Moscow lost radio contact with the orbital platform for more than 20 hours from 1840 local time (1540 GMT) on Monday
Mir flight director Vladimir Solovyev said the sudden loss of battery power on the station had yet to be fully explained. He said that when the problem was discovered, controllers on the ground shut down non-essential systems to allow the station's solar-powered batteries to recharge.
A link was then re-established shortly after 1600 on Tuesday.
The unprecedented blackout has raised the concern that the accident-prone craft could spin dangerously out of control before the Russians have a chance to bring it down safely at the end of February as planned.
Controlled descent
Regular radio communication is essential to maintain the platform's position. Mission control usually makes contact with Mir once or twice a day. For much of Tuesday, it was doing so every 90 minutes without success.
Russian officials have been working hard to play down the possibility that this procedure may go wrong.
"There is no risk that the station will fall to Earth," spokeswoman Vera Medvedkova stressed. "It is orbiting 315 kilometres (200 miles) above the Earth, and can remain there until March 15, 2001." After this date, Mir will run out of fuel.
International station
Russian officials said that even if contact was permanently lost with Mir, the station would take three months to crash to Earth because of its current altitude.
But they admit that large chunks of the 140-tonne station could survive re-entry into the Earth's atmosphere, and some of these pieces could weigh up to 700kg (1,540lbs).
Moscow has a two-man team on standby, ready to go up to Mir if it is deemed necessary to carry out an early inspection. This is the same crew that will fly on the planned February mission to prepare the craft for ditching.
The decision to scrap Mir was taken because Moscow wants to concentrate its resources on the new International Space Station (ISS). This 16-nation project has been subjected to repeated delays because of funding problems with Russian modules. Mir's last crew returned to earth in July.