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MWA: The Mileura Widefield Array
MWA Web site
I. General project/facility description
The MWA project aims to develop powerful new capabilities for radio
astronomy below about 1.6 GHz, optimized for wide fields of view and
unprecedented sensitivity for a variety of survey applications. The
first stage of the MWA is underway as a joint project led by MIT and
the CSIRO Australia Telescope National Facility (ATNF), with strong
participation from the CfA and a number of Australian universities, as
well as the government of Western Australia.
The initial goal of the MWA project is to create two complementary and
co-located by substantially independent scientifically-capable
demonstration instruments, one led by MIT in the 80-300 MHz
frequency range (the Low Frequency Demonstrator: LFD)
and the other led by ATNF in the 800-1600 MHz range (the New
Technology Demonstrator: NTD). We focus here on the US-led LFD.
- Overview of the facility/project
The MWA/LFD is a university based, innovative
instrument development program that may serve as a pathfinder for the
Square Kilometer Array (SKA; discussed separately in this report).
Although a low-cost demonstrator instrument, the MWA/LFD will provide
world-class science capability for studies of the Epoch of
Reionization (EOR), transient radio emission and high precision
remote sensing of the heliosphere. It will have an effective collective
area of ~8000 square meters at 200 MHz, and will have capability in the
range from 80-300 MHz. Operations are planned to start in 2007.
Mileura is a remote livestock ranch in outback Western Australia,
remarkably free of man-made RFI because of its location far from
population centers in an area being formally designated as a radio
quiet zone. It is the centimeter/meter wave equivalent of a high,
dry and dark site.
- Managing institution and organization
The MWA/LFD is led by MIT, with involvement both of the Center for
Space Research (CSR) on campus and the Haystack Observatory. The
project leader/manager is located at Haystack and workpackages are
shared between the US and Australia. The EOR scientific
collaboration, focused on the primary astronomical scientific goal, is
led by CSR. The LFD science program is based on active involvment of all
academic partners, currently (Jan 2005) including participants from MIT,
CfA, Caltech, Cornell, NRAO, NRL, UCSD, several institutions in Australia
as well as Japan and Germany.
The detailed management plan involves the MWA joint development with
the ATNF-led NTD project allowing for efficient sharing of resources,
work packages and developments. Extensive communication and
coordination between the separate LFD and NTD project management
teams is built into the overall structure. The MWA Executive
Group includes the Directors of the Haystack Observatory and the
ATNF. Numerous other senior experienced personnel oversee specific
- Funding source(s)
The LFD is a collaboration between several partner institutions and
organizations, all of whom plan to provide significant funding toward
the total expected cost (LFD only) of $10M. The largest single
component of funding is $4.25M requested from the NSF in Sept 2004.
Most of the remaining funds from partners are already secure, pending
approval of the NSF grant.
Due to the significant heliospheric and space weather component of the
LWA science goals, part of the NSF funding has been requested from
ATM and part from AST. ATM has already funded a study at Haystack
and CSR on space weather applications of the MWA. A $2.0M grant from
the NSF ITR program in 2001-4 supported design work on the LOFAR project,
focused on frequencies above 80 MHz, and on low angular resolution
applications for the core region of the array. This work was transferred
to the LFD, and both the technical and scientific design of the LFD lie on
the original development path. In addition to the NSF funds, MIT has
invested $0.8M in institutional funds, so that $2.8M has been spent on the
LFD to date.
- Construction history and cost
Future facility; NYA
Construction is not expected to start before the end of 2005. The
projected construction cost is ~$10M, including development,
hardware, software, infrastructure and 1 year of operations and
science analysis. These costs are based on coordination with the
approved Australian NTD project.
- Operational history and cost
Future facility; NYA
The US share of operating costs for the full MWA (not the demonstrator)
in the next decade
is estimated to be ~$2M/year, assuming substantial US investment
in a low frequency capability.
II. Technical details
- Specifics of telescope/instrument
The LFD will contain 8000 dual-polarization dipole antennas
optimized for the 80-300 MHz frequency range, arranged as 500
"tiles", each a 4 X 4 array of dipoles. The array will have no
moving parts, and all telescope functions including pointing
will be performed by electronic manipulation of dipole signals,
each of which contains information from ~4 steradians of sky
centered on the zenith. Each tile will perform an analog
beamforming operation, narrowing the field of view to a fully
steerable ~25 degrees at 150 MHz. The 500 tiles will be scattered
across a roughly 1.5 km region, forming an array with very high
imaging quality, and a field of view of several hundred square
degrees at a resolution of several arcminutes. FPGA-based
massively parallel digital hardware will select and condition a
32 MHz instantaneous bandwidth, and perform cross-correlation and
digital array beamforming. Software for array calibration, as well
as to support specific science goals will be developed.
- New capabilities anticipated/planned in next
The LFD array design is a major departure from conventional approaches,
with simple brute-force computing favored over fine-tuning and
precision in the antennas and receivers. As such, the LFD plays
a unique and vital technology development and demonstration role for
the future of radio astronomy.
The successful completion and operation of the LFD would, by
mid-2008, act as a springboard to implementation of the full MWA
as an international user facility in the next decade.
The ATNF goal is to build a sensitive high-redshift HI survey
instrument for pursuing Dark Energy research, operating down to
around 500 MHz. Assuming this comes to pass, the LFD side of the MWA
project may lead to several science driven technology developments,
which in order of perceived likelihood are:
The total cost of a low-frequency component of the full MWA
implementing most of the above features, and if built as a
standalone facility, has been estimated at $60-70M. A major
US involvement, including cost sharing from existing and/or
new partners, might require NSF investment in the $20M range
in the next 5-10 years. This low cost of a major new research
facility is a consequence of the inexpensive nature of low-frequency
analog hardware, and the design emphasis on digital systems subject
to Moore's Law. The most costly single item will be software related
to calibration and widefield imaging, an area where synergy with
Australian widefield efforts will be maximized.
This work constitutes important technology development for future
large radio telescope arrays of which the SKA (discussed separately)
is the pre-eminent example. A single design approach cannot
efficiently cover the full SKA frequency range, which spans a factor
of several hundred. The US SKA technology development
program (SKA-TDP) is focused on solutions based on small
paraboloids, best suited to higher frequencies. The LFD focus
instead explores the important 100-600 MHz range, where phased
array technology offers key advantages over steerable paraboloids.
Radio array design is a rapidly moving field driven by
digital advances, and the LFD demonstrator approach maximizes
options for efficient and cost-effective future growth.
- Greatly increased collecting area and sensitivity
(factor > 10)
- Inclusion of long baselines to expand the range of science
- Expansion of digital capabilities (bandwidth, number of
- Expansion of frequency coverage up to ~500 MHz
- Expansion of frequency coverage below 80 MHz
III. User profile
- % of "open skies" time
The LFD will become operational in late 2007, and is projected to run
in low-cost campaign mode for one year. During that time,
experiments will be scheduled, executed and results analyzed, by
science collaborations made up of researchers from LFD partner
institutions as well as outside researchers whose collaboration has
been prearranged. As the project moves forward, user-oriented
software will be developed as funds permit, building upon experience
from operating the demonstrator. We anticipate that open skies time
will be introduced in 2008-9, and will steadily be increased toward
100% as the full MWA user facility is implemented.
- Institutional affiliations of users
At present, there are three key science areas and associated science
collaborations, dealing with EOR, transients and heliospheric
research. Formal collaborations are still developing, but currently
(Dec 2004), 7 different US institutions, 5 Australian institutions,
one European and one Japanese institution are represented. Informal
expressions of interest span a much wider range of institutions.
Project policy is to actively broaden such participation in LFD
science based on contribution of resources as well as interest.
- Student access, involvement,
The LFD will be a training ground for US students with both
technical and scientific interests. Students will have access to
data through their affiliation with supervisors who are established
members of the LFD collaborations. One MIT student is currently
involved in early deployment of prototype systems and will spend
time in Australia. Another student is starting work on cosmological
simulations at the CfA.
In general, the LFD represents a good opportunity for multiple
student thesis projects, with such a large volume and variety of data
products to be generated. Particularly, LFD project policy is to
strongly encourage graduate students in instrument development and
subsequent research, emphasizing the revitalization of technological
IV. Science Overview
- Current forefront scientific
Future facility; NA.
Although the instrument is not yet built, active research associated
with the project is being conducted, primarily on the Epoch of
Reionization and on heliospheric science. Current work focuses on
theoretical expectations, and understanding how to design the LFD
for maximum scientific impact.
- Major discoveries (through 1999)
Future facility; NA
- Science highlights of last 5 years
Future facility; NA
- Main future science questions to be addressed
- Detecting and characterizing the redshifted 21 cm HI signal
from the cosmological epochs of reheating and reionization (EOR),
between redshifts of 6.5 and 16. By virtue of its wide field of view,
the LFD will have sufficient sensitivity to measure the predicted power
spectrum of fluctuations due to structure in the neutral IGM, to the presence
of bubbles caused by the first ionizing sources, and to spin temperature
gradients generated by the reheating process. It will also be able to
image "holes" in the neutral IGM caused by quasar-generated Strömgren
spheres. For EOR studies, control of systematics and removal of
foregrounds are the primary technical challenges, and are central
to the LFD design
- Characterizing the dynamic radio sky, with a sensitivity 6
orders of magnitude better than previous searches in this frequency band.
The LFD design includes the All Sky Monitor, with continuous
monitoring for transient sources on all timescales longer than 0.5
seconds, yielding excellent discovery potential. As for EOR and as for
previous instruments in this band, systematic errors, not collecting
area will be the limiting factor, and the LFD design is focused on
- Remotely sensing the solar wind plasma and disturbances in it,
and placing constraints on the magnetic fields, via scintillation and
Faraday rotation observations. The volume and nature of data to be
generated by the LFD can lead to significantly improved space weather
prediction. The capability of constraining magnetic fields is unique and
essential for such prediction.
- Several secondary science goals, including studies of pulsars,
the ISM, the ionosphere, recombination lines, and solar burst imaging.
- Synergies with other major forefront
- VLA: provides useful information on the 327 MHz and 74 MHz sky, as
well as ionospheric behavior. VLA data are already in use for
- ATA: Scientifically, LFD and ATA cover complementary
frequencies ranges, beneficial to transient source studies. Some of
the technical challenges have similar solutions and discussions
regarding sharing of IP for digital filterbank implementations in
FPGA devices are ongoing, for example.
- SWIFT, HETE-2, GLAST, LSST, LIGO: These facilities will act as
triggers for MWA observing. The electronic agility of the LFD will
allow efficient followup.
- Unique contributions
The key projects are all unique to the LFD and cannot be replicated
by other existing or planned instruments on this timescale and with
these performance levels. The
combination of unique attibutes such as relatively unexplored
frequency range, a continuously and fully accessible field of view
of several hundred square degrees, high surface brightness
sensitivity, high fractional processed bandwidth, fully electronic
operation with multibeaming, electronic pointing and tuning, and superb
instantanous point spread function plus tight control of systematics,
all in one instrument, delivers unique research capability.
V. Education/Outreach activities
- Visitor facility
- Student programs
- Other (as apply)
VI. Documentation/website URLs
- URL of facility website
Note that this website is under development.
- URL of EPO website
- URL(s) of any brief overviews of
- URL(s) of miscellaneous
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Last modified: Mon Feb 14 10:38:00 EST 2005