Mission to Mars complete the sequence to pass a test, and the crew dispatches a robotic rover to reproduce the completed signal. Following the transmission, an opening appears in the side of the structure, which Jim, Terri, and Luke enter, while Phil remains at the repaired Earth return vehicle with orders to launch, with or without them, at the agreed time. The opening seals behind them, disrupting radio communication with Phil, and a three-dimensional projection of the solar system depicts the planet Mars, covered with water, being struck by a large asteroid and rendered uninhabitable. A recreation of a Martian then reveals that
The Tenth Planet of malevolent cyborgs that became a recurring adversary in later "Doctor Who" stories. The "tenth planet" in the title makes reference to a fictional lost planet in Earth's Solar System; at the time of production, the Solar System was generally held to consist of nine planets, prior to the redesignation of Pluto as a minor planet. "The Tenth Planet" is an incomplete "Doctor Who" serial – one of many serials that were affected by the BBC's policy of wiping archived programmes in the 1960s and 70s. Only three of the four episodes are currently held in the BBC archives; the