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An asteroid-spotting satellite is subjected to a test chamber on Earth.

Testing to see how the Canadian Space Agency's asteroid-hunting satellite, NEOSSat, fares against radio frequencies.

Photograph courtesy Janice Lang, DRDC

Andrew Fazekas

for National Geographic News

Published February 20, 2013

Earth received a wake-up call last week with a double shot of incoming space rocks—the near miss of asteroid DA14 and the Russian meteor explosion. Our planet is in a cosmic shooting gallery and more work needs to be done to survey menacing asteroids, astronomers say.

Now the Canadian Space Agency is stepping up to the plate to help do just that with the launch of a new sentinel to detect and track near-Earth objects (NEOs). The pint-size space telescope is hitching a ride into orbit aboard an Indian rocket on February 25.

Even though the Near-Earth Object Space Surveillance Satellite (NEOSSat) might find it challenging to hunt down relatively smaller size meteors, like the one that crashed in Russia last week, it will be the first telescope in orbit dedicated to keeping tabs on what's buzzing around Earth. ("Pictures: Meteorite Hits Russia.")

In addition to keeping an eye out for space rocks, NEOSSat will pull double duty by monitoring traffic among the increasing crowd of orbiting satellites—guarding against collisions between wayward space junk. (Learn about how satellite collisions create dangerous debris.)

In recent years there have been a few head-on collisions between orbiting satellites and several near misses with the International Space Station, making this a concern for satellite providers and space agencies.

Suitcase-size Sentinel

Weighing in at a mere 143 pounds (65 kilograms), this $12 million suitcase-size satellite will spend half its time pinpointing asteroids. Researchers say it could find at least a hundred new ones during its first year of operation—some of which currently have undetected orbits between the Earth and the sun.

"This spacecraft is designed to be able to search the sky near the sun, which is difficult for Earth-based telescopes to do, and so it therefore complements ground-based search programs," said Alan Hildebrand, planetary scientist at the University of Calgary in Alberta, Canada, and lead scientist for the NEOSSat mission.

Outfitted with a special sunshade, the telescope will be pointed precisely within a 45 degree angle of the sun in order to continuously snap hundred-second-long exposures that the team hopes will eventually reveal at least 50 percent of the asteroids half a mile (one kilometer) across or larger within Earth's orbit around the sun.

Asteroids from far out in the solar system sometimes swing past Earth, but the most dangerous ones are those that continually cross Earth's orbit—like the inner-Earth objects (IEOs), or Atira class asteroids, which shuttle between our planet and the sun.

NEOSSat's six-inch-wide (15-centimeter-wide) telescope is no larger than those used by many backyard astronomers. But when observing space from Earth, there is simply too much scattered sunshine and atmosphere, making it difficult to spot IEOs, added Hildebrand.

Flying in a polar orbit some 435 miles (700 kilometers) above the blurring effects of the atmosphere, the tiny spacecraft will be on duty around the clock, "so it should be able to spot asteroids that are even fainter than what some of the current ground-based surveys are capable of," he said.

Celestial Hide-and-Seek

Robert Jedicke, an astronomer at the University of Hawaii, who is not involved with the mission, calls Atira asteroids the champions in the hide-and-seek-game of NEO surveying. (Learn how the University of Hawaii is monitoring asteroids.)

Some NEOs hide in plain sight, said Jedicke. They move like asteroids much farther away from Earth, fooling observers into thinking the NEO is more distant than it actually is. And we can't spot some IEOs simply because they're hidden in the sun's glare, he added.

"Finding them will allow us to fine-tune the calculations of the risk of Earth impact and to test our theories that govern the evolution of asteroid orbits out of the main belt into the region near Earth."

While the technology for finding potentially dangerous asteroids has matured over the past couple of decades, most of the asteroids—larger than the Russian meteor—that can cause serious damage haven't been discovered yet, warned Jedicke.

"Just like the Chelyabinsk meteor, right now, the most likely warning time we have of an asteroid impact is zero," he said.

"While NEOSSat will make an important contribution to the goal of reducing the NEO impact risk, there will still be much left to be done."

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