Nasa astronauts repair pump in rare spacewalk

Two US astronauts have successfully repaired a critical cooling system pump at the International Space Station, the US space agency Nasa says. Rick Mastracchio and Mike Hopkins completed a spacewalk of 7.5 hours to replace the faulty ammonia pump. via Pocket http://www.bbc.co.uk/news/science-environment-25512534#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa