2 years ago
WASHINGTON, DC (WUSA) -- The American military has a ten second window each day for the next several days to pull off a technological feat that, in theory, sounds almost impossible.
It plans to fire a missile from a cruiser in the Pacific Ocean and blast from earth orbit a falling spy satellite that has a thousand pounds of toxic chemical fuel on board and which, itself, weighs about five thousand pounds.
If allowed to fall naturally to earth, there is a risk the toxic fuel could make ill earthlings in its way. The satellite itself would be expected to break up as it re-entered earth atmosphere, with about half it's bulk expected to survive and fall to earth.
"It is difficult, certainly not an easy task. They are trying to shoot down something that is traveling very fast. The closer that the intercept missile gets to it, the less opportunity it will have to change its course to be able to intercept," said Raymond Sedwick, a professor at the University of Maryland who teaches aerospace engineering.
"There is difficulty associated with the fact that these missiles are designed to be heat-seeking missiles and the spacecraft, because it is basically dead, is not producing any heat signature of its own. The fact that the satellite is re-entering the atmosphere means there will be a certain amount of heat that will be generated, so they're most likely going to make modifications ... to account for the lower level of heat generation," Sedwick told 9NEWS NOW.
Success means reliance on both hardware and software designed especially for the task. "You have to have the hardware capability to be able to change your trajectory very rapidly, especially towards the end.. you have to be able to process the information that's coming in very rapidly, obviously in real time.. They're going to have to possibly re-calibrate the trajectory, certainly in the last few seconds before impact in a very timely manner.
"A lot of the tracking is probably done on board. I don't know how much of it would actually be done with the ground actually being in the loop for the control. It's most likely they will set it on its initial trajectory and then at some point, as it closes in on the spacecraft, the missile will probably be doing its own tracking and updates."
The satellite will be targeted when it is at a low point in its orbit. That should reduce the debris field that would otherwise be floating in space, endangering spacecraft for decades to come.
"If we fail, the satellite comes down in just the way that it would have come down before, so really it's kind of a zero sum game there. If we succeed, then I think the benefit is that we've reduced the likelihood of a very large piece of the satellite coming down in a potentially populated area.
"One of the big concerns about this particular spacecraft is that it still has its full complement of propellant on board which is hydrazine and it's a fairly dangerous chemical in large quantities, so what they want to do is try to minimize the possibility of that coming down into a populated area, scattering the hydrazine, possibly creating a cloud that might go over the populated area," Sedwick said.
Written by 9NEWS NOW
