deg (bias error, 3sigma) <0.01deg (random error, 3sigma) Status Ground Test Model (GTM) was fabricated and tested. GTM satisfies all MSS s design target. Japan Aerospace Exploration Agency (JAXA) / STDRC 6

8 Radiation Test for Commercial APS Gamma rays irradiation test with Co60 The APS operated normally and did not lose any function in 25krad expose. The dark current level was increased after gamma irradiation and recuperated after annealing. The reduction of the sensitivity was not identified. Shift in dark current (Gamma irradiation test) CMOS sensor output LSB Sample_1 Sample_2 Sample 3 0 Before irradiation Irradiation#1 (5krad) Annealing#1 Irradiat ion#2 (20krad) Annealing#2 Japan Aerospace Exploration Agency (JAXA) / STDRC 7

9 Radiation Test for Commercial APS Proton irradiation test The APS operated normally and did not lose any function in 25krad expose. The increase of the dark current level and pixel-to-pixel variations of the dark current were identified. Some recoveries out of degradation were confirmed after annealing. The reduction of the sensitivity was not identified. 10 Shift in dark current (Proton irradiation test ) CMOS sensor output LSB krad 25krad 0 Before irradiation Irradiation Annealing Japan Aerospace Exploration Agency (JAXA) / STDRC 8

10 Radiation Test for Commercial APS Summary of the radiation tests Minor degradation of several optical characteristics of the APS was identified in gamma and proton irradiation test. However the MSS is expected to maintain all functions and necessary optical performance in 25krad irradiation. Japan Aerospace Exploration Agency (JAXA) / STDRC 9

11 Optical Performance Test Objective To evaluate the accuracy (bias and random error) of the MSS over the whole FOV. To defined transfer function. To evaluate the effect of spin rate on the performance of the MSS. MSS on gimbal system MSS output (pixel coordinates of intersection point of sunlight) rotation Sunlight (from solar simulator) Transfer Function rotation Sun incident direction (two axis angles of gimbal system) Japan Aerospace Exploration Agency (JAXA) / STDRC 10

12 Optical Performance Test Bias error evaluation Bias error satisfied the target specification (<0.1deg) over whole FOV Error in horizontal angle determination Error in vartical angle determination Error in horizontal angle determination Error in vartical angle determination Bias error[deg] Bias error[deg] Sensor angle of incidence [deg] (horizontal scanning) Sensor angle of incidence [deg] (vertical scanning) Japan Aerospace Exploration Agency (JAXA) / STDRC 11

13 Optical Performance Test Random error evaluation The random error is associated with the strength of the sun incidence. Random error satisfied the target specification Error in horizontal angle determination Error in vertical angle determination Strength of sun incidence Error in horizontal angle determination Error in vertical angle determination Strength of sun incidence Random error (3σ ) [deg] Strength of sun incidence [LSB] Random error (3σ ) [deg] Strength of sun incidence [LSB] Sensor angle of incidence [deg] (horizontal scanning) Sensor angle of incidence [deg] (vertical scanning) Japan Aerospace Exploration Agency (JAXA) / STDRC 12

14 Optical Performance Test Dynamic performance evaluation MSS data was acquired in the situation that the gimbal was rotating. Remarkable increase of the performance error was not identified in 6RPM Sun incident angle (true value) Static test data "+6rpm" "-6rpm" Vertical angle[deg] Horizontal angle[deg] Japan Aerospace Exploration Agency (JAXA) / STDRC 13

15 Optical Performance Test Summary of the optical performance tests Both the bias error and the random error of the MSS satisfied the target specification. It was confirmed that the MSS can maintain its optical performance in the rate of 6RPM. Item Test result Target value Bias Error [deg] (3 sigma) Random Error [deg] (3 sigma ave.) Horizontal < Vertical < Horizontal < Vertical < < 0.1 < 0.01 Japan Aerospace Exploration Agency (JAXA) / STDRC 14

16 Summary JAXA is developing the new type of Micro Sun Sensor. The MSS adopts a CMOS APS as a detector and a FPGA for signal processing. The GTM (Ground Test Model) of the MSS was fabricated and tested. The major design of the FM (flight model) could be established. The environmental tests for GTM are planned in this year. After the series of environmental test, the MSS FM will be stated to produce for the MicroLabSat-II. Japan Aerospace Exploration Agency (JAXA) / STDRC 15

17 Thank you for your attention! Japan Aerospace Exploration Agency (JAXA) / STDRC 16

Small satellite activity in Japan Name Cubesat (XI) Cubesat

Organization JAXA/ISTA/ STDRC Mass 1kg 1kg 50kg 50kg 54kg 60kg

Microsat bus demo, precursor misson, training Advanced

observation, engineering experiment Launch 2003 2003 2002 TBD

operation In operation Under In operation Under Preparing for

18 Small satellite activity in Japan Name Cubesat (XI) Cubesat (CUTE-1) WEOS SOHLA-1 MicroLabSat MicroLabSat 2 INDEX Organization JAXA/ISTA/ STDRC Mass 1kg 1kg 50kg 50kg 54kg 60kg 70kg Main mission Education, technology demo. Education, technology demo. Whale ecology observation Training, technology demo. Microsat bus demo, precursor misson, training Advanced microsat bus and space technology demo, training Aurora observation, engineering experiment Launch TBD 2002 TBD 2005 STATUS Univ. of Tokyo Tokyo Inst. of Tech. Chiba Inst. of Tech. SOHLA (SMEs union) JAXA/ISTA/ STDRC JAXA/ISAS In operation In operation In operation Under In operation Under Preparing for development development launch Furthermore, several small satellite projects are also being planned by other universities and organizations in Japan. Japan Aerospace Exploration Agency (JAXA) / STDRC 17

MicroabSat-II Satellite Main characteristics 50kg-class micro-satellite Earth oriented 3-axis attitude control Carry and release a nano-satellite on orbit Item Size Mass Power Attitude Comm.

19 MicroabSat-II Satellite Main characteristics 50kg-class micro-satellite Earth oriented 3-axis attitude control Carry and release a nano-satellite on orbit Item Size Mass Power Attitude Comm. Characteristics 600(W) 600(D) 500(H)mm 200(W) 200(D) 150(H)mm(NanoSat) 60kg(Total), 5kg(NanoSat) 100W Earth oriented 3-Axis control Micro LabSat II Ground Station: S-band, 4kbps(Up), 1.6Mbps(Down) NanoSat Ground Station: S-band Micro LabSat II NanoSat: TBD Nano satellite Orbit LEO, Sun synchronous Launch TBD (The completion of development < 2008) MicroLabSat-II image Japan Aerospace Exploration Agency (JAXA) / STDRC 18

satellite Up Link Down Link Up Link Down Link Down Link Up Link Ground Station Ground Station Ground Station Before

20 Experiment in collaboration with NanoSat GPS data Magnetometor GPS data Magnetometor Nano satellite Inter-satellite communication GPS data High resolution camera Micro labsat II Micro labsat II Same frequency Magnetometor Nano satellite Up Link Down Link Up Link Down Link Down Link Up Link Ground Station Ground Station Ground Station Before release nano satellite Experiment image in collaboration with nano-satellite Japan Aerospace Exploration Agency (JAXA) / STDRC 19

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untitled Ver.1 29/5/2009 1 UNISEC (UNIversity Space Engineering Consortium) UNITEC-1 (UNIsec Technological Experiment Carrier-1) 2010 5 UNITEC-1 GHz C CW UNISEC AMSAT UNITEC-1 TBD CW UNITEC-1, 2 1. UNITEC-1 UNISEC