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Spacecraft Tracking with Chinese VLBI Network Xiuzhong Zhang and Chinese VLBI Network Team Shanghai Astronomical Observatory Chinese Academy of Sciences. Outline. 1. introduction 2. Configuration of tracking test system 3. Some test observation results
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Spacecraft Tracking with Chinese VLBI NetworkXiuzhong Zhang and Chinese VLBI Network TeamShanghai AstronomicalObservatoryChinese Academy of Sciences 4th IVS General Meeting
Outline 1. introduction 2. Configuration of tracking test system 3. Some test observation results 4. Plan of VLBI spacecraft tracking in China
1. Introduction • VLBI system with highest resolution technique is used for astronomers in radio wave domain; • e-VLBI has got rapid progress in the past 4-5 years; • More and more computing power with a single IC chip; • With these characteristics, VLBI system becomes to possible to make real time tracking for spacecraft orbiting application.
Huygens VLBI tracking team (abbreviated) JIVEESA-ESTECNASA-JPLNRAO I.M.Avruch C.. van’t Klooster S.Asmar W.Brisken H.Bignall J.-P.Lebreton W.Folkner F.Ghigo A.Brunthaler R.A.Preston G.Langston R.M.Campbell J.Romney M.A.Garrett L.I.Gurvits, R.Oerlemans S.V.Pogrebenko ASTRONATNFU TasmaniaNICT (CRL) A.R.Foley J.Lovell G.Cimo T.Kondo C.Phillips. S.Elingsen U Bonn J. Reynolds B.Reid M.Bird R.Sault. T.Tzioumis NAO ChinaHelsinki UISAS T.An (ShAO) A.Mujunen R.Dodson X.Hong (ShAO) J.Ritakari S.Huang (ShAO) D.Jiang (ShAO) X.Liu (UAO) 12 institutes and international organizations in 7 countries
Spacecraft TT&C Signal Characteristics • Narrow bandwidth several hundred KHz • Relative strong signal to noise rate • Special signal spectrum with special structure • The dynamic range of signal amplitude relative large
Spacecraft tracking with VLBI in China • CVN started spacecraft tracking science 2001 • Different orbit spacecraft have been observed with VLBI system. i.e. GEO, TC-1, TC-2, SMART-1, deep space probe • VLBI tracking of the Venus balloon • Many system equipment have been improved • Prepare to do the orbiting of CE-1 • Study of spacecraft tracking method
Nanshan (Urumqi) at sunrise Seshan (Shanghai)
工艺设备——上海测站子系统(天线改造后) Up: New S band feedback Left:New S/X band feedback
Test Observations in March 17 – 20, 2005 • SH(25m), UR(25m), KM(3m telescope) • CVN Disk Array recorder • S Band for TC-1, S/X Band for Radio Source 8 MHz Bandwidth for TC-1 and Radio Source • Radio Source : 3C454.3,3C84 for correct the difference of station clocks
Test observations in Mar. 17 – 20, 2005 with TC-1 Apogee : > 80000Km
Orbiting result with VLBI Resuduals delay: 1.5624m(mean), 12.4448m(RMS)
SMART-1 TT&C downlink signal Right Above : sheshan station Right Down : Urumqi station
Observation of Smart-1 (SH – UR) Sept. 22, 2004 UTC, the distance between Smart-1 and the earth is more than 280,000Km . Used 0.5 second data via FTP for fringe checking, with these data, the delay accuracy is 0.6ns and delay rate accuracy is 1.8ps/s.
Smart-1 orbiting with VLBI Observation Observe time (UT):March 20, 2005 10h30m 16h50m Orbit of Smart-1:polar orbit, apogee 2833Km,perigee 498Km,period 4.95 hours station:Seshan (25m),Nanshan(25m),Kunming(3m)。 Frequetion of carrie wave :2235.10 MHz Observe frequency: 2230.992238.99 MHz Bandwidth:8.0 MHz 。 Radio source :3C84,4C39.25,3C279。 MK5A recorder, 16 Mbps, Data processing :Shanghai VLBI data processing center Integration time :4s
Smart-1 S Band (2.2GHz) downlink Signal Wide Band mode dB MHz Narrow Band mode dB MHz
The compare results of delay and delay rate between VLBI observe and ESA Smart-1 reconstruction orbit Resuduals Delay Resuduals delay rate SH - UR SH - UR KM - SH KM - SH KM - UR KM - UR
Future Plans • Develop and create a 4 stations VLBI network for astronomy and spacecraft tracking • Prepare to do the near real time orbit tracking of CE-1 (Chinese lunar project, will be launched in 2007) • Study the method of Deep space spacecraft tracking