PoS(IX EVN Symposium)049 http://pos.sissa.it/ † , H. Saito, and M. Tsuboi ∗ [email protected].jaxa.jp Speaker. Yoshinodai 3-1-1, Sagamihara, Kanagawa, 229-8510, Japan Following the success of the first spacefrom VLBI European mission, VLBI VSOP-1 commnunity, Japanese (HALCA), group with started theThe contributions the ASTRO-G next satellite project can VSOP-2 (ASTRO-G). observeapogee, at 1,000km 8, perigee, 22 and and40 43 the micro GHz inclination arcsecond bands, of resolution and at 31 hasjet 43 degree, the GHz. in which orbit AGN, Observational can of targets accretion of 25,000km make disksstarts. ASTRO-G image around are Current the with the planned black root about launch hole, of period2012) the astronomical is with jet, the the and H-IIA begining masers rocket. of inNow 2013 galaxies (within the and the development Japanese of fiscaldevelop ASTRO-G year the is of rough design in of phase-B, eachas components so-called we on expected, the the in the basic satellite, very and design special checkingof environment phase, ASTRO-G on ASTRO-G will the more when orbit. work precisely we We than can that also we getWe also the expected system started in capability the the international initial activities phase such ofScience as the Council), the project. and starting other the international VISC-2 collaborations. (VSOP-2 International ∗ † Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. c ° The 9th European VLBI Network Symposiumand on EVN The Users role Meeting of VLBISeptember in 23-26, the 2008 Golden Age for RadioBologna, Astronomy Italy Japan Aerospace Exploration Agency, Japan E-mail: Y. Murata The VSOP-2 (ASTRO-G) project PoS(IX EVN Symposium)049 1 Y. Murata G -

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r a l o S Figure 2: Phase referencing VLBI is a method to improve the sensitivity and accuracy of the VLBI We can not observe two frequencies simultaneously, because different frequency bands use the The data sampled onboard is sent through a broadband down link of observation. ASTRO-G has the capability tomore do phase than referencing. 2 We need sources thecontrol (target function to moment and change gyro calibrators), for and fast-position precise switching orbit capability accuracy. for ASTRO-G the will separation have of 4 3 degree within 37.5 GHz with a bittransfer rate carrier of signal 1 to the Gbps local quadrature oscillatorsWe phase of hope shift observing to system keying have is (QPSK) sent at modulation. with leastThey the The 3 up-link are phase tracking at expected 40 stations to GHz. be in in the Japan, world Spain, for and obtaining one sufficient more. observation time. different feed horns, but we canand switch the two bit frequencies levels at of least the withinor analog-to-digital one “256 converter minute. MHz (ADC) The and of bandwidth 1 ASTRO-G are bit”.used “128 We in MHz will case and use 2 ground 2-bit bit”, sampling radioGbps) mode telescopes mode in to can normal get observe case. better 2-bit, The sensitivity 2 1-bit for mode the channels, will continuum 256 sources. be MHz bandwidth (total 2 Short Title for header modules, which are deployed onwider the bandwidth to orbit. get Each themm-wave effective band receivers data has by for Stirling LHC rotation cycle and measure refrigerator RHC observation. formance 22 of polarizations, ASTRO-G and the has and 43 higher cooled has GHz frequency bands. bands,being to There this get are frequency the many band large better used radio perfor- for telescopes down-linkand at satellite 8 geodesy communication GHz VLBI from in observation, space the research though world, service, thisThe 22 band and is 43 not GHz allocated bands for involve the H radio astronomy service. masers, respectively. PoS(IX EVN Symposium)049 Y. Murata , which is smaller than s R 13 O and/or SiO maser spots can 2 4 ] 5 ]). Then, VSOP-2 will make clear how such gas accretes into the YSO and 6 O masers of NGC4258 is a famous example of disk masers resolved by VLBI. Cos- 2 VSOP-2 project was proposed to ISAS/JAXA in October, 2005, and approved to move to We design each components and estimate the size, weight, power consumption, thermal in- The H Recently, we had a 2 scientific meetings for VSOP-2. One is the VSOP-2 symposium held Targets of ASTRO-G are the root of the jet in AGN (ie accretion disks around the black hole), Young stellar objects (YSO) are as well promising targets of VSOP-2. Though VSOP-2 cannot We use both satellite laser ranging (SLR) and GPS systems for a high accuracy orbit deter- phase-A (Concept design phase) innition March review 2006. in March After 2007, the and concept2007. the design, JAXA we The reviewed for had ASTRO-G approving a project asdesign system formally a phase). defi- project started in from JAXA in July, April 2007, and it isterface, now of in the phase-B satellite (basic and the endurance for radiation, vibration, and temperature environments. 4. The current status in Sagamihara, Japan in 2007,Germany and in May, the 2008. other is the scientific workshop of VSOP-2 held in Bonn, how the angular momentum is exchanged.surface And of we YSO. already Direct knew imaging that of large these flares flares occur may around be the a fantasticmology target using of disk VSOP-2. masers of galaxies may be another scientific target of VSOP-2. 3. VSOP-2 Scientific Objectives astronomical jet, and masers insecond galaxies at and 43 GHz starts. will make Thedented possible high quality. to angular The study synthesized resolution the beam neighborhood of sizes of 38 of an micro VSOP-2 AGN corresponds black arc- hole to in unprece- Short Title for header 1 minute. The antennavibrating itself the soft is antenna very structure.[ soft structure, we need the attitude control method without observe thermal emission from gas in/around YSO, motions of H the predicted accretion disk ofThe M resolving 87. an accretion Using disk VSOP-2,Blazars are will we also solve will key the sources image for following theobservations exploring problems of accretion the VSOP-2 about nature disk will and the resolve of physics the AGN of M87. gapX-ray jet AGN between observation. jets. formation. the The emission high-resolution region and core expected by the trace structure and kinematicsof of such the gas gas. (e.g., [ or position and transversal velocity, and acceleration mination. The target accuracyagainst of ground-base the VLBI. orbit The determination altitudeGPS of is constellation. ASTRO-G at around least It the 10 isfour apogee cm difficult satellites, is to to higher which get than receive are any that thehas required advantage of a signals to a corner when determine cube ASTRO-G the reflector isantenna, orbit for to arround satellite of get laser apogee ASTRO-G the ranging orbit directly. over at data the around ASTRO-G the earth-pointing also higher system altittude. of Ka-band link PoS(IX EVN Symposium)049 Y. Murata SEFD sys T , which shows the 1 A η } 2 ) λ / πε 4 ( {− exp S 5 η ) are also estimated based on the basic design. Current A η 27.8 1.0032.9 1.0035.6 0.87 0.98 0.88 0.61 0.60 90 0.58 52 0.35 6100 65 3600 7550 x-pol. − − − 0 η Expected antenna performances of ASTRO-G antenna and SEFD ] We made one-module engineering model (EM), and the thermal model test was Table 1: 7 [GHz] [dB] [dB] [K] [Jy] XK 8.0-8.8Q 20.6-22.6 56.3 64.9 41.0-45.0 0.64 0.67 70.8 0.68 The characteristics of the receiver is another part of the important component to decide the The values of the antenna efficency ( Antenna is one of the important component to decide the ASTRO-G characteristics. We started Band Freq. Gain estimated antenna efficiency, the system noisebands. temperature, and We the will SEFDs be of able ASTRO-Gthe to for radiation achieve condition three the of performance ASTRO-G is at veryduring least hard the because at it mission the will begin life pass of radiation time.with belt the over The the life 3000 radiation performances time. times test at of However, the the end antenna of components. the life time are under investigation guess of the observing performance of ASTRO-G are summarized in table capability of the radio telescope. Thelow ultra-low loss noise and feed un-conditionally and stable polarizer,22 amplifier (LNA), and are 43 required GHz to are getK cooled to by enough 30 a capability K Stirling-cycle of and refrigerator. the(GaAs the MMIC) dual We receiver. developed technology circular The GaAs for polarization feed these monolithic LNAsthe horns LNAs. microwave at receiver are integrated The system. cooled circuits LNA to This at 100 is 8model cooled GHz (BBM) passively. is The phase located noise at are temperatures the(estimated 60 of radiator for K LNAs panel some at at of the components) 8 bread lossnoise GHz, board and temperatures 20 noise at K of the the at receiver(EM) basic 22 phase components design GHz, in and phase. autumn and estimate 2008. 35 system We K will at make 43 receivers GHz. at the We engineering measured model carried our in August-September, 2008 tothe confirm radio the thermal wave mathematical test model. forsurface We also of the made the 1.5m test module size by moduleto the with photogrammetry confirm method, the the and electro-magnetic compact measure mathematical the rangethe gain model. system. characteristics and beam of Based pattern, the We on antenna measured these at the test the results basic we design phase. can estimate Purpose of the basic design isservations. to The confirm review of the the satellite basic system2009, design works and (PDR: under the preliminary the design detailed requirements review) design ofwill will phase happen ob- be in (phase-C) the 2010, to middle following of the produce basicthe the design. test detailed Manufacture of design of the the of components flight each ant model final will component be test 2010, will then be 2011 -the 2012. developments and experiments of the breadboardthe model (BBM) basic or design engineering model in (EM)VIII, for 2008. which is The JAXA’s engineering deploymentaccuracy satellite mechanism of launched of the in the antenna, December,each antenna ASTRO-G 2006. module.[ adopted is To newly same get developed as higher radial that surface rib-hoop of cable ETS- structure in Short Title for header PoS(IX EVN Symposium)049 , 538 Y. Murata Astrophys.J. 6 1825 955 281 , in press , in press , in press , pp.012048 52 et al et al et al et al Science PASJ "Approaching Micro-Arcsecond Resolution with VSOP-2: Astrophysics and Proc. "The Universe Under the Microscope - Astrophysics at High Angular "Approaching Micro-Arcsecond Resolution with VSOP-2: Astrophysics and "Approaching Micro-Arcsecond Resolution with VSOP-2: Astrophysics and , ed Y Hagiwara , ed Y Hagiwara , ed Y Hagiwara , ed R. Schoedel 751 Technology" Technology" Technology" Resolution" We need a world-wide collaboration for VSOP-2 both in space and ground telescopes to give Though we put 3 names on this paper, the ASTRO-G project is supported by many people from [6] H. Imai, O. Kameya, T. Sasao, M. Miyoshi, S. Deguchi, S. Horiuchi,[7] Y. Asaki K. 2000, Higuchi 2008 [3] H. Saito 2008 [4] M. Tsuboi 2008 [5] Sakai S 2008 [1] H. Hirabayashi et al. 1998 [2] H. Hirabayashi et al. 2000 Short Title for header 5. VSOP-2 International Collaborations a sufficient quantity of observationthe VSOP-1 time project. for However, international nternational astronomicalthe collaboration VSOP community, is International as a Science complicated we Council issue. (VISC-1) didscientific as VSOP-1 in an aspects formed international related body of to the providefully guidance mission. in on We maximizing are scientific acknowledging resultVISC-2. that with VISC-1 The VSOP-1. functioned primary function success- In ofrelevant a VISC-2 to similar science will operation fashion be of to for the form VSOP-2, VSOP-2approximately an mission. twice we international per VISC-2 formed year consensus expects to and about have more issues face-to-face frequently meeting teleconferences. Acknowledgments JAXA, National Astronomical Observatory, Japan, HoseiKagoshima University, University, Osaka Yamaguchi University, Prefacture Gifu University, University, and other Japanese radiocommunity. astronomy References