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Damaged satellites can wreak havoc on our favourite technologies, like cell phones and GPS, while giant asteroids could pose a threat to our planet. But a new Canadian telescope the size of a suitcase will help astronomers prevent close encounters of the dangerous kind.
With close to 1000 working satellites, about 18,000 chunks of space junk and at least 15,000 asteroids relatively close to Earth, somebody needs to keep track of things. And that's what Canada aims to do once the Near-Earth Object Surveillance Satellite (NEOSSat) space telescope is launched, anticipated for the spring of 2012.
NEOSSat will be the world's first orbiting eye-in-the-sky ' designed to help monitor both satellites and asteroids. It will be operated jointly by the Canadian Space Agency (CSA) and Defence Research and Development Canada (DRDC), an agency of the Department of National Defence.
Once in space, NEOSSat will spend its time in a geocentric orbit about 800 kilometres above Earth. That’s similar to the altitude of the International Space Station, and not far from a variety of other satellites. It will circle Earth every 100 minutes.
Preventing satellite pile-ups
Part of NEOSSat’s value is keeping track of the world’s satellites ' helping to prevent them from colliding with each other or with space debris. “We’ll be looking at objects that orbit anywhere from 15,000 to 40,000 kilometres above the Earth’s surface,” says Dr. Brad Wallace, a defence scientist at DRDC. In that range are a variety of satellites from various countries that help route communications signals (including cell phone, television and radio signals), monitor weather and ocean traffic, operate personal global positioning systems (like the GPS devices in our cars) and much more.
Cleaning up after ourselves in space
Astronomer Ken Tapping from the NRC Herzberg Institute of Astrophysics explains why orbiting junk is a messy problem.
“As a society, we have stuff happening in the background that many people don’t really realize is space-connected,” says Dr. Wallace. “The more you look at how space hardware is tied in with things we take for granted, like your cell phone or GPS, you realize how important it is.” Clearly, damaged satellites can create a lot of havoc.
The problem is how-to keep track of the 18,000-plus objects orbiting Earth. So far, monitoring is done through the U.S. Space Surveillance Network, which mainly uses ground-based telescopes and radars on Earth’s surface. If a possible collision between satellites (or a satellite and space debris) is detected, a functional satellite can generally be given a remote-controlled nudge to get out of the way. But sometimes the control of a satellite is lost ? due to anything from a collision to a short circuit ' and this can mean trouble for other nearby satellites if it gets in their way.
“One of the most important things that satellite operators need to know is where an inoperative satellite is relative to their satellite. That’s why monitoring is important,” says Lauchie Scott, a defence scientist at DRDC. Canada previously played a role in monitoring satellites from the 1950s to the 1980s using ground-based telescopes, but NEOSSat has a huge advantage over them. Because it stays above the Earth’s atmosphere, it’s not affected by clouds or the day-night cycle, and can be used for observing around the clock.
Getting up close with asteroids
Half of the time NEOSSat will be used by DRDC for tracking satellites, while the other half it will be used by the Canadian Space Agency for tracking and studying near-Earth asteroids. In this case, “near-Earth” means objects whose orbits periodically bring them to within about 45 million kilometres of the Earth.
The Canadian Space Agency will work with University of Calgary researchers on the Near Earth Space Surveillance mission. According to Rob Cardinal, a University of Calgary researcher on the team, there are three main reasons to observe asteroids. One is to garner scientific details about the early solar system. “Asteroids are remnants from the formation of the solar system. They’re a relatively untouched sampling of the primordial solar system,” he says.
Asteroids that are about 140 metres in diameter could cause local damage if one ever hit Earth, depending on where it landed, but wouldn’t be catastrophic to our planet.
A second reason is to gather information about asteroids with the eventual goal of tapping them as a source of natural resources, such as iron or other metals. But that can’t happen until more is understood about how individual asteroid orbits work, their size and likely composition, how solid they are, and more. Besides helping researchers answer such questions, NEOSSat will study a new class of recently discovered asteroids, called the Atiras, which orbit entirely within the Earth's orbit.
A third reason is planetary defence. “If an asteroid is going to hit us, we want to know about it beforehand with a view to avoiding such an encounter,” says Cardinal. Fortunately, such an encounter is highly unlikely. He points out that devastating impacts occur at a rate of maybe once every 100,000 years.
Asteroids that are about 140 metres in diameter could cause local damage if one ever hit Earth, depending on where it landed, but wouldn’t be catastrophic to our planet. It’s estimated there are about 15,000 asteroids this size or larger in the near-Earth range.
“If they’re larger than 1000 metres in diameter, they pose a potential global catastrophe, and there are roughly 1000 of those classified as near-Earth asteroids,” Cardinal says. “While it’s unlikely that any of these asteroids will hit Earth, we hope that NEOSSat will give us advance warning of any close calls.”
ISSN 1927-0275 = Dimensions (Ottawa. Online)