Mystery force may be due to mirrors

Portuguese physicists report that they have identified the unknown force whose influence on outward bound interplanetary space probes has puzzled scientists since 1998.

O, Pioneers! (Part 1): The motes in God's eye

March 2012 marks the fortieth anniversary of the launch of one of the most extraordinary spacecraft ever constructed - Pioneer 10 - the first true deep space probe. The story of the Voyager spacecraft is well known but that ...