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 But Canada?s satellite-tracking optical telescopes and cameras have been replaced by newer sensors, and radar is not good at tracking high-altitude satellites, Carroll said.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."