Nora Tallis is sent on a scientific mission on Elaaden to understand what causes the sinkholes. According to her, they could be caused by pockets of brittle calcium carbonate deep below the ground. These pockets break down and collapse causeing a chain reaction all the way to the surface. This could also account for all the sand on the planet.
During her investigation, her shuttle overheated which forced her to land in a sinkhole. Eventually she ran out of water and was forced to trade the thruster of her ship to some scavengers for water. Without the thruster, she is stuck on the planet and the scavengers refuse to trade it back. Pathfinder Ryder may decide to help her to recover her thruster. If Ryder rescues her, she goes back to the Nexus and gives an interview to Heleus News Service to relate her adventure.