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. Last Updated: 07/27/2016

Cosmonauts Prepare Mir for Thruster

Two cosmonauts on Mir made their fourth spacewalk this month as they pushed ahead Friday with efforts to install a new thruster engine on the space station.

The three-stage installation process began last Saturday when Talgat Musabayev and Nikolai Budarin detached and abandoned the old engine. Friday's mission involved a series of preparatory steps, and in the final stage, the new thruster will be put in place during a spacewalk Wednesday, officials said.

The engine keeps the Mir's solar panels pointing toward the sun so they can absorb the maximum amount of energy. The old engine, which had been in operation since 1992, ran out of fuel and had to be replaced.

Friday's 6 1/2 hour spacewalk began 15 minutes behind schedule because Budarin experienced some trouble with the radio on his spacesuit, which he managed to fix, and the mission proceeded with no further hitches

The spacewalk was the fourth of five this month, an unusually heavy schedule.