Adelaide Brooke Captain Adelaide Brooke , Ph . D ( 12 May 1999 - 21 November 2059 ) was briefly a companion of the Tenth Doctor . During the Daleks ' attempt to destroy reality , she ended up being orphaned when both of her parents never returned home . She was raised by her grandmother afterwards and , as the years passed , eventually became a mother and grandmother herself . She was commander of Bowie Base One on Mars in the late 2050s . In November 2059 , the base came under attack by a water - based entity called the Flood . This provoked her to give up her life to prevent the viral lifeforms from infecting humanity . It gave her granddaughter Susie Fontana Brooke the desire to be a pioneer of space travel . However , the Doctor interfered with Brooke ' s fate , and she took matters into her own hands to make sure critical events of time would not be cancelled out , through suicide . She was hailed as a hero in the new timeline , still inspiring her granddaughter to continue the Brooke tradition to go into space . Biography . Early life . Adelaide was born in Finchley , North London on 12 May 1999 . She was a child during the Dalek s ' abduction and invasion of Earth in 2009 . Her father told her to stay in the house while he searched for her mother . Neither of her parents were ever seen again . The young Adelaide was spotted by a Dalek , but it deliberately spared her . The event inspired Adelaide to go into space . The Doctor believed the Dalek recognised her as a fixed point in history . ( TV : " The Waters of Mars " ) Colony on Mars . She studied at Cambridge University , and achieved a first honours degree in combined Physics and Mathematics . She transferred to Rice University in 2017 , where she earned her doctorate in Physics . After Rice , she worked at NASA ' s Johnson Space Center in Houston , Texas . Brooke became the first NASA candidate selected who was not a United States citizen . After an intensive , two - year training programme , she served on shuttle missions . Despite her youth and inexperience at NASA , she was selected to head up Project Pit Stop , which used the Moon as a re - fuelling base for planetary exploration . This was highly successful ; exploratory , unmanned shuttles were dispatched to Neptune and Jupiter via the moon . The data they obtained greatly increased humanity ' s knowledge of these planets . According to her obituary , at the age of forty - two ( presumably in 2041 ) , she was a member of a three - person mission to Mars . She was the first woman to land there . Afterwards , she campaigned to have Mars chosen as a location for colonisation . However , the Tenth Doctor claimed the nine people on the Bowie Base One colony in 2058 was made up of the " very first humans on Mars " , including Adelaide . In 2058 , when Adelaide was now a grandmother , she led an international team to Mars , the first human colony on the planet . She found fame on Earth as a result . ( TV : " The Waters of Mars " ) Meeting the Doctor . In 2059 , after seventeen months of success , two of her crew were taken over by the Flood . She tried to contain the infection . After realising this was impossible , she ordered evacuation . Adelaide was suspicious of the newly arrived Tenth Doctor ' s actions and comments . She forced him to tell her the truth : Bowie Base One was going to be destroyed and the crew killed . This was a fixed point in time . He could not save her . Though she struggled to save the colonists , when the Doctor returned to help , she resigned herself to her fate and set the base ' s self - destruct timer . When the Doctor saved Mia Bennett , Yuri Kerenski and her , returning them to Earth in front of Adelaide ' s house , she realised her survival would alter her granddaughter ' s life and human history . She grew angry with the Doctor when he dismissed the problem and referred to her fellow survivors as " little people . " She took her own life to preserve the timeline . ( TV : " The Waters of Mars " ) Legacy . Her granddaughter , Susie Fontana Brooke , was inspired by her memory . She went into space and piloted the first lightspeed ship to Proxima Centauri . Her descendants led humanity throughout space , including to the Dragon Star , the Celestial Belt of the Winter Queen , and the Map of the Watersnake Wormhole s . One of them fell in love with a Tandonian prince and created a new species . Though the Doctor saved three people from Bowie Base One , Adelaide ' s suicide ensured that the timeline was not altered significantly . Her death was the fixed point in time . The only evident change was that history now recorded that she died on Earth rather than on Mars , and that she had committed suicide under " unexplained circumstances " . Mia and Yuri told the world the story of Bowie Base One and hailed her as a hero . This , not the mystery of her death on Mars , was what inspired her granddaughter . ( TV : " The Waters of Mars " ) Personality . Adelaide Brooke was a strict and serious woman who often showed other people a cool demeanour ; she reserved her warmth for her family . Though she cared about her crew , she treated them in a professional manner and demanded decorum and discipline . One of her crew noted that she only gave compliments if the situation was serious . Adelaide was a selfless woman who sacrificed herself to preserve history . Though she knew the Doctor for less than a day , she quickly grew to accept that he was a time traveller even before she travelled in the TARDIS . She was angry with the Doctor when he rescued her , insisting , " The ' Time Lord victorious ' is wrong ! " , and was aghast that he could have changed the history of the entire human race . ( TV : " The Waters of Mars " )