Overview of the Small Optical TrAnsponder (SOTA) Project Space Communications Laboratory Wireless Networks Research Center National Institute of Information and Communications Technology (NICT)
Satellite mass v.s Data rate of Satellites ever launched 1.0E+12 Data rate for Earth observation satellites [bps] 1.0E+09 1.0E+06 1.0E+03 Micro satellites TerraSAR-X WorldView1 EROS-B Formosat2 GeoEye-1 Orbview3 Kompsat2 ALOS Orbview4 JERS1 EOS-PM1 Ikonos2 Radarsat1 TopSat QuickBird2 Lewis ERSEnvisat1 Landsat ADEOS Spot UK-DMC2 RazakSat-1 MOS 1B MOS 1A Terra UK-DMC1 EROS-A IRS-1A,1B,1C AS1000 AlSat Orbview2 TRMM MicroLabSat EarlyBird Cute-1.7 PRISM TOMS-EP Cute-I 1 10 100 1000 10000 Satellite mass [kg] 2
Laser-Communication Infrastructure for Micro-Satellites Short-term space verification by micro satellites (2~3 years) High-end communications by mid/small satellites (5~ years) Data rate for Earth observation satellites [bps] 1.0E+12 1.0E+09 1.0E+06 1.0E+03 New area covered by SOCRATES/SOTA Cute-I Cute-1.7 Optical ~Mbps Micro satellites RF ~kbps PRISM WorldView1 EROS-B Formosat2 GeoEye-1 Orbview3 Kompsat2 ALOS Orbview4 JERS1 EOS-PM1 Ikonos2 Radarsat1 TopSat QuickBird2 ~100Mbps Lewis ERSEnvisat1 Landsat ADEOS Spot UK-DMC2 RazakSat-1 MOS 1B MOS 1A Terra UK-DMC1 EROS-A IRS-1A,1B,1C AS1000 AlSat Orbview2 TRMM MicroLabSat Mid/small satellites Gbps EarlyBird TOMS-EP TerraSAR-X 1 10 100 1000 10000 Quasi-real-time data transmission via site diversity Offline transmission only Satellite mass [kg] 3
Research Activities on Space Laser Communications in NICT 1995 2000 2005 2010 2015 2020 ETS-VI (KIKU6) 1994-1995 http://www.jaxa.jp/projects/sat/ets6/index_j.html GEO-GND OICETS (KIRARI) 2005-2009 http://www.jaxa.jp/projects/sat/oicets/index_j.html LEO-GND GEO-LEO ETS-IX 2021 GEO-GND SOCRATES 2014-2016 RISESAT with Tohoku Univ. LEO-GND 2017? LEO-GND 4
Overview of SOTA SOTA: Small Optical TrAnsponder Data rate : 1 10 Mbps Wavelength : Tx 0.8 / 0.98 / 1.55 µm Rx 1.064 µm Beam pointing : Az - El mount + Fine-pointing mirror SOCRATES 衛星に組み込まれた SOTA Mass : 6.2 kg (including optical and control part) One of the smallest optical-communication terminals for spacecraft equipment 5
Development of SOTA Project started PDR CDR Launch End of operation 2010 2011 2012 2013 2014 2015 2016 2017 QKD lasers Coarse sensor Fine sensor Checkout Experiments SOTA Workshop Receiver Transmitting Laser BBM model Mass: 5.3 kg, Power: 22.8 W Size: W149xD188xH160 PFM model Mass: 6.2 kg, Power: 39.5 W Size: W65xD114xH138 6
Major Specifications of SOTA SOTA-OPT Mass Power consumption Gimbal range Link range Wavelength Data Rate 5.9 kg (incl. both the optical part & electric part) Sleep Standby Tx2,3, Tx1 mode 4 1.7W 2.0W 15.7W 12.6W Az: >±50deg, El: -22deg~+78deg Less than1000 km Tx1: 976 nm Tx2 and Tx3 : 0.8 μm Tx4 : 1549 nm Rx: 1064 nm, Acquisition/Tracking: 1064 nm 1Mbps / 10Mbps (selectable) Photograph and Layout of SOTA-PFM optics (Proto Flight Model) 7
Small Satellite SOCRATES Satellite bus developed by AES SOTA Solar Paddle Size W496 x D495 x H485 mm Mass : 48kg AES Attitude control : 3-axis stabilization 8
Optical Ground Station in Koganei (1-m Diameter) - 1-m diameter reflective telescope - Improved tracking ability for LEO satellites - Focus availability: 5 ports (Cassegrain, Nasmyth, Coude ) Koganei Major specification Mount Altazimuth Focus Classical Cassegrain Diameter f1000 mm D/f F12 Tracking accuracy LEOs < 10 arcsec Stars < 0.4 arcsec (EL > 30 deg.) Stars < 1 arcsec (EL=15~30 deg.) Angle coverage Azimuth ±270 deg. Elevation 15~88 deg. Total mass 7.5 t Tube mass 1.3 t Nasmyth payload mass 1 t (max) 9
Launch 24th of May, 2014 Piggyback satellite of the ALOS-2 DAICHI-2 Advanced Land Observing Satellite http://h2a.mhi.co.jp/mission/results/index.html Orbit : Sun-synchronous sub-recurrent orbit Altitude : 628km 10
- Configuration of SOTA Experiment - Ground system 3) Beacon laser Small satellite system Optical ground station (OGS) (NICT Koganei) 4) Tx laser Small Optical TrAnsponder (SOTA) Direct Comm. Small camera 1) Parameters 6) Telemetry TT&C station 2) Commands TT&C 5) Telemetry data Data & control signals Image data & control Small satellite bus *TT&C: Tracking, Telemetry and Control 11
Schedule of Conducted Experiments Date Event May 24, 2014 SOCRATES Launch ~ July Check out of the satellite ~ Oct. Check out of the OGS and the SOTA Nov. ~ May, 2015 ~ Spring, 2016 ~ Experiments for the NICT Start of international experiment campaign Resumption of international experiment campaign 12
Statistics of Total 184 Passes Satellite Trouble 2 passes 26% Both Uplink Downlink Established 47 passes Bad Weather Forecast 67 passes No Go 38 % Go 62 % 21% Only Uplink Established 21 passes Failed (due to Satellite) 17 passes Failed (due to OGS) 30 passes 13
Success Criteria No. Experiment items Contents Status Minimum success M1 Start-up check of Demonstration of COTS parts equipment Done M2 Confirmation of optical Demonstration of COTS parts sensors etc. Done Success S1 Tracking test Confirmation of orbit, bus attitude control and mounted equipment Done S2 Acquisition of the received signal, data acquisition at Propagation data different wavelengths (Uplink: 1064nm / Downlink: acquisition TX1, TX4) Done S3 BER measurement Downlink: TX1, TX4 Done Full success F1 Data transmission Confirmation of data transmission functions ( Data: experiment CAM / PRBS / Sample image ) ( Downlink: TX1, TX4) Done F2 Error correcting code LDGM and RS codes Done E1 E2 Polarization measurement International experiment Extra success Weak coherent pulses are measured by single photon counting detectors (SPCMs). Experiment with other international optical ground stations (OGSs) except for Koganei OGS. Done Done 14
Site-Diversity Technology Weather-monitoring stations Whole-sky monitor camera Optical communication satellite Cloud Laser beam OGS control center OGS http://sstg.nict.go.jp 15
Optical Ground Stations Network Koganei 1m Koganei 1.5m Okinawa 1m Kashima 1m 16
Overview of In-orbit Experimental Results with SOTA Overview of the SOTA project NICT s New OGS In-orbit performance of SOTA Atmospheric-turbulence analysis BER measurement Data-transmission experiment Error-correcting code experiment QKD-related experiments LEO-satellite optical observation with NICT portable telescope Optical detection for SOTA downlink experiment using SSPD International joint-experiment campaign 17
Summary (1) Space-to-ground laser-communication experiments with the SOTA terminal have been successfully conducted. (2) Almost all of the success criteria from minimum- to extra-success have been done, including international experiments. (3) World first lasercomm technology for a 50-kgclass micro-satellite was verified with several international partners globally, which has opened the door to a variety of applications to be exploited soon with the rise of mega-constellations. 18