The following information is quoted from Jonathan McDowell's
Space Report No. 591 (draft):

USA 193
-------

The NRO's experimental USA 193 surveillance satellite, which was
reported to be crippled soon after its launch on a Delta II in Dec 2006
into a 351 x 365 km x 58 deg orbit, is approaching reentry. Orbital
data from independent observers show that the satellite's trajectory has
slowly decayed since launch due to friction with the atmosphere; by Jan
22 it was in a 275 x 279 km x 58 deg orbit dropping about 1 km a day,
and the decrease in height will soon accelerate catastrophically. The
satellite is thought to have been intended to test prototype instruments
for future spy satellites, possibly including a radar sensor; it was
reportedly developed by Lockheed Martin (LM-Sunnyvale has experience in
recon satellites, but LM-Denver is involved in the Space Radar area;
both groups could be involved). Reports of 'dangerous material' on board
the satellite may refer to hydrazine orbit adjust propellant; mass
of the spacecraft is probably around 2000 to 3000 kg. It's fairly rare
for satellite payloads of this mass to have an uncontrolled reentry -
only one or two a year - but empty rocket stages as heavy as this come
down about once every three weeks, so the media attention accorded this
particular event seems overenthusiastic to me.

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