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,…)
On April 1, 2004 CRL and TAO will be reorganized as theNational Institute of Information and Communications Technology
Spacecraft Navigation with VLBI: Motivation
Required for increased accuracy for future space missions: – For landing, orbiting, & saving energy
R&RR
R01
R02
VLBI
+
SC Astrometry
On April 1, 2004 CRL and TAO will be reorganized as theNational 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
VLB
I Observations
Apr. MayMar.Jan. Feb. Jun.
May 22, 24, 27
June 4
Mizusawa(NAO)
Kashima(CRL)
Koganei(CRL)
Usuda(ISAS)
Yamaguchi(Yamaguchi Univ.)
Gifu(Gifu Univ.)
Kagoshima(ISAS)(uplink)
Tomakomai(Hokkaido Univ.)
Tsukuba(GSI)
AlgonquinSGL & NRCan
Japanese and Canadian VLBI Stations participated in NOZOMI VLBI observations.
ISAS,CRL,NAOJ, GSI,Gifu Univ, Yamaguchi Univ. Hokkaido Univ.SGL, NRCan supported.
On April 1, 2004 CRL and TAO will be reorganized as theNational Institute of Information and Communications Technology
For astrometry of S.C.Tasks to be done are
• VLBI for Finite distance radio source– A New VLBI delay Model corresponding to the CONS
ENSUS 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
VLBI delay model for finite distance radio source
VLBI for finite distance radio source
Normal VLBI
c
SB
Y-XB
BB
XX YY
SS
c
KB
YX RR 00
0Y0X RRK
(Fukuhisma 1993 A&A)
BB
XX YY
RX0
RX0
KK
VLBI delay model for finite distance radio source
c
cccc
VUγ
ct
ττ
eeeeg
202
220222
22
12
1
2
21
2
2)1(1
VR
wVKVR
bVwVbK
c
ccc
VUγ
ct
ττe
eeeeg
)(1
21
2
2)1(1
20
022
22
0
12wVK
VKbVwVbK
CONSENSUS MODEL (M.Eubanks 1991)
Finite Distance VLBI MODEL (Sekido & Fukushima 2003)
On April 1, 2004 CRL and TAO will be reorganized as theNational Institute of Information and Communications Technology
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, dg/dt, p)(O) with software correlator.
• Computing O-C and least square parameter estimation
xx
y
y
CO
Group Delay(Post-fit Residual)
Rate residual
Delay Residual
Orbit motion
Group Delay(Domestic Baselines)
6/4(VLBI)
6/4(R&RR)
May 27
June 4
Origin is Orbit on May 27, which was Determined by ISAS with R&RROrigin is Orbit on June 4.
Phase delayClosure of Phase delay(Kashima-Usuda-Tsukuba)
Kashima-Usuda-Tsukuba
On April 1, 2004 CRL and TAO will be reorganized as theNational Institute of Information and Communications Technology
Phase Delay
Analysis
Po
st F
it D
elay
Res
idu
al (
sec) 4 June 2003
The OD(ISAS) is correct?
x
yx
f
ff
dt
d
seems to be correct, since),()( ODXYZ
))(,(
))(,())(,(
NAOJ
CRLISAS
True delay rate is obtainable from Doppler data.
Then, is XYZ(OD) really correct? Or remaining bugs in our analysis ?.
S ~ 6 arc sec
Comparison with a priori d/dt computed from XYZ(OD)
(9000km)
On April 1, 2004 CRL and TAO will be reorganized as theNational Institute of Information and Communications Technology
Summary• NOZOMI VLBI observations were performed with domest
ic 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 wit
h Group/Phase delay observables.• Problem of inconsistency in the coordinates need to be s
olved.• 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 theNational Institute of Information and Communications Technology
SpaceOrbit of
NOZOMI
Apr. MayMar.Jan. Feb. Jun.
Group Delay(Range signal)
ClosureObservation mode= 2MHz, 2bit
On April 1, 2004 CRL and TAO will be reorganized as theNational Institute of Information and Communications Technology
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 theNational Institute of Information and Communications Technology
Spacecraft Navigation
R&RR
R01
R02
VLBI
+
On April 1, 2004 CRL and TAO will be reorganized as theNational Institute of Information and Communications Technology
Observation： IP-VLBI Sampler board
• Sampling rate:40k-16MHz• Quantization bit: 1-8bit• 4ch/board• 10MHz,1PPS inputs
K5 VLBI System
