The National Science Foundation (NSF) has awarded
$1.5 million over three years to help support early development of a
massive new radio telescope by a Cornell University-led U.S.
consortium of 10 universities and institutions. The proposed
telescope would have 100 times the sensitivity of today’s best radio
telescopes, enabling it to “see” back to a primeval epoch by
detecting galaxies in the early universe and hydrogen gas before it
formed in the galaxies.

The telescope, the Square Kilometer Array (SKA), would cost in the
area of $1 billion and would be among the largest scientific
instruments ever assembled. Eight national consortia from around the
world are competing for the winning design and the site, which are
not likely to be chosen until about 2007.

Part of the NSF funding will be used to investigate feed antennas and
low-temperature receivers, says James Cordes, professor of astronomy
at Cornell, who is principal investigator on the research agency’s
award. The funding also will be used to investigate the problem of
radio frequency (RF) interference that the SKA, with its wide
bandwidth, will be subject to. “Part of the NSF funds will be used
for taking data, acquiring data with existing facilities such as the
Arecibo Observatory, and using prototypes for excising RF,” says
Cordes.

The many problems that the development of the SKA will face depend on
both its design and its siting. The U.S. consortium, chaired by
Yervant Terzian, the David C. Duncan Professor in the Physical
Sciences at Cornell, is discussing a telescope made up of about 100
stations, each made up of several hundred antennas, and spread out
over a continentwide distance. In this way the antennas would form a
telescope, called an interferometer, in which radio signals from
distant objects in the universe are captured by separate antennas and
brought together at a central processor. Indeed, the SKA would be by
far the largest interferometer ever built. (Although the array would
cover an immense area, the actual collecting surfaces would cover a
square kilometer, if placed end to end.) “The U.S. concept is that if
we can design a basic building block — consisting of a single
antenna — we will need to stamp out many thousands of them,” says
Cordes. The challenge, he observes, is to design an antenna and the
receiver system that will go with it, plus all of the necessary
digital electronics, that would keep the cost of the SKA at $1
billion, an extremely low cost by current radio telescope standards.
“We need to make the cost per square meter as small as possible,”
says Cordes.

The NSF funding, he says, will be used to investigate such a design,
with some of the work being carried out at Cornell by Cordes and by
German Cortes-Medellin, a senior research associate with the National
Astronomy and Ionosphere Center (NAIC) at Cornell, which manages the
Arecibo Observatory in Puerto Rico for the NSF. Cordes will be
collaborating with John Dickey, professor of astronomy at the
University of Minnesota, and Steven Ellingson, a research scientist
at Ohio State University, and with researchers at another NSF
facility, the National Radio Astronomy Observatory in Socorro, N.M.
All collaborating institutions are members of the U.S. SKA consortium.

At a recent meeting of the consortium at Cornell, Terzian noted that
the Southwest United States is a strong contender for the site of the
SKA. The general siting criteria, he explained, include both
construction and operating costs, as well as finding a site for “the
best science.” The data that will be acquired in coming months, he
said, will include wind data, radio quietness, RF surveys, nature
conservancy, labor costs and the costs of fiber optics. However,
notes Cordes, there will be insufficient funds in the initial NSF
grant to pay for the actual site testing. This would be covered by a
second proposal that has been submitted to the NSF.

Wearing his other hat as chairman of the international site selection
committee, Terzian said there will be an international gathering of
the consortia (from the United States, Canada, Europe, India, China
and Australia) at the Arecibo Observatory, Puerto Rico, in January to
discuss the process of making the selections for the location of the
SKA.

In the meantime, Cordes and his colleagues also are considering what
would be a “realistic” scientific program for the SKA. “We want to
see what the universe looked like before the galaxies were formed,”
he says. “One of our scientific goals is to nail down when the epoch
of reionization took place. This will be part of the process of
mapping out the whole timeline for hydrogen in the universe.”

Other members of the U.S. consortium, besides Cornell, Ohio State and
the University of Minnesota, are the California Institute of
Technology, Harvard-Smithsonian Center for Astrophysics,
Massachusetts Institute of Technology, Naval Research Laboratory,
SETI Institute, the University of California-Berkeley and the
University of New Mexico. For more details see
http://www.usska.org/main.html.