archive: SETI FW: Larger than Earth telescope reveals ancient quasars

SETI FW: Larger than Earth telescope reveals ancient quasars

Larry Klaes ( )
Fri, 18 Sep 1998 11:42:50 -0400

From: JPL Media Relations Office
Sent: Thursday, September 17, 1998 10:25 PM
Subject: Larger than Earth telescope reveals ancient quasars

PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011

Contact: John G. Watson

FOR IMMEDIATE RELEASE September 17, 1998


Images of quasars billions of light-years away are among the
striking initial results of the Very Long Base Interferometry
(VLBI) Space Observatory Program, a new type of astronomy mission
that uses a combination of satellite- and Earth-based radio
antennas to create a telescope larger than Earth.

Initial results of the radio interferometry mission,
launched in February 1997 by Japan's Institute of Space and
Astronautical Science (ISAS), are reported in the September 18,
1998, issue of Science magazine.

NASA's Jet Propulsion Laboratory, Pasadena, CA, is part of
an international consortium of organizations that support the
mission, that creates the largest astronomical "instrument" ever
built -- a radio telescope more than two-and-a-half times the
diameter of the Earth. One of the most complex space missions
ever attempted, Space VLBI has given astronomers one of their
sharpest views yet of the universe.

The Science article releases four new images, all depicting
quasars whose emissions are estimated to have traveled billions
of years to reach Earth. "These images probe some of the most
distant and ancient objects in the universe, giving us a glimpse
of quasars as they existed billions of years ago," said co-author
Dr. Robert Preston, project scientist for the mission at JPL.
"These powerful objects exist at the center of many galaxies,
including our own familiar Milky Way, which has a weak version of
a quasar."

Key results detailed in the article revolve around images of
extremely distant objects created through a combination of raw
data from the space radio telescope and an array of ground radio
telescopes, along with highly sophisticated digital imaging
techniques. Of special note is the value of such images in
clearly resolving individual components in the observed quasars'
jets, which are composed of material rushing away from quasars at
nearly the speed of light. The four quasar images are available

Quasars are enormously bright point-like optical objects,
often shining with an intensity many hundreds of times that of an
entire galaxy. It is believed that quasars are powered by gas and
the remnants of stars spiraling into black holes that have masses
of millions to billions of times that of our Sun. Black holes are
objects that are so massive that no light or matter can escape
from them. Some of the material rushing into the black hole is
thought to be thrown away at enormous speeds to form the observed
narrow, radio-emitting jets. By studying these jets, astronomers
hope to learn more about the black holes that power them.

Very long baseline interferometry is a technique used by
radio astronomers that electronically links widely separated
radio telescopes together to form a single instrument with
extraordinarily sharp "vision," or resolving power. The wider the
distance between the telescopes, the greater the resolving power.
By taking this technique into space for the first time,
astronomers have approximately tripled the resolving power
previously available with only ground-based telescopes. The Space
VLBI satellite system has resolving power more than 100 times
greater than the Hubble Space Telescope has at optical
wavelengths. In fact, its resolving power is almost equivalent to
being able to see a grain of rice in Tokyo from Los Angeles.

The project, a major international undertaking, is led by
Japan's ISAS, backed by the National Astronomical Observatory of
Japan. Collaborators include JPL; the National Science
Foundation's National Radio Astronomy Observatory (NRAO); the
Canadian Space Agency; the Australia Telescope National Facility;
the European VLBI Network and the Joint Institute for Very Long
Baseline Interferometry in Europe. More than 50 scientists
associated with these and other collaborating institutions
contributed to report published in Science magazine overview

The Space VLBI project's eight meter (26-foot)-diameter
orbiting radio telescope observes celestial radio sources in
concert with a number of the world's ground-based radio
telescopes. It is in an elliptical orbit, varying between 1,000
and 20,000 kilometers (620 to 12,400 miles) above the Earth's
surface. This orbit provides a wide range of distances between
the satellite and ground-based telescopes, which is important for
producing a high-quality image of the radio source being
observed. One orbit of the Earth takes about six hours.

Approximately 40 radio telescopes from more than 15
countries have committed time to co-observe with the satellite.
These telescopes include NASA's Deep Space Network antennas in
California, Spain, and Australia; the National Science
Foundation's Very Long Baseline Array (VLBA), an array of 10
telescopes spanning the United States from Hawaii to Saint Croix;
the European VLBI Network, more than a dozen telescopes ranging
from the United Kingdom to China; a Southern Hemisphere array of
telescopes stretching from eastern Australia to South Africa; and
Japan's network of domestic radio telescopes.

JPL manages the U.S. Space Very Long Baseline
Interferometry project for NASA's Office of Space Science,
Washington, D.C. JPL is a division of the California Institute of



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