astroengine writes "After the discovery of an ammonia coolant leak supplying one of the solar arrays on Thursday (video), International Space Station managers have decided to plan for an unscheduled spacewalk on Saturday to repair the problem. The final decision about whether to go ahead with the extravehicular activity will be made late on Friday. 'Good Morning, Earth! Big change in plans, spacewalk tomorrow, Chris Cassidy and Tom Marshburn are getting suits and airlock ready. Cool!', tweeted the Space Station's Expedition 35 Commander, Chris Hadfield, on hearing the news an emergency EVA may be required of his crew. 'The whole team is ticking like clockwork, readying for tomorrow. I am so proud to be Commander of this crew. Such great, capable, fun people.'"