Warp ellipse

A warp ellipse was a temporal and space-based hazard that could capture and disrupt the flight of spacecraft and time travel vessels. It could lock craft in a perpetual orbit in time and space. (DW: Mawdryn Undead)

Mawdryn's spacecraft entered a warp ellipse 3000 years prior to the 20th century, the ship however was close enough to Earth to enable its transmat system to function enabling them to set up a transmat relay system on Earth. (DW: Mawdryn Undead)