One of the greatest threats to life on Earth is the danger of a large asteroid impact. Yet astronomers cannot currently visualize many asteroids clearly enough to predict whether their paths threaten collision. Canadian scientists hope to change that.
A joint effort by the Canadian Space Agency and Defense Research Development Canada (DRDC) will make Canada the first nation to launch a space-based telescope designed to monitor the approximately 100,000 asteroids with diameters greater than 140 metres that orbit the Sun near Earth. The project, dubbed the Near-Earth Object Surveillance Satellite (NEOSSat), aims to shed light on the location and path of near-Earth asteroids, and catalogue those with diameters larger than one kilometre.
The 12-million dollar plan treads on the heels of the 2003 Canadian MOST project, which monitors the age of stars. This project demonstrated that a relatively inexpensive microsatellite can effectively collect data not easily accessed from the ground.
While current ground-based efforts monitor some asteroids and comets, they are less effective at detecting Atens asteroids. They are almost completely unable to detect interior-to-Earth’s-orbit (IEO) asteroids, whose orbit around the Sun passes within Earth’s own movements. Viewing these potentially hazardous asteroids from the ground is difficult. They can only be viewed at sunrise and sunset, when sky-glow can interfere with data collection.
From a Sun-synchronous orbit 700 kilometers above the Earth and traveling from pole to pole every 100 minutes, NEOSSat will be able to monitor asteroids 24 hours a day, including the Atens and IEOs.
Above Earth’s atmosphere, NEOSSat will have a clear view of space, able to capture four images every 125 minutes. Due to the reduced sky background, NEOSSat will photograph objects reflecting as little as 50 photons of light. These images will be collected and processed at the University of Calgary under the supervision of Dr. Alan Hildebrand, Canada Research Chair in Planetary Science. Once processed, the images will reveal moving objects that will be manually verified.
Hildebrand currently leads the University of Calgary’s ground-based asteroid detection program and believes that “NEOSSat will find ‘low and slow’ asteroids before they pass by our planet and sprint missions could be launched to explore them when they are in the vicinity of the Earth.”
If the NEOSSat mission is successful, the monitoring of near-Earth asteroids could lessen the use of certain ground-based telescopes, freeing up telescope time for scientists pursuing other lines of inquiry.
Although much of NEOSSat’s attention centres around the analysis of near-Earth asteroids, plans for the project are two-pronged. Data collected on these asteroids will be used by scientists of the Near-Earth Space Surveillance project in Calgary. Owing to its relatively low orbit, NEOSSat will also monitor objects around the Earth.
This second project, named the High-Earth Orbit Space Surveillance, is overseen by the DRDC and led by Dr. Brad Wallace. They aim to provide information about artificial satellites, including those used for communication and weather monitoring, in deep orbit around the Earth. This information will help Canadian Forces’ effort to accurately map space objects that could pose collision risks for space stations and shuttles. It will also decipher objects that may pose a security risk to Canadian assets.
The High-Earth Orbit Space Surveillance project will supplement NORAD’s existing aerospace warning mission and act as pathfinder technology, potentially leading to the launch of more surveillance telescopes that require less of Canadian Forces’ funds.
NEOSSat will “hitch-hike” into Earth’s orbit aboard another spacecraft in 2010. The public is encouraged to monitor the progress of the mission and support the endeavour. Include your name aboard the satellite by logging onto the NEOSSat website at www.neossat.ca
