To reconstruct the meteor's original orbit around the Sun, they used six different properties of its trajectory through Earth's atmosphere.

BBC: Russia meteor's origin tracked down

The control unit ends up in a lower orbit, but it can then use solar power and the electrodynamic properties of the tether to return to its original orbit.

ECONOMIST: Spaceflight on a shoestring | The

Russian efforts to keep Mir in orbit past an original retirement date of June have irritated the United States, which has pressed Moscow to focus its meager resources on the International Space Station.

CNN: Space crew reaches Mir for possibly last mission

Lockheed Martin's original SBIRS contract includes HEO payloads, two geosynchronous orbit (GEO) satellites, as well as ground-based assets to receive and process the infrared data.

ENGADGET: First piece of SBIRS missile defense system launched, not shot down