Kaldor

Kaldor was a desert planet colonised by humans for the many minerals in its sands, among which were zelanite, keefan, and lucanol (which was most prized).

Astronomical data
According to one account, Kaldor was in fact Japetus, one of the moons of Jupiter (PROSE: Legacy). However, most other sources agreed that it was a planet outside of Earth's Solar System. (AUDIO: Occam's Razor, COMIC: Crisis on Kaldor)

Features
The most prominent structure on the planet was Kaldor City, one of three original man-made colonies on the planet, populated by humans with sandminer robot servants that tended to their whims and also helped manage the sandminers themselves. The city itself was surrounded by the Outer Zones, which were inhabited by less wealthy members of the society. (AUDIO: Occam's Razor) There were also several mountains near Kaldor, which Liv Chenka climbed with her father when she was a child. (AUDIO: The Sonomancer)

The sandminers which collected minerals from the deserts needed to keep moving to avoid sinking into the sand, and windstorms constantly swept over the desert. (TV: The Robots of Death)

History
By the 29th century, the Founding Families, descendants of the original terraformers, were well established as the governing body of Kaldor, in charge of the powerful Kaldor City Company. (AUDIO: Occam's Razor) While the people of Kaldor were aware that they were descended from off-world colonists, they purposefully isolated themselves from any contact with other planets for generations, as the Company feared that it might lead to loss of profits. (AUDIO: Occam's Razor). Some of Kaldor's inhabitants did not even know the name of the planet Earth. (AUDIO: Metafiction)

The Fourth Doctor and Leela visited Kaldor in the 29th century, and became involved in a plot by Taren Capel to make the robots kill all humans. (TV: The Robots of Death)

Several years later, the Fendahl tried to invade Kaldor, posing as Taren Capel and using his Tarenist followers. (AUDIO: Checkmate)

Firstmaster Chairholder Kiy Uvanov proposed that Kaldor open up to trade with other human colonies. (AUDIO: Metafiction) Eventually, the people of Kaldor came into contact with other planets and launched spaceships such as The Lorelei to sell robots to other planets, including Ventalis. (AUDIO: Robophobia) By the 39th century, minerals were sent to Io for distribution throughout the Galactic Federation. (PROSE: Legacy)

Behind the scenes

 * In the book Doctor Who: 100 Scariest Monsters, Kaldor is misspelled Caldor.
 * The comic Crisis on Kaldor has the Doctor stating the planet's name to be Kaldor, while the name was previously only thought to be applied to the city.
 * PROSE: Legacy claims that TV: The Robots of Death was set on the moon Japetus, but all other sources indicate that it is located on the planet Kaldor.