Radio Astronomy Applications GroupKashima Space Research Center

National Institute of Information and Communications TechnologyEGU2005

GI3-1TH5P-0057GI3-1TH5P-0057

A preliminary result of precise positioning of the interplanetaryA preliminary result of precise positioning of the interplanetaryspacecraft using differential VLBI measurementsspacecraft using differential VLBI measurements

ICHIKAWA Ryuichi(ICHIKAWA Ryuichi(richi@nict.go.jprichi@nict.go.jp))(1)(1), SEKIDO Mamoru, SEKIDO Mamoru(1)(1), TAKEUCHI Hiroshi, TAKEUCHI Hiroshi(1)(1), KIMURA Moritaka, KIMURA Moritaka(1)(1),,KOYAMA YasuhiroKOYAMA Yasuhiro(1)(1), KONDO Tetsuro, KONDO Tetsuro(1)(1), OSAKI Hiroo, MOCHIDUKI Nanako, OSAKI Hiroo, MOCHIDUKI Nanako (2)(2), MURATA Yasuhiro, MURATA Yasuhiro(2)(2),,

YOSHIKAWA Makoto.YOSHIKAWA Makoto.(2)(2), OHNISHI Takafumi, OHNISHI Takafumi(3)(3), and Spacecraft DVLBI group, and Spacecraft DVLBI group (4)(4)

(1) (1) Kashima Space Research Center, Kashima Space Research Center, National Institute of Information and Communications Technology, JAPANNational Institute of Information and Communications Technology, JAPAN (2)(2) Institute of Space and Astronautical Science, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency,Japan Aerospace Exploration Agency,

(3)(3) Space Solutions Department, Advanced Science Solutions Group, Fujitsu LimitedSpace Solutions Department, Advanced Science Solutions Group, Fujitsu Limited..(4)(4) JAXA, NAO, GSI, Hokkaido Univ., Gifu Univ., Yamaguchi Univ., and SGL/CRESTech JAXA, NAO, GSI, Hokkaido Univ., Gifu Univ., Yamaguchi Univ., and SGL/CRESTech

GI3-1TH5P-0057GI3-1TH5P-0057

A preliminary result of precise positioning of the interplanetaryA preliminary result of precise positioning of the interplanetaryspacecraft using differential VLBI measurementsspacecraft using differential VLBI measurements

ICHIKAWA Ryuichi(ICHIKAWA Ryuichi(richi@nict.go.jprichi@nict.go.jp))(1)(1), SEKIDO Mamoru, SEKIDO Mamoru(1)(1), TAKEUCHI Hiroshi, TAKEUCHI Hiroshi(1)(1), KIMURA Moritaka, KIMURA Moritaka(1)(1),,KOYAMA YasuhiroKOYAMA Yasuhiro(1)(1), KONDO Tetsuro, KONDO Tetsuro(1)(1), OSAKI Hiroo, MOCHIDUKI Nanako, OSAKI Hiroo, MOCHIDUKI Nanako (2)(2), MURATA Yasuhiro, MURATA Yasuhiro(2)(2),,

YOSHIKAWA Makoto.YOSHIKAWA Makoto.(2)(2), OHNISHI Takafumi, OHNISHI Takafumi(3)(3), and Spacecraft DVLBI group, and Spacecraft DVLBI group (4)(4)

(1) (1) Kashima Space Research Center, Kashima Space Research Center, National Institute of Information and Communications Technology, JAPANNational Institute of Information and Communications Technology, JAPAN (2)(2) Institute of Space and Astronautical Science, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency,Japan Aerospace Exploration Agency,

(3)(3) Space Solutions Department, Advanced Science Solutions Group, Fujitsu LimitedSpace Solutions Department, Advanced Science Solutions Group, Fujitsu Limited..(4)(4) JAXA, NAO, GSI, Hokkaido Univ., Gifu Univ., Yamaguchi Univ., and SGL/CRESTech JAXA, NAO, GSI, Hokkaido Univ., Gifu Univ., Yamaguchi Univ., and SGL/CRESTech

ABSTRCATABSTRCAT

The precise and quasi-realtime navigation of the intThe precise and quasi-realtime navigation of the interplanetary spacecraft using VLBI technique is currently erplanetary spacecraft using VLBI technique is currently under development at NICT(National Institute of Informunder development at NICT(National Institute of Information and Communications [former CRL]). We performeation and Communications [former CRL]). We performed more than 30 VLBI experiments for the Japan's NOZOd more than 30 VLBI experiments for the Japan's NOZOMI Mars probe from September 2002 until June 2003. MI Mars probe from September 2002 until June 2003. The fringe products of group delays were successfully dThe fringe products of group delays were successfully detected from these VLBI experiments in spite of weak aetected from these VLBI experiments in spite of weak and narrow-bandwidth NOZOMI signal. The group delays nd narrow-bandwidth NOZOMI signal. The group delays were used to validate the operational orbit determinatiowere used to validate the operational orbit determination based on the range and range rate (R&RR) data sets n based on the range and range rate (R&RR) data sets by ISAS/JAXA.by ISAS/JAXA.

Though the rms scatter of the group delays of VLBI Though the rms scatter of the group delays of VLBI data in the joint analysis with R&RR observables are reldata in the joint analysis with R&RR observables are relatively large up to several tens nanoseconds, the both ratively large up to several tens nanoseconds, the both results are consistent with each other. We also derived esults are consistent with each other. We also derived phase delay by using updated correlation software. The phase delay by using updated correlation software. The estimated position based on the phase delays are consestimated position based on the phase delays are consistent with the R&RR results within several tens of milli-istent with the R&RR results within several tens of milli-arc second. In particular, the declinations determined barc second. In particular, the declinations determined by phase delay signals are identical with those obtained y phase delay signals are identical with those obtained by R&RR values.by R&RR values.

We perform another VLBI experiments for tracking We perform another VLBI experiments for tracking HAYABUSA spacecraft. HAYABUSA, which means “FalcoHAYABUSA spacecraft. HAYABUSA, which means “Falcon” in Japanese, was launched on May 9 2003, and has n” in Japanese, was launched on May 9 2003, and has been flying steadily towards an asteroid named “Itokawbeen flying steadily towards an asteroid named “Itokawa”, after the late Dr. Hideo Itokawa, the father of Japan'a”, after the late Dr. Hideo Itokawa, the father of Japan's space development program. HAYABUSA is traveling ts space development program. HAYABUSA is traveling through space using an ion engine. It will orbit the asterhrough space using an ion engine. It will orbit the asteroid, land on it, and bring back a sample from its surfacoid, land on it, and bring back a sample from its surface.e.

The first HAYABUSA VLBI experiment was performeThe first HAYABUSA VLBI experiment was performed at X-band(8.4 GHz) using six VLBI stations in Japan od at X-band(8.4 GHz) using six VLBI stations in Japan on November 26, 2003. We could detect group delay frin November 26, 2003. We could detect group delay fringes of HAYABUSA range and telemetry signals for the nges of HAYABUSA range and telemetry signals for the Kashima-Usuda baseline. According to the comparison Kashima-Usuda baseline. According to the comparison between group delays and R&RR results, average of rebetween group delays and R&RR results, average of residuals are larger than 100 nanoseconds. The large scsiduals are larger than 100 nanoseconds. The large scattering of the group delays are shown at the several eattering of the group delays are shown at the several epochs. On the other hand, the relatively small scatterinpochs. On the other hand, the relatively small scattering less than 10 nanoseconds are shown during the perig less than 10 nanoseconds are shown during the period between 05:00UT and about 07:30UT. It is considerod between 05:00UT and about 07:30UT. It is considered that the difference between them is caused by the ced that the difference between them is caused by the characteristic of the radio signals transmitted from HAYAharacteristic of the radio signals transmitted from HAYABUSA.BUSA.

We also performed HAYABUSA VLBI experiment on We also performed HAYABUSA VLBI experiment on October 16 and 18, 2004 in order to evaluate reducing October 16 and 18, 2004 in order to evaluate reducing propagation delays due to the ionosphere and neutral apropagation delays due to the ionosphere and neutral atmosphere using differential VLBI technique. In this exptmosphere using differential VLBI technique. In this experiment, we acquire the VLBI data using both K5 systeeriment, we acquire the VLBI data using both K5 system and state-of-art Gigabit system. The hybrid correlatiom and state-of-art Gigabit system. The hybrid correlation processing based on the Gigabit system and the DBBn processing based on the Gigabit system and the DBBC (Digital Baseband Converter) filtering technique is sigC (Digital Baseband Converter) filtering technique is significantly efficient to detect fringes of weak radio sourcnificantly efficient to detect fringes of weak radio sources which have small separation angle from the spacecres which have small separation angle from the spacecraft.aft.

Quasar

q

s

B: baseline vector

K5 VLBI System K5 VLBI System

Detected NOZOMI fringe

Basic Concept ofDifferential VLBI

(DVLBI) observation

Data SamplingBoards

Data SamplingBoards

observationobservation(~7 hours)(~7 hours)

correlationcorrelationprocessingprocessing(~9 hours)(~9 hours)

analysisanalysis(~1 hour)(~1 hour)

orbit determinationorbit determination

optical fiber link

data transferdata transfer(~2 hours)(~2 hours)

Figure 1: Schematic image Figure 1: Schematic image showing spacecraft VLBI showing spacecraft VLBI data flow and analysis in data flow and analysis in this studythis study

taking onlytaking only20 hours !!20 hours !!taking onlytaking only20 hours !!20 hours !!

May 27

June 4

Origin is Orbit on June 4.

[(c)ISAS/JAXA]

6/4(VLBI)6/4(R&RR)

Orbit motion

Origin is Orbit on May 27, which was Determined by ISAS with R&RR

© ISAS/JAXA

Figure 2: HAYABUSA mission scenarioFigure 2: HAYABUSA mission scenario