A cosmonaut conducts a previous spacewalk outside Mir. Photo: NASA TV

MirCorp will mark another milestone in space history today when the first commercially financed spacewalk is performed from the Mir station.

The Mir crew will perform an EVA (extravehicular activity) of approximately six hours, carrying out a series of maintenance tasks and experimental work.

This spacewalk is part of a long-duration mission organized by MirCorp, the private company that holds an exclusive lease for commercial activity on the Russian-built and owned Mir station.

Cosmonauts Sergei Zalyotin and Alexander Kalery boarded Mir April 6, reactivating the facility after it had been left uninhabited for eight months. Russia would have been forced to allow Mir to burn up in the Earth's atmosphere earlier this year had MirCorp not provided private financing to maintain it in orbit.

"Today's spacewalk is another demonstration of how a commercial space station should operate," MirCorp President Jeffrey Manber said. "The cosmonauts have done an excellent job reactivating Mir, and they now are adding a new dimension by taking their work into the full void of space."

During the spacewalk, a sealing material will be tested on the station's exterior, and certain scientific equipment will be disassembled. In addition, Mir's core module the oldest element of the space station will be inspected, as will one of the solar arrays on the Kristall module.

The Holland-based MirCorp was formed earlier this year to develop commercial operations on Mir. The company acts as a facilitator, beginning with the establishment of business conditions for Mir's use, and continuing through successful completion of a userís activity on board the station.

MirCorp is 60 percent owned by RSC Energia the manufacturer and operator of Mir while the remaining 40 percent held by its financial investors.

The spacewalk will start at 2:40 p.m. Moscow time and end at approximately 8:30 p.m. Moscow time.