NSF PR 00-46 - June 15, 2000
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Astronomers Win Protection for Key Part of Spectrum
Astronomers using the millimeter-wave region of the
radio spectrum have won crucial protection for their
science. The 2,500 delegates to the World Radiocommunication
Conference (WCR 2000) have given final approval to
dedicated spectrum allocations for radio astronomy.
The delegates recently concluded a month of deliberations
in Istanbul, Turkey.
The new millimeter-wave allocations represent the culmination
of more than three years of cooperative planning by
radio astronomers in many countries.
Millimeter waves - high-frequency radio waves - have
come of age as an astronomical tool in the last ten
years. They are one of the last technological frontiers
WRC-00 has protected for science all the frequencies
between 71 and 275 Gigahertz that radio astronomers
currently use, adding more than 90 GHz of spectrum
to the 44 GHz already set aside in this frequency
range. As a result, radio astronomy is now allocated
most of the frequencies between 71 and 275 GHz that
can get through the earth's atmosphere.
"We have formal access to all three atmospheric ‘windows,’
apart from their very edges," said Tom Gergely of
the National Science Foundation's (NSF) Astronomy
Division, one of the U.S. delegates to WRC-2000.
The WRC also changed the frequencies allocated to satellite
downlinks within the 71-275 GHz range to frequencies
not used for science. Since no satellites yet operate
at these high frequencies, no equipment needs to be
"Commercial technologies are not fully developed above
50 GHz," said Klaus Ruf, chairman of the Inter-Union
Commission for the Allocation of Frequencies. "The
WRC's actions mean that, when they are, radio astronomers
should be able to share this part of the spectrum
with most terrestrial services."
The World Radiocommunication Conference is held every
two to three years. Member countries of the International
Telecommunication Union meet at the WRC to parcel
out the radio frequency spectrum between radio-based
applications such as personal communications, satellite
broadcasting, GPS and amateur radio, and the sciences
of radio astronomy, earth exploration and deep space
research. The WRC also coordinates sharing between
these services in the same radio bands.
WRC decisions are incorporated into the Radio Regulations
that govern radio services worldwide.
The new spectrum allocations for radio astronomy are
the first since 1979. Millimeter-wave astronomy was
then in its infancy and many of its needs were not
yet known. As astronomers began to explore this region
of the spectrum they found spectral lines from many
interesting molecules in space. Many of those lines
had not fallen into the areas originally set aside
for astronomy, but most will be under the new allocations.
"It's a win for millimeter-wave science," said John
Whiteoak of the Australia Telescope National Facility,
Australian delegate to WRC-2000. "This secures its
The protection is a significant step for both existing
millimeter-wave telescopes and new ones such as the
Atacama Large Millimeter Array (ALMA) now being planned
by a US-European consortium. Even at its isolated
site in Chile's Atacama Desert, ALMA would be vulnerable
to interference from satellite emissions. Sensitive
radio astronomy receivers are blinded by these emissions,
just as an optical telescope would be by a searchlight.
"There is more energy at millimeter and sub-millimeter
wavelengths washing through the universe than there
is of light or any other kind of radiation," said
ALMA project scientist, Al Wootten of the National
Radio Astronomy Observatory. "Imaging the sources
of this energy can tell us a great deal about the
formation of stars and galaxies, and even planets."
The changes were welcomed by Johannes Andersen, General
Secretary of the International Astronomical Union,
which represents astronomers worldwide.
"Protecting our ability to observe the universe is
the top priority for the International Astronomical
Union," Andersen said. "This action shows that international
bodies accept the need for environmental emission
standards in space as well as on Earth, for the benefit