1986 By 1986 , International Space Command had regular lunar flights and maintained a tracking station in Antarctica . ( TV : " The Tenth Planet " ; PROSE : " Mondas Passing " ) Several companion s of the Doctor were born in 1986 : Rose Tyler , being roughly 19 years old at the start of her travels with the Ninth Doctor ( TV : " The Unquiet Dead " , " Dalek " , " Army of Ghosts " ) on 5 March 2005 , ( TV : " Aliens of London " ) Martha Jones , ( PROSE : " Wooden Heart " , " The Story of Martha " ) and Clara Oswald . ( TV : " Death in Heaven " ) While in a bubble prison , Iris Wildthyme imagined singing a duet with Elton John at Freddie Mercury ' s 40th birthday party in 1986 . ( AUDIO : " Whatever Happened to Iris Wildthyme ? " ) Dated events . Prior to December . On 28 January , the space shuttle " Challenger " exploded . ( PROSE : " Return of the Living Dad " , " Father Time " ) On 26 April , the nuclear power plant in Chernobyl in the Soviet Union went into meltdown . ( COMIC : " Black Destiny " ; AUDIO : " Power Play " ) 40 , 000 people died of cancer as a result of the disaster . ( PROSE : " Iceberg " ) In September , Edward Grainger was invited to a dinner with three of his former British Intelligence colleagues . ( PROSE : " Old Boys " ) On 23 November , Clara Oswald was born . ( TV : " Death in Heaven " ) December . In December , human s first detected the planet Mondas returning to the solar system . It apparently was in orbit between Mars and Venus . The manned atmospheric probe Zeus IV was destroyed by the planet ' s Cyberman inhabitants and they launched an attack on Earth , starting with the Snowcap base in Antarctica . They planned to use a Z - bomb located there to destroy Earth as one of the two worlds needed to be destroyed to save the other . When they failed , Mondas was destroyed instead . Present for these events was the First Doctor and while the Cybermen were defeated , the strain of the conflict led to his subsequent regeneration from his first incarnation into his second . ( TV : " The Tenth Planet " ) Refusing to regenerate , the Twelfth Doctor ' s TARDIS took him to the South Pole where he encountered the First Doctor as he himself was hesitating to change . ( TV : " The Doctor Falls " ) This caused a timeline error which resulted in World War I combatant Archibald Hamish Lethbridge - Stewart being deposited at that time before the two Doctors , causing a glass avatar of the Testimony to pursue him . After saving Lethbridge - Stewart ' s life , the two Doctors parted ways with the First Doctor returning to meet his fate at the South Pole while the Twelfth Doctor faced his own regeneration . ( TV : " Twice Upon a Time " ) Professor Allison Williams led the scientific team which investigated the Cyberman ship in Antarctica . ( PROSE : " The Power of the Daleks " ) Twenty years after they helped the First Doctor prevent the return of Mondas in the then - future year of 1986 in their personal timelines , Ben Jackson and Polly Wright — who had gone their separate ways in life following a brief relationship after their return to Earth on 20 July 1966 — reunited on New Year ' s Eve in 1986 , which was by then their present . Ben believed that numerous governments may have covered up the return of Mondas and the Cybermen invasion of the Snowcap . ( PROSE : " Mondas Passing " ) Undated events . Toshiko Sato ' s family moved back to the UK from Japan this year . ( TV : " Greeks Bearing Gifts " ) James Stevens ' former father - in - law Lord Howarth died this year . His ex - wife Natasha allowed him to see his son Will . ( PROSE : " Who Killed Kennedy " )