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Decaying spy satellite USA 193

USA-193 has now been hit by a missile fired from a US warship near Hawaii. The debris from the satellite will re-enter the atmosphere over the coming weeks. It is not yet known whether the hydrazine fuel tank was ruptured by the missile, which was the primary purpose of the firing.

Launch

USA 193 was launched on December 14th, 2006 from Vandenberg Air Force Base in California. The launch vehicle was a Delta II. Shortly after reaching orbit, ground controllers lost the ability to control the satellite, and have never regained it.

Purpose

The exact design and purpose of USA 193 are, or course, closely guarded secrets, but specialists believe it is probably a high resolution radar satellite which was intended to produce images for the National Reconnaissance Office (NRO).

When and where will it hit the Earth ?

Now that the satellite has been broken up by the missile collision, the debris will come down over wide area over the coming weeks as they are slowed by atmospheric friction. Re-entry will happen when the pieces reach about 100km. The plot below shows the decay of USA-193 before it was hit by the missile.

USA 193 orbital height in km

What are the risks ?

The risk to people on the ground was extremely low, and since the missile hit broke up the satellite into many smaller pieces, the risk should be even lower. The Earth is large and two-thirds of it is covered by ocean. Most of the satellite will burn up in the upper atmosphere, but a few large pieces are expected to survive the re-entry and fall to Earth. It would be very unlikely for any of them to hit someone. The main hazard was the hydrazine fuel which is very toxic, and hopefully the tank has been ruptured by the missile and the hydrazine been dipersed into space. This was the main reason given by the US government for the missile strike.

Where are the pieces of USA 193 now ?

You can see the current position of USA-193 would have been in the ground track below. The missile strike created many pieces of debris, but they should be centred roughly on the position below, although dispersing more and more as time goes by.

USA-193 Ground Track

Can I see it before re-entry?

The following links show the predictions for USA-193, assuming it was not hit by the missile, the first link shows just visible passes (ie in the night when the satellite is sunlit) and the second link shows all passes, which could be useful if you wish to try and see a re-entry fireball.

Visible pass predictions for your location

All pass predictions for your location

 

DLR