Transcript VLBI Observation for Spacecraft Navigation (NOZOMI) – Data
VLBI Observation for Spacecraft Navigation (NOZOMI) – Data Processing and Analysis Status Repot
M.Sekido, R.Ichikawa,H.Osaki, T.Kondo,Y.Koyama(CRL) M.Yoshikawa,T.Ohnishi(ISAS), W.Cannon, A.Novikov (SGL), M.Berube(NRCan), NOZOMI VLBI group(CRL,ISAS,NAOJ,GSI,…)
Spacecraft Navigation with VLBI: Motivation
Required for increased accuracy for future space missions: – For landing, orbiting, & saving energy
R&RR + R
01
VLBI R
02
SC Astrometry On April 1, 2004 CRL and TAO will be reorganized as the National Institute of Information and Communications Technology
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 some period May 22, 24, 27 Jan. Feb.
Mar.
Apr. May Jun.
June 4
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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.
Gifu (Gifu Univ.) Yamaguchi (Yamaguchi Univ.) Tomakomai (Hokkaido Univ.) Usuda (ISAS) Kagoshima(ISAS) (uplink) Koganei (CRL) Algonquin SGL & NRCan Mizusawa (NAO) Tsukuba (GSI) Kashima (CRL)
For astrometry of S.C.
Tasks to be done are
• VLBI for Finite distance radio source – A New VLBI delay Model corresponding to the CONSENSUS model.
• Narrow band width 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
On April 1, 2004 CRL and TAO will be reorganized as the National Institute of Information and Communications Technology
VLBI delay model for finite distance radio source
Normal VLBI VLBI for finite distance radio source
B
X Y
B
S
c
B
K
c
X B S Y R
X0
R
X0
K
R 0X
R
0
X
R 0Y
R
0
Y
X
(Fukuhisma 1993 A&A)
K B Y
VLBI delay model for finite distance radio source
CONSENSUS MODEL (M.Eubanks 1991)
c
b
τ
2
τ
1
t g
K
0 1 ( 1
γ
)
U V e
2
K
0 2
V
e
( 2
c
V
e
2
w
2 1
w
2 )
c
V
e c
2
b
1
K
0
V
e
2
c
Finite Distance VLBI MODEL (Sekido & Fukushima 2003)
τ
2
τ
1
t g
K
b
c
1 ( 1
γ
)
U
V e
2 2 2
V
c
2
e
1
w
2
R
02
V
e
V
2
c c
2
b
1
R
02
V
2
c
K
V
e
2
c
2
w
2
Analysis Procedure
• Compute a priori (delay, rate) (C) and partials – We modified
CALC9
for our use(finite VLBI). ( Thanks to NASA/GSFC group for permission to use) • Extracting Observable ( g , d g /dt , p )(O) with software correlator.
• Computing O-C and least square parameter estimation
y
O
C
y
x
x On April 1, 2004 CRL and TAO will be reorganized as the National Institute of Information and Communications Technology
Group Delay (Post-fit Residual) Rate residual Delay Residual
Group Delay ( Domestic Baselines)
6/4(R&RR) 6/4(VLBI ) June 4 May 27 Origin is Orbit on June 4.
Origin is Orbit on May 27, which was Determined by ISAS with R&RR
Phase delay
Closure of Phase delay (Kashima-Usuda-Tsukuba) Kashima-Usuda-Tsukuba
Phase Delay Analysis
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4 June 2003
The
OD
(ISAS) is correct?
d
dt
f x
f y
True delay rate is obtainable
f
from Doppler data.
x
Comparison with a priori d /dt
XYZ
(
OD
) ( , ) computed from XYZ(OD) ( seems to be correct, since , )(
ISAS
) ( , )(
CRL
)
(9000km)
( , )(
NAOJ
)
S ~ 6 arc sec
Then, is XYZ(OD) really correct? Or remaining bugs in our analysis ?.
Summary
•
NOZOMI
VLBI observations were performed with domestic and intercontinental baselines.
• Finite VLBI delay model was derived.
• An analysis software is developed with that delay model based on
CALC9
.
• Preliminary astrometric SC coordinates were obtained with Group/Phase delay observables.
• Problem of inconsistency in the coordinates need to be solved.
• Solution with full baselines have to be obtained.
• Next step:SC Astrometry-> Orbit estimation
On April 1, 2004 CRL and TAO will be reorganized as the National Institute of Information and Communications Technology
Orbit of
NOZOMI
Space
Jan. Feb.
Mar.
Apr. May Jun.
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Group Delay (Range signal)
Closure Observation mode = 2MHz, 2bit
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
On April 1, 2004 CRL and TAO will be reorganized as the National Institute of Information and Communications Technology
Spacecraft Navigation
R&RR + R
01
VLBI R
02
On April 1, 2004 CRL and TAO will be reorganized as the National Institute of Information and Communications Technology
Observation
： IP-VLBI Sampler board
K5 VLBI System
• Sampling rate:40k-16MHz • Quantization bit: 1-8bit • 4ch/board • 10MHz,1PPS inputs
On April 1, 2004 CRL and TAO will be reorganized as the National Institute of Information and Communications Technology