Asteroids are like cancer. Early detection is the key to effective treatment. An asteroid wiped out the dinosaurs. A big enough asteroid could wipe out humanity if we do not find it years before it strikes Earth. Therefore a cheap Canadian space telescope satellite designed to search for asteroids is a really good idea.
Canada is building the world’s first space telescope designed to detect and track asteroids as well as satellites. Called NEOSSat (Near Earth Object Surveillance Satellite), this spacecraft will provide a significant improvement in surveillance of asteroids that pose a collision hazard with Earth and innovative technologies for tracking satellites in orbit high above our planet. Weighing in at a mere 65-kilograms, this dual-use $12-million mission builds upon Canada’s expertise in compact “microsatellite” design. NEOSSat will be the size of a large suitcase, and is cost-effective because of its small size and ability to “piggyback” on the launch of other spacecraft. The mission is funded by Defence Research Development Canada(DRDC) and the Canadian Space Agency(CSA). Together CSA and DRDC formed a Joint Project Office to manage the NEOSSat design, construction and launch phases. NEOSSat is expected to be launched into space in 2010. The two projects that will use NEOSSat are HEOSS (High Earth Orbit Space Surveillance) and the NESS (Near Earth Space Surveillance) asteroid search program.
But if the Canadians find an asteroid is going to wipe us out will they burrow under ground and not tell anyone else? More room for them, eh?
Although NEOSSat’s 15-centimetre telescope is smaller than most amateur astronomers’, its location approximately 700 kilometres above Earth’s atmosphere will give it a huge advantage in searching the blackness of space for faint signs of moving asteroids. Twisting and turning hundreds of times each day, orbiting from pole to pole every 50 minutes, and generating power from the Sun, NEOSSat will send dozens of images to the ground each time it passes over Canada. Due to the ultra-low sky background provided by the vacuum of space, NEOSSat will be able to detect asteroids delivering as few as 50 photons of light in a 100-second exposure.
We really ought to put up some more powerful satellites and find all the asteroids at a much faster rate. Why not remove this risk from our lives?
Smaller asteroids are more dangerous than previously thought.
ALBUQUERQUE, N.M. — The stunning amount of forest devastation at Tunguska a century ago in Siberia may have been caused by an asteroid only a fraction as large as previously published estimates, Sandia National Laboratories supercomputer simulations suggest.
“The asteroid that caused the extensive damage was much smaller than we had thought,” says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. “That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed.”
Because smaller asteroids approach Earth statistically more frequently than larger ones, he says, “We should be making more efforts at detecting the smaller ones than we have till now.”
We need to search harder for the larger number of smaller asteroids. Our risk of death and destruction from asteroids is larger than previously believed.
The Tunguska blast has a downward direction that amplifies its destructive effect on the surface of the Earth.
Simulations show that the material of an incoming asteroid is compressed by the increasing resistance of Earth’s atmosphere. As it penetrates deeper, the more and more resistant atmospheric wall causes it to explode as an airburst that precipitates the downward flow of heated gas.
Because of the additional energy transported toward the surface by the fireball, what scientists had thought to be an explosion between 10 and 20 megatons was more likely only three to five megatons. The physical size of the asteroid, says Boslough, depends upon its speed and whether it is porous or nonporous, icy or waterless, and other material characteristics.
We should try much harder to identify the asteroids that are going to collide with the Earth in the future. The sooner we identify them the easier it will be to deflect them from their paths.
The Tunguska event felled over 80 million trees and is a topic of active research which has generated lots of cool photographs.