NEXT SPACE VLBI MISSION, ASTRO-G (VSOP-2) AND ITS SPECTRUM MANAGEMENT ASTRO-G Project (JAXA) Y. Murata

（

JAXA)

VLBI Space Observatory Programme

HALCA and VSOP (1997-2005)

Highly Advanced Laboratory for Communications and Astronomy Observing bands: 1.6, 5.0 GHz (22 GHz) Launch: Feb. 12, 1997 Apogee 21,000km Perigee 560 km 380 minutes period Phase Link & Data Transmission: Downlink 128 Mbps QPSK @ 14.2 GHz Uplink CW @ 15.3 GHz

3C345 VLBA VSOP

TT&C: S-band with LGA

Beamwidth 100 Rs at 5 GHz for M87

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

3C273 Jet Structure Plasma torus Plasma Torus in absorption 4-years jet monitoring 1928+738

ASTRO-G (VSOP-2)

–

V LBI S pace O bservatory P rogramme – 2

Compared to VSOP:

10 times

higher sensitivity

10 times

higher frequency

10 times

higher resolution

observation with ～ 40 m arcseconds 9.26 m Antenna for Radio Astronomy Observing bands

8, 22, 43 GHz Dual polarization Phase-referencing capability Mass 1200kg (Nominal) 1 Gbps Data Downlink

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

Astrophysics with ASTRO-G (VSOP-2)

Radio galaxies Quasars Magnetic fields of galaxies Observe astronomical objects with the highest resolution.

Jets from the accretion disks around black holes Generate VLBI array with Ground Radio Telescopes.

Comparison of Telescope Resolutions

Radio IR UV Optical X γ 1

SKA １

mas VSOP

VERA

ASTRO-G(VSOP-2)

Current Telescopes Lobanov, A.P. 2003, SKA Memo 38

Comparison of ASTRO-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 SLR Required 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

Sub Reflector r Solar Paddle

副鏡

Ka Ant for VLBI Link

SOLAR-B

9.6

ｍ 主鏡

Orbit Apogee Height 25,000 km Perogee Height 1,000 km Inclination 31

°

Orbit Period 7.5 h Satelite Size Mass 1,200 kg Power 2,000 W

天体方向

Observation Target Main Reflector

• • • •

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

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) HALCA （ 1997 ） Mesh + Tension Truss Need higher accuracy module Offset-cassegrain antenna ETS-VIII （ Dec. 2006 ）

Large Deployable Antennas (2/2

)

Improve Surface accuracy (0.4mmrms) ETS-VIII 2GHz, ASTRO-G 43GHz Azimuthal Hoop Cable & Radial Rib. Cable Network

Y X

Development Module (2003) Seven Modules (Stow / Deployment)

ASTRO-G Observing System

ASTRO-G tracking station

Phase Transfer Uplink

Frequency 40 GHz No Modulation TX-Power 100mW

Ground Link Station

Diameter >10m Over 3 stations

Data Storage H Maser Phase Comparison

High Gain Antenna

Diameter: 80cm

ASTRO-G

VLBI Data Downlink

Frequency 37-38 GHz Bit Rate 1 Gbps Modulation QPSK TX-Power 25 W

Data Storage

Capacity 4 TB / 8 hours

Precision Oribt Determination

Precision Laser Reflectors

ASTRO-G 25,000x1,000km

Ground Laser Stations Postioning Accuracy <10 cm GPS

20,000km

GPS

1,2 GPS Sats @ Apogee.

Many GPS Sats @ Perigee

Astro-G Operation and Data flow

Scheduling

Tracking Station Satellite Operation Ground telescopes Data Analysis Correlator •

Note: very similar to HALCA operation and data flow

Current Status of ASTRO-G

System Definition Review 19 Mar. 2007 PROJECT Official START 1 Jul, 2007 Basic 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 instruments Critical Design Review (March 2010) 6 month delay to the last schedule

Sub-reflector Antenna Tower Bus System

Basic Design

Solar Array Paddle 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)

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

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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, Correlators).

•

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 functions 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)

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pre-meeting

•

Dec. 2007 @ Sagamihara

• •

April, 2009 @Telecon May, 2009 First F-F Meeting in Bonn

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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.), + Astrometry 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 10-20 radio telescopes around the world.

40 GHz 37-38 GHz Ground Tracking Stations 3-4 stations in the world.

Commanding Station JAXA commanding station

Frequency Management Activities

1.

2.

3.

•

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

• •

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

• • •

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 clear now.

ASTRO-G frequency Selection Observing 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)

–

V LBI S pace O bservatory P rogramme – 2

Compared to VSOP:

10 times

higher sensitivity

10 times

higher frequency

10 times

higher resolution

observation with ～ 40 m arcseconds 9.26 m Antenna for Radio Astronomy Observing bands

8, 22, 43 GHz Dual polarization Phase-referencing capability Mass 1200kg (Nominal) 1 Gbps Data Downlink

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