Jupiter to several seconds, and short bursts (or S-bursts) that had a duration of less than a hundredth of a second. Scientists discovered that there were three forms of radio signals transmitted from Jupiter. Since 1973 a number of automated spacecraft have visited Jupiter, most notably the "Pioneer 10" space probe, the first spacecraft to get close enough to Jupiter to send back revelations about the properties and phenomena of the Solar System's largest planet. Flights to other planets within the Solar System are accomplished at a cost in energy, which is described by the net change in velocity of the
The Tenth Planet last episode remains missing, although several short clips, including the regeneration sequence, have been discovered intact. In 2013, "The Tenth Planet" was released on DVD with a full-length animated reconstruction of its missing footage. The Doctor and his companions Ben and Polly arrive in the TARDIS at the South Pole in the year 1986. Nearby they find the Snowcap Base, a space tracking station commanded by General Cutler. The base is supervising the mission of the "Zeus IV" spaceship, running a routine probe on the Earth's atmosphere. The spaceship is drawn off-course by an unknown force, and Snowcap monitoring staff