Originally written as a Christmas special entitled "Red Christmas", starring Helen Mirren as Adelaide, the episode according to head writer and executive producer Russell T Davies, the special is closely linked to the next two episodes but is not the first part of a three-part story.
"The Waters of Mars" was first broadcast on a Sunday, the only non-Christmas episode of the revived series to air outside the usual Saturday evening slot, until "The Woman Who Fell to Earth", in 2018.
As they interrogate him, he discovers that 21 November 2059 is a "fixed point" in time; the base will inevitably explode, killing the entire crew, but Adelaide's death will inspire her granddaughter to explore space.
Having intervened to avert Adelaide's death, which was supposed to be inevitable, the Doctor declares that he now has the power to change the future of the human race and that nobody can stop him.
Adelaide deems his actions morally wrong, particularly as they may cause her granddaughter's exploration of space to never occur, and steps into her home.
The Doctor enters the TARDIS and defiantly answers his own question with "no" before starting the engines, hoping to escape his fate.
[13] Producer Nikki Wilson described Captain Adelaide Brooke, played by actress Lindsay Duncan, as "the Doctor's cleverest and most strong-minded companion yet.
"[8] David Tennant said, "Well, she's not really a companion like the others have been... She's very wary of the Doctor; she's not the sort of person you could imagine hooking up with him and riding off into the sunset... she's kind of the alpha male in the room, really.
[24] More accurate, consolidated statistics from the BARB state that official ratings ended up at 10.32 million viewers for the UK premiere and that "The Waters of Mars" was the fifth most watched programme of the week.
[26] Though Robert Colvile of The Daily Telegraph criticised "the glaring inconsistencies" between this episode and the Doctor's previous frequent historical interventions, he complimented the scenario for "allow[ing] us to watch Tennant wrestle with his conscience and curiosity ... [in what] was a logical progression for the character".
Like Wollaston, Colvile was "not sure what the children will have made of it, but it set things up intriguingly for Tennant’s final two-part adventure".