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Astrometry Observation of Spacecraft with Phase delay

This paper presents astrometric observations of spacecraft using phase delay measurements. VLBI observations of the NOZOMI Mars mission were conducted, and a delay model for finite distance radio sources was used to determine precise spacecraft coordinates. The results demonstrate the potential of VLBI for spacecraft navigation and energy-saving maneuvers.

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Astrometry Observation of Spacecraft with Phase delay

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  1. Astrometry Observation of Spacecraft with Phase delay M.Sekido, R.Ichikawa, H.Osaki, T.Kondo, Y.Koyama(NICT) M.Yoshikawa, T.Ohnishi(ISAS), W.Cannon, A.Novikov (SGL), M.Berube(NRCan), NOZOMI VLBI group (NICT,ISAS,NAOJ,GSI,Gifu Univ., Yamaguchi Univ., Hokkaido Univ.)

  2. VLBI R&RR + R02 R01 SC Astrometry Spacecraft Navigation with VLBI: Motivation Precise orbit determination is requested for precise landing, orbiting, & saving energy in maneuver :

  3. VLBI Observations NOZOMI’s Earth Swing-by • Japanese first Mars mission NOZOMI was observed during the period between two earth swing-bys.

  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. S B X Y RX0 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)

  6. Relativistic VLBI delay model for finite distance radio source CONSENSUS MODEL (M.Eubanks 1991) Finite Distance VLBI MODEL (Sekido & Fukushima 2004)

  7. Analysis Procedure • C: Compute a priori (delay) and partials • We modified CALC9for our use(finite VLBI). (Thanks to NASA/GSFC group) • O:Extracting Observable (tp) with software correlator. • O-C: least square parameter estimation True Orbit Apiori Orbit

  8. ~100 nano sec. Signal type from Spacecraft quasor (frq.) ~1MHz Group Delay(Post-fit Residual)

  9. Phase delay

  10. Tomakomai Yamaguchi Gifu Closure phase delay 1280km ９００ｋｍ ５００ｋｍ As result of phase connection, Very precise delay observable was obtained over 24 hours. (June 4th experiments)

  11. Including Algonquin Baseline Phase delay solution’s track by adding baselines (June 4th) Origin is determined orbit with R&RR

  12. Summary • VLBI observations of spacecraftwere performed with domestic and intercontinental baselines. • Relativistic Finite VLBI delay model and analysis software were developed and implemented based on CALC9. • Phase delay was derived in precision of 20 pico sec for long time span. • SC coordinates estimated by VLBI agreed with that of R&RR when Determined (R&RR) orbit was used as a priori. • Next problem is SC coordinates started from Predicted orbit.

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