LOGAN, Utah
– Canadian space and defense agencies are considering construction
of a small space telescope to detect possible Earth-whacking asteroids
and train the military to track satellites in high orbits.
"We want
to watch for rocks in the sky that might hit the Earth or that
we might want to mine," said Kieran Carroll, space projects
manager for Dynacon Enterprises Ltd. in Mississauga, Ontario,
near Toronto. "And while we are up there looking, we might
as well be space traffic cops and learn how to keep track of all
the high-orbit satellites."
Concept studies
for NESS – the Near Earth Space Surveillance satellite –
are underway with the support of the Canadian Space Agency and
Department of National Defense, Carroll said during the 14th annual
Conference on Small Satellites in Logan, Utah.
The meeting,
which ended August 24, was sponsored by the American Institute
of Aeronautics and Astronautics and Utah State University’s
Space Dynamics Laboratory.
Dynacon now
is prime contractor building another microsatellite to carry Canada’s
first space telescope, MOST, which stands for Microvariability
and Oscillations of Stars because the 6-inch- (15-centimeter-)
wide telescope will study so-called "starquakes" for
clues to the age of the universe.
MOST is due
for launch into low Earth orbit from Vandenberg Air Force Base,
California in early 2003 as a secondary payload to Canada’s
Radarsat 2 on a Boeing Delta 2 rocket.
NESS would
be Canada’s second space telescope, modeled after the 115-pound
(52-kilogram) MOST, but with possible improvements, including
a larger telescope and better computer, Carroll said.
He described
MOST as a suitcase-shaped box measuring 25 by 23 by 10 inches
(63 by 58 by 25 centimeters).
Carroll estimated
NESS would cost $3 million to $4 million in U.S. dollars.
An orbiting
asteroid search would be more effective at detecting a class of
Earth-threatening asteroids named Atens, which spend much of their
time inside Earth’s orbit, and thus closer to the sun and
in daylit skies. There is no "sky glow" in space to
prevent daytime observations. Baffles to block sunlight could
let NESS look for asteroids closer to the sun.
About 65 Atens
have been discovered, but some scientists believe there may be
several hundred larger than 0.6 mile (1 kilometer) wide, as well
as tens of thousands smaller ones.
Newly discovered
asteroids frequently are lost to view within days. NESS would
be able to track them longer than ground-based telescopes, allowing
better determinations of their orbits, and thus the threat they
pose to Earth, Carroll said. NESS also would study asteroids,
including their mineral composition for possible space mining.
As for satellite
tracking, Carroll said Canada is looking for new ways to fulfill
its responsibilities as the United States’ partner in the
North American Aerospace Defense Command, which watches for attacking
missiles and tracks some 23,000 man-made objects in space.
Radar and
optical telescopes have tracked most satellites from the ground.
But Canada’s satellite-tracking optical telescopes and cameras
have been replaced by newer sensors, and radar is not good at
tracking high-altitude satellites, Carroll said.
"Canada’s
Department of National Defense has recently initiated a Surveillance
of Space (SOS) program in order to contribute new Canadian sensors
to the Space Surveillance Network," Carroll and colleagues
wrote in a paper prepared for the satellite conference.
The SOS program
will include new ground-based telescopes and "will also involve
Canada launching a satellite system to track other satellites,"
particularly those in high orbits, wrote Carroll and researchers
from the universities of Calgary, Victoria and British Columbia.
Canada’s
Defense Research Establishment contracted with Dynacon "to
study how a microsatellite (NESS) based on the MOST design could
be used to conduct experimental satellite-tracking activities,"
they added.
Carroll said
NESS would be used for research "so the Canadian military
can learn about operating surveillance satellites" before
building a bigger system.
Why track
high-orbit satellites?
"NORAD
and U.S. Space Command want to know what’s up in space,"
said John Pike, space policy analyst for the Federation of American
Scientists in Washington.
"The
Russians may have [in high orbits] a few signals-intelligence
(eavesdropping) satellites, a few early-warning satellites and
they certainly have a lot of communications satellites,"
Pike said. "We want to know what their capabilities are and
what they might monitor."
Carroll said
NESS could track malfunctioning communications satellites to help
prevent collisions with other satellites, and also monitor high-altitude
Russian and Chinese communications satellites.
Pike called
the proposed NESS satellite "a bargain at the price."
However, the
money might be better spent on ground-based telescopes to search
for asteroids, said Brian Marsden, director of the International
Astronomical Union’s Minor Planet Center, which tallies and
reports asteroid and comet discoveries.
"A few
million dollars is indeed a lot of money," he said from Cambridge,
Massachusetts. "That’s comparable to the amount put
into ground-based [asteroid-detection] work around the world."
Marsden also
said the Canadians should make the telescope aperture larger than
6 inches (15 centimeters). Nevertheless, a small orbiting telescope
"could be quite useful" because it would not be affected
by clouds, the atmosphere, the moon or daylight, and could look
for asteroids closer to the sun.
He said the
danger posed by Aten asteroids "certainly is not being addressed
by the ground-based programs."
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