**DA 01-1258**

**Released: May 22, 2001**

Scientific Uses of the Spectrum and Spectrum Policy

*A tutorial on Radio Astronomy, Earth Exploration Satellite Service,
and*

*the Space Research Service*

The FCC's Office of Engineering and Technology is sponsoring a tutorial
by Dr. Paul G. Steffes, a Professor in the School of Electrical and
Computer Engineering at the Georgia Institute of Technology. The
presentation will begin at 10:30 a.m. on Tuesday, May 29 in the
Commission Meeting Room (TWC-305), 445 12^TH^ Street, S.W., Washington,
D.C. and will last approximately one and one-half hours.

The Radio Astronomy Service, the Earth Exploration Satellite Service,
and the Space Research Service employ ultra-sensitive receivers to
measure natural emissions from objects in space and from the earth's
atmosphere and surface. These services have been instrumental in
improving our understanding of the earth and our universe and have
practical implications that may not be obvious, such as weather
tracking, land use management and other essential sciences.

Through the use of radio astronomy, scientists have in recent years made
the first discovery of planets outside the solar system, circling a
distant pulsar. Measurements of radio spectral line emissions have
identified and characterized the birth sites of stars in our own galaxy
and the complex distribution and evolution of galaxies in the universe.
They have also provided unique insights into the structure and
composition of the atmospheres of the planets in our own solar system.
Radio astronomy measurements of the cosmic background both from
earth-based radio telescopes (the Radio Astronomy Service) and from
space-based radio telescopes such as NASA's Cosmic Background Explorer,
or COBE (Space Research Service) have detected ripples generated in the
early universe, which later formed the stars and galaxies we see today.
Observations of supernovas have witnessed the creation and distribution
of the heavy elements essential to the formation of planets like earth,
and of life itself.

The Earth Exploration Satellite Service represents a unique resource for
monitoring the earth's global atmospheric and surface conditions, and
has made vital contributions to the study of land resource management,
hazard prediction, meteorology, ocean studies, atmospheric chemistry,
and global change. Currently, instruments operating in the EESS bands
provide regular and reliable quantitative measurements that support an
extensive array of scientific, commercial and government (civil and
military) users. Applications include aviation forecasts; flood,
hurricane, and severe storm warning and tracking; seasonal climate
forecasts, monitoring of climate variability, studies of the ocean
surface and internal structure; and monitoring of tropospheric and
stratospheric ozone.

Much of this research is conducted on portions of the radio spectrum
through the use of "passive" operations, which do not employ any sort of
transmitter, but measure electro-magnetic energy. As passive users of
the spectrum, radio astronomers and earth scientists have no control
over the frequencies that they must use for their observations or over
the nature of the signals they receive. These parameters are determined
by the laws of nature. Generally, the emissions that radio astronomers
receive are extremely weak -- a typical radio telescope only receives
about one-trillionth of a watt from even the strongest cosmic source,
and routinely receives radiation from sources even one million times
weaker than that. Because radio astronomy receivers are designed to
detect such remarkably weak signals, spectrum management and spectrum
policy decisions are of great significance to this scientific community.

Facilitating passive services research can pose a significant challenge
to spectrum policy makers, given the increasing demand for, and
intensity of, use of spectrum.

This presentation will provide a broad overview of the scientific uses
of the radio spectrum and discuss research that uses portions of the
radio spectrum occupied by "passive" services (i.e., those that do not
use any transmitters). In this tutorial, Dr. Steffes will discuss how
such passive services are used for scientific research. The tutorial
will also address sources of interference, as well as the problems that
policy makers encounter in addressing the needs of the scientific
community while also addressing increasing demands for electromagnetic
spectrum usage. This presentation has been developed for a general
audience and does not require previous study of electrical engineering
or physics. Technical approaches to the analysis and remediation of
these problems will also be discussed.

Members of the public may attend the presentation, and every effort will
be made to accommodate as many people as possible. Admittance, however,
will be limited to the seating available in the Commission meeting room.
Please allow sufficient time for clearance through Commission security
before the presentation begins. For additional information, please
contact Tom Derenge at 202-418-2451 (e-mail:
[tderenge@fcc.gov](mailto:tderrenge@fcc.gov))