1 / 24

M.Sekido, R.Ichikawa,H.Osaki, T.Kondo,Y.Koyama (National Institute of Information and

ASTROMETRY OBSERVATION OF SPACECRAFT WITH VERY LONG BASELINE INTERFEROMETRY - --- A STEP OF VLBI APPLICATION FOR SPACECRAFT NAVIGATION ----. M.Sekido, R.Ichikawa,H.Osaki, T.Kondo,Y.Koyama (National Institute of Information and Communications Technology :NICT,Japan)

tcobos
Download Presentation

M.Sekido, R.Ichikawa,H.Osaki, T.Kondo,Y.Koyama (National Institute of Information and

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ASTROMETRY OBSERVATION OF SPACECRAFT WITH VERY LONGBASELINE INTERFEROMETRY---- A STEP OF VLBI APPLICATION FOR SPACECRAFT NAVIGATION ---- M.Sekido, R.Ichikawa,H.Osaki, T.Kondo,Y.Koyama (National Institute of Information and Communications Technology :NICT,Japan) M.Yoshikawa,T.Ohnishi(ISAS,Japan), W.Cannon, A.Novikov (SGL,Canada), M.Berube (NRCan,Canada), and NOZOMI VLBI group(NICT,ISAS,NAOJ,GSI,Gifu Univ. Yamaguchi Univ., Hokkaido Univ., Japan)

  2. VLBI R&RR + R02 R01 SC Astrometry Spacecraft Navigation with VLBI: Motivation Requirments for increased accuracy of orbit control for future space missions: • For landing, orbiting, & saving energy

  3. Jun. Jan. Feb. Mar. Apr. May May 22, 24, 27 VLBI Observations June 4 NOZOMI’s Earth Swing-by • NOZOMI was launched in July 1998. • Due to some troubles, new orbit plan with Earth swing-by was proposed. • R&RR observations were difficult in a period.

  4. Japanese and Canadian VLBI Stations participated in NOZOMI VLBI observations. ISAS,CRL,NAOJ, GSI,Gifu Univ, Yamaguchi Univ. Hokkaido Univ. SGL, NRCan supported. Algonquin SGL & NRCan Tomakomai (Hokkaido Univ.) Mizusawa (NAO) Usuda (ISAS) Gifu (Gifu Univ.) Tsukuba (GSI) Yamaguchi (Yamaguchi Univ.) Koganei (CRL) Kashima (CRL) Kagoshima(ISAS) (uplink)

  5. For astrometry of S.C.Tasks to be done are • VLBI delay mode for Finite distance radio source • A New VLBI delay Model corresponding to the CONSENSUS model. • Narrow band width of the signal • Group delay or Phase delay • Delay Resolution: (nano/pico seconds) • Ambiguity problem • Data Processing and Analysis software • IP-sampler boards recording to HD • Software correlation & Analysis software

  6. S B X Y RY0 RX0 K B X Y VLBI delay model for finite distance radio source Normal VLBI VLBI for finite distance radio source (Fukuhisma 1993 A&A)

  7. VLBI delay model for finite distance radio source CONSENSUS MODEL (M.Eubanks 1991) Finite Distance VLBI MODEL (Sekido & Fukushima 2003)

  8. Finite-Infinite : Delay Difference

  9. Analysis Procedure for SC Astometory I. Compute a priori (delay, rate) (C) and partials • We modified “CALC9”for our use(finite VLBI). (Thanks to GSFC/ NASA group for permission to use) II. Extracting Observable (tg, tp)(O) with software correlator. III. Computing O-C and least square parameter estimation

  10. Observable: Phase Delay & Group delay 2p n ambiguity tg:Group Delay Dtp ~ 1/RF ~1 pico second Phase Phase Delay Dtg ~ 1/BW ~1 nano second (Spacecraft) Band width 0 Frequency

  11. Group Delay(Post-fit Residual) Rate residual Delay Residual

  12. Group Delay(Domestic Baselines) 6/4(R&RR) 6/4(VLBI) June 4 Orbit motion May 27 Origin is Orbit on May 27, which was Determined by ISAS with R&RR Origin is Orbit on June 4.

  13. Closure of Phase delay (Kashima-Usuda-Tsukuba) Kashima-Usuda-Tsukuba Phase delay

  14. Post Fit Delay Residual (sec) PredictedOrbit Determined Orbit Phase Delay Analysis 4 June 2003

  15. Predicted Orbit Determined Orbit Estimated Coordinates

  16. Summary • NOZOMI VLBI observations were performed with domestic and intercontinental baselines. • Formula for Finite VLBI delay model was derived. • An analysis software is developed with that delay model based on CALC9. • Astrometric SC coordinates were obtained with Group/Phase delay observables.

  17. Summary • Least square solution with Predicted orbit did not give consistent solution with determined orbit. =>Probably due to nonlinearity of observable. =>Iterative solution will solve this problem. • Next step: SC Astrometry => Orbit estimation Thank you for attention.

  18. Orbit of NOZOMI Jun. Jan. Feb. Mar. Apr. May Space

  19. Group Delay(Range signal) Closure Observation mode = 2MHz, 2bit

  20. Spacecraft Navigation with VLBI : Motivation Required for increased accuracy for future space missions: • For landing, orbiting, & saving energy • JPL/NASA has been employed • Japanese Space Agency (ISAS+NASDA=JAXA) • NOZOMI(Japanese Mars Explorer) • Needs to support orbit determination with VLBI. • Mission as our own Project

  21. VLBI R&RR + R02 R01 Spacecraft Navigation

  22. Observation：IP-VLBI Sampler board K5VLBISystem • Sampling rate:40k-16MHz • Quantization bit: 1-8bit • 4ch/board • 10MHz,1PPS inputs

More Related