1. 上海天文台 Shanghai Astronomical Observatory 4th IVS General Meeting Spacecraft Tracking with Chinese VLBI Network Xiuzhong Zhang and Chinese VLBI Network Team Shanghai Astronomical Observatory Chinese Academy of Sciences

2. 上海天文台 Shanghai Astronomical Observatory Outline 1. introduction 2. Configuration of tracking test system 3. Some test observation results 4. Plan of VLBI spacecraft tracking in China

3. 上海天文台 Shanghai Astronomical Observatory 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. 1. Introduction

4. 上海天文台 Shanghai Astronomical Observatory Some events of spacecraft tracking with VLBI 1980s: VLA as a supersensitive deep space “ downlink ” station 1980s: NASA DSN stations (Goldstone, Robledo, Tidbinbilla) begin their VLBI duties 1984-86: VLBI tracking of the Venus baloons (VEGA mission) and VEGA-Giotto Pathfinder experiment (Intercosmos-ESA-NASA) 1990s: phase-referencing “ satellite-3C279 ” demo (Asaki, Sasao et al.) Activities of Spacecraft tracking with VLBI in Japan 2005: Radio Astronomy segment of the Huygens mission

5. 上海天文台 Shanghai Astronomical Observatory Huygens the Titan Probe as seen with a VLBI magnifier Leonid Gurvits and VLBI tracking team Joint Institute for VLBI in Europe (JIVE) Dwingeloo, The Netherlands

6. 上海天文台 Shanghai Astronomical Observatory Huygens VLBI tracking team (abbreviated) JIVEESA-ESTECNASA-JPLNRAO I.M.AvruchC.. van’t KloosterS.AsmarW.Brisken H.BignallJ.-P.LebretonW.FolknerF.Ghigo A.Brunthaler R.A.PrestonG.Langston R.M.Campbell J.Romney M.A.Garrett L.I.Gurvits, R.Oerlemans S.V.Pogrebenko ASTRONATNFU TasmaniaNICT (CRL) A.R.FoleyJ.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.MujunenR.Dodson X.Hong(ShAO)J.Ritakari S.Huang(ShAO) D.Jiang(ShAO) X.Liu(UAO) 12 institutes and international organizations in 7 countries

7. 上海天文台 Shanghai Astronomical Observatory 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

8. 上海天文台 Shanghai Astronomical Observatory 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 Spacecraft tracking with VLBI in China

9. 上海天文台 Shanghai Astronomical Observatory VLBI Stations in China

10. 上海天文台 Shanghai Astronomical Observatory Nanshan (Urumqi) at sunrise Seshan (Shanghai)

11. 上海天文台 Shanghai Astronomical Observatory Beijing & Kunming station in constraction

12. 上海天文台 Shanghai Astronomical Observatory Test bed for receiver noise test

13. 上海天文台 Shanghai Astronomical Observatory 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

14. 上海天文台 Shanghai Astronomical Observatory New Antenna service system in Seshan station

15. 上海天文台 Shanghai Astronomical Observatory New S/X band Cryogenic Receivers in Seshan Station

16. 上海天文台 Shanghai Astronomical Observatory New S/X band Cryogenic Receivers in Nanshan Station

17. 上海天文台 Shanghai Astronomical Observatory New Pcal in Nanshan Station

18. 上海天文台 Shanghai Astronomical Observatory 5 Station Correlator in developing

19. 上海天文台 Shanghai Astronomical Observatory 3. Some test observation results

20. 上海天文台 Shanghai Astronomical Observatory 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

21. 上海天文台 Shanghai Astronomical Observatory Test observations in Mar. 17 – 20, 2005 with TC-1 Apogee : > 80000Km

22. 上海天文台 Shanghai Astronomical Observatory Orbiting result with VLBI Resuduals delay: 1.5624m(mean), 12.4448m(RMS)

23. 上海天文台 Shanghai Astronomical Observatory SMART-1 TT&C downlink signal Right Above : sheshan station Right Down : Urumqi station

24. 上海天文台 Shanghai Astronomical Observatory

25. 上海天文台 Shanghai Astronomical Observatory 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.

26. 上海天文台 Shanghai Astronomical Observatory Smart-1 orbiting with VLBI Observation Observe time (UT) ： March 20, 2005 10 h 30 m  16 h 50 m 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 ： 2230.99  2238.99 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

27. 上海天文台 Shanghai Astronomical Observatory Smart-1 S Band (2.2GHz) downlink Signal dB MHz Wide Band mode Narrow Band mode

28. 上海天文台 Shanghai Astronomical Observatory The compare results of delay and delay rate between VLBI observe and ESA Smart-1 reconstruction orbit Resuduals DelayResuduals delay rate SH - UR KM - SH KM - UR SH - UR KM - SH KM - UR

29. 上海天文台 Shanghai Astronomical Observatory 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

30. 上海天文台 Shanghai Astronomical Observatory Thanks !