Guinevere One

Guinevere One was a Human-built space probe sent to explore Mars in 2006 in order to look for signs of life. On Christmas Eve 2006, it was intercepted by a Sycorax spaceship and never reached its destination. Among other articles, it contained a sample of A+ blood that Daniel Llewellyn placed on board which the Sycorax exploited, using blood control. (DW: The Christmas Invasion)

Behind the Scenes
Part of the inspiration for Guinevere One came from the failed Real World British probe Beagle 2, which would have landed on Mars in December 2003.

The probe is described as Britain's first mission to Mars, which contradicts the events of The Ambassadors of Death which featured a manned British mission to Mars during the UNIT era, which while still ambiguous as to its exact dating, is still said to have occurred at some point prior to The Christmas Invasion.