Some time in the next few days the US navy will fire a rocket in order to shoot down a satellite carrying 454 kilograms of the very poisonous substance hydrazine. By blowing the satellite up, the hydrazine tank will explode dispersing the gas to a low concentration level If the tank is not blown up, it would likely survive re-entry. If it burst on contact with the earth, several city blocks could be covered with deadly gas.
Most likely, the satellite will not hit a few city block, and the military says it is most likely to come down in a desolate area. But, the military has said a lot of things in the past that they just made up, so who knows. (BBC)
In any event, about half of the 2,700 kilogram satellite is expected to make it to the surface of the earth.
One distinct possibiltiy is that the navy rocket could fail to hit the satellite, which would demonstrate the effectiveness of the United State's national defense system, showing a weakness which would likely be exploited by, for example, the Canadians. Those of us in northern states should be on the lookout for an invasion from Canada. There have been reports for some time now that the Canadians have been massing on the border, so this is pretty serious.
The satellite will first 'feel' the atmosphere doing well above Mach 20. Given its unaerodynamic design and utter lack of re-entry shielding, it will fair far worse than Columbia did when it came in with damaged shielding. Hypersonic plasma works wonders as a cutting torch.
I can't believe anyone is worried about the hydrazine tank not coming undone during reentry. My money says there is something else on the DoD satellite that they want destroyed.
The US government has never worried about old Soviet satellites de-orbiting, and some of those were powered by nuclear reactors.
Hint: it's a spy satellite.
I think that's the main idea, to test the defensive systems ability to shoot down a 'missile'.
And there was an actual plan to invade the United States, just as the United States had plans to invade Canada (as they've already done more than once).
Is hydrazine a greenhouse gas?
Hydrazine is a liquid. It is rocket fuel. The hydrazine is pushed through a tube or something made of a particular metal, which causes it (the hydrazine) to break apart chemically, converting to a hot, quickly expanding, gas. It is commonly used as the "retrorocket" fuel on satellites and such, but it has been used as a rocket fuel pretty much since there have been rockets.
This is actually more of an anti-satellite test than an anti-missile test. There is at least a chance that the military is telling the truth about the hydrazine tank. If the hydrazine is frozen in a spherical tank, that tank might well reach the ground close to intact, only containing not a solid but a very hot liquid. But even CNN mentioned that there are probably other things on the satellite that the military would prefer not survive through reentry.
Hydrazine is a liquid. It is rocket fuel. The hydrazine is pushed through a tube or something made of a particular metal, which causes it (the hydrazine) to break apart chemically, converting to a hot, quickly expanding, gas.
The hydrazine systems I've seen consist of tanks of pressurized N2H4 that is piped over catalyst bed heaters. The heaters rapidly break down the hydrazine into hot gas to provide thrust.