FASR: The Frequency Agile Solar Radiotelescope

Link to FASR Web site

I. General project/facility description

1. Overview of the facility/project
   The Frequency Agile Solar Radiotelescope (FASR) is a new initiative. It was recommended for construction by the Astronomy and Astrophysics Decadal Survey (where the Radio and Submillimeter Panel considered its technical feasibility, while its science was rated by the Solar Panel), and more recently, it was rated number one among small projects by the Solar and Space Physics Decadal Survey "The Sun to the Earth -- and Beyond". Briefly, FASR will be a solar dedicated radio telescope designed to perform dynamic, wideband, imaging spectroscopy with angular, spectral, and temporal resolution commensurate with the physical phenomena that occur on the Sun. A proposal to develop a design and development plan (FASR DDP) will be submitted by AUI on behalf of a consortium of universities and other institutions to the NSF ATM Division in early 2005 in anticipation that a proposal for construction and operation of the instrument would be prepared for submission in 2006.
   FASR's planned construction start is in 2007, first science in 2009, and completion in 2011. FASR data and data products will be fully available to the solar physics and solar-terrestrial communities.

2. Managing institution and organization
   The FASR Project will be implemented through a new organization under management by Associated Universities, Inc. Definition of, and detailed planning for, the new organization will occur under the FASR DDP during 2005-6.

3. Funding source(s)
   It is expected that the bulk of the funding will originate from the NSF. We expect roughly 5% from foreign partners, mostly through in-kind contributions. Funding possibilities will also be explored with NASA and AFRL.

4. Construction history and cost
   Future facility: NYA.
   At this time, the cost estimate is very uncertain, but a full-up facility may require $50M for construction (including software "construction"; see below). FASR will not need to be further instrumented.

5. Operational history and cost
   Future facility: NYA.
   A conservative estimate based on 15% of construction is $7.5M/yr. This number would include operations and maintenance, as well as pipeline data processing and archiving. See discussion of "operational mode" below.

II. Technical details

1. Specifics of telescope/instrument
   

   Angular resolution	20/freq(GHz) arcsec
   Frequency range	30 MHz to 30 GHz
   Number channel pairs	2-4
   Total instantaneous BW	~2 GHz
   Frequency resolution	0.3-3 GHz: 0.1% <0.3 or >3 GHz: 1%
   Time resolution	0.3-3 GHz: 10 ms <0.3 or >3 GHz: 100 ms
   Polarization	I, V (Q, U possible)
   Number antennas	3-30 GHz: ~100 0.3-3 GHz: ~80 <0.3 GHz: ~60
   Size antennas	3-30 GHz: 2 m 0.3-3 GHz: 6 m <0.3 GHz: LPDA
   Maximum antenna spacing	6 km
   Absolute positions	1 arcsec
   Absolute flux calibration	<5%
   |ΔTB| (snapshot)	1000 K

   Note that the instrument noise is dominated by the source over most of the frequency band. The sensitivity of the instrument strongly depends on the phenomenon being observed. It is anticipated that solar flares and radio bursts will be imaged with a dynamic range of 10⁴-10⁶:1 whereas quiet Sun phenomena will be imaged with a dynamic range of 10²-10⁴:1.
   Operational mode:   As a dedicated (rather than general purpose) facility for solar research, FASR would operate in a manner rather different from other radio facilities but common to the solar community. The FASR schematic model is to pipeline as much of the data calibration, reduction, and processing as possible. An interim archive containing ~10 Tbytes a day will be formed each day and over-written a day later (with safeguards, etc). A number of quicklook data products will be produced from the interim archive for forecasting, "now-casting", and planning by other instruments and missions. Several general-purpose and application-driven archival data bases will be derived from the interim archive. For example, flares will be treated differently from CMEs, and CMEs will be treated differently from active regions, active regions will be ttreated differently from the quiet Sun. Each will have its own averaging requirements in the spatial, spectral, and temporal domains. It is expected that only 10s of Gbytes of data will be permanently archived each day.
   Users will interact with the permanent archive in two ways. There will be a pipeline reduction of the data that produces a standard suite of data products: e.g., brightness temperature maps in data cube form as functions of time and frequency, maps of physical quantities derived therefrom (e.g., coronal magnetograms), and data logs of phenomena and events of interest. We expect the majority of FASR users to use these standard data products, much as users now use SOHO EIT or TRACE images. Most of our users will not be expert (or even non-expert) radio interferometrists. However, for those who are comfortable with it, or are willing to learn, users will be encouraged to exercise the option of accessing the visibility data and calibration parameters so that they can reduce and analyze the data themselves at their home institution.
   We will also make it possible for user-defined data selection criteria to be applied to the interim archive so that "guest observer" specialized archives are supported (at very low cost!). Finally, since it is unlikely that we can simultaneously support all science requirements simultaneously when we populate the interim archive (the equivalent of supporting a logical .AND. function on all instrument specifications regarding spectral, temporal, and spatial resolution) we may, in fact, encourage and support proposals from the community to operate the instrument in non-standard modes for certain experiments. We may well outgrow the need for for this as compute power, mass storage, data bandwidths, etc, continue to grow.

2. New capabilities anticipated/planned in next 5-10 years
   Future facility; included in the technical planning of the FASR DDP will be clear identification of upgrade paths for the instrument.

III. User profile

1. % of "open skies" time
   100%

2. Institutional affiliations of users
   Data will be available to all users without prejudice.

3. Student access, involvement, usage
   We will strongly encourage and plan for student involvement in all phases of the project.

IV. Science Overview

1. Current forefront scientific programs
   Future facility: NA.

2. Major discoveries (through 1999)
   Future facility: NA.

3. Science highlights of last 5 years
   Future facility: NA.

4. Main future science questions to be addressed
   
   • Measurement of coronal magnetic fields
     • coronal magnetography
     • nature and evolution of coronal magnetic fields
     • energy storage and release in magnetic fields
     • coronal seismology
   • Physics of flares
     • magnetic energy release
     • electron acceleration and transport
     • plasma heating
     • role of flares in solar energetic particles
   • Drivers of Space Weather
     • origin and acceleration of coronal mass ejections
     • prominence eruptions
     • fast solar wind streams
     • role of CMEs in SEPs
   • The Thermal Sun
     • structure and dynamics of the solar atmosphere
     • solar and chromospheric heating
     • formation and structure of solar prominences/filaments
   It is expected that, as a well-calibrated instrument that is operational for at least a solar cycle (2 x 11 yrs), FASR will make major contributions to synoptic studies. It is also expected to play a significant programmatic role in forecasting and "now-casting" solar and space weather activity.
   Finally, it should be emphasized that as a new, innovative, and wholly unique instrument, FASR is expected to make entirely unanticipated discoveries.

5. Synergies with other major forefront facilities
   
   • ATST will be a ground based 4m telescope optimized to observer the Sun at optical and IR wavelengths. Among ATST's science goals is the nature and evolution of magnetic fields in the solar atmosphere. The ATST will exploit the Zeeman and Hanle effects to constrain coronal magnetic fields. The direct and indirect measurements of coronal magnetic fields provided by FASR will greatly supplement and complement such measurements.

   • FASR will provide the solar, heliospheric, and space physics communities with highly complementary data that will add significantly to their science missions. A common theme for many of these instruments and missions is the desire to understand solar magnetic fields. Most emphasize magnetic field measurements at photospheric or chromospheric heights. Only FASR will provide direct measurements of coronal magnetic fields.
     • STEREO will perform stereographic observations of CMEs from space based satellites in both optical and radiowave bands. FASR will provide unique observations of the nascent stages of the CMEs observed by STEREO at greater distances from the Sun.
     • Solar B will use a suite of instruments operating at optical, UV, and SXR wavelengths to study fundamental plasma astrophysics on the Sun, including the magnetic dynamo, magnetic fields, flare mechanisms, coronal heating, solar wind acceleration, and more. FASR will complement the morphological measurements of magnetic structures and the quantitative measurements of magnetic fields in the low solar atmosphere.
     • SDO, a NASA LWS mission, will perform high-resolution optical, UV, and EUV observations from space in order to address outstanding questions regarding the solar magnetic dynamo, energy transport in the solar atmosphere, and the radiative output of the Sun. Key science goals of FASR include coronal magnetography, the structure of the quiescent solar atmosphere, and synoptic studies of the Sun's radiative output. FASR is therefore well-matched to SDO science goals and excellent synergy is expected.
     • SIRA is an instrument in the planning stages, a cluster of microsats designed to perform low-frequency radio interferometric imaging of the Sun from space. SIRA will image coherent radio bursts of type II (shocks) and type III (beams) from the outer corona into the interplanetary medium to 1 AU. As an instrument that will observe the source of such bursts, FASR will add enormously to the science mission of SIRA.

6. Unique contributions
   
   • FASR will provide access to a number of complementary radio observational diagnostics that enable the coronal magnetic field to be measured or strongly constrained. These will provide new, unique, and fundamental new inputs to the outstanding problem of magnetic energy storage and release in the solar corona, as manifested by flares, coronal mass ejections, and other solar phenomena.
   • As an ultra-wideband radioheliograph, FASR will provide a comprehensive and integrated view of many observational phenomena. This is because FASR will provide an inherently three-dimensional view of the solar chromosphere and corona. For example, in the case of a flare and associated CME, FASR will simultaneously image the energy release volume through associated dm-wavelength coherent radio bursts, electron acceleration and transport processes through the cm-wavelength incoherent gyrosynchrotron radiation, the genesis of the CME and prominence eruption in the low corona, and the associated "EIT wave" in thermal chromospheric emission. This would provide an unprecedented view of the spatial and temporal couplings between each of these phenomena.

V. Education/Outreach activities

1. Visitor facility
   Future facility: NYA
2. Student programs
   Future facility: NYA

VI. Documentation/website URLs

1. URL of facility website
   The FASR website is currently http://www.ovsa.njit.edu/fasr. The website will move to its own domain during the FASR DDP.

2. URL of EPO website
   Future facility: NYA
3. URL(s) of any brief overviews of project/facility
   See: http://www.ovsa.njit.edu/fasr
4. URL(s) of miscellaneous documentation
   See: http://www.ovsa.njit.edu/fasr