What will they use to shoot at and destroy the satellite?
An AEGIS-class cruiser will fire modified SM-3 missiles from a position northwest of Hawaii, as the satellite approaches on a directly overhead path.
What was this satellite doing, and why is it falling?
The satellite was launched 14 months ago to test a new generation of optical and radar reconnaissance sensors, but its control computer failed almost immediately.
What will it look like? Will there be a big spectacle?
After the initial launch, the missile warheads will maneuver by firing steering rocket pulses appearing as sideways flashes from its main body, which will be watched on telescope trackers onboard the launch ship. A flare of light will mark a successful intercept and the bright target blip may turn to a cloud of smaller blips.
Will we be able to see anything from Earth?
As the satellite disintegrates from the impact, the unused rocket fuel should make an expanding cloud in the sky that might be visible from Hawaii, depending on whether or not it is day or night. The cloud may persist for 20-30 minutes as it orbits Earth at 5 miles per second.
What potential dangers or risks are involved?
Planners must make certain that other objects are not in the line of fire, although the rocket's limited altitude capability should keep it well short of valuable spacecraft such as the international space station.
What happens to the debris?
The debris will burn up in days or weeks, because of the target's very low altitude and because small fragments are much more severely slowed down by air drag than large intact objects.
Why can't they just let the satellite fall from orbit naturally?
Pieces from satellites of this size tend to reach the ground, but predicting where is impossible. Heavy objects have a very slight chance of hitting somebody, and unused rocket fuel might conceivably contaminate small areas. Worst of all, top secret hardware such as sensor equipment or the control computer's memory unit might be recovered and be exploited by hostile intelligence services.
Can the United States do this unilaterally?
Yes, there are no legal sanctions on any nation doing anything it wants to its own property in space. In fact, since each nation is responsible for damage caused by any of its space objects, it can be argued that the United States is obligated by international law to do something like this.
Will this action anger any other countries?
The usual suspects, both overseas and domestically. The Russians might feel compelled to dust off their own ground-launched and air-launched anti-satellite weapons or use a standard anti-missile missile from their test rangein Kazakhstan. China can't complain, but North Korea and Iran will. In the United States, groups lobbying against U.S. 'space weaponziation' will see it as proof the United States wants to build — or secretly, already has built — such weapons all along. But all this noise may focus attention on the wider issue of weapons in space (not Earth-launched weapons against space targets).
How is this different from China's satellite shootdown last year?
In technical terms, it's not very different, although the Chinese rocket reached a lot farther into space than the U.S. system is capable of. In ethical terms, the U.S. action is supposedly a remedial measure taken to enhance safety, while the Chinese action looked a lot more like a weapons test to threaten other countries. The U.S. rocket to be used does not appear to be even capable of reaching operational satellites of other nations.