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

HALCA and VSOP ( ) 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 14.2 GHz Uplink 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

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 Current Telescopes VERA Radio IR Optical UV X γ １ mas 1 SKA ASTRO-G(VSOP-2)

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

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 module Offset-cassegrain antenna HALCA （ 1997 ） ETS-VIII （ Dec ）

Large Deployable Antennas (2/2 ) Seven Modules (Stow / Deployment) Azimuthal Hoop Cable & Radial Rib. Cable Network X Y 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 Downlink Frequency GHz Bit Rate 1 Gbps Modulation QPSK TX-Power 25 W High Gain Antenna Diameter: 80cm Data Storage Capacity 4 TB / 8 hours Phase Transfer Uplink Frequency 40 GHz No Modulation TX-Power 100mW Phase Comparison Ground Link Station Diameter >10m Over 3 stations ASTRO-G

Precision Oribt Determination GPS Precision Laser Reflectors Postioning Accuracy <10 cm Ground Laser Stations ASTRO-G 25,000x1,000km GPS 20,000km 1,2 GPS Apogee. Many GPS Perigee

Astro-G Operation and Data flow Ground telescopes Tracking Station Satellite Operation Correlator Data Analysis Scheduling Note: very similar to HALCA operation and data flow

Current Status of ASTRO-G System Definition Review 19 Mar 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

Basic Design Sub-reflector Antenna Tower Bus System Solar Array Paddle Ka HGA Main Reflector

International Matters Meetings –Tracking station meetings Greenbank, Aug Sagamihara, Dec –VSOP-2 symposium (Dec 3-7, Sagamihara) 135 participants. Half from outside of Japan (13 countries) –VSOP-2 Science Meeting (14-16, 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, 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) –pre-meeting Dec. Sagamihara April, 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.), + 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 TelescopesGround Tracking Stations Commanding Station 40 GHz GHz 3-4 stations in the world 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, 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 GHz, Down GHz Sharing studies in 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 GHz downlink Space VLBI (SVLBI) system : Recommendation ITU-R SA 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: