What is the news item mainly about?

NASA astronauts successfully installed a new ammonia pump on the International Space Station Monday during their third spacewalk to make the emergency repairs. The astronauts do not yet know whether their efforts were enough to restore the space station’s cooling system to full capacity.
    It took three spacewalks, totaling more than 22 hours, but astronauts Doug Wheelock and Tracy Caldwell Dyson managed to move the 350-kilogram replacement pump into position. They tightened bolts and made connections so ammonia could flow into the module.
    NASA called the success "a big step in the right direction". The space station’s cooling system has been running at half capacity for more than two weeks. On July 31, an ammonia pump failed. Another module continued to pump coolant through a separate loop, but astronauts had to power down non-essential equipment to prevent overheating.
    The space station’s deputy program manager, Kirk Shireman, said the team did an outstanding job coping with what he called "a major malfunction".