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)

Apart from blood the satellite also contained:
 * Whale song
 * Bird song
 * Spoken greetings in 120 languages
 * Music
 * Water
 * Wheat seeds

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.
 * The probe's name is spelled in differing ways by BBC Wales Graphics throughout the episode. On some screens, it appears as "Guinivere One" — much to the chagrin of Russell T Davies and Julie Gardner in the in-vision commentary to The Christmas Invasion on the series 2 DVD boxset.