Astrometry Observation of Spacecraft with Phase delay

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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.)

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Spacecraft Navigation with VLBI Motivation

• Precise orbit determination is requested for
  precise landing, orbiting, saving energy in
  maneuver

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NOZOMIs Earth Swing-by

• Japanese first Mars mission NOZOMI was observed
  during the period between two earth swing-bys.

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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)
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VLBI delay model for finite distance radio source
VLBI for finite distance radio source
Normal VLBI
(Fukuhisma 1993 AA)
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Relativistic VLBI delay model for finite distance
radio source
CONSENSUS MODEL (M.Eubanks 1991)
Finite Distance VLBI MODEL (Sekido Fukushima
2004)
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Analysis Procedure

• C Compute a priori (delay) and partials
• We modified CALC9 for our use(finite VLBI).
• (Thanks to NASA/GSFC group)
• OExtracting Observable (tp) with software
  correlator.
• O-C least square parameter estimation

True Orbit
Apiori Orbit
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Group Delay(Post-fit Residual)
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Phase delay
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Closure phase delay
1280km
900km
500km
As result of phase connection, Very precise delay
observable was obtained over 24 hours. (June 4th
experiments)
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Phase delay solutions track by adding baselines
(June 4th)
Origin is determined orbit with RRR
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Summary

• VLBI observations of spacecraft were 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 RRR when Determined (RRR) orbit was used as
  a priori.
• Next problem is SC coordinates started from
  Predicted orbit.