NEXT SPACE VLBI MISSION, ASTRO-G (VSOP-2)

ANDITS SPECTRUM MANAGEMENT

ASTRO-G Project (JAXA)

Y. Murata 　（ JAXA)

HALCA and VSOP (1997-2005)Highly Advanced Laboratory for Communications and Astronomy

VLBI Space Observatory Programme

3C345

VLBA VSOP

Launch: Feb. 12, 1997 Apogee 21,000km Perigee 560 km 380 minutes period

Observing bands:

1.6, 5.0 GHz

(22 GHz)

Phase Link & Data Transmission:

Downlink 128 Mbps QPSK

@ 14.2 GHz

Uplink CW @ 15.3 GHz

TT&C: S-band with LGA

Plasma torus

VSOP with HALCA

• The first space VLBI imaging mission

• Studied AGN environment and jet physics– Structure and kinematics of jet

in AGN– Absorption near the core and

study of torus structure– Existence of high brightness

temperature sources

Also Pulsars, X-ray binaries, OH masers

Beamwidth 100 Rs at 5 GHz for M87

Plasma Torus in absorption

4-years jet monitoring

3C273

Jet Structure

1928+738

ASTRO-G (VSOP-2) – VLBI Space Observatory Programme – 2

10 times higher sensitivity

10 times higher frequency observation

10 times higher resolution with ～ 40 arcseconds

Observing bands 8, 22, 43 GHz

Dual polarization

Phase-referencing capability

The next generation Space VLBI (SVLBI) mission following the VSOP mission

9.26 m Antenna for

Radio Astronomy

Mass 1200kg (Nominal)

1 Gbps Data Downlink

Compared to VSOP:

Astrophysics with ASTRO-G (VSOP-2)

Generate VLBI array with Ground Radio Telescopes.

Magnetic fields of galaxies

Jets from the accretion disks around black holes

Radio galaxies

Quasars

Observe astronomical objects with the highest resolution.

Lobanov, A.P. 2003, SKA Memo 38

Comparison of Telescope Resolutions

VSOP

CurrentTelescopes

VERA

Radio IROptical

UV X γ

１mas

1SKA

ASTRO-G(VSOP-2)

Comparison ofASTRO-G/VSOP-2 and HALCA/VSOP

• More information on fine structure and magnetic field from AGN jets and cores– Higher resolution with polarization capability

• Higher sensitivity– With 2 polarization, 8 times wider bandwidth (only continuum sources)

• High agility attitude control system using control moment gyros– Improved calibration capability (ASTRO-G can observe calibrators, HALCA could not)– Phase-referencing observations enabled

Allows weaker source detection by extending integration time and astrometry observations

• High accuracy navigation using onboard GPSR and SLRRequired for phase-referencing

ASTRO-G Satellite Configuration• 9.3-m offset Cassegrain antenna with module structures

– Light weight– gimbal adjuster– focusing system

– Mass (wet) 1200Kg– Power 2000W

第２２号科学衛星　SOLAR-B ASTRO-G Configuration

Orbit 　 Apogee Height 25,000 km 　 Perogee Height 1,000 km 　 Inclination 31° 　 Orbit Period 7.5 h

Solar Paddle

rSolar Paddle天体方向

副鏡

主鏡

9.6 ｍ

Ka Ant for VLBI Link

Satelite Size Mass 1,200 kg Power 　 　 2,000 W

Observation Target Satellite For VLBI•　 9 meter Deployable Antenna for 43GHz• Cooled LNA （ 30 K ）•　 1 Gbps Down Link•　 Phase Compensation Observation　 Target Switching (3deg manoeuvre in 15 sec) Orbit Determnation with 10 cm Accuracy

Solar Paddle

Sub Reflector

Main Reflector

Rocket & Orbit

• Launch Rocket is H2A – Launch epoch; FY 2012– Single or Shared Launch is not decided now.

• ASTRO-G Orbit (HALCA)– Apogee Height: 25,000 km (21,300 km)– Perigee Height: 1,000 km (560 km)– Inclination 31°(31 °)– Orbit Period 7.5 hours (6.3 h)

Key Technology: Large Deployable Antenna

Module-type offset-Cassegrain antenna(use ETS-VIII deployment mechanism)

Mesh + Tension Truss

Need higher accuracy moduleOffset-cassegrain antenna

HALCA （ 1997 ）

ETS-VIII （ Dec. 2006 ）

Large Deployable Antennas (2/2)

Seven Modules (Stow / Deployment)

Azimuthal Hoop Cable & Radial Rib. Cable Network

XY

Development Module (2003)

Improve Surface accuracy (0.4mmrms)ETS-VIII 2GHz, ASTRO-G 43GHz

ASTRO-G Observing System

ASTRO-G tracking station

H Maser

Data Storage

VLBI Data DownlinkFrequency 37-38 GHzBit Rate 1 GbpsModulation QPSKTX-Power 25 W

High Gain AntennaDiameter: 80cm

Data StorageCapacity 4 TB / 8 hours

Phase Transfer UplinkFrequency 40 GHzNo ModulationTX-Power 100mW

Phase Comparison

Ground Link Station Diameter >10mOver 3 stations

ASTRO-G

Precision Oribt Determination

GPS

Precision LaserReflectors

Postioning Accuracy<10 cm

Ground Laser Stations

ASTRO-G25,000x1,000km

GPS20,000km

1,2 GPS Sats @ Apogee.Many GPS Sats @ Perigee

Astro-G Operation and Data flow

Ground telescopes

Tracking

Station

Satellite Operation

Correlator

Data Analysis

SchedulingScheduling

• Note: very similar to HALCA operation and data flow

Current Status of ASTRO-G

System Definition Review 19 Mar. 2007PROJECT Official START 1 Jul, 2007Basic Design of the satellite system (April 2007 – March 2008) Structure and Thermal model analysis is on going. Thermal deformation, Fix of the interfaces.Preliminary Design Review #1 (February – June 2008) 3 month delay For instruments need to start detailed design earlier. Main Reflector, Structures, Cryostat, Ka-HGA Preliminary Design Review #2 (March 2009) Other instrumentsCritical Design Review (March 2010) 6 month delay to the last schedule

Basic DesignSub-reflector

Antenna Tower

Bus System Solar ArrayPaddle

Ka HGA

Main Reflector

International Matters

• Meetings– Tracking station meetings

• #4 @ Greenbank, Aug. 2007• #5 @ Sagamihara, Dec. 2007

– VSOP-2 symposium (Dec 3-7, 2007 @ Sagamihara) • 135 participants. Half from outside of Japan (13 countries)

– VSOP-2 Science Meeting (14-16, 2008 @ Bonn)

• Proposals– SAMURAI proposal (submitted in Jan. 2008)

• Proposal to NASA Mission of opportunity for US VSOP-2 supports (Tracking station, VLBA, JPL project office and navigation. See. NRAO report)

– European Proposals FP7 SPIRIT • ESA Nationally Led proposal (Tracking station, SVLBI use of GRT, Correlat

ors).

International Matters (2)• VISC-2 Formation

– VISC-2(VSOP-2 International Science Council) We form VISC-2 to make consensus related to scientific operations of VSOP-2. Possible VISC-2 fu

nctions are selection of KSPs, scientific scheduling, decisions of international relations, scientific operations. (Finally decided in the first VISC-2 meeting in Bonn in May, 2008)

– pre-meeting • Dec. 2007 @ Sagamihara• April, 2009 @Telecon• May, 2009 First F-F Meeting in Bonn

– Members: • Ex-officio(ISAS/JAXA): H.Saito, M.Tsuboi • Institutional members (12):ISAS(1): Y.Murata (co-chair), NAOJ(1): M.Inoue, JVN(1): K.Fujisawa 　EAVN (1): H.Kobayashi, KVN/KASI (1): S.-H.Cho, NRAO(1): J.Ulvestad( JPL(1): D.Murphy ), JIVE(1): L.Gurvits, EVN(1): A.Zensus (co-chair)OAN(1): R.Bachiller, ATNF(1): P.Edwards, GVWG(1): J.Romney (NRAO)• At-large members (3): D. Gabuzda (Univ. Collage Cork, Ireland), S.Kameno (Kagoshima Univ.), + Astrome

try person (TBD)• VISC2 adviser (2): D.Jauncey, H.Hirabayashi• Liaison (1): R.Schilizzi (ISPO (International SKA Project Office))• Secretary(1): Y.Hagiwara (NAOJ)

ASTRO-G radio frequency usage

Ground Radio Telescopes Ground Tracking StationsCommanding

Station

40 GHz 37-38 GHz

3-4 stations in the world.10-20 radio telescopes around the world.

JAXA commanding

station

Frequency Management Activities

1. Frequency Selection:• Observing bands, Space VLBI (Up/downlink data), TT&C

2. SFCG (Space Frequency Coordination Group)• Coordination among space agencies• Information for ASTRO-G was submitted in September, 2007

3. ITU-R SG7• General SVLBI (Space VLBI) coordination have already done by US (JPL)

group at WP7B. Recommendation ITU-R SA.1344 : SVLBI system description “Preferred frequency bands and bandwidths for Space VLBI” Up 40-40.5 GHz, Down 37-38 GHz• Sharing studies in 37-38 GHz band are going now.• Observing band protection in radio astronomy bands in 22/43 GHz is not cl

ear now.

ASTRO-G frequency SelectionObserving band:

8.0 – 8.8 GHz, 20.6 – 22.6 GHz, 41.0 – 43.0 GHz

ASTRO-G (VSOP-2) Specifications (1/2)

Status of the frequency sharing study for ASTRO-G in 37-38 GHz downlink

•Space VLBI (SVLBI) system : Recommendation ITU-R SA.1344.

•Drafting Group 3 in ITU-R SG-7 Working Party 7B (WP7B)

•Sharing study to Lunar systems (SRS) and FSS.

•WP7B chairman's report (Document 7B/168-E) was released last February

•VSOP-2/ASTRO-G parameters are in Table 3.1 in Annex 8 to document 7B/168-E. But some of the parameters in this table have already updated. Difference of the table is as follows:

ASTRO-G (VSOP-2) – VLBI Space Observatory Programme – 2

10 times higher sensitivity

10 times higher frequency observation

10 times higher resolution with ～ 40 arcseconds

Observing bands 8, 22, 43 GHz

Dual polarization

Phase-referencing capability

The next generation Space VLBI (SVLBI) mission following the VSOP mission

9.26 m Antenna for

Radio Astronomy

Mass 1200kg (Nominal)

1 Gbps Data Downlink

Compared to VSOP: