International VLBI tracking of SELENE

N.Kawano, H.Hanada and K.MatsumotoNAOJ

Main Sat.

V-star

R-starConcept of SELENE

By T. Iwata

( JAXA)

VLBI satellite (Vstar)

Solar Cell

Spin Stabilizer

Co-linear antenna

Existence of core ? Internal structure ?

Given by Gusev and Kawano

RSAT/VRAD

Relay satellite100km×2400km

Lunar orbiter100km±25km

JAXA/ISAS UDSC

JAXA new GN VRAD satellite100km×800km

radio source

transponder

transponder

radio source

NAOJ VERA foreign sites

Quasar

Gravity field of lunar limb (VRAD) far-side (RSAT)

TLM/CMD

From T.iwata

Doppler data coverage of main satellite

●2-way Doppler●4-way Doppler

Near-sideFar-side

By K.Matsumoto

VLBI obs. is effective in “Face-on”

Edge-on

Face-on

Gravity

Line of sight

Improvement by VLBI

Spherical harmonics

By Rstar. By VLBI

VERA Network for SELENE

Baseline~2000km

0 1 day

Sep. 2007 　　　　　 Aug.2008

0 　 30 days

8 hours

Nominal VLBI observation for SELENE

Regular obs.

~12days

~12days/month x 12

Total: ~1200 hours

El>15deg.

International VLBI Network

15 20 25 30 35 40

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MizusawaUrumqiWettzell

Time (day) From August 1215 20 25 30 35 40

Ele

vati

on (

deg)

Time (day)

80

60

40

20

25 3027.5

0 1 day

0 4 days

Sep. 2007 　　　　　 Aug.2008

0 　 30 days

4 hours x4

3~4 days x 2

4 hours

1 month x 2 , “Face-on”

Intensive international VLBI observation

Extended obs.

~12days

~12days/month x 2

Total: 64 hours Total: ~100 hours

Core obs. Extended Obs.

Center frequency 2212 MHz 2218 MHz 2287 MHz 8456 MHz

Band width CW CW CW CW

Sample rate 200 ksps 200 ksps 200 ksps 200 ksps

Recording Hard disc

EIRP 24 mW 24 mW 24 mW 250 mW(Rstar)

38 mW(Vstar)

Polarization RHCP RHCP RHCP RHCP

Specifications of signals from Vstar and Rstar

Orbits of three satellites Main orbiter Perilune Apolune Inclination Period

Main orbiter 100 km 100 km 90 deg. ~120 min.

Vstar 100 km 800km 90 deg. ~153 min.

Rstar 100 km 2400 km 90 deg. ~240 min.

Thank you for your attention.