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.

4th IVS General Meeting

上海天文台Shanghai Astronomical Observatory

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

4. Plan of VLBI spacecraft tracking in China


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


Huygens VLBI tracking team (abbreviated)

JIVE ESA-ESTEC NASA-JPL NRAOI.M.Avruch C.. van’t Klooster S.Asmar W.BriskenH.Bignall J.-P.Lebreton W.Folkner F.GhigoA.Brunthaler R.A.Preston G.LangstonR.M.Campbell J.RomneyM.A.Garrett L.I.Gurvits, R.OerlemansS.V.Pogrebenko

ASTRON ATNF U Tasmania NICT (CRL)A.R.Foley J.Lovell G.Cimo T.Kondo

C.Phillips. S.Elingsen

U Bonn J. Reynolds B.ReidM.Bird R.Sault.

T.Tzioumis

NAO China Helsinki U ISAST.An (ShAO) A.Mujunen R.DodsonX.Hong (ShAO) J.RitakariS.Huang (ShAO)D.Jiang (ShAO)X.Liu (UAO)

12 institutes and international 12 institutes and international organizations in 7 countriesorganizations 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


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


VLBI Stations in China


Nanshan (Urumqi) at sunrise

Seshan (Shanghai)


Beijing & Kunming station in constraction


Test bed for receiver noise test


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


New Antenna service system in Seshan station


New S/X band Cryogenic Receivers in Seshan Station


New S/X band Cryogenic Receivers in Nanshan Station


New Pcal in Nanshan Station


5 Station Correlator in developing


3. Some test observation results


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 Source8 MHz Bandwidth for TC-1 and Radio Sour

ce

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 signalRight Above : sheshan stationRight 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

dB

dB

MHz

MHz

Wide Band mode

Narrow Band mode


The compare results of delay and delay rate between

VLBI observe and ESA Smart-1 reconstruction orbit

Resuduals Delay Resuduals delay rate

SH - UR

KM - SH

KM - UR

SH - UR

KM - SH

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


Thanks !

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.

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